Title: Ecology of the south Florida coral reefs: a community profile
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FWS/OBS 82/08
MMS 84-0038
August 1984


THE ECOLOGY OF THE SOUTH FLORIDA CORAL REEFS:
A COMMUNITY PROFILE



by

Walter C. Jaap
Florida Department of Natural Resources
Marine Research Laboratory
St. Petersburg, Florida 33701


Project Officer

J. Kenneth Adams
Minerals Management Service
Gulf of Mexico OCS Region
Post Office Box 7944
Metairie, Louisiana 70010



Prepared for

National Coastal Ecosystems Team
Division of Biological Services
Research and Development
Fish and Wildlife Service
U.S. Department of the Interior
Washington, D.C. 20240

and

Gulf of Mexico OCS Regional Office
Minerals Management Service
U.S. Department of the Interior
Metairie, Louisiana 70010




DISCLAIMER


The opinions, findings, conclusions, or recommendations expressed in this report are those of the authors
and do not necessarily reflect the views of the U.S. Fish and Wildlife Service or the Minerals Management Service
unless so designated by other authorized documents.
This contractual report was edited to the standards of the Division of Biological Services and does not
conform entirely to the technical editing guidelines of the Minerals Management Service.



















































Library of Congress Card Number 83-600549.

This report should be cited as follows:

Jaap, W.C. 1984. The ecology of the south Florida coral reefs: a community profile. U.S. Fish WildL Serv.
FWS/OBS 82/08. 138 pp.







PREFACE


This profile of the coral reef community of south Florida is one in a series of community profiles that
treat coastal and marine habitats important to humans. Coral reefs are highly productive habitats which provide
living space and protection from predation for large populations of invertebrates and fishes, many of which have
commercial value. Coral reefs also provide an important economic benefit by attracting tourists to south Florida.
The information in the report can give a basic understanding of the coral reef community and its role
in the regional ecosystem of south Florida. The primary geographic area covered lies seaward of the coast from
Miami south and west to the Dry Tortugas. References are provided for those seeking indepth treatment of a
specific facet of coral reef ecology. The format, style, and level of presentation make this synthesis report adapt-
able to a variety of needs such as the preparation of environmental assessment reports, supplementary reading in
marine science courses, and the education of participants in the democratic process of natural resource manage-
ment.
Comments on or requests for this report should be directed to:


Information Transfer Specialist
National Coastal Ecosystems Team
U.S. Fish and Wildlife Service
NASA/Slidell Computer Complex
1010 Gause Boulevard
Slidell, Louisiana 70458
(504) 255-6511


Records Management Section (OPS-4)
Gulf of Mexico OCS Region
Minerals Management Service
Post Office Box 7944
Metairie, Louisiana 70010
(504) 8374720 ext. 2519






CONTENTS

Page

DISCLAIMER ii

PREFACE ii

TABLES vi

FIGURES vii

COLOR PLATES viii

ABBREVIATIONS x

CONVERSION FACTORS xi

ACKNOWLEDGMENTS xii

CHAPTER 1. CHARACTERIZATION OF THE RESOURCE. 1

Overview 1
Coral Reef Distribution 1
(1.3) Community Distribution 3
1.4 Historical Resume' of Florida Coral Reef Research 3
1.5 Economic Significance 4

CHAPTER 2. THE ENVIRONMENT 7

2.1 Climate 7
2.2 Hurricanes 7
2.3 Solar Radiation 8
2.4 Seawater Temperature 8
2.5 Tides 11
2.6 Salinity 11
2.7 Dissolved Oxygen 11
2.8 Turbidity 11
2<)9 Currents 12
2.10 Geological Setting 12
2.11 Geologic History and Processes 12

CHAPTER 3. CORAL REEF COMMUNITY TYPES 17

3.1 Introduction 17
3.2 Live Bottom Community 17
3.3 Patch Reef Community 17
S3.4 Transitional Reef Community 20
3.5 Major Bank Reef Communities 24

CHAPTER 4. CORAL REEF BENTHOS 34

4.1 Introduction 34
4. 2 Algae by Harold Humm 34
(( Sponges by G. P. Schmahl 37
4.4 Cnidaria 40
4.5 Other Benthic Groups 48







CHAPTER 5. PLANKTON by J. O. Roger Johansson 49

\(P Introduction 49
5.2 Taxonomic Composition and Spatial Distribution 49
Diurnal Migrations 50
34) Summary 50

CHAPTER 6. REEF FISH by James T. Tilmant 52

6.1 Reproduction and Recruitment 52
6.2 Food Habits and Trophic Structure 53
6.3 Movement 54
6.4 Social Organization 55
6.5 Ecological Aspects of Reef Fish Diversity 55
6.6 Community Descriptions 56
6.7 Reef Fish Management 62

CHAPTER 7. CORAL REEF ECOLOGY 64

7.1 Introduction 64
7.2 Physical-Chemical Environment 64
7.3 Community Structure 65
7.4 Diversity 65
7.5 Symbiosis 68
7.6 Predator-Prey Relations 71
7.7 Productivity 71
7.8 Coral Reef Models 72
7.9 Natural Impacts 74

CHAPTER 8. MANAGEMENT 76

8.1 Human Impacts 76
8.2 Coral Reef Resource Management 81
8.3 Management and Mitigation Recommendations 82

COLOR PLATES 84

LITERATURE CITED 115






TABLES

Page

1 Commercial landings of reef-related species in Monroe County, 1980 (NMFS 1981) 5
2 Monthly air temperatures (oC) for Miami and Key West (NOAA 1981) 7
3 Monthly precipitation (mm) for Miami and Key West (NOAA 1981) 7
4 Monthly wind speed (km/hr) and direction for Miami and Key West (NOAA 1981) 8
5 Major hurricanes crossing the coral reefs from 1873 to 1966 (Sugg et al. 1970) 9
6 Reef seawater temperatures (oC) (Vaughan 1918) 9
7 Bottom (3 m) seawater temperature (C) at Elkhorn Control Reef, Biscayne
National Park, 1978 (from daily thermograph data, Biscayne National Park) 10
8 Tidal ranges for several southeast Florida reefs (NOAA 1981) 11
9 Salinities in the Florida reef tract and vicinity 12
10 Age and growth rate of Recent Florida reefs (Shinn et al. 1977; Shinn 1980) 15
11 Live bottom corals from Schooner Reef, Biscayne National Park (four 1-m2
quadrants; Jaap and Wheaton 1977 MS) 19
12a Octocorals at Dome Reef (two 20-m transects, 1977; Wheaton, in preparation a) 21
12b Octocorals at Dome Control Reef (two 20-m transects, 1977; Wheaton in preparation a) 21
13a Stony corals at Dome Reef (two 25-m transects, 1977; Jaap, unpublished) 22
13b Stony corals at Dome Control Reef (two 25-m transects; Jaap, unpublished) 22
14 Attributes of stony coral associations, Biscayne National Park, based on several
line transects at each reef (8 reefs, 18 transects) (Jaap, unpublished) 23
15a Elkhorn Reef stony coral fauna (four 4-m2 plots sampled per reef, 1978; Jaap,
unpublished) 25
15b Elkhorn Control Reef stony coral fauna (four 4-m2 plots sampled per reef, 1978;
Jaap, unpublished) 25
16a Elkhorn Reef octocoral fauna (three 20-m transects, 1977; Wheaton, unpublished b) 26
16b Elkhorn Control Reef octocoral fauna (three 20-m transects, 1977; Wheaton,
unpublished b) 26
17 Ajax Reef stony coral fauna at 17 m (fifteen 1-m2 plots; Jaap, unpublished) 27
) Bank reef zonation patterns 28
19 Carysfort Reef stony coral fauna at 14-15 m (ten 1-m2 plots; Jaap, unpublished) 29
20 French Reef stony coral fauna at 6 m (twenty-seven 1-m2 plots; Jaap, unpublished) 30
21 Grecian Rocks zonation pattern (Shinn 1963, 1980) 30
22 Molasses Reef stony coral fauna at 5-6 m (twenty-five 1-m2 plots; Jaap, unpublished) 31
23 Looe Key Reef stony coral fauna at 1-27 m (fifteen 1-m2 plots; Jaap, unpublished), 32
24 Classification of major reef benthic Cnidaria 40
25 Octocoral fauna in shallow (<30 m) southeast Florida reef communities
(Bayer 1961; Opresko 1973; Wheaton 1981, in preparation b) 42
26 Southeast Florida reef Scleractinia 43
27 Growth rates of scleractinian species from Florida and the Bahamas 46
28 Time series for abundance, density, and dispersion of stony corals at Elkhorn
Reef (one 4-m2 plot) (Jaap, unpublished) 47
29 Comparison of the most abundant reef fish families among three Florida coral
reef areas as indicated by Jones and Thompson (1978) visual census methods 57
30 Coral reef fishes most commonly observed by divers on reefs 57
31 Recent reef shipwrecks 77






FIGURES

Page

S Tropical coral reef communities off south Florida. 2
Monthly mean air temperature for Key West and Miami (NOAA 1981). Data base is 29
years for Key West; 38, Miami. 7
3 Monthly minimum air temperature for Key West and Miami (NOAA 1981). Data base
is 29 years for Key West; 38, Miami. 7
4 Monthly mean precipitation for Key West and Miami (NOAA 1981). Data base is 29
years for Key West; 38, Miami. 8
5 Monthly mean wind velocity for Key West and Miami (NOAA 1981). Data base is 29
years for Key West; 38, Miami. 8
6 Monthly minimum, mean, and maximum seawater temperature at Fowey Rocks,
1879-1912 (Vaughan 1918). 10
7 Monthly minimum, mean, and maximum seawater temperature at Carysfort Reef,
1878-1899 (Vaughan 1918). 10
8 Monthly minimum, mean, and maximum seawater temperature at Sand Key, 1878-1890
(Vaughan 1918). 10
9 Monthly minimum, mean, and maximum seawater temperature at Dry Tortugas,
1879-1907 (Vaughan 1918). 10
10 Minimum monthly seawater temperature at Carysfort Reef, Dry Tortugas, and Fowey Rocks. 10
11 Monthly minimum, mean, and maximum seawater temperature (3m) at Elkhom Control
Reef, Biscayne National Park, 1978 (from thermograph data, Biscayne National Park). 11
12 Components of the Gulf Stream System (Maul 1976). 13
13 Sea-level change during the Holocene Period (Ginsberg, Comparative Sedimentology
Laboratory, University of Miami, Florida). 14
14 Sea-level change in a Bahamian shelf reef system during the last 10,600 years (Hine
and Neuman 1977). 15
15 Calcium carbonate flow model based on a Barbados fringing reef (Stearn et al. 1977). 16
16 Coral reefs in Biscayne National Park. 18
John Pennekamp Coral Reef State Park and Key Largo National Marine Sanctuary. 27
Cross-sectional diagram of Looe Key Reef. 28
19 Cross-sectional diagram of Bird Key Reef. 33
20 Classification of Bird Key Reef and Dry Tortugas based on abundance of stony corals
using group average sorting and Czekanowski's coefficient. 67
21 Similarity of coral fauna on Florida reefs using group average sorting and Czekanowski's
coefficient. 68
22 Electron micrograph of Agaricia fragilis zooxanthella, 6,590 magnification. 69
23 Electron micrograph of Agaricia fragilis zooxanthella, 14,660 magnification. 70
24 Time series of a 2x2 meter area of Elkhorn Reef, 1978. 72
25 Time series of a 2x2 meter area of Elkhorn Reef, 1979. 72
26 Time series of a 2x2 meter area of Elkhorn Reef, 1980. 72
27 Time series of a 2x2 meter area of Elkhorn Reef, 1981. 72






COLOR PLATES

Page

la Satellite photograph of southeast Florida. Note large passes between islands in
the middle Keys. Florida Bay lies between the mainland and the Keys. 84
lb French Reef off Key Largo. Waves breaking on the reef flat; dive boats anchored
on the deeper spur and groove zone. 84
2a Looe Key National Marine Sanctuary viewed from seaward to landward. The
western area has deep reef development. Photo: Bill Becker, Newfound Harbor
Marine Institute. 85
2b Looe Key spur and groove zone, boats are between 20 and 30 ft long. White area
(mid left of photograph) is where the M/V Lola was aground. Photo: Bill
Becker, Newfound Harbor Marine Institute. 85
3a Grecian Rocks Reef, Key Largo National Marine Sanctuary. The dense cover
of coral is mostly Acropora spp. (brown color). 86
3b Fire coral Millepora complanata Middle Sambo Reef. 86
4a Octocoral Pseudopterogorgia acerosa hardgrounds off Soldier Key. 87
4b Staghorn coral (Acropora cervicornis) Eastern Sambo Reef. 87
5a Elkhorn or moosehorn coral (Acropora palmata) (heavy blades) and fused
staghorn coral (A. prolifera) (right). 88
5b Star coral Montastraea annularis at Elkhorn Reef, Biscayne National Park. 88
6a Brain coral Diploria strigosa on Elkhorn Reef. 89
6b Large star coral Montastraea cavernosa. 89
7a Pillar coral (Dendrogyra cylindrus) off Key Largo. 90
7b Coral polyp, central mouth, ring of tentacles; small knobs on the tentacles are
the nematocysts, color from algal symbionts, zooxanthellae. 90
8a Acropora palmata ovary with an unfertilized egg. 91
8b Closeup photograph of the brain coral Colpophyllia natans with two feather
duster worms (Spirobranchus giganteus) at French Reef. 91
9a Stony coral skeleton of Scolymia lacera, Florida Middle Ground. 92
9b Large tub sponge Xestospongia muta. 92
10a A large colony of elkhorn coral (Acropora palmata) turned over during a winter
storm at Elkhorn Reef. New branches are developing from the former base area. 93
10b Vegetative recruitment from branch fragments of Acropora palmata. 93
1 la Patch reefs, aerial view, John Pennekamp Coral Reef State Park; halos surround the reef. 94
1 lb Patch reef, aerial closeup, John Pennekamp Coral Reef State Park. 94
12a Small patch reef, Montastraea and Diploria spp. 95
12b Seagrass Thalassia testudinum, adjacent to patch reefs. 95
13a Patch reef community; note the many juvenile fish. 96
13b A Siderastrea siderea star coral with protruding sponge ostia, octocorals, and
a young Haemulon sp. 96
14a Bank reef, reef flat zone, barren except for encrusting algae. 97
14b Bank reef, shallow spur and groove zone; fire corals and Palythoa are the
conspicuous organisms. 97
15a Bank reef, shallow spur and groove zone; fire coral and juvenile bluehead wrasse
(Thalassoma bifasciatum). 98
15b Bank reef, deep spur and groove zone, elkhorn coral (Acropora palmata). 98
16a Deep spur and groove zone, elkhorn coral (Acropora palmata) with resident
schoolmaster snapper (Lutjanus apodus). 99
16b Bank reef, forereef zone. 99
17a Bank reef, forereef zone; note extreme competition for space. 100
17b Bank reef, deep reef zone, platy lettuce coral (Agaricia lamarcki), French
Reef, Key Largo National Marine Sanctuary. 100
18a Censusing coral at Elkhorn Reef, Biscayne National Park. 101
18b Fireworm (Hermodice carunculata), a coral-eating marine worm seen here
feeding on staghorn coral (Acropora cervicornis). 101
19a Diploria strigosa infected by black ring disease caused by the blue-green algae
Oscillitoria on Hens and Chickens Reef. 102
19b Spiny lobster (Panulirus argus), patch reef off Key Largo. 102






20a Grecian Rocks, Key Largo National Marine Sanctuary; elkhorn coral with
schools of sergeant major fish (Abudefdufsaxatilis). 103
20b Schools of fish at an unnamed reef off Islamorada. 103
21a Southern stingray (Dasyatis americana) near the Benwood wreck, Key Largo
National Marine Sanctuary. 104
21b Longjaw squirrelfish (Holocentrus ascensionis), Molasses Reef, Key Largo National
Marine Sanctuary. 104
22a Porkfish (Anisotremus virginicus) and yellow goatfish (Mulloidichthys martinicus),
Molasses Reef, Key Largo National Marine Sanctuary. 105
22b Gray angelfish (Pomacanthus arcuatus), Eastern Sambo Reef. 105
23a French angelfish (Pomacanthus paru), unnamed reef off Islamorada. 106
23b Nassau grouper (Epinephelus striatus), Sand Key Reef. 106
24a Glassy sweeper (Pempheris schomburgki), French Reef, Key Largo National
Marine Sanctuary. 107
24b Fire coral, Millepora complanata, following heat stress; zooxanthellae expulsion
caused bleached appearance. 107
25a Unknown pathogenic condition (white) in Acropora palmata. 108
25b Mobidity-mortality in Diploria strigosa caused by fish-collecting poison (rotenone
and organic carrier). 108
26a Shipwrecked Captain Alien on Middle Sambo Reef, 1973. 109
26b Motor Vessel Lola and salvage barge on Looe Key Reef, 1976. 109
27a Discarded steel from the Lola in the spur and groove tract. 110
27b Anchor on coral. 110
28a Boats tied up to anchor buoys at Molasses Reef, Key Largo National Marine Sanctuary. 111
28b Eyebolt securing anchor buoys to the reef platform at French Reef, Key Largo
National Marine Sanctuary. 111
29a Scars on elkhorn coral (Acropora palmata) caused by a boat propeller, Elkhorn Reef,
Biscayne National Park. 112
29b Fish trap without a buoy line (ghost trap) on unnamed reef off Islamorada. 112
30a Steel junk from Carysfort lighthouse on the reef flat. 113
30b Accumulated batteries from Carysfort lighthouse on the reef flat. Batteries are
used in the lighthouse operation. 113
31a Lobster trap buoy line tangled in elkhorn coral (Acropora palmata) at Sand Key
Reef, September 1983. 114
31b Zooxanthellae expulsion, Eastern Sambo Reef, August-September 1983. 114






ABBREVIATIONS


BNP
CG
DER
DNR
DOA
DOS
EPA
FWS
GS
JPCRSP
KLNMS


LKNMS
MMS
NMFS
NOAA
NPS
PHC
Std. Dev. or SD
USACE
YBP


Biscayne National Park
(U.S.) Coast Guard
Department of Environmental Regulation (Florida)
Department of Natural Resources (Florida)
Department of Administration (Florida)
Department of State (Florida)
(U.S.) Environmental Protection Agency
(U.S.) Fish and Wildlife Service
(U.S.) Geological Survey
John Pennekamp Coral Reef State Park
Key Largo National Marine Sanctuary (originally
referred to as Key Largo Coral Reef Marine Sanctuary
in early General Management Plan developed by NOAA)
Looe Key National Marine Sanctuary
Minerals Management Service
National Marine Fisheries Service
National Oceanic and Agniospheric Administration
National Park Service
Petroleum hydrocarbons
Standard deviation
U.S. Army Corps of Engineers
Years Before Present






CONVERSION FACTORS



Metric to U.S. Customary


Multiply

millimeters (mm)
centimeters (cm)
meters
kilometers (km)

square meters (m2)
square kilometers (km2)
hectares (ha)


liters (1)
cubic meters (m3)
cubic meters (m3)

milligrams (mg)
grams (g)
kilograms (kg)
metric tons (mt)
metric tons (mt)
kilocalories (kcal)

Celsius degrees


To Obtain


0.03937
0.3937
3.281
0.6214

10.76
0.3861
2.471


0.2642
35.31
0.0008110

0.00003527
0.03527
2.205
2,205.0
1.102
3.968


1.8(Co) + 32


inches
inches
feet
miles

square feet
square miles
acres

gallons
cubic feet
acre-feet

ounces
ounces
pounds
pounds
short tons
BTU


Fahrenheit degrees


U.S. Customary to Metric


inches
inches
feet (ft)
fathoms
miles (mi)
nautical miles (nmi)

square feet (ft2)
square miles (mi2)
acres

gallons (gal)
cubic feet (ft3)
acre-feet

ounces (oz)
pounds (lb)
short tons (ton)
BTU

Fahrenheit degrees


25.40
2.54
0.3048
1.829
1.609
1.852

0.0929
2.590
0.4047


3.785
0.02831
1,233.0


28.35
0.4536
0.9072
0.2520


0.5556 (F0- 32)


millimeters
centimeters
meters
meters
kilometers
kilometers


square meters
square kilometers
hectares

liters
cubic meters
cubic meters

grams
kilograms
metric tons
kilocalories

Celsius degrees





ACKNOWLEDGMENTS


Funding for development and publication of this document was jointly sponsored by the Fish and
Wildlife Service and the Minerals Management Service of the U.S. Department of the Interior.
Many people had a direct or indirect influence in the creation of this document. The responsibility for
content and format are those of the principal author (W. Jaap); H. Humm wrote the section on algae; G.
Schmahl, sponges; R. Johansson, plankton; and J. Tilmant, fish. Reviewers included T. Bright, G. Bruger, J.H.
Hudson, J. Bohnsack, G. Huntsman, J. Lang, and J. Wells; these individuals are thanked for their criticisms and
suggestions for improvement. Karilyn Jaap and Alanzo Felder assisted with preliminary typing, organizing the
literature, and editing. The Florida Department of Natural Resources Bureau of Marine Research, St. Petersburg,
aided and contributed in the areas of library resources, unpublished data and graphics, and use of photographic
files. The following individuals are thanked for their assistance: E. Joyce, C. Futch, K. Steidinger, W. Lyons,
D. Camp, J. Wheaton, W. Marovec, E. Truby, M. Krost, and L. Tester. The U.S. National Park Service is also
thanked for the freedom to use field data from the Biscayne National Park coral reef study. The concepts
and foundation for this document are based on experience and most of all the cross flow of information from
a great number of individuals who have studied Florida's coral reefs. The following people directly or indirectly
provided stimulation and information for this document: John Wells, Robert Ginsburg, Eugene Shinn, J.H.
Hudson, Jennifer Wheaton, J. Morgan Wells, David Oleson, Peter Betzer, Lowell Thomas, Norm Blake, Phillip
Dustan, John Halas, Gary Davis, and Yosse Loya.
Ken Adams (formerly with the U.S. Fish and Wildlife Service, now with the Minerals Management
Service) is expressly thanked for his patience and prodding. He saw the need for this report and his efforts have
aided the author in resolving problems and getting the work confleted. Gaye Farris (U.S. Fish and Wildlife
Service editor) was responsible for the final editing which greatly improved the coherence and readability of this
report. Betty Brody performed the Herculean effort of proofreading.
We thank the Minerals Management Service, Gulf of Mexico Regional Office, for printing this docu-
ment with color plates which increase the scientific usefulness of the report. Larry Handley, Carla Langley,
Debbie Miller, Ruth Monical, Cynthia Nicholson, Patricia Thaggard, Cathy Cartwright, Marilyn Parker, and
Mimi Griffitt of that office contributed yeoman efforts to the completion of this publication.
This publication is dedicated to all who seek the truth, especially Taylor Alexander; lost friends Lin
Brown and Frank Wescott; and especially Karilyn.







CHAPTER 1


CHARACTERIZATION OF THE RESOURCE


1.1 OVERVIEW

Coral reefs are highly complex and diverse
communities of biota, a phenomenon of the tropics
and subtropics limited by such factors as suitable sub-
stratum, temperature, light, and. sedimentation.. In
simplest terms coral reefs are concentrated complexes
of corals and other organisms that construct a limestone
structure in shallow water.In the initial building process,
a set of primary framework builders set down the first
structure; later colonizers add to the volume. Skeletal
breakdown by physical and biological actions creates
carbonate sediments, which are recycled by other biolog-
ical processes or are cemented to the reef framework
through biological or geochemical processes.
The coral reef complex found off southeast
Florida represents a mosaic that exhibits extreme
variability in all parameters used to evaluate biological
communities. Coral reefs provide a wide spectrum of
vocational and recreational activities. Many important
fisheries are directly tied to these reef communities;
a reef's principal resource value (economically) is as a
highly productive habitat: it concentrates marine protein
in a localized area. Coral reefs also play a significant
role in the tourist industry of southeast Florida.
While the level of reef usage is increasing as
southeast Florida experiences rapid population growth,
management of these reef communities tends to lag or
is unresponsive to the problems described herein.
Scientific and lay literature has reported real
and potential threats to southeast Florida coral reefs
(Straughn 1972; Voss 1973; Davis 1977a; Dustan
1977b; Bright et al. 1981). Impacts have included vessel
groundings and sinkings, oil spills, anchor damage, beach
renourishment dredging, fishery activities (lobster trap
recovery), tropical fish and invertebrate collecting,
shipwreck salvage, and diving-related activities. Individ-
ually __these acts do_ not greatly affect the resource
vitality, but the chronic and synergistic nature of some
of these acts is cause for concern.
The goal of this document is to serve as a refer-
ence for those interested and concerned individuals
responsible for environmental management of the
resource, as well as those seeking a better understanding
of Florida's coral reefs.

1.2 CORAL REEF DISTRIBUTION

Although the tropical coral reef communities
found off southeast Florida (Figure 1) are the emphasis
of this report, a brief summary of coral reef distributions
throughout Florida will aid in understanding this re-
source. From the Georgia border to near Fort Pierce on
the Atlantic coast, in depths of 15-50 m, Oculina (pret-
zel coral) bank communities are the dominant coral
community (Avent et al. 1977; Reed 1980). These are


low-diversity coral assemblages, but important fishery
habitat. Grouper find refuge, feed, and breed in and near
these structures. From Stuart (St. Lucie Inlet) to near
Palm Beach is a transitional community of Oculina bank
flora and fauna and hardier elements of the tropical reef
biota. This region is characterized by the convergence of
the temperate and subtropical climate zones. From Palm
Beach southward to Miami (Cape Florida) elements of
the tropical coral reef biota become increasingly impor-
tant in a north-to-south gradient; however, the building
of three-dimensional reef structures does not occur. This
area is characterized as an octocoral-dominated hard-
ground community (Goldberg 1973a). The two stony
corals most responsible for reef building (Acropora
palmata, elkhorn coral, and Montastraea annularis, star
coral) rarely occur here, and currently do not actively
build reefs. Acropora palmata was once an important
reef builder in this area, but it ceased building reefs
about 4,000 years before present (YBP) (Lighty 1977;
Lighty et al. 1978). Today only a few isolated colonies
are found nortl of Fort Lauderdale.

The region of maximum coral reef dAeveloment
is restricted to south and west of.Cape Florida4offshre
of the Florida Keys archipelago (Figure 1). This small
chain of islands extending from Soldier Key to Dry
Tortugas exhibits a diverse pattern of hardgrounds,
patch reefs, and bank reefs from 25 m to 13 km.-off-
shore. This is the only shallow water (< 10 m) tropical
coral reef ecosystemfoundon the Continental Shelf of
North America, and has been referred to as "The Florida
Reef Tract" (Vaughan 1914a). This discontinuous
assemblage of reefs forms an arc paralleling the Keys'
coastline in a general southwesterly trend. Landward,
the reefs are bounded by the Keys and a series of shal-
low embayments (Biscayne Bay, Card and Barnes
Sounds, and Florida Bay); seaward of the reefs are the
Straits of Florida and the Florida Current. The Florida
Curet subsystem of the Gulf Strea plans an
important role in the existence and maintenance of coral
reefs off southeast Florida. It modifies the environment
by moderating winter temperatures. The current's source
is tropical; hence, its _waters are significantly warmer
than resident shelf water masses. .duringthe. winter,
thereby modifying winter thermal conditions such that
offshore reef development is not hindered by extremely
cold weather that occasionally occurs when cold fronts
intrude into southeast Florida. Inshore patch reefs
however, are more vulnerable tpo cold extremes-csaused
by winter weather The current system is dynamic, and
eddies or meanders bring considerable volumes of water
into the reef environment. This brings plankton, a food
source, and new recruitment from nonresident popula-
tions to the reefs. The significace ofthe_ lorida Cur-
rent cannot be overestimated when considering coral
reef existence off southeast Florida.














,COLLIER COUNTY


MONROE COUNTY


'' \



S4~L,


DADE COUNTY


FOWEY
ROCKS


HOMESTEAD


KEY LARGO


SCALE OF MILES


CORAL REEF
STATE PARK
ALLIGATOR
REEF oC


MARQUESAS


Figure 1. Tropical coral reef communities off south Florida.


GULF OF
MEXICO


0 5 10


20 30


mmm 1 -





The Keys or islands act as barriers to cross shelf
water transport from shalloweLrbays and sounds. These
bays are very shallow hence much influenced by mete-
orological events. Temperature, salinity, and turbidity
can be significantly affected, Heavy rainfall,_Adrought,
and winter cold fronts are the major influences. Coral
reef distribution patterns reflect the extent of water
exchange between the bays and sounds and the Atlantic.
The larger northern Keys (Elliott and Largo) hayee eten-
sive reef deyvelQpmentoff-their coastal he middlKeys,
which are smaller and more separated, have nuimrous
chann&els communicating with Florida Bay(Plate la) and
exhibit lessrteLdeve-elonment_-thanthe-jperaQrwer
Kemy The influence of Florida Bay on water quality
negatively affects reef development in the middle
.Keys area.
Major bank reefs off the Florida Keys include
Carysfort, Elbow, Key Largo Dry Docks, Grecian
Rocks (Plate 3a), French (Plate lb), Molasses, Alligator,
Tennessee, Sombrero, Looe Key (Plate 2a and b),
Eastern, Middle, and Western Sambos, American Shoals,
Eastern and Western Dry Rocks, Rock Keys, and Sand
Key. Dry Tortugas is studded with various coral reefs
(Davis 1979, 1982).
Off the west coast of Florida. tropical reef
development is nonexistent. Ledges and outcroppings
are a special rocky habitat which supports an association
of hardy corals and other biota; however, they do not
construct three-dimensional reefs. The Florida Middle
Ground (a fossil reef formation about 157 km northwest
of Tampa Bay), r hule e\hihting higher diJers!it in coral
species, is not an active coral reef comparable with those
found off southeast Florida. These areas in the eastern
Gulf of Mexico, however, are critical habitats that
should be provided with rational management, especially
since important fisheries are found in association with
the gulf live bottom communities.

1.3 COMMUNITY DISTRIBUTION

The Florida Keys possess coral reef communities
similar to those found in the Caribbean and other
tropical Atlantic areas. The reefs are bathymetrically
distributed from less than 1 to 41 m deep. Large-scale
synoptic mapping of the Keys' reefs has been recently
completed (Marszalek et al. 1977; Marszalek 1981,
1982). Caution should be exercised when interpreting
these maps, as they use mapping units based on geo-
logical and biological criteria, and in some cases errant
interpretation could occur due to their large scale and
criteria used.
The basic pattern of marine communities in
southeast Florida (where commercial development has
not occurred) is one of a shoreline dominated by man-
groves, rocky intertidal, or sedimentary environments.
From the intertidal zone to Hawk Channel is a mosaic of
environments including sediments, seagrass exposed
Pleistocene rock, and some patch reefs. Seaward of
Hawk Channel, patch reef abundance and frequency
increase and bank reefs begin to occur. Seagrass is often
abundant and sediment is coarser. Seaward of the bank


reefs the sea bottom (where it has been investigated)
consists of sediments, sponge habitats, and rubble, with
occasional rocky outcrops that generally parallel the
basic reefs.
The coral refssearasses, and mangrovesare all
integrated intQ _t.he -coastaL-ecosyst.emoQf southeastern
Florida. Motile species and trophic energy_ webs are
Intiegf t iatndILinterrplated amnng the thr-eec-Qmmuni-
ties.

1.4 HISTORICAL RESUME' OF FLORIDA CORAL
REEF RESEARCH

Arbitrarily, coral reef research can be chrono-
logically placed into three periods: early (to 1900),
middle (1900 to 1950), and recent (1950 to present).
Early research was descriptive and taxonomic, and was
stimulated by the need to provide safe navigation for
marine commerce. National security also had some
influence in that the Caribbean Sea prior to 1860 was
frequented by pirates and European naval powers.
During the age of discovery, the Florida coastline was
crudely mapped by the Spanish and English. Agassiz
(1852, 1869, 1880, 1885, 1888), LeConte (1857), Hunt
(1863), and Pourtales (1863-1869, 1871, 1878, 1880)
provided the earliest reef descriptions and details about
the coast. They also initiated systematic description of
the many organisms found in and near the coral reefs.
During the middle period, establishment of the
Tortugas Laboratory on Loggerhead Key by the Car-
negie Institution was the most significant factor bene-
fiting coral reef studies during the first half of the
twentieth century. Alfred G. Mayer and his colleagues
conducted much fundamental coral reef research from
the Tortugas Laboratory. Mayer (1914, 1916, 1918)
determined the thermal tolerances of tropical marine
organisms in general and reef coral in particular. T.
Wayland Vaughan was the most prolific Carnegie reef
researcher, reporting on the geology of Tortugas, south
Florida, and the Bahamas (Vaughan 1909, 1910, 1912,
1914a, 1914b, 1914c, 1914e, 1915a; Vaughan and Shaw
1916). He studied the taxonomy and growth rates of
scleractinian corals (Vaughan 1911, 1914d, 1915b),
summarized seawater temperatures at reef tract light-
houses (1918), and reported on the Tortugas current
structure (1935). Other students of scleractinian corals
include Duerden (1904), postlarval development in
Siderastrea radians; Matthai (1916), systematics; Bosch-
ma (1925, 1929), postlarval development in Manicina
areolata; Wells (1932), thermal tolerance knowledge;
and Yonge (1935a, 1935b, 1937), M. areolata aute-
cology, taxonomy of Siderastrea spp., and mucus
production in stony corals. Other reef-related research
from the Carnegie laboratory includes work by Cary
(1914, 1916, 1918a, 1918b), Octocorallia; Taylor
(1928), algae; deLaubenfels (1936), Porifera; and
Longley and Hildebrand (1941), fish. Another first for
the Tortugas laboratory was that the first underwater
color photographs of coral reefs were taken by Longley
at Tortugas. Dole (1914) and Dole and Chambers (1918)
reported on salinity at Tortugas and off Fowey Rocks






lighthouse. LeCompte (1937) described some Tortugas
reefs. Wells (1933, unpublished) contains considerable
information on the Tortugas reefs. A fire destroyed the
Tortugas Laboratory in 1937; it was never rebuilt.
Verrill (1902), Smith (1943, 1948, 1971),
Vaughan and Wells (1943), and Wells (1956) are the
relevant scleractinian taxonomic and systematic refer-
ences. During the recent period (1950 to present) there
has been a great proliferation of scientific literature
dealing with Florida coral reefs. Growth rates of coral
species were detailed by Broecker and Thurber (1965),
Shinn (1966), Jaap (1974), Landon (1975), Emiliani et
al. (1978), Dodge (1980), and Hudson (1981). Popu-
lation dynamics of scleractinian corals were reported by
Dustan (1977a). Brooks (1963), Halley (1979), Davis
(1982), and Porter et al. (1982) added to Tortugas
information.
Ecological studies and reviews include Smith et
al. (1950), Voss and Voss (1955), Jones (1963, 1977),
Glynn (1973), Hudson et al. (1976), Hudson (1981),
Goldberg (1973a, 1973b), Antonius (1974a), Kissling
(1975), and Shinn (1975). Coral reef fish studies in-
cluded Springer and McErlean (1962a, 1962b), Starck
(1968), Starck and Davis (1966), Bohlke and Chaplin
(1968), Emery (1973), and Jones and Thompson
(1978). Reef morphology and physiography were
reported by Stephenson and Stephenson (1950), Shinn
(1966), Kissling (1965), Starck and Schroeder (1965),
Starck (1966), Straughan (1978), Turmel and Swanson
(1971), Weeks (1972), Hannau and Mock (1973), and
Avent et al. (1977).
Geological literature includes Ginsburg (1956),
Brooks (1963), Alt and Brooks (1965), Hoffmeister and
Multer (1968), Duane and Meisberger (1969), Enos
(1970), Multer (1971), Raymond (1972), Ginsburg
(1973), Enos (1974), Gleason (1974), Hoffmeister
(1974), Enos (1977), Lighty (1977), Lighty et al.
(1978), Shinn (1980), Mitchell-Tapping (1981), and
Ghiold and Enos (1982). Geographical research includes
work by Ginsburg and Shinn (164), Marszalek et al.
(1977), Marszalek (1981, 1982), Reed (1980), and
Stoddart and Fosberg (1981).
Guidebooks or general references to Florida reefs
include Hoffmeister et al. (1964), Ginsburg (1972a,
1972b), Zeiller (1974), Voss (1976), Greenberg (1977),
Colin (1978a), and Kaplan (1982). Hurricane impacts on
Florida reefs have been documented by Springer and
McErlean (1962a), Ball et al. (1967), Perkins and Enos
(1968), and Shinn (1975). The effect on coral reefs by
other meteorological phenomena was studied by Jaap
(1979), Walker (1981), and Roberts et al. (1982).
Physical and chemical oceanography adjacent to the reef
tract includes studies by Hela (1952), Chew (1954),
Stommel (1959), Wennekens (1959), McCallum and
Stockman (1964), Gordon and Dera (1969), Hanson and
Poindexter (1972), Lee (1975), Lee and Mayer (1977),
Lee and Mooers (1977), and Leming (1979).
The Octocorallia were reported on by Goldberg
(1973a, 1973b), Opresko (1973), Cairns (1977), and
Wheaton (1981). Underseas parks were reported on by
Voss et al. (1969), Spotte (1972), Tzimoulis (1975), and


Jameson (1981). Florida Current plankton was reported
on by Bsharah (1957). Emery (1968) discussed coral
reef plankton. Coral predators and boring and rasping
biota were reported by Robertson (1963), Ebbs (1966),
Antonius (1974b), Hein and Risk (1975), and Hudson
(1977). Physiology of reef corals, particularly the
symbiotic relationships of corals with zooxanthellae, was
studied by Kanwisher and Wainwright (1967), Kriegel
(1972), Chalker (1976, 1977), and Chalker and Taylor
(1978). Reports on the impact of human activities
include McCloskey and Chesher (1971), Hubbard and
Pocock (1972), Straughan (1972), Voss (1973), Anto-
nius (1974b, 1976, 1977), Courtenay et al. (1974),
Griffin (1974), Jaap and Wheaton (1975), Manker
(1975), Shinn (1975), Chan (1976), Britt and Associates
(1977), Davis (1977a), Dustan (1977b), and Bright et al.
(1981). Coral reef growth rates in Florida were reported
by Hoffmeister and Multer (1964), Shinn et al. (1977),
and Shinn (1980).
Echinoid distributions in John Pennekamp Coral
Reef State Park were studied by Kier and Grant (1965).
Miller 'et al. (1977) reported on diatoms in the park.
Jameson (1981) reported on the biology, geology, and
cultural resources in deeper regions of the Key Largo
National Marine Sanctuary. Workshop and symposia
literature includes Stursa (1974) and Taylor (1977).
Shinn (1979) detailed collecting-permit requirements for
biological and geological sampling in the Keys' area.

1.5 ECONOMIC SIGNIFICANCE

Exploitation of Florida's reef resources began
with the Caloosa Indians, who harvested marine protein
.(fishes, lobsters, and conchs), shells, and coral for
trading. Excavated middens occasionally contain coral
artifacts. During the mid-17th to late-19th centuries, the
Florida reefs posed a significant navigational hazard to
Europeans and Americans. Today, salvagers recover gold,
silver, and artifacts from the numerous shipwrecks
adjacent to, the reefs. Many reefs are named for ship-
wrecks. Looe Key Reef is named for the 44-gun British
Frigate, the HMS Looe, which was wrecked on the reef
the morning of 5 February 1744. Molasses Reef is
named for an unknown vessel laden with molasses that
foundered there.
Early Florida Keys' settlers had a thriving enter-
prise of luring unsuspecting ships onto the reefs with
false beacons. They then claimed salvage rights on the
wreck, salvaged the cargos, and auctioned them off.
Wood from the vessels was also salvaged. Many of the
older homes in Key West are constructed with salvaged
ship timbers. In an effort to reduce the shipwrecks, early
coral reef work was directed toward mitigating the
hazards. This resulted in the lighthouse construction
between 1825 and 1886 on the most dangerous reefs.
These lighthouses significantly changed the nature of the
Keys' economy. Fishing, cigar making, sponge har-
vesting, and agriculture replaced shipwrecking as the
major economic endeavor at Key West.
Commercial sale of coral began in Key West
around 1830 and remained a poorly organized cottage






industry until 1950. During that period collectors
used either grappling hooks from boats or hand har-
vested while reef diving. The industry changed with the
advent of scuba diving and the increased interest by the
general public in the marine environment. There was
increased demand for coral by tourists as well as for
export to northern markets. No quantitative data exist
on the magnitude or economics of the coral harvest. It is
suspected that commercial coral harvest at no time
employed more than 20 individuals working on a part-
time seasonal basis. In 1973 and 1975 Florida enacted
statutes making it illegal to collect, sell, or damage stony
corals (Millepora and Scleractinia) and two species of sea
fan (Gorgonia) within State waters. In 1976, the Federal
Government (Bureau of Land Management) wrote
regulations under the authority of the Outer Continental
Shelf Lands Act to protect corals and reefs in the area
under federal jurisdiction (beyond the 3-mi limit in the
Atlantic). The Fifth Circuit Court of Appeals, however,
ruled that these regulations can only be applied when
active mineral or petroleum exploration or production is
occurring in the immediate vicinity of the coral. Current-
ly, the Gulf of Mexico and South Atlantic Fishery
Management Councils are preparing a management plan
for corals and coral reefs in the region between North
Carolina and the Texas-Mexican border.
Today, coral being sold is foreign. From 1977 to
1979, 200,000 pieces of coral were imported with a
dockside value of $31,500. Retail markup would place
the value of imported coral at about $95,000. Most of
this coral came from the Philippines, where collecting
and selling coral is illegal, but enforcement is difficult
because of the thousands of islands belonging to this
nation.
Economically, Florida coral reefs directly or
indirectly generate an estimated $30 million-$50 million "
annually within the Monroe County region. These
monies come from all aspects of fishing, diving, educa-
tion, and research. Commercial fishing in particular
depends heavily on the coral reef habitats. Most of the
sought-after species spend all or part oftheirives in the
reefs. Eor some species, the coral reefs are a nursery area
where juveniles mature into adults. Many species breed
andior feed itrhin the confines of the coral reef. Resi-
dent fish populations may only seek shelter and refuge
in the reef and feed in the nearby surrounding grass
flats or the open sea. The life history patterns of indi-
vidual species vary, but the reef is a critical link to the
success of these species. Table 1 presents commercial
landings of reef-related species in Monroe County for
1980.
Diving as a sport and hobby attracts more than a
million people to the Florida Keys annually. These
divers rent and purchase equipment, charter tours to the
reefs, and purchase food and lodging. Tourists come
from as nearby as Homestead and Miami, and as far
away as Europe and Canada. A 1979 Skindiver magazine
survey indicated that the Florida Keys was the most
popular diving location in the United States among
traveling divers. The survey reported that the average
diver spent about $718 per trip. There are 40 businesses


Table 1
Commercial landings of reef-related species in Monroe
County, 1980 (NMFS 1981).


Weight Value
Species (Ib) ($)


Ballyhoo
Jacks
Dolphin
Grouper & scamp
Hogfish
Jewfish
Shark
Snappers
Lane
Mangrove
Mutton
Red
Vermilion
Yellowtail
Triggerfish
Warsaw grouper
Spiny lobster
Spanish lobster

Total


311,724
29,881
89,977
509,794
34,184
32,646
175,643

15,526
240,117
160,469
15,532
915
735,104
105
3,371
4,656,018
28,199


85,871
2,674
33,099
451,014
17,965
5,312
18,365

6,890
127,530
131,419
20,820
861
730,744
19
1,324
10,132,913
67,814


7,039,205 11,834,634_


in Monroe County devoted entirely to tourist diving. For
the most part this activity is a nonconsumptive form of
reef usage. Most tourists come to experience the reef
environment firsthand and to observe fish. Some divers
do spearfish and catch lobsters. Spearfishing is banned in
some marine parks and sanctuaries, i.e., John Penne-
kamp Coral Reef State Park, Key Largo National Marine
Sanctuary (JPCRSP-KLNMS), and Ft. Jefferson Nation-
al Monument. Much of the tourist diving is concentrated
offshore of Key Largo in JPCRSP-KLNMS, off Big
Pine Key at Looe Key National Marine Sanctuary
(LKNMS), and off Key West.
Besides diving, there are glass-bottom boat tours
that allow the nondiver to enjoy the reef firsthand
without getting wet. Charter airplanes also fly tourists
over the reefs. Tourist gift shops market many reef-
related souvenirs, from colorful T-shirts to postcards.
All levels of education, from elementary to
graduate school (including youth organizations, scouts,
sea camps, and diving schools), bring students to the
coral reefs to supplement classroom experiences. Special
publications, documentaries, and movies about the coral
reefs are produced. These are an economic and educa-
tional benefit to the Nation.
Economic impacts of applied and basic research
on coral reef communities include equipment rentals, air
fills, and lodging. Potential commercial applications
of this research will benefit pharmacology (anti-cancer
compounds from various reef organisms are being






tested), medicine (artificial bones), geology, reef fish-
eries management, aquaria, mariculture techniques, and
archaeology.
Revenue from all these activities renters the
south Florida economy and generates employment for
many other people in the service sectors. The corals'
greatest value, however, is as a living resource, and not as


an item of commerce. Their habitat value and attraction
to divers are worth far more than as an item of com-
merce. While coral reefs remain on the seafloor, they are
like a good investment: they continue to generate
monies through the marine protein harvested there and
the divers who come to enjoy them. As curios, they
bring a smaller dividend to a fewer number of people.






CHAPTER 2

THE ENVIRONMENT


2.1 CLIMATE


The climate of southeast Florida is characterized
as subtropical marine in Miami and tropical maritime in
Key West (NOAA 1981). The region is heavily influ-
enced by the adjacent marine environments; the Florida
Current, Gulf of Mexico, and Atlantic Ocean affect the
terrestrial and marine climates during different seasons.
Daily average air temperatures in Key West range from
lows of 18.80 C during January to highs of 31.90 C in
August (NOAA 1981). Compared to those of Key West,
Miami air temperatures are measurably lower in winter
and slightly lower during summer (Table 2 and Figures 2
and 3). There is a dry season from November to April in
Miami and November to May in Key West. Key West
averages 1,007.4 mm of precipitation annually; Miami,
1,518.9 mm (Table 3 and Figure 4). Key West's weather
station is within 0.5 km of the coast and is more repre-
sentative of the reef situation. Throughout most of the
year southeast and east-southeast winds prevail, and
velocities normally range from 10 to 20 km/hr; wind
velocity is less during the summer (Table 4 and Figure
5).

2.2 HURRICANES

Severe hurricanes are common meteorological
phenomena in southeast Florida. A formal hurricane



Table 2

Monthly air temperatures (C) for Miami and Key West
(NOAA 1981).

Miami Key West
Period Range Mean Range Mean


January 14.8-24.2 19.6 18.8-24.2 21.5
February 15.0-24.8 19.9 19.2-24.8 22.0
March 17.2-26.4 21.8 21.0-26.3 23.7
April 19.6-28.2 23.9 23.1-28.1 25.6
May 21.5-29.6 25.6 24.7-29.6 27.2
June 23.3-31.1 27.2 26.2-31.1 28.6
July 24.2-31.7 27.9 26.7-31.8 29.2
August 24.3-32.2 28.3 26.6-31.9 29.3
September 23.9-31.3 27.6 25.9-31.0 28.4
October 21.7-29.2 25.4 24.0-28.9 26.4
November 18.1-26.6 22.3 21.4-26.4 .23.9
December 15.6-24.8 20.2 19.2-24.7 21.9

Yearly 14.8-32.2 24.2 18.8-31.9 25.7

aClimate data base for Miami = 38 years;
Key West = 29 years.


] KEY WEST
O MIAMI


J F MA M J J A S O N D
Figure 2. Monthly mean air temperature for Key
West and Miami (NOAA 1981). Data base is 29 years
for Key West; 38, Miami.


0 MIAMI
O KEY WEST


J F M A M J J A S O N D
Figure 3. Monthly minimum air temperature for
Key West and Miami (NOAA 1981). Data base is 29
years for Key West; 38, Miami.

Table 3

Monthly precipitation (mm) for Miami and Key West
(NOAA 1981).

Miami Key West
Month mean mean


January 54.6 42.4
February 49.5 47.0
March 52.6 39.6
April 91.4 55.1
May 155.4 63.8
June 228.6 115.6
July 175.5 104.4
August 170.7 113.5
September 222.0 186.4
October 207.8 141.5
November 69.1 67.8
December 41.7 38.6


Yearly total 1,518.9 1,015.7

aClimate data base for Miami = 38 years;
Key West = 29 years.





3001 KEY WEST
0 MIAMI


0 1- 1 I i I i- I
J F M A M J J A S O N D
Figure 4. Monthly mean precipitation for Key
West and Miami (NOAA 1981). Data base is 29 years
for Key West; 38, Miami.



Table 4
Monthly wind speed (km/hr) and direction for Miami and
Key West (NOAA 1981).

Miami Key West
Month Mean Direction Mean Direction
speed speed
(km/hr) (km/hr)

January 15.3 NNW 19.5 NE
February 16.3 ESE 19.6 SE
March 16.9 SE 20.3 SE
April 17.2 ESE 20.6 ESE
May 15.4 ESE 17.4 ESE
June 13.2 SE 15.6 SE
July 12.7 SE 15.9 ESE
August 12.7 SE 15.4 ESE
September 13.2 ESE 16.3 ESE
October 15.0 ENE 18.2 ENE
November 15.4 N 19.5 ENE
December 14.8 N 19.5 NE

Yearly 14.8 ESE 18.2 ESE


aClimate data base for Miami = 38 years;
Key West = 29 years.



21- O MIAMI
0 KEY WEST
19

m 17

15

13

11
J F M A M J J A S O N D
Figure 5. Monthly mean wind velocity for Key
West and Miami (NOAA 1981). Data base is 29
years for Key West; 38, Miami.


season exists from 1 June to 30 November. Thirteen
major hurricanes have passed across the reef tract and
struck the Florida Keys since 1894. Criteria for a major
hurricane include one or more of the following: 200-
km/hr wind speed; winds reaching out 160 km from the
hurricane eye; barometric pressure of 716.28 mm of
mercury or less; and/or tide surge of 2.7 m or greater.
The Florida Keys has a greater probability of hurricane
impact (one in seven) than any other Florida coastal area
(Florida Department of Natural Resources 1974). Facts
pertaining to hurricane impacts on coral reefs will be
detailed in the reef ecology chapter. Table 5 summarizes
major hurricanes that have crossed the reef tract since
1873.


2.3 SOLAR RADIATION


Peak solar radiation occurs between 0900 and
1500 hr in Florida (Barnes and Taylor 1973). Trans-
mittance through the water column is greatest at solar
noon; albedo (reflection) is significant during early
morning and late afternoon. According to Hanson and
Poindexter (1972), maximum solar energy was expended
at the air-sea interface from 1000 to 1400 hr; most of
the energy was expended in heating the water column.
Gordon and Dera (1969) studied solar radiation atten-
uation between Key Largo and Great Abaco Island,
Bahamas, and found that in the surface layers (0-5 m)
the attenuation (diffusion coefficient) was 0.11-0.57
Kd/m between Miami and the Florida Current. Hanson
and Poindexter (1972) reported that the amount of solar
radiation impinging on the bottom at 13 m ranged
between 5% and 17%; zenith angle, cloud cover, wave
.action, and turbidity all influenced transmittance.
Kanwisher and Wainwright (1967) reported that Florida
reef corals required between 200 and 700 footcandles
(fc) of solar illumination for autotrophic self-reliance
(compensation point). On clear days these values cor-
related with a depth of about 30 m.

2.4 SEAWATER TEMPERATURE

The most extensive data base for reef seawater
temperatures appears in Vaughan (1918). These data
came from several lighthouses and Ft. Jefferson, Dry
Tortugas, and are summarized in Table 6 and Figures
6-10. More recent data from a patch reef in Biscayne
National Park are presented in Table 7 and Figure 11.
Temperature extremes are from 140 to 380 C; most
annual ranges are from 180 to 300 C. Mean values are
above 18 C, the threshold temperature generally ac-
cepted for structural reef development by reef building
corals (Wells 1956). Temperature variability (range and
standard deviation) is greater during the winter. In
recent winters (since 1976), polar air masses have cooled
coastal waters, causing fish kills and coral mortalities.
Areas that have suffered the greatest harm from thermal
stresses are off Loggerhead Key, Dry Tortugas (staghorn
coral thickets), and patch reefs off Plantation Key (Hens
and Chickens and The Rocks). Cold water masses are
created in Florida Bay during the winter passage of polar





Table 5


Major hurricanes crossing the coral reefs from 1873 to 1966 (Sugg et al. 1970).

Hurricane Date Wind speed Tide height
name Day Year (km/hr) (m)

18-30 September 1894 167 (est.)
1896 161 (est.)
27 August 1900
11-22 October 1906
6-13 October 1909
9-23 October 1910 177-201 (est.) 5
2-15 September 1919 177 (est.)
11-22 September 1926 222 2-4
22 September-4 October 1929 -
31 August-7 September 1933 201-225
29 August-10 September 1935 322 5-6
30 October-8 November 1935 121
3-14 October 1941 121-198
12-23 October 1944 193 2-4
11-20 September 1945 175-315 2-4
5-14 October 1946 129 5
9-16 October 1947
18-25 September 1948 196 2-6
3-15 October 1948 161 2
Easy 1-9 September 1950 117
King 13-19 October 1950 196-241 2
Donna 29 August-13 September 1960 225-322 4
Cleo 20 August-3 September 1964 177-217 2 (est.)
Betsy 27 August-12 September 1965 266 (gusts) 2-3
Alma 4-14 June 1966 201
Inez 21 September-11 October 1966 21-150 2




Table 6

Reef seawater temperatures (oC) (Vaughan 1918).

Reef
Tortugas Sand Key Carysfort Fowey Rocks
(1879-1907) (1878-1890) (1878-1899) (1879-1912)
Month Range Mean Range Mean Range Mean Range Mean


January 19.4-24.8 22.1 17.9-24.1 21.8 18.2-25.9 22.5 15.8-26.2 22.2
February 18.7-24.4 22.1 18.3-25.3 22.8 20.6-24.8 23.0 15.6-24.5 22.5
March 19.6-25.4 22.8 20.4-27.3 23.8 21.1-25.6 23.1 18.7-27.4 22.9
April 17.9-25.8 23.6 22.5-28.5 26.1 22.4-26.4 23.9 21.0-29.4 24.4
May 21.9-28.3 25.6 25.8-29.9 28.2 24.0-27.9 25.5 21.4-29.2 26.2
June 23.6-29.3 27.2 27.7-32.2 29.8 25.4-29.4 28.8 21.5-29.6 27.2
July 24.7-31.1 28.8 29.9-31.9 31.1 27.1-30.2 30.0 23.4-30.9 28.3
August 24.2-30.9 29.3 29.2-32.2 30.7 26.5-30.3 30.0 23.5-31.2 28.7
September. 24.1-30.5 28.8 28.7-31.2 30.3 27.2-30.1 29.6 22.9-30.7 28.3
October 22.5-29.4 27.3 24.5-30.1 27.6 23.8-29.1 27.6 22.3-29.4 27.0
November 21.4-28.0 25.3 22.3-27.1 25.1 23.0-28.7 25.5 20.0-28.4 25.0
December 21.3-26.4 23.2 18.4-26.0 22.5 21.0-27.3 23.3 15.8-27.9 23.1



















J F MA M J J A S ON D

Figure 6. Monthly minimum, mean, and maximum
seawater temperature at Fowey Rocks, 1879-1912
(Vaughan 1918).


30-



SO MAXIMUM
0 MEAN
A MINIMUM
10..
J F M A M J J A S O N D

Figure 7. Monthly minimum, mean, and maximum
seawater temperature at Carysfort Reef, 1878-1899
(Vaughan 1918).


40-



30-
-.-I

0-


10
J

Figure 8.
seawater
(Vaughan


6 MAXIMUM N
O MEAN
O MINIMUM

F M A M J J A S O N D
Monthly minimum, mean, and maximum
temperature at Sand Key, 1878-1890
1918).


J'u ~ MAXIMUM
O MEAN
O MINIMUM
10 .,. .,
J F M A M J A S ON D

Figure 9. Monthly minimum, mean, and maximum
seawater temperature at Dry Tortugas, 1879-1907
(Vaughan 1918).


O CARYSFORT
O DRY TORTUGAS
A FOWEY ROCKS


J F M A M J J A S O


N D


Figure 10. Minimum monthly seawater temperature
at Carysfort Reef, Dry Tortugas, and Fowey Rocks.


Table 7

Bottom (3 m) seawater temperature (OC) at Elkhorn
Control Reef, Biscayne National Park, 1978 (from
daily thermograph data, Biscayne National Park).

Standard
Month Range Mean deviation


January 17.5-23.1 20.8 1.3
February 16.7-22.4 20.0 1.4
March 20.4-23.8 22.3 0.9
April 22.3-25.1 24.2 0.7
May 24.5-27.8 26.6 0.7
June 27.2-30.3 28.6 0.8
July 28.5-30.3 29.3 0.4
August 28.7-30.3 29.4 0.4
September 28.4-29.9 29.0 0.4
October 25.2-29.6 28.0 1.3
November 25.1-27.0 25.9 0.4
December 23.8-26.1 24.9 0.8





32
28-
32
2, 24

S20- MINIMUM
O MEAN
16- a MAXIMUM

12 .. .
J F M A M J J A S O N D
Figure 11. Monthly minimum, mean, and maximum
seawater temperature (3m) at Elkhorn Control
Reef, Biscayne National Park, 1978 (from thermo-
graph data, Biscayne National Park).



air masses (Roberts et al. 1982). Offshore (into the
Atlantic) transport is the effect of tidal pumping,
northerly winds, and density gradients. Communities
adjacent to tidal channels suffer the greatest impact
from this thermal stress. Conversely, during the summer,
the Florida Bay water may become hyperthermal
(> 310 C) because of solar heating, and communities
near tidal passes are more affected.
Seawater temperature reflects the annual climatic
cycle: seawater temperatures are lowest from December
through March. Temperature peaks in August or early
September and cools throughout the fall and winter.
A comparison of seawater temperature with air temper-
ature (Tables 2, 6, and 7) for Miami with the recent
Biscayne National Park data shows that mean seawater
temperature is warmer than mean air temperature
throughout the year.

2.5 TIDES

The Atlantic coast from Miami to Key West
exhibits a semidiurnal tidal pattern. The area close to
Key West is influenced by the Gulf of Mexico, which
experiences semidaily or daily tides. Table 8 presents
mean and spring tide ranges for several reefs. The major
effect of tides on reef communities is the reduction of


Table 8
Tidal ranges for several southeast Florida reefs
(NOAA 1981).


Mean
Location tide level Mean tide Spring range
(m) (m) (m)

Fowey Rocks 0.4 0.7 0.7
Molasses Reef 0.3 0.7 0.8
Alligator Reef 0.4 0.6 0.7
Sand Key Reef 0.2 0.4 0.5
Garden Key, 0.2 0.3 Not given
Dry Tortugas


water depth during spring low tides when shallow reef
flats may be near emergent. During the summer, if wind
speed is low, heating of the water column may cause
hyperthermic conditions such that zooxanthellae (sym-
biotic algae within the coral tissue) may be expelled
(Jaap 1979; Hudson, in press). During the winter the
reef flat water may be hypothermic, again causing
thermal stress (Hudson et al. 1976; Hudson, in press).
A trend of decreasing mean levels and ranges is
noted as one approaches the Gulf of Mexico. Tidal cur-
rents for the reef area are not presented in the Tide
Current Tables prepared by the National Oceanic and
Atmospheric Administration. There are significant tidal
currents between Florida Bay and the Atlantic.

2.6 SALINITY

The reef tract area experiences oceanic salinities
as summarized in Table 9. The region adjacent to Bis-
cayne Bay is an area where heavy rainfall can reduce
salinities for short periods. Dole and Chambers (1918)
reported that heavy precipitation in Miami almost
always was followed by temporary reduction in chlorin-
ity and salinity at Fowey Rocks 24 hr later. Flat low
land, porous soils, and distance offshore minimize the
effect of rainfall on salinity in the reef tract areas.
Rarely, entrained Mississippi River spring runoff
is carried along the inshore side of the Florida Current.
This water mass has salinities of 32-34 ppt, which is
within the tolerance limits of reef corals.
Diurnal salinity fluctuations at Margot Fish Shoal
ranged from 37.8 to 37.3 ppt because of evaporation
and precipitation (Jones 1963).
During hot summer periods, density sinking on
shallow reef areas is common. Evaporation creates dense
hypersaline surface layers which sink and mix poorly
with subsurface cooler waters. Swimmers can feel and
see this phenomenon.


2.7 DISSOLVED OXYGEN

Jones (1963) and Jaap and Wheaton (1975)
provide limited information on dissolved oxygen. The
water column ranges diurnally from 90% to 125%
oxygen saturation. Daily maximum values are attained
between 1400 and 1600 hr (Jones 1963).

2.8 TURBIDITY

Transparency (equivalent Secchi disc depth) for
several stations off the Florida Keys was reported by
Williams et al. (1960). They reported that the equivalent
Secchi distances ranged from 4.5 to 35 m in this area.
Variability of water clarity is considerable. Following
storms the water may be nearly opaque. Plankton and
suspended matter also affect water clarity.
Water clarity and sedimentation rates for a
dredge operation near Basin Hills, Key Largo, were
reported by Griffin (1974). Ambient or background
suspension concentration in the water column ranged





Table 9


Salinities in the Florida reef tract and vicinity.

Salinity
Location Dates range (ppt) Source


Dry Tortugas 1913 35.2 36.1 Dole 1914
Fowey Rocks 1914-1916 34.2 -38.6 Dole and Chambers 1918
Soldier Key 1945-1946 33.1 37.1 Smith et al. 1950
Key West area 1953-1954 33.3 -37.0 Chew 1954
Margot Fish Shoal 1961-1963 36.8 37.3 Jones 1963


from 0.5 to 3.7 mg/l at a nearshore patch reef. Suspen-
sion concentration within the dredge plume ranged from
18 to 212 mg/1. These levels are probably comparable to
the upper limits on the reef tract following a hurricane
or major storm.

2.9 CURRENTS

A warm water current (the Florida Current)
flows through the Straits of Florida. Wust (1924)
calculated that 26 m3/sec pass through the constricted
area between Florida and Cuba. The current's velocity is
in the magnitude of 150 cm/sec. It is composed of two
water masses in its surface layers. The eastern core is
composed of Caribbean water that flows into the Gulf
of Mexico through the Straits of Yucatan; the western
or nearshore portion of the current is composed of
water that flows from the Gulf of Mexico (Wennekens
1959). The Florida Current comes closest to Florida off
Palm Beach, where the central axis is about 15 km off
the coast. Off Dry Tortugas the current is 124 km south
of the islands. The current is very dynamic and meanders
a good deal. Generation of eddies off the main body of
tlfe current ringq crnrent water onto the shelf and to
tereef environments. __As noted earlier, the_ current
moderates winter temperature and brings plankton of
Caribbean origin into the reefs. Maul (1976) presented
the variability of various components of the Gulf Stream
system (Figure 12). Schomer and Drew (1982) recently
reviewed the physical and chemical environment of
southern Florida.

2.10 GEOLOGICAL SETTING

The following information is paraphrased from a
field guide to south Florida sediments (Ginsburg 1972a).
The Florida-Bahamas region is a carbonate platform part
of the Atlantic and Gulf coastal province. The platform
is dissected by deep-water channels. The most important
consideration here is the Straits of Florida, which is
nearly 550 m deep. Marine portions of this platform are
generally shallow, less than 16 m deep in most places.
Deep test drilling in the area indicates the platform has
had a history of continuous subsidence and deposi-
tion of shallow-water carbonates and evaporites. Maxi-
mum depths of drill penetration (5,486 m at Cay Sal


Bank) imply that no near-surface formations older than
upper Miocene are extant. The Florida pennisula south
of Lake Okeechobee has been a carbonate depositional
region during portions of the Mesozoic and throughout
the Cenozoic. Recent carbonate sediments are grossly
similar to older material. Two major strata dominate the
southern Florida coastal areas from Miami southward
along the keys. The Key Largo formation is a reef facies
formed during the Pleistocene and will be discussed in
more detail later. The Miami formation is also a Pleis-
tocene stratum that is composed of oolite and bryozoan
skeletons.

2.11 GEOLOGIC HISTORY AND PROCESSES

During the past 20 million years, major change
has occurred in western Atlantic coral reefs. Previously,
a cosmopolitan reef biota was found throughout the
tropics. Twenty million YBP, a land barrier emerged
terminating water movement between the Indian Ocean
and the Mediterranean Sea. Approximately 7 million
YBP, the Central American Isthmus developed, separat-
ing the Caribbean Sea and Atlantic Ocean from the
Pacific Ocean. What was previously a circum-equatorial
tropical zone had thus been isolated into separate
biogeographic provinces. During the late Oligocene and
early Miocene, 20-30 million YBP, the western Atlantic
area experienced its greatest proliferation of reef build-
ing. During the Pleistocene (at least 1 million YBP),
major environmental change extirpated the Pan Atlantic-
Pacific biota. Glacial periods occurred during this time;
during each period, sea level was drastically reduced and
the marine climate was cooler. Pacific genera of Sclerac-
tinia that were eliminated from the western Atlantic
include Stylophora, Pocillopora, Goniastrea, Goniopora,
Pavona, and Seriatopora (Newell 1971).
In Florida, a major coral reef community devel-
oped during the last major interglacial period, San-
gamon, 100,000-112,000 YBP; it was killed during
the last glacial advance (Wisconsin) because of the
reduction in sea level and the cooler climate. This
Pleistocene reef, known as the Key Largo formation,
extends from Miami Beach to at least Dry Tortugas and
seaward to the Straits of Florida. It varies in thickness
from 23 to 61 m or more; the basement has not been
reached in several cores. Wherever its base has been lo-






















30'










25:










200


Figure 12. Components of the Gulf Stream System (Maul 1976).


*





cated, the formation was found to rest atop calcareous-
quartz sands. From near Miami to Big Pine Key the Key
Largo formation is found near the surface, but from Big
Pine Key to Key West it is overlain by the Miami Oolite
formation, which may be upwards of 12 m thick (Hoff-
meister and Multer 1968). Hoffmeister and Multer
(1968) and Hoffmeister (1974) reported that the ex-
posed portion of the Key Largo formation in the Florida
Keys is representative of a low-wave-energy patch-reef
community. The main evidence for this is that certain
scleractinian corals, in particular Acropora palmata
(elkhorn coral), are absent in the fossil record. Presum-
ably a series of events occurred such that the seaward
part of the Key Largo formation did, at one time,
possess high wave-energy communities similar to today's
reefs; however, as sea level rose during the Holocene
transgression, these fossil communities were appar-
ently eroded away by wave action. Hoffmeister (1974)
reported that a core made near Looe Key Reef recovered
fragments of A. palmata from 18 m below the surface.
The Holocene transgression of sea level (Figures
13 and 14) indicates that 10,000 years ago the sea level
was about 30 m lower than today (Lighty et al. 1982).
Shinn et al. (1977) cored several recent reefs from Miami
Beach to Dry Tortugas and dated initial growth from
5,250 to 7,160 YBP. Reef growth or accretion rates


ranged from 0.65 to 4.85 m/1,000 years (Table 10;
Shinn et al. 1977). For comparison, Adey (1977)
reported reef growth off St. Croix, U. S. Virgin Islands,
was 15 m/1,000 years (this is the upper limit for Carib-
bean reef growth). Shinn et al. (1977) reported that the
base of recent reefs was Pleistocene Key Largo Reef,
fossil mangrove peat, and cross-bedded quartz fossil sand
dunes.
More recently, an extensive barrier reef existed
off the Ft. Lauderdale area, but it was extirpated about
7,000 YBP (Lighty 1977; Lighty et al. 1978). This reef
was a shallow-water Acropora palmata community. The
demise of this reef was attributed to environmental
change caused by increasing sea level (Lighty et al.
1978). Recent coral reef growth off the Florida Keys
started from 5,000 to 7,000 years ago.
Development of a coral reef integrates biological,
geological, chemical, and physical processes. Soon after
the first coral colonies settle and start to grow, the
breakdown of organism skeletons by biological and
physical agents occurs. Sediments created by these
activities become a part of the reef.
Finer sediments filter into voids and borings, and
the coarser fractions fill the interstitial space between
the reef framework. Reef tract sediments are carbonate
and are dominated by algal and coral skeletal material


EUSTATIC CHANGES IN SEA LEVEL
YEARS xl03


2 4 6 8 10 12 14 16 18 20 22 24


ENVELOPE ENCLOSES
20 15 PUBLISHED CURVES
CURRAY & SHEPARD
1972


FAIRBRIDGE 1960


MILLIMAN & EMERY
1968


CURRAY 1965


Figure 13. Sea-level change during the Holocene Period (Ginsberg, Comparative Sedimentology Laboratory,
University of Miami, Florida).

































Figure 14. Sea-level change in a Bahamian shelf reef system during the last 10,600 years (Hine
and Neuman 1977).


Table 10

Age and growth rate of Recent Florida reefs (Shinn et al. 1977; Shinn 1980).

Base age (YBP) Accretion Growth rate
Reef (with confidence limits) (m) (m/1,000 yr)


Long Key 5,630120 5.0 0.65
Carysfort 5,25085 7.3 0.86-4.85
Grecian Rocks 5,950100 9.5 6-8
Bahia Honda 7,16085 4.6-8.2 1.14
Looe Key 6,58090 7.3 1.12
Bird Key 6,01790 13.7 1.36-4.85


(Ginsburg 1956). Halimeda and other codiacean algal
plates are the most common algal skeletal material. The
sedimentary material becomes incorporated into the reef
framework through the process of being bound to the
platform by crustose coralline algae and through the
geochemical processes of in situ cementation by high
magnesium calcite cements. Ginsburg and Schroeder
(1973), among others, detailed the processes of marine
cements in coral reefs.
Steam et al. (1977) presented the most recent
quantitative budget of calcium carbonate (CaCO3)
within a coral reef ecosystem (Figure 15). This was
based on the study of a Barbados fringing reef. While the
magnitude of individual components may differ, the
concepts are valid and applicable to Florida reefs. Steam


et al. concluded that crustose coralline algae and stony
corals (nine species) annually fixed 163 metric tons of
CaC03 on a reef platform with a surface area of 10,800
m2 (9 kg CaC03/m2/year). For comparison, nonreef
depositional marine environments in southeastern Flor-
ida are reported to produce 0.25-1 kg CaCO3/m2/year
(Stockman et al. 1967; Moore 1972).
Ghiold and Enos (1982) studied CaC03 produc-
tion in the brain coral Diploria labyrinthiformis from
several patch reefs in John Pennekamp Coral Reef State
Park (JPCRSP)-Key Largo National Marine Sanctuary
(KLNMS). Production (CaC03) was 11.80.3 kg
CaC03/m2/year of area occupied by the colony. Porites
astreoides annual CaC03 production ranged from
13.63.5 to 14.03.1 kg/m2/year at Middle Sambo Reef












































Figure 15. Calcium carbonate
1977).


near Key West (Kissling 1977). Montastraea annularis
has demonstrated annual CaC03 production of 20 kg
CaCO3/m2/year in Barbados (Steam et al. 1977).
Ghiold and Enos (1982) extrapolated production
values to vertical reef accretion rates of 2.2 m/1,000


flow model based on a Barbados fringing reef (Stearn et al.


years, which is within the magnitude of Holocene reef
growth in Florida (Shinn et al. 1977).
Frost et al. (1977) and Taylor (1977) contain
many papers about coral reef geology.







CHAPTER 3


CORAL REEF COMMUNITY TYPES


3.1 INTRODUCTION

A biotic community as defined by E.P. Odum
(1971) is any assemblage of populations living in a pre-
scribed area of physical habitat. Four discernible coral
community types occur off soLuti`astl FIorida.1 Gener-
ally in a seaward progression are found live bottoms,
patch reefs, transitional reefs, and bank reefs -The
relief (height above bottom) of these communities and
the dominance of stony corals as a structural element
increase in a similar ~progressjin. All of these communi-
ties can be physically characterized as shallow water,
wave-resistant, three-dimensional carbonate accretions
constructed by limestone-secreting organisms (prin-
cipally corals, algae, and bryozoans) on a pre-existing
hard substrate. This basic structural component is
augmented by other community members, sedentary
and mobile, permanent and transient.

3.2 LIVE BOTTOM COMMUNITY

The live bottom community, also known as
hardground, is generally found closest to shore, e.g., in
tidal passes, under bridges, and short distances seaward
of the intertidal zone. It usually occupies exposed fossil
reef formations, limestone, and other rocky substrates.
I he laiunl and llorrl elements are not consistent, and
the assemblage is usually visually dominated by octo-
corals, algae, sponges, and smaller hardy stony coral
species.
These communities do not actively accrete or
build massive structures. They support diverse inverte-
brate and vertebralc ..'rim initie s and provide an impor-
tant nursery area for commercial and sport harvested
species. Live bottom habitats are scattered from St.
Lucie Inlet southward to Dry Tortugas in depths ranging
from less than 1 m to beyond 30 m. While these descrip-
tions may imply a single community type, the nearshore
and offshore types differ greatly-in-species composition.
In either case the octoccr:ds....fi c,:,rl.f ..flrn dominate
in terms of numerical abundance and density. An
example of an offshore live bottom community is
the reef (Schooner Reef) at number 2 buoy in Biscayne
National Park (BNP, Figure 16) off Elliott Key. It exhib-
its little relief with the exception of a small ballast pile
from an old shipwreck on the north side off the reef.
The platform is limestone with small ledges, solution
holes, and pockets of sediments. It is heavily colonized



Darwin (1842), based on his experiences in the Pacific
and Indian Oceans, defined three types of coral reefs:
fringing, barrier, and atoll. Although many attempts
have been made to extrapolate these forms to Atlantic
coral reefs, Darwinian-defined reefs do not presently
occur in Florida.


by octocorals and a sparse number of stony (hard) corals
(Table 11). The live bottom community may vary in size
from a small area of tens of square meters to one of
several hundred square meters. The stony corals most
commonly found in the nearshore associations include
Siderastrea radians, Porites porites, P. astreoides, Mani-
cina areolata, Solenastrea hyades, and S. bournoni.
Along with these species, Diploria clivosa, Millepora
alcicornis, and Dichocoenia stellaris are commonly
found in deeper communities. The region surrounding
the live bottom communities is sedimentary, seagrass,
rock, or sponge. The seagrass community is treated in
detail in Zieman (1982).
Stony coral species are commonly found in the
seagrass and sedimentary environments adjacent to the
reef communities. These are Manicina areolata, Porites
porites, Cladocora arbuscula, and Siderastrea radians,
hardy tolerant species that do not attain great size.


3.3 PATCH REEF COMMUNITY

Patch reefs (Plates 11a, 11b, and 12a) are the
second iajor t pe of coral coinmuniti., and they-are a
most conspicuous element in this region. Their distri-
bution is mostly seaward of Key Largo and Elliott Key;
however, they also occur off Big Pine Key, Key West,
and Dry Tortugas. They are usually found seaward of
Hawk Channel, but a few very nearshore patch reefs
exist. Two examples of nearshore patch reefs are (1) an
assemblage of patch reefs just to the north of Caesar's
Creek (BNP) and (2) a small reef just off Cow Key
Channel, Boca Chica Key. Both of these reefs present
the general impression of survival under marginal con-
ditions.
A patch reef characteristically has upward of 3 m
of relief and is dome-shaped,_ The Lurr.-unding- bottom
may be sedimentary, seagrass (Plate 12b), or rock.Most
patch reefs off southeast Florida are found in 2- to 9-m
depths; their upper surface may be nearly emergent at
low tide, exemplified by Basin Hill Shoals off Key
Largo. Patch reefs are roughly circular in outline and
vary in size from about 30-700 m in diameter. Because
of dUl'erent jge-. ot the numerous patch reefs and their
local environmental conditions, generalizations fail to
adequately characterize them. Jones (1963, 1977)
presented information about their physical and chemical
environment near Margot Fish Shoal off Elliott Key and
the dynamics of developmental stages. Smith and Tyler
(1975) and Jones (1977) presented the view that the
patch reef community is similar to a super organism, in
that it goes through several life stages. The nature of the
community reflects the reef's age. While the coral
community goes through its cycle of development, the
fish assemblages change according to niche availability.
An assumed developmental sketch of a patch reef would
include the following:































BISCAYNE BAY


REEF


REEF


BISCAYNE
NATIONAL PARK

NAUTICAL MILES
0 1 2 3


Figure 16. Coral reefs in Biscayne National Park.





Table 11


Live bottom corals from Schooner Reef, Biscayne National Park (four 1-m2 quadrants; Jaap and Wheaton 1977 MS.).

Percent Mean
B.I.b No. of of total no. of
Species Typea (ranking) Frequency colonies colonies colonies/m2


Plexaura homomalla
Porites porites
Gorgonia ventalina
Pseudopterogorgia americana
Briareum asbestinum
Eunicea tourneforti
Muricea atlantica
Pseudoplexaura porosa
Plexaurella fusifera
Eunicea succinea
Plexaura flexuosa
Muriceopsis flavida
Porites astreoides
Plexaurella dichotoma
Millepora alcicornis
Pseudoplexaura flagellosa
S Eunicea laciniata
Agaricia agaricites
Plexaurella grisea
Eunicea mammosa
Pseudoplexaura wagenaari
Dichocoenia stellaris
Pseudopterogorgia acerosa
Eunicea calyculata
Eunicea fusca
Favia fragum
Pseudopterogorgia kallos
Pseudopterogorgia bipinnata
Siderastrea siderea
Montastraea cavernosa
Total


18
18
14
14
10
8
8
6
5
25
11
10
6
3
7
4
2
2
2
2
2
2
1
1
1
1
1
1
1
1
187


9.63
9.63
7.49
7.49
5.35
4.28
4.28
3.21
2.67
13.37
5.88
5.35
3.21
1.60
3.74
2.14
1.07
1.07
1.07
1.07
1.07
1.07
0.53
0.53
0.53
0.53
0.53
0.53
0.53
0.53


4.50
4.50
3.50
3.50
2.50
2.00
2.00
1.50
1.25
6.25
2.75
2.50
1.50
0.75
1.75
1.00
0.50
0.50
0.50
0.50
0.50
0.50
0.25
0.25
0.25
0.25
0.25
0.25
0.25
0.25


Density

Mean colonies/m2 = 46.75
Standard deviation = 15.46
Range = 25-61


Mean species/m2 = 18.50
Standard deviation = 4.53
Range = 13-21


Diversity indicesc

H' = 4.27
H'max. = 4.91
J' = 0.87


ao = octocoral, S = stony coral.
bB. I. = Biological Index, McCloskey (1970).
cDiversity computed with log2.





(1) Initial pioneering settlement of coral larvae
on appropriate substrates. These species might include
Porites porites, Manicina areolata, and Favia fragum.
They would be preparatory colonizers which would
eventually die and their skeletons would become the
hard substrate that the major framework corals would
settle on. If the bottom were rocky, this stage might be
unnecessary.
(2) The settlement and growth, both upward and
outward, of the primary framework builders. While
other coral species are common in the patch reef com-
munity, Siderastrea siderea, Montastraea annularis,
Diploria strigosa, D. labyrinthiformis, and Colpophyllia
natans build the massive frame or three-dimensional
structure of most reefs. Shortly after the framework
element has settled, the boring and rasping fauna starts
the production of reef sediment. Sediments fill inter-
stitial space and are incorporated into the reef frame. In
time, some coral deaths occur providing space for
settlement of coral larvae, an essential element for
growth of the reef. The newly developing reef is a focal
point for attracting the diverse flora and fauna common
to the coral reefs. Some of this occurs because of larval
settlement, especially for the sessile species. Mobile
invertebrates and vertebrates (some residents, some
temporary refugees) move to the reef as niches favorable
to their requirements become available (Plates 13a and
b).
(3) The maturing stage. During this stage the reef
grows upward and outward, providing surface area for
secondary colonizers. The major framework builders
attain 2 m in diameter and greater. The boring and
rasping fauna excavate considerable material from the
basal surfaces of the corals, creating a labyrinth of caves
that become occupied by a cryptic biota. In time, these
caves and tunnels are enlarged, and larger fish and
invertebrates take refuge in them. The new niches within
the interior of the reef are colonized by a wide taxo-
nomic spectrum of shade-loving organisms.
(4) The fully mature stage. Because the primary
framework-building corals have approached sea level,
upward growth is limited. The undersurface of these
corals is cavernous, and in time the framework becomes
so weakened that the upper surface may collapse inward
forming a rubble or boulderlike surface. This is usually
irregularly flat and, in many cases, is dominated by
octocorals. Haystacklike colonies of M. annularis appear
to have large dead areas that are colonized by other
species (Millepora alcicornis and Gorgonia ventalina).
If the reef completely collapses from a major storm or
vessel grounding, the former major relief patch reef
becomes a low-relief pile of rubble that is usually domi-
nated by octocorals and nonframework building stony
corals. In this growth and decay of the patch reef
community into the live bottom community, geo-
chemical processes play an important role in cementing
and binding sediments.
The association of coral found on any particular
patch reef is most probably governed by random chance.
Some patch reefs have very diverse stony coral faunas
while other reefs, only a few meters or kilometers away,


have a less diverse, nearly monospecific fauna. Patch
reefs exhibit extreme variability in coral abundance,
density, and diversity (Table 14). Macrobenthic algae
constituted from 0% to 7% of the linear biomass, sponge
0% to 3.6%. Octocorals constituted a numerically domi-
nant element; however, their linear biomass and macro-
habitat potential are less than many of the stony corals,
especially the massive framework builders. Octocorals do
occupy much of the space on the mature older patch
reefs. There appears to be a competitive exclusion by
octocorals in the interior of older patch reefs. A repre-
sentative patch reef is the reef at buoy number 4 (Dome
Reef) in BNP 16. It is about 250 m in diameter. The
greatest relief is about 2 m and is found on the north-
west side. Tables 12a and b and 13a and b present
the octocoral and stony corals found in this reef based
on several transects. Reef organic linear biomass based
on line transect surveys from four patch reefs in Bis-
cayne National Park shows that mean stony coral cover
was 25.710.6% in the stony coral-dominated zones
(Table 14). In the interior octocoral-dominated zones
the organic linear biomass for stony corals was 14.3%
9.7% (Table 14). There is usually a halo of barren sand
and reef talus (rubble) with sparse grasses and algae sur-
rounding the periphery of most patch reefs (Plates 11 a
and b). The rubble, composed mostly of dead coral
colonies that have been swept away from the reef by
storms, is potential substrate for colonization. Outward
reef expansion is presumably dependent on the reef talus
in sedimentary environments for substrate creation.
Halos around some patch reefs resulted from the black
sea urchin (Diadema antillarum) feeding nocturnally on
algae and seagrasses surrounding the reef, according to
Sammarco (1972), Ogden et al. (1973), and Sammarco
et al. (1974). Randall (1965), however, reported that
herbivorous reef fish were responsible for patch reef
halos. In either case, the herbivorous consumers graze
away the flora adjacent to the reef, creating a barren
zone or halo.
Patch reefs are important habitats for manyreef
fish, permanent and transient (Plate 13a). They provide
shelter, food, and breeding ground for mobile fauna. The
spiny lobster (Panulirus argus) (Plate 19b) utilizes patch
reef habitats during part of its life history.
Like most reefs, patch reefs show a temporal
change when storms or temperature extremes disturb the
communities. Smaller coral colonies are dislodged and
transported from their growth positions. If the new
position is favorable, they may continue to grow; if not,
they may die. This is especially true for octocorals and
encrusting colonies of Millepora that are on unstable
substrates, principally octocoral axes. These colonies
may be swept completely off the reef by heavy wave
surge. There appears to be high mortality due to this
stress; if so, intense recruitment usually prevents large
open areas.

3.4 TRANSITIONAL REEF COMMUNITY

The term transitional reef is used to describe
those reefs that have the rudiments of bank reefs (see





Table 12a


Octocorals at Dome Reef (two 20-m transects, 1977; Wheaton, in preparation a).


Species
Plexaura flexuosa
Plexaura homomalla
Pseudoplexaura porosa
Pseudopterogorgia acerosa
Pseudoplexaura flagellosa
Gorgonia ventalina
Pseudopterogorgia americana
Briareum asbestinum
Plexaurella fusifera
Eunicea tourneforti
Plexaurella nutans
Eunicea fusca
Eunicea succinea
Muricea atlantica
Eunicea laciniata
Eunicea calyculata
Plexaurella grisea
Muricea elongata
Eunicea mammosa
Total


aB.I. = Biological Index, McCloskey (1970).



Table 12b

Octocorals at Dome Control Reef (two 20-m transects, 1977; Wheaton, in preparation a).

Percent
B.I.a No. of of total
Species (ranking) Frequency colonies colonies

Plexaura homomalla 40 2 49 19.76
Pseudoplexaura porosa 36 2 30 12.10
Plexaura flexuosa 35 2 32 12.90
Pseudopterogorgia americana 35 2 26 10.48
Pseudopterogorgia acerosa 34 2 25 10.08
Gorgonia ventalina 27 2 10 4.03
Briareum asbestinum 26 2 12 4.84
Eunicea tourneforti 26 2 9 3.63
Pseudoplexaura flagellosa 26 2 12 4.84
Eunicea calyculata 26 2 12 4.84
Eunicea succinea 22 2 4 1.61
Plexaurella fusifera 22 2 4 1.61
Plexaurella grisea 22 2 4 1.61
Muricea elongata 22 2 4 1.61
Eunicea fusca 21 2 3 1.21
Muricea atlantica 21 2 3 1.21
Muriceopsis flavida 14 1 5 2.02
Eunicea laciniata 11 1 2 0.81
Plexaurella nutans 10 1 1 0.40
Eunicea clavigera 10 1 1 0.40
Total 248
aB.I. = Biological Index, McCloskey (1970).


B.I.a
(ranking)
39
36
36
34
31
31
30
29
26
25
22
15
14
12
12
10
10
10
10


Frequency
2
2
2
2
2
2
2
2
2
2
2
1
1
1
1
1
1
1
1


No. of
colonies
41
29
28
29
12
12
17
10
7
6
2
4
3
4
4
1
1
1
1
212


Percent
of total
colonies
19.33
13.67
13.20
13.67
5.66
5.66
8.01
4.71
3.30
2.83
0.94
1.88
1.41
1.88
1.88
0.47
0.47
0.47
0.47





Table 13a
Stony corals at Dome Reef (two 25-m transects, 1977; Jaap, unpublished).
Percent Percent
B.I.a No. of of total Cover of total
Species (ranking) Frequency colonies colonies (cm) cover
Montastraea annularis 40 2 21 53.85 880 0.6592 Density
Millepora alcicornis 38 2 8 20.51 140 0.1049
Siderastrea siderea 36 2 2 5.13 30 0.0225 Mean colonies/trans. = 19.50
Porites porites 36 2 2 5.13 15 0.0112 Standard deviation = 2.12
Colpophyllia natans 19 1 1 2.56 170 0.1273
Dichocoenia stellaris 19 1 1 2.56 10 0.0075 Diversity indicesb
Mycetophyllia ferox 19 1 1 2.56 65 0.0487
Porites astreoides 19 1 1 2.56 5 0.0037 H' = 2.20
Favia fragum 19 1 1 2.56 5 0.0037 H' max. = 2.20
Diploria clivosa 19 1 1 2.56 15 0.0112 J' = 0.66
Total 39 1,335
aB.I. = Biological Index, McCloskey (1970). bDiversity computed with log2.


Table 13b
Stony corals at Dome Control Reefa (two 25-m transects, 1977; Jaap, unpublished).

Percent Percent
B.I.b No. of of total Cover of total
Species (ranking) Frequency colonies colonies (cm) cover


Siderastrea siderea 39 2 10 33.33 290 31.69 Density
Dichocoenia stellaris 38 2 4 13.33 105 11.48
Agaricia agaricites 36 2 2 6.67 20 2.19 Mean colonies/tran. = 15.00
Millepora alcicornis 20 1 3 10.00 75 8.20 Standard deviation = 11.31
Montastraea annularis 19 1 1 3.33 280 30.60
Porites astreoides 18 1 2 6.67 25 2.73 Diversity indicesc
Porites porites 18 1 2 6.67 25 2.73
Diploria labyrinthiformis 18 1 2 6.67 40 4.73 H' = 2.88
Montastraea cavernosa 18 1 2 6.67 45 4.92 H' max. = 3.32
Favia fragum 17 1 1 3.33 5 0.55 J' = 0.87
Eusmilia fastigiata 17 1 1 3.33 5 0.55
Total 30 915

aReef similarity = affinity between Dome experimental and control reefs: Jaccard's coefficient = 0.3333; Morisita's coefficient = 0.5295.
B.I. = Biological Index, McCloskey (1970).
cDiversity computed with log,.





Table 14


Attributes of stony coral associations, Biscayne National Park,
based on several line transects at each reef (8 reefs, 18 transects) (Jaap, unpublished).

Stony coral associations
Transitional
Attributes bank reefs Patch reefs Livebottom


Transectsa
(1977)


Dominant species



% of colonies

Unique species


E 2, 3; EC 1,2, 3:
5 transects

Acropora cervicornis
Acropora palmata
Porites astreoides


St 1, 2; StC 1; D 1,2;
DC 1: 6 transects

Montastraea annularis


44.2


Millepora complanata
Siderastrea radians


Stephanocoenia michelinii,
Colpophyllia natans,
Mycetophyllia ferox,
Mycetophyllia lamarckiana


E 1; Sc 1, 2; ScC 1,2;
StC 2;:DC 2: 7 transects


Porites porites
Millepora alcicornis


48.2


Diploria labyrinthiformis


No. of species

No. of colonies

Diversity indicesb
H'n
H'c
H' max.

J'n
J'c

% cover (- SD)

Algae
Sponge
Octocoral
Stony coral

Abiotic substrate
(sand, + rubble +
rock)


2.79
2.57
3.58


0.3 +0.3
0.7 10.8
25.2 1 12.8
28.9 15.1


46.7 + 9.3


aE: Elkhorn Reef
D: Dome Reef
Sc: Schooner Reef
St: Star Reef
C: Control Reef, e.g., StC; Star Control Reef.
bH'n, J'n computed by abundance.
H'c, J'c computed by cover.


2.89
2.14
4.00

0.72
0.54


2.84
2.91
3.81

0.75
0.76


1.7 2.7
1.1 1.4
23.2 11.4
25.7 10.6


48.4 12.1


2.0 2.5
2.7 +3.3
38.3 15.3
14.3 9.7


42 19.0






Section 3.5) but are not as fully developed. They can
be thought of as embryonic bank ree .or a seriof
coalesced patch reefs, or well-developed hardgrounds
with relief. The marginal bank reefs found inshore of
Pacific Reef and continuing south to Pennekamp Park
boundary in BNP are examples of the embryonic bank
reefs. They possess a well-developed reef flat with some
trend of spur development by Acropora palmata on the
seaward fringe. The reef at number 1 buoy (Elkhorn
Reef) at BNP (Plate 18a) exemplifies these reefs.
Elkhorn Reef is about 500 m long in its north/south
axis and some 200 m long in its east/west axis. The reef
flat is a rocky platform with undercut solution holes and
ledges and sedimentary environments seaward and
landward. Off the northeast reef flat there are several
large haystack colonies of Montastraea annularis (Plate
5b), which are extensively excavated on the under-
surface. Their upper surfaces are dead, in some cases
supporting the sea fan, Gorgonia ventalina. The area
seaward of the reef flat platform is visually domi-
nated by octocorals and occasional large clusters of
Porites porites. There is a slight slope tohte-rmef-lthat that
in some places fas deins~T-lissters of Acropora palmata,
elkhorn coral. A summary of coral species, abundance,
and density is presented in Tables 15a, 15b, 16a, and
16b.
Acropora palmata colonies on the reef flat
interface are situated with major branches oriented into
prevailing seas, east/southeast. On the reef flat small,
more uniformly oriented colonies in less dense aggrega-
tions are common. They are associated with colonies of
Millepora complanata, Gorgonia ventalina, and Diploria
clivosa. This coral often propagates or spreads by vege-
tative "fragments" (Plate 10b). Broken fragments
settle in the nearby bottom and in a short time are
solidly attached. They grow upward forming new colo-
nies. The clustered distribution of this species is proba-
bly related to the fact that fragments are not transported
great distances from parent colonies. Mergner (1977)
reported that M. complanata (Plate 3b) is an indicator of
heavy wave surge. It is common in the reef flats and spur
and groove tract areas where wave surge is greatest.
Acropora cervicornis (Plate 4b), the other common
stony coral, occurs in small patches. It is not firmly
attached to the bottom and is moved about a good deal
during storms. Porites astreoides and P. porites are also
very common on the reef flat. The former is firmly
attached, while the latter is not.
On occasion, dislodged A. cervicornis colonies
come in contact with A. palmata colonies; a gall or fuse
is formed by a rejection reaction where the tissues of the
two colonies meet. The tapering cylindrical branches of
A. cervicornis grow upward entwined with the flat
frondose branches of A. palmata. A. palmata overgrows
A. cervicornis when they are in contact (J. C. Lang,
University of Texas, Austin; personal observation).
Another type of transitional reef develops on
the artificial substrates found throughout the reef tract.
They attract reef biota and in time become very reeflike.
They include shipwrecks and other materials. A good
example is the Benwood wreck in KLNMS. This large


steel ship sank during WWII and has numerous corals and
other sessile growth. The fish fauna is similar to those
of nearby natural reefs. The "French wreck" is a similar
phenomenon off Loggerhead Key, Dry Tortugas. Arti-
ficial reef substrate is also provided by ballast stone or
large blocks of igneous rock that were lost in shipwrecks.
These are also colonized by reef organisms, notably
Millepora sp. A number of large barges and ships have
been purposely scuttled in waters of 30 m and greater as
fish havens; these also develop natural reef growth.

3.5 MAJOR BANK REEF COMMUNITIES

Bank reefs are typically elongated and form a
narrow, linear, discontinuous arc from Miami south and
west along the Keys to the Dry Tortugas. They are
located near the abrupt change in bottom slope, which
marks the seaward edge of the Floridan Plateau and they
occur mostly between the 5- and 10-m depth contours.
The distinctive features of these reefs are the
occurence of Acropora palmata, the coral zonation by
depth (Table 18 and Figure 18), and the seaward spur
and groove formation.
Major bank reefs vary in morphology and species
composition. Some, such as Long and Ajax Reefs
(Figure 16 and Table 17), off Elliott Key, are sparsely
developed in their shallow zones, but below 12 m there
is growth on antecedent reef platforms. Better developed
bank reefs exhibit a zonation which varies from reef to
reef. Reef age, relative position, hydrodynamics, and
underlying topography are the major influences on
differences in reef morphology and zonation. The
general pattern is presented in Table 18. Specific details
for individual reefs are given below.

Carysfort Reef

Carysfort Reef (Figure 17) is the northernmost
reef in the KLNMS system. A large lighthouse is near
the north end of the reef flat. The reef flat has an
extensive concentration of Acropora palmata on its
seaward flank. The spur and groove formations are in an
early stage of development. Seaward portions of the reef
flat grade into a nearly barren area that separates the A.
palmata colonies from the buttress zone. The buttress
zone has extensive areas of low relief residual spurs and
grooves that have coral development. Haystack size
colonies of Montastraea annularis and fields of A.
cervicornis are common. The reef platform terminates at
about 27 m. Table 19 presents density and abundance
information for the stony corals in the 14- to 15-m
depth range. A broad expanse of rock separates the
reef platform proper from hard-substrate deep reef
communities. These deeper communities were described
by Jaap (1981) and Wheaton (1981). Outlying com-
munities continue to a depth of about 41 m. The stony
coral composition is similar to that of the deep reef;
Agaricia lamarcki, A. fragilis, and Helioseris cucullata are
the dominant species on vertical faces, while Siderastrea
siderea, M. cavernosa, and Madracis mirabilis are com-
mon on the horizontal surfaces.





Table 15a
Elkhorn Reef stony coral fauna (four 4-m2 plots sampled per reef, 1978; Jaap, unpublished).


Species
Porites astreoides
Acropora cervicornis
Diploria clivosa
Porites porites
Acropora palmata
Siderastrea siderea
Millepora alcicornis
Palythoa sp.
Millepora complanata
Favia fragum
Diploria strigosa
Dichocoenia stellaris


B.I.a
(ranking)
315
210
132
95
59
57
38
19
19
18
18
18


Frequency
16
11
7
5
3
3
2
1
1
1
1
1


No. of
colonies
60
15
11
7
6
4
3
1
1
1
1
1


Percent
of total
colonies
54.05
13.51
9.91
6.31
5.41
3.60
2.70
0.90
0.90
0.90
0.90
0.90


Mean no.
colonies/m2
3.7500
0.9375
0.6875
0.4375
0.3750
0.2500
0.1875
0.6250
0.6250
0.6250
0.6250
0.6250


Total


Density

Mean colonies/m2 = 6.94
Standard deviation = 2.35
Range = 3-12

Diversity indices

Mean species/m2 = 3.31
Standard deviation = 1.54
Range = 1-6


H' = 2.99
H' max. = 3.59
J' = 0.64


aB.I. = Biological Index, McCloskey (1970).

Table 15b
Elkhom Control Reef stony coral fauna (four 4-m2 plots sampled per reef, 1978; Jaap, unpublished).
Percent
B.I.a No. of of total Mean no.
Species (ranking) Frequency colonies colonies colonies/m2

Porites astreoides 260 14 68 59.65 4.2500 Density
Millepora alcicornis 146 8 9 7.89 0.5625
Diploria clivosa 115 6 7 6.14 0.4375 Mean colonies/m2 = 7.13
Acropora cervicornis 96 5 6 5.26 0.3750 Standard deviation = 2.35
Porites porites 94 5 7 6.14 0.4375 Range = 3-9
Agaricia agaricites 76 4 6 5.26 0.3750
Siderastrea siderea 56 3 5 4.39 0.3125 Mean species/m2 = 3.19
Palythoa sp. 38 2 2 1.75 0.1250 Standard deviation = 1.22
Dichocoenia stellaris 20 1 1 0.88 0.6250 Range = 1-5
Millepora complanata 19 1 1 0.88 0.6250
Porites branneri 19 1 1 0.88 0.6250 Diversity indices
Favia fragum 19 1 1 0.88 0.6250
H' = 2.22
Total 114 H'max. = 3.58
J' = 0.62
aB.I. = Biological Index, McCloskey (1970).





Table 16a


Elkhorn Reef octocoral fauna (three 20-m transects, 1977; Wheaton, in preparation b).

Percent
No. of of total
Species B.I.a Frequency colonies colonies


Gorgonia ventalina 59 3 46 22.01
Eunicea succinea 56 3 31 14.83
Plexaura flexuosa 55 3 28 13.40
Pseudopterogorgia americana 54 3 35 16.75
Plexaura homomalla 48 3 13 6.22
Muricea atlantica 46 3 9 4.31
Pseudoplexaura porosa 45 3 7 3.35
Pseudoplexaura flagellosa 42 3 3 1.44
Eunicea tourneforti 34 2 17 8.13
Plexaurella fusifera 29 2 5 2.39
Pseudopterogorgia acerosa 27 2 3 1.44
Eunicea laciniata 27 2 3 1.44
Pseudopterogorgia kallos 16 1 6 2.87
Muriceopsis flavida 13 1 1 0.48
Eunicea calyculata 13 1 1 0.48
Plexaurella dichotoma 13 1 1 0.48
Total 209


aB.I. = Biological Index, McCloskey (1970).

Table 16b

Elkhorn Control Reef octocoral fauna (three 20-m transects, 1977; Wheaton, in preparation b).

Percent
No. of of total
Species B.I.a Frequency colonies colonies


Pseudopterogorgia americana 54 3 39 13.27
Eunicea succinea 55 3 50 17.01
Gorgonia ventalina 54 3 49 16.67
Plexaura homomalla 52 3 29 9.86
Pseudoplexaura crucis 52 3 32 10.88
Plexaura flexuosa 51 3 31 10.54
Eunicea tourneforti 43 3 15 5.10
Muricea atlantica 40 3 11 3.74
Pseudoplexaura porosa 39 3 10 3.40
Pterogorgia citrina 37 3 8 2.72
Muriceopsis flavida 35 3 4 1.36
Pseudoplexaura flagellosa 28 2 7 2.38
Plexaurella dichotoma 24 2 3 1.02
Plexaurella fusifera 22 2 3 1.02
Eunicea fusca 13 1 1 0.34
Briareum asbestinum 13 1 1 0.34
Eunicea calyculata 10 1 1 0.34
Total 294


aB.I. = Biological Index, McCloskey (1970).





Table 17
Ajax Reef stony coral fauna at 17 m (fifteen


Species


Montastraea annularis
Siderastrea siderea
Millepora alcicornis
Montastraea cavernosa
Stephanocoenia michelinii
Madracis decactis
Porites astreoides
Agaricia agaricites
Dichocoenia stellaris
Porites porites
Eusmilia fastigiata
Agaricia lamarcki
Siderastrea radians
Diploria labyrinthiformis
Meandrina meandrites
Acropora cervicornis
Mycetophyllia aliciae
Madracis mirabilis
Mycetophyllia lamarckiana
Helioseris cucullata
Colpophyllia natans


B.I.a
(ranking)
32
32
25
18
10
9
8
5
3
3
3
2
2
2
2
2
1
1
1
1
1


Total species
Total colonies


Density, square meter
Species:
Colonies:


aB.I. = Biological Index, McCloskey (1970).
bD.I. = Dispersion Index, Elliott (1971): C = Contagious (clustered), R = Random, U = Uniform.


Key Largo Coral Reef Marine Sanctuary
S!


"C


kC." q


Biscayne


John Pennekamp Coral Reef State Park


d Hawk Channel
des
-yr^^^Key Largo

Barnes Souncd go Blackwater
Sound Buttonwood
Card Sound Sound

Figure 17. John Pennekamp Coral Reef State Park and Key Largo National Marine Sanctuary.


Abundance
52
50
32
21
14
9
8
5
3
3
3
2
2
2
2
2
1
1
1
1
1


Mean
6.13
14.33


Std. dev.
2.36
6.59


Range
1-9
1 -27


0
ealb


1-m2 plots; Jaap, unpublished).
Percent
of total Densit
colonies Mean Std
24.19 3.47 2
23.26 4.17 2
14.88 2.13 1
9.77 1.40 1
6.51 0.93 1
4.19 0.60 0
3.72 0.53 0
2.33 0.40 0
1.40 0.20 0
1.40 0.20 0
1.40 0.20 0
0.93 0.13 0
0.93 0.13 0
0.93 0.13 0
0.93 0.13 0
0.93 0.13 0
0.47 0.07 0
0.47 0.07 0
0.47 0.07 0
0.47 0.07 0
0.47 0.07 0


y
.dev.
.92
.86
.96
.55
.75
.74
.64
.51
.56
.77
.41
.52
.35
.52
.35
.35
.26
.26
.26
.26
.26


D.I.b
C
C
R
R
C
R
R
R
R
C
R
C
R
C
R
R
R
R
R
R
R







Table 18


Bank reef zonation patterns.

Depth
Zone (m) Conspicuous organisms


Back reef/rubble area 0.6- 1.8 Porites astreoides, Favia fragum

Reef flat 0.6- 1.2 Diploria clivosa, Porites astreoides,
(Plate 14a) Crustose coralline algae

Shallow spur and groove 1.2- 2.4 Millepora complanata, Palythoa sp.
(Plates 14b and 15a)

Deep spur and groove 2.4 4.6 Gorgonia ventalina,
(Plates 15b and 16a) Acropora palmata

Buttress or fore-reef 4.6 30.0 Montastraea annularis, Diploria
(Plates 16b and 17a) strigosa, Colpophyllia natans

Deep reef 41.1 Helioseris cucullata, Agaricia fragilis,
(Plate 17b) Madracis mirabilis


Figure 18. Cross-sectional diagram of Looe Key Reef.




Table 19


Carysfort Reef stony coral fauna at 14 15 m (ten 1-m2 plots; Jaap, unpublished).

Percent
B.I.a of total Density
Species (ranking) Abundance colonies Mean Std.dev. D.I.b


Montastraea annularis 18 45 36.00 4.50 3.70 C
Acropora cervicornis 11 26 20.80 2.60 4.60 C
Agaricia agaricites 8 15 12.00 1.50 3.10 C
Siderastrea siderea 6 6 4.80 0.60 0.80 R
Porites porites 5 12 9.60 1.20 3.50 C
Stephanocoenia michelinii 5 7 5.60 0.70 1.90 C
Porites astreoides 5 7 5.60 0.70 1.90 C
Colpophyllia natans 2 2 1.60 0.20 0.40 R
Mycetophyllia aliciae 2 2 1.60 0.20 0.40 R
Mycetophyllia lamarckiana 2 2 1.60 0.20 0.40 R
Millepora alcicornis 2 2 1.60 0.20 0.60 C
Helioseris cucullata 1 1 0.80 0.10 0.30 R



Total species 12
Total colonies 125

Density, square meter Mean Std. dev. Range
Species: 3.70 1.06 2-5
Colonies: 12.50 8.44 4-31


aB.I. = Biological Index, McCloskey (1970).
bD.I. = Dispersion Index, Elliott (1971): C = Contagious (clustered), R = Random, U = Uniform.


French Reef


Grecian Rocks


French Reef, KLNMS (Figure 17; Plate lb)
is farther south and is a popular reef for dive tours. It
has a widely separated reef flat and poorly developed
shallow spur and groove zones. The deep spur and
groove zone is well developed and has cavernous tunnels
through many of the spurs. Acropora palmata and M.
annularis are the dominant stony corals on the spur
formations. The spurs are usually 5-6 m deep on their
tops; this limits the firecoral Millepora complanata and
the yellow mat zooanthid Palythoa sp. from this reef
zone. Table 20 presents information on the abundances
and densities of stony corals from the deep spur and
groove zone at French Reef. The deep spur and groove
zone merges with a well-developed fore-reef buttress
zone. Seaward outcrops similar to those at Carysfort
Reef are also present seaward of French Reef. A deep-
reef survey seaward of about 40 m characterized the
bottom as sedimentary with occasional sponges, tilefish
burrows, and occasional outcrops of limestone with
epibenthic reef biota (Jameson 1981). A few solitary
corals (Paracyathus puchellus) were collected. Algal
nodules were found between 33 and 45 m (Shinn 1981).


Grecian Rocks, KLNMS (Plate 3a), described in
detail by Shinn (1963, 1980), is located somewhat
inshore of the main reef line of Carysfort, Elbow,
French, and Molasses Reefs. Unlike most bank reefs,
Grecian Rocks has no fore reef or buttress zone. The
zonational pattern includes five zones based on Shinn's
(1963) terminology (Table 21). It is about 600 m long
and 200 m wide with the long axis in a northeast/south-
west trend. The reef is surrounded by sediments and has
a narrow bathymetric range of 1.5-7.6 m.

Key Largo Dry Rocks

Key Largo Dry Rocks is near and similar to
Grecian Rocks, but has greater depth and more defined
spur and groove development. Orientation of A. palmata
branches are toward the prevailing seas, east to east/
southeast.
Key Largo Dry Rocks received much study
following Hurricane Donna in 1960 (Ball et al. 1967;
Shinn 1975). At that time the charts referred to Grecian
Rocks as Key Largo Dry Rocks and vice versa.





Table 20


French Reef stony coral fauna at 6 m (twenty-seven 1-m2 plots; Jaap, unpublished).

Percent
B.I.a of total Density
Species (ranking) Abundance colonies Mean Std.dev. D.I.


Acropora cervicornis 40 172 51.05 6.40 9.10 C
Millepora alcicornis 32 50 14.84 1.90 1.90 R
Acropora palmata 20 42 12.46 1.60 1.60 R
Agaricia agaricites 17 18 5.34 0.74 1.23 C
Montastraea annularis 16 19 5.64 0.72 1.00 R
Siderastrea siderea 13 14 4.15 0.50 0.83 R
Porites astreoides 12 14 4.15 0.50 0.93 R
Dichocoenia stellaris 2 2 0.59 0.11 0.32 R
Mycetophyllia sp. 1 1 0.30 0.03 0.21 R
Colpophyllia natans 1 1 0.30 0.03 0.21 R
Porites porites 1 1 0.30 0.03 0.21 R
Montastraea cavernosa 1 1 0.30 0.03 0.21 R
Favia fragum 1 1 0.30 0.03 0.21 R
Diploria clivosa 1 1 0.30 0.03 0.21 R



Total species 14
Total colonies 337

Density, square meter Mean Std. dev. Range
Species: 3.37 1.71 1 -6
Colonies: 12.48 8.74 1 -36


aB.I. = Biological Index, McCloskey (1970).
bD.I. = Dispersion Index, Elliott (1971): C = Contagious (clustered), R = Random, U = Uniform.






Table 21

Grecian Rocks zonation pattern (Shinn 1963, 1980).


Depth Conspicuous organisms
Zone (m) and remarks


Back reef 0-0.9 Nonoriented Acropora palmata,
A. cervicornis

Reef flat 0 0.9 A. palmata

Acropora palmata 0 1.2 Oriented A. palmata

Weak spur and groove 1.2 1.8 Montastraea annularis, M. complanata

Seaward rubble 1.8 2.4 Mostly coral rubble, few Siderastrea
siderea and M. annularis






Since the hurricane, staghorn corals (A. cer-
vicornis) have overgrown a great deal of Key Largo Dry
Rocks previously unoccupied by reef corals. The slower
growing star corals in the reef proper are also being
overgrown by the more rapid growing staghorn corals.
Shinn (1975) reported on this phenomenon and has
followed up the situation with annual inspections of a
particular set of colonies that are being encroached upon
by A. cervicornis.

Molasses Reef

Molasses Reef, KLNMS (Figure 17), is the
southernmost of the offshore bank reefs in the park
system. It is the most popular reef with scuba diving
tourists and has a large lighthouse that makes it very
easy to find. This reef fits most of the patterns defined
in Table 18; however, its reef flat is located a relatively
long distance from the spur and groove zone. The
buttress zone is quite narrow, but has large colonies of


M. annularis just seaward of the deep spur and groove
zone. Table 22 provides information on the densities and
abundances of stony corals in the spur and groove zone
at Molasses Reef. The investigation of seaward zones
with a submersible revealed rocky outcrops and sedi-
mentary environments similar to those described for
Carysfort and French Reefs (Jaap 1981).

Looe Key Reef

The zonation and morphology of Looe Key
Reef, Looe Key National Marine Sanctuary (Plates 2a
and b) are presented in Figure 18. Table 23 lists the
density and abundance of stony coral fauna on Looe
Key Reef. The major significant difference in this reef
from others is the wide area between the buttress zone
and the deep reef. In the northeastern part of the reef,
the deep reef does not exist; however, in the south-
western end, the deep reef community is evident in
patches between sedimentary deposits. Shinn et al. (in


Table 22


Molasses Reef stony coral fauna at 5 6 m (twenty-five 1-m2 plots; Jaap, unpublished).

Percent
B.I.a of total Density
Species (ranking) Abundance colonies Mean Std.dev. D.I.b


Acropora palmata 43 108 33.23 4.33 3.43 C
Acropora cervicornis 39 125 38.46 5.00 6.31 C
Montastraea annularis 19 38 11.69 1.53 4.11 C
Millepora alcicornis 17 20 6.15 0.82 1.00 R
Siderastrea siderea 6 6 1.85 0.22 0.73 C
Millepora complanata 4 5 1.54 0.21 0.50 R
Agaricia agaricites 4 4 1.23 0.20 0.51 R
Montastraea cavernosa 3 3 0.92 0.10 0.43 R
Porites astreoides 2 2 0.62 0.10 0.32 R
Favia fragum 2 2 0.62 0.10 0.43 R
Diploria labyrinthiformis 2 2 0.62 0.10 0.32 R
Madracis mirabilis 2 3 0.92 0.11 0.60 C
Mycetophyllia lamarckiana 2 2 0.62 0.10 0.30 R
Colophyllia natans 2 2 0.62 0.10 0.41 R
Dichocoenia stokesii 1 1 0.31 0.04 0.21 R
Meandrina meandrites 1 1 0.31 0.04 0.21 R
Mycetophyllia aliciae 1 1 0.31 0.04 0.21 R



Total species 17
Total colonies 325

Density, square meter Mean Std. dev. Range
Species: 3.36 1.55 1 -7
Colonies: 13.00 6.71 4-29


aB.I. = Biological Index, McCloskey (1970).
bD.I. = Dispersion Index, Elliott (1971): C = Contagious (clustered), R = Random, U = Uniform.





Table 23


Looe Key Reef stony coral fauna at 1 27 m (fifteen 1-m2 plots; Jaap, unpublished).

Percent
B.I.a of total Density
Species (ranking) Abundance colonies Mean Std.dev. D.I.


Porites astreoides 23 52 26.94 3.51 3.72 C
Millepora complanata 19 47 24.35 3.13 4.61 C
Agaricia agaricites 16 35 18.13 2.32 3.33 C
Porites porites 7 8 4.15 0.51 1.34 R
Favia fragum 6 7 3.63 0.50 0.62 R
Siderastrea siderea 6 8 4.15 0.51 1.13 R
Acropora cervicornis 6 7 3.63 0.50 1.10 C
Madracis decactis 5 9 4.66 0.61 1.63 C
Stephanocoenia michelinii 4 5 2.59 0.32 0.70 R
Siderastrea radians 3 4 2.09 0.30 0.82 C
Montastraea cavernosa 3 3 1.55 0.23 0.83 C
Mycetophyllia lamarckiana 2 2 1.04 0.12 0.42 R
Millepora alcicornis 2 2 1.04 0.12 0.50 C
Acropora palmata 1 1 0.52 0.10 0.30 R
Montastraea annularis 1 2 1.04 0.12 0.42 R
Meandrina meandrites 1 1 0.52 0.10 0.32 R



Total species 16
Total colonies 193

Density, square meter Mean Std. dev. Range
Species: 4.06 2.19 1-8
Colonies: 12.19 9.29 3-34


aB.I. = Biological Index, McCloskey (1970).
bD.I. = Dispersion Index, Elliott (1971): C = Contagious (clustered), R = Random, U = Uniform.


press) reported that net sediment transport was to the
southwest and that sediment was slowly covering the
reef's deeper areas.

Eastern and Middle Sambo, Eastern Dry Rocks, Rock
Key, and Sand Key Reefs

These reefs follow the general bank reef pattern.
They have well-developed seaward platforms that are
separated from the main reef structure and that have
significant relief. Again, these platforms are separated
from the main reef body by sediments.


Bird Key Reef

Bird Key Reef, Dry Tortugas National Monu-
ment (Figure 19), is unusual in that it does not have a
spur and groove zone in shallow water, and A. palmata is
not found at all in this reef community. The major coral
accretion is in waters deeper than 10 m on an antecedent
spur and groove formation that apparently developed
during a lower Holocene sea level stand. Shinn et al.
(1977) reported that cores bored on the shallow areas of
Bird Key Reef revealed that the reef was not founded on
a solidified platform but rather on considerable uncon-














Reef Flat


BIRD KEY REEF
24' 36.6'
82 52.3'


Dista 'VVe
ne(m) 120* ~


Figure 19. Cross-sectional diagram of Bird Key Reef.


solidated sediments overlying a Pleistocene basement.
The shallowness of the reef and severe winter temper-
atures probably prevent A. palmata from occurring on
the shallow reef at Bird Key.

Summary

No universal pattern exists; each reef has dif-
ferent features. Major controls include geographic con-
figuration of the Florida Keys archipelago (Ginsburg
and Shinn 1964); winter cold fronts chijirg Florida
Keys water masses (Hudson et al. 1976, Walker et al.


1982); reef age or stage of development (Shinn et al.
1977, 1981); and relationships with sedimentary en-
vironments (Giiisburg 1956, Shinn et al. 1981). Com-
munity structure patterns reflect the stage of reef
development. For example, spur and groove construc-
tion requires long term dense aggregations of Acropora
palmata (Shinn 1963; Shinn et al. 1981). Development
of the spur and groove habitat in turn creates micro-
habitats (niches) that are necessary for the existence of
other reef organisms. For example, the Millepora com-
planata association is found in the turbulent shallower
portions of the spur and groove habitat (Mergner 1977).






CHAPTER 4


CORAL REEF BENTHOS


4.1 INTRODUCTION

The benthos (bottom-dwelling organisms) within
a coral reef is complex, diverse, and for many taxa,
poorly knQwn. Benthos in a coral reef constitutes the
critical biota or foundation species. In particular, the
corals and crustose coralline algae are most significant in
niche creation for the other multitudes of species.
Complexity is shown by the infaunal boring biota;
reports of species within a single coral head ranged from
30 to 220 and the number of individuals ranged from
797 to 8.267 (McCloskey 1970; Gibbs 1971). Most orga-
nisms were polychaetes, a group that is poorly under-
stood. Because it would be literally impossible at this
time to compile a total benthic community profile, this
chapter will cover those groups which are critical to
the community: algae, sponges, and Cnidarians (e.g.,
corals). Since corals are major elements of the reef,
emphasis will be on the Milleporina, Octocorallia, and
Scleractinia.
Volumes 2 and 3 of Biology and Geology of
Coral Reefs (Jones and Endean 1973, 1976) contain
information on many benthic groups, but the major
emphasis is on Indo-Pacific reefs. Although the infor-
mation can be extrapolated in many cases to Florida, the
species are for the most part different. Recently, Rutzler
and Macintyre (1982b) published a fine volume on the
biota from the barrier reef at Carrie Bow Cay off Stann
Creek Town, Belize.

4.2 ALGAE
(by Harold Humm, Department of Marine Science,
University of South Florida, St. Petersburg)

Historical

Knowledge of the benthic algae found on coral
reefs of southeast Florida is based largely on inference
from work done on coral reefs in the West Indies,
especially in the Virgin Islands, Puerto Rico, Jamaica,
Curacao, Barbados, Guadalupe, and Martinique. There
are many seaside research facilities open to visiting
scientists in the Caribbean area but only one in southeast
Florida, and that with limited facilities for visitors. Thus,
for these and other reasons, studies of the benthic algal
flora of Florida coral reefs are sparse.
William Randolph Taylor of the University of
Michigan was the first to make a significant contribution
to the knowledge about the species of benthic algae
found on Florida coral reefs, after he spent the summers
of 1924-1926 at the Carnegie Laboratory, Dry Tortugas.
Taylor's work at Tortugas was a general floristic survey;
his field data provided information on species associated
with reef environments. These data are included in
Taylor (1928) and Taylor (1960), Marine Algae of the
Tropical and Subtropical Coasts of the Americas, still
available from the University of Michigan Press.


Earlier references for the study of benthic algae
found on Florida reefs and the western Atlantic in
general include Harvey (1852, 1853, 1858); Vicker
(1908); Collins (1909); Borgesen (1913-1920); Collins
and Harvey (1917); and Howe (1918, 1920).
Contemporary studies of great value include
Earle (1969, 1972b), which list virtually all algae known
to occur on Florida's coral reefs.
Grazing on algae of coral reefs is discussed by
Randall (1961a), Mathieson et al. (1975), Wanders
(1977), and Brawley and Adey (1981).
Productivity of algal components within coral
reef communities, including those that bore into lime-
stone and the coral symbionts, is treated by Marsh
(1970), Littler (1973), and Vooren (1981).
Colonization and succession of reef algae were
reported by Adey and Vasser (1975), Wanders (1977),
and Brawley and Adey (1981). Algal zonation at
Curacao was described by van den Hoek et al. (1975).
Algae that bore into coral and limestone were
studied experimentally by Perkins and Tsentas (1976).
Coralline algal ridges (Note: these are not found in
Florida) are reported by Adey (1975, 1978). The coral-
line algae were recently treated by Johansen (1981).
The only recent reef algae study from Florida
reefs is Eiseman (1981), who made diving observations
and collections during the KLNMS deep reef survey
using a submersible. The study began at a 30-m depth
and reported 60 species from reef and lithothamnion
cobble habitats. The algal species from these two habi-
tats were virtually exclusive.

Algae in Coral Reefs

One of the characteristics of coral reefs the world
over is the apparent paucity of benthic macroalgae on
and around the reefs, at least to the casual observer.
"Where are the plants?" might be an immediate question
of a biologist who is familiar with temperate or boreal
seas and views a coral reef for the first time because
rocky substrata in clear, shallow water would normally
support a dense stand of large benthic algae.
A significant biological control of algae on coral
reefs is the competition for space with other epibenthic
sessile organisms. The diversity of organisms on a coral
reef probably exceeds that of all other marine eco-
systems. The sessile animals occupy space that would
otherwise be colonized by benthic algae. On recently
exposed limestone substrates, especially following
physical impact, benthic algae may be the first colo-
nizers, but they are usually replaced by sponges, tuni-
cates, corals, and bryozoans after a short period. An-
other major biological control on benthic macroalgae
is grazing by the herbivorous invertebrates and fish.
Of all shallow-water marine ecosystems, none are more
profoundly affected by grazing than coral reefs.
The effects of grazing on coral reefs have been







demonstrated experimentally in many reef studies, al-
though apparently not in Florida, by placing a barrier
over a selected site and observing the response of the
algae that are protected from most grazing. Randall
(1961b), working in Hawaii, found a significant differ-
ence between the algal cover inside an enclosure and that
of areas outside it after 2 months. Inside the enclosure
the algae grew to normal height and breadth (to 30 mm);
outside the enclosure, the algae averaged 1 mm in height.
In Lameshure Bay, St. John, Virgin Islands, Randall
excluded fish, but allowed herbivorous sea urchins
(Diadema antillarum) in the closed area. Results showed
that the fish were the major grazers. While the urchins
also fed on algae, their action did not affect the algae as
severely as did the fish. Randall also showed that parrot-
fish and surgeonfish graze on seagrass adjacent to the
reef, thereby causing the sand halos around patch reefs.
Research conducted during the submersible habitat
study known as Tektite II at Lameshur Bay, St. John,
Virgin Islands, confirmed and expanded Randall's
observations on grazing. Fish grazing was found to be a
major factor influencing biomass and species diversity of
benthic algae on coral reefs. In addition to cage exper-
iments, algae was transplanted from elsewhere to the
reef; the algae was rapidly eaten. Grazing pressure was
intense to a distance of 30 m; beyond that distance it
gradually tapered off (Earle 1972a; Mathieson et al.
1975).
Ogden (1976) reported on algae-grazer relation-
ships on coral reefs and reported those algae that grazers
tend to avoid. Prolific algal growth occurred only in
areas inaccessible to grazing herbivores, such as wave-
washed surfaces and beachrock benches. Ogden and
Lobel (1978) summarized the role of herbivorous fish
and urchins in coral reef communities with special
reference to reefs around St. Croix, Virgin Islands.
A comprehensive study of the effects of elim-
ination or reduction of grazing by means of cages was
reported by Wanders (1977), who worked at Curacao.
His results are applicable to Florida reefs. He found that
crustose coralline algae depend upon grazing for protec-
tion from competition by erect fleshy algae. Under a
cage that covered a patch of coralline algae, the fleshy
algae soon colonized the surface of crustose species,
resulting in the death of the crustose species. The
crustose forms were penetrated by microscopic species
that bored into the limestone. When clean artificial
substrates were placed under cages on the reef, a succes-
sion was observed as the fleshy algae colonized it. During
the first 6-8 weeks the colonizers were principally
filamentous brown and green algae of the genera Grif-
fordia, Cladophora, and Enteromorpha. After 10-15
weeks these were replaced by larger filamentous and
parenchymatous species, in particular, the filamentous
red algae Centroceras clavulatum and Wrangelia argus; a
small, erect-growing coralline red, Jania capillacea; the
larger red algae Spyridia filamentosa, Pterocladia amer-
icana, and Laurencia microcladia; and the flat, dichot-
omous brown algae Dictyota dichotoma. All of these are
common species on Florida coral reefs and can be found
where succession on new substrates would be similar to


the experiment at Curacao. Wanders concluded that
grazing does note reduce the primary productivity per
unit area in Curacao, but only affects species compo-
sition.
Brawley and Adey (1981) observed the effects of
another category of grazers on coral reefs (other than
fish and macroinvertebrates such as urchins) that might
be referred to as micrograzers, crustaceans of the Order
Amphipoda. In a coral reef microcosm in the Smith-
sonian Institution, Washington, D.C., they observed that
a tube-building amphipod of the genus Amphithoe
grazed selectively on filamentous algae. They suggested
that this micrograzer may help reduce competition for
the encrusting coralline algae.
While grazing by fish is a major factor in the
paucity of fleshy algae in coral reef habitats, there are a
few coral reef fish whose activity has the opposite effect.
One of these is the three-spot damselfish, Pomacentrus
planifrons. It establishes a territory, especially in the
proximity of Acropora cervicornis, A. palmata, and
Montastraea annularis, and then bites segments, strips, or
patches of the coral, killing the polyps. These dead coral
areas are colonized in a few days by a variety of erect
-growing fleshy algae: The damselfish, by its unusual
aggressive habit of defending its territory, keeps out algal
grazers and thus maintains extensive patches of fleshy
algae on the reef where normally they would not exist.
Detailed observations on the damselfish and their algal
lawns were reported in Jamaica by Brawley and Adey
(1977) and in other Caribbean localities including
Jamaica by Kaufman (1977). The three-spot damselfish
occurs on Florida's coral reefs as do all the algae species
recorded and listed by Brawley and Adey from Discov-
ery Bay, Jamaica. The exception is Halimeda goreauii.

Algal Groups

Benthic algae of tropical coral reefs can be
categorized into four major groups, all occupying areas
of the reef itself or areas under the influence of grazers
inhabiting the reef. They are crustose coralline algae
that encrust corals, reef rock, and other limestone
skeletal material; filamentous and fleshy algae, which
occur as sparse vegetation and dense vegetation; algae
on unconsolidated sediments, which are erect macro-
algae of the order Siphonales and mats of bluegreen
algae; and excavating or boring algae.

Crustose Coralline Algae

The most distinctive and characteristic algal
group of the coral reef is the crust-forming coralline red
algae Rhodophyceae, order Cryptonemiales, family
Corallinaceae, subfamily Melobesieae. These algae form a
thin or massive crust with or without erect branches and
are calcified throughout. When living, they are usually a
shade of red in low light, but may be yellow-brown in
surface light. They are chalk-white when dead, but soon
become greenish as a result of the establishment of the
green and bluegreen algae that bore into limestone and
lend color to the upper few to 5 mm of the skeleton.







Crustose corallines form small, scattered colonies
or large, distinct patches. On Florida reefs, there may be
some degree of development of incipient algal ridges, a
formation found extensively on coral reefs in the eastern
Caribbean Sea (Adey 1978). Coralline algae are common
on the underside of corals such as Acropora spp. and
colonize dead coral fragments that break off and fall to
the seafloor. Large patches are found on the reef plat-
form limestone, the living surface layer covering former-
ly living veneers of the same species. Minute species that
form small, thin crusts are often epiphytic upon larger,
fleshy algae, seagrass leaves, octocoral skeletons, mollusk
shells, and hydroid colony bases. Crustose corallines are
best developed in shallow, turbulent areas where light
intensity is high and fish grazers are partially deterred by
wave forces.
Colonization, succession, and growth rate of the
tropical crustose coralline algae were unknown until the
study of Adey and Vassar (1975) in St. Croix. Their
results probably apply in Florida, which has fewer
species, for April through November. Adey and Vassar
(1975) reported that the margins of a crust grow 1-2
mm/month and that accretion rates are 1-5 mm/year,
depending on herbivore grazing, especially parrot-
fish.

Filamentous and Fleshy Algae

Filamentous and fleshy algae are uncalcified
coral-reef macroalgae that colonize coral rubble and reef
limestones. This group is most adversely affected by
grazing. Two subdivisions are recognized: the dense and
sparse vegetation. They comprise the same species,
although the dense community, if not spatially limited
to crevices or small patches, exhibits greater species
diversity. The sparse community occurs in areas re-
ceiving the heaviest grazing pressure, resulting in cropped
forms often 1-2 mm high. There is a transition of sparse
community on or near the reef to the dense community
located away from the reef, resulting from a gradient in
grazing pressure.

Unconsolidated Sediment Algae

Few algae have the functional ability to anchor
in unconsolidated sediment. For this reason, the sea-
grasses, rooted forms that evolved on land and radiated
into the marine environment, dominate shallow sedi-
mentary habitats, especially in tropical regions. There
are, however, a few specialized algae on loose sedimen-
tary environments; these are especially well represented
in coral reef habitats.
There are two major groups capable of colonizing
sandy or muddy bottom areas. The bluegreen algae
(Cyanobacteria) form mats and penetrate the sediment
to some extent. Green algae, belonging to the order
Siphonales, erect coenocytic plants (lacking cell walls)
having a dense cluster of root-like rhizoids at the base
that provides a firm anchorage in unconsolidated sedi-
ments. Mathieson et al. (1975) included an underwater
photograph of this community.


The mat-forming bluegreen algae community is
composed primarily of filamentous species (sensu
Drouet 1968), e.g., Microcoleus lyngbyaceus and Schizo-
thrix calcicola. Other filamentous species, including
Porphyrosiphon notarisii and Schizothrix arenaria,
and several coccoid (spherical) species are usually
associated with these mats. Ginsburg (1972b) reported
that the filaments of mat-forming bluegreens grow
upward during the day and selectively trap sediment
particles at night; horizontal growth of another species
results in binding of trapped sediments.
Erect-growing anchored green algae in sediments
are found within the genera Halimeda, Penicillus, Udo-
tea, Rhizocephalus, A vrainvillea, and Caulerpa. They are
usually scattered and scarce immediately around the
reefs, but become progressively more abundant away
from the reef proper as grazing pressure is reduced. The
dense cluster of rhizoids that anchor these plants stabi-
lizes the sediments and absorbs nutrients. Since these
algae are coenocytic, transport of nutrients to the tops
and of photosynthetic products to the rhizoids is carried
on rapidly in conjunction with cytoplasmic streaming.
They are a unique group of highly evolved green algae, as
advanced among the algae as the flowering plants on
land.
Members of this group also contribute signif-
icantly to calcium carbonate production and sediment
on and around the reef. This is especially notable among
the species of Halimeda.

Excavating or Boring Algae

Among the least conspicuous and most often
overlooked algae are those possessing the ability to bore
into limestone by dissolving it as they grow. To the
unaided eye they are visible as a greenish tinge or dis-
coloration at the surface of dead coral, mollusk shells,
dead coralline algae, and other limestone material.
Boring algae belong to three taxonomic groups. Most are
bluegreen (Cyanobacteria), some are green (Chloro-
phyta), and the remaining one (Xanthophyta) has no
common name.
Representatives of three families of bluegreen
algae are known from Florida coral reefs: Entophysalis
deusta, family Chamaesiphonaceae; Schizothrix cal-
cicola, family Oscillatoriaceae; Mastigocoleus testarum,
family Stigonemataceae. The green algae Gomontia
ployrhiza and the xanthophyte Ostreobium quekettii
are known from Florida.
These algae are collected by dissolving a small
sample of greenish limestone in dilute hydrochloric acid
and examining isolated filaments. Keys to the species are
found in Humm and Wicks (1980). A comprehensive
experimental study of limestone-boring algae is found in
Perkins and Tsentas (1976); the study was from St.
Croix. They reported five bluegreen and three green
algae species. One of their bluegreens, Calothrix sp.
(Calothrix crustacea; sensu Drouet 1968), has not been
reported as a boring alga in Florida; however, it is
abundant on Florida reefs and must be presumed to be a
borer. Algae that bore into limestone contribute signif-






icantly to the dissolving of limestone, adding calcium
and bicarbonate to the mineral pool in the reef environ-
ment.

4.3 SPONGES
(by G.P. Schmahl, South Florida Research Center,
U.S. National Park Service, Homestead).

Sponges (Porifera) are an important component
of the benthic fauna of Florida reef. Although not
usually dominant, sponges are common in most reef
zones and can be especially abundant in certain situ-
ations. Substrate analysis of the benthic fauna on
selected upper Florida Keys patch reefs indicated a
sponge component ranging from 1.2% to 9.2% of the
surface area sampled (Jaap and Wheaton 1977).

Taxonomy

Sponges are grouped into four classes. The largest
is the Demospongiae, which account for 95% of all
recent species. Virtually all common shallow water reef
sponges are demosponges with most of the remainder be-
longing to the class Calcarea. The Demospongiae are
characterized by skeletal components consisting of
siliceous spicules that are supplemented or replaced by
organic spongin, which forms fibers or acts as a ce-
menting element. The skeleton of the Calcarea, as the
name implies, is made up of calcareous, usually triradiate
spicules. A third class of sponges, the Sclerospongiae,
secrete a compound skeleton of siliceous spicules,
spongin fibers, and calcium carbonate. Sclerosponges can
be an important structural component of some deep fore
reef environments (Lang et al. 1975) but have not been
reported from Florida reefs (Dustan et al. 1976). The
fourth class of sponges, the Hexactinellida, are mainly
deep water species and are characterized by hexactinal
(six-rayed) megascleres (type of spicule).
Classification of the sponges is based primarily
on the size and shape of the spicules (megascleres and
microscleres) and the organization of the skeletal matrix
of spicules and organic fibers found within the various
species. Gross morphology, surface texture, color, and
arrangement of the incurrent and excurrent ostia are also
considered important. Recently, studies in the areas of
comparative biochemistry (Bergquist and Hartman
1969), reproductive life history characteristics (Levi
1957), structure and function of sponge cells (Simpson
1968), and ecology have contributed much to clarify
taxonomic organization. In spite of this, classification of
the Porifera is still in a state of change and confusion.
However, the widespread use of scuba, in situ color
photography, and standardized collecting techniques
have all helped in the field identification of major
sponge species. Field guides are now available (Voss
1976; Colin 1978a; Kaplan 1982) which offer to the
nonspecialist some information on Caribbean reef
sponges. Of these, the identifications given in Kaplan
(1982) are the most up-to-date. Inconsistencies in
nomenclature found in these publications reflect the
confusion that surrounds sponge systematics. Most


common sponge species have characteristic shapes,
colors, and habitat preferences which allow them to be
identified confidently in the field, at least within a
specified geographic area (e.g., Florida).
Of the more technical taxonomic literature on
Caribbean sponges, only a few were based on collections
primarily from Florida. An early work that described
some Florida reef sponges was that of Carter (1885).
Later Florida studies on the sponges of the Gulf of
Mexico by de Laubenfels (1953) and Little (1963) also
included some reef species. The most complete work of
sponge taxonomy for Florida reef sponges was made by
de Laubenfels (1936) in the Dry Tortugas. Although
now somewhat out of date in terms of the present
interpretation of sponge classification, this is an impor-
tant work in that all known Caribbean sponge families
were listed and their taxonomic characteristics des-
cribed. Since the sponge fauna found on Florida reefs
is decidedly West Indian, taxonomic works from other
areas of the Caribbean are sufficient for most Florida
species. Recent studies of this type include those from
the Bahamas (de Laubenfels 1949; Wiedenmayer 1977),
Bermuda (de Laubenfels 1950), Jamaica (Hechtel 1965),
and Curacao (van Soest 1978, 1980). The studies by
Wiedenmayer (1977) and van Soest (1980) introduced
new classificatory interpretations. Taxonomic works on
burrowing sponges likely to be found in Florida include
Pang (1973a, 1973b) and Rutzler (1974).
A definitive list of Florida sponge species does
not exist. de Laubenfels (1936) described 76 species
from the Dry Tortugas, but 5 were dredged from 1,047
m and 9 others were collected from sites ranging from
70 to 90 m, which is out of the range of most typical
Florida coral reef growth. Wiedenmayer (1977) des-
cribed 87 shallow water species from the western Ba-
hamas in a work that reevaluates the validity of scientific
names applied to many common reef species. Careful
reference to synonymy must be taken into consideration
when comparing Wiedenmayer's (1977) lists with those
of previous workers. Given the proximity of his study
site, it is reasonable to assume that most of the 87
species Wiedenmayer (1977) described can also be found
in Florida. Fifty-seven species of sponges have been
recorded from Bermuda (de Laubenfels 1950) and
Jamaica (Hechtel 1965). Of the species treated by
Wiedenmayer (1977), 39 listed are from the Dry Tor-
tugas and 22 from the Florida Keys. These lists were the
result of a literature review and not based on field
studies, so the actual number of species in these local-
ities is open to question.
A brief survey of sponges of the Dry Tortugas by
National Park Service investigators revealed 85 species,
only 43 of which were recorded by de Laubenfels
(1936), and 57 of which were among the 87 species
described by Wiedenmayer (1977). The low overlap of
species lists indicates a species pool much larger than
reported by any one study; the number of species
present is seemingly correlated with the amount of time
spent looking. It is important to note that the above
studies deal with all sponge species encountered in the
area, including those common in lagoonal areas, man-







groves, and inshore pilings. Those sponges that dominate
in reef areas are a more or less distinct group and, with
some overlap, are substantially different from those
which are abundant in lagoonal areas (Wiedenmayer
1977). An extensive study of the patch reefs of Biscayne
National Park (upper Florida Keys) reported the occur-
rence of 98 species associated only with inshore reefs in
less than 10 m of water (Schmahl and Tilmant 1980).
Additional species have been collected from deeper
water on the outer bank reefs. From the evidence so far,
a conservative estimate of the sponge species occurring
on or around Florida reefs must be at least 120.

Autecology

Sponges exhibit both asexual and sexual repro-
duction. Asexually sponges may be regenerated from
fragments, gemmules, and reduction bodies. Sexually,
the group has both dioecious and hermaphroditic
,species. Fertilization is usually internal and both ovip-
arous and viviparous species are common. This fact
forms the basis of the division of the Demospongiae into
its two main subclasses: Tetractinomorpha (oviparous)
and Ceractinomorpha (viviparous), although exceptions
are known. Viviparous species usually incubate paren-
chymula (solid) larvae, while development in oviparous
forms is usually external.
Amphiblastula (hollow) larvae are exhibited by a
third subclass of Demospongiae, the Homoscleromorpha,
and some calcareous forms. A promising method that
may be used to access the extent of asexual reproduc-
tion in an area is the ability of sponges to recognize
tissue of like genetic composition ("self"). Experiments
may be carried out whereby strains can be recognized
through differential acceptance of tissue from other
individuals in an area (Kaye and Ortiz 1981). Repro-
duction in sponges was reviewed by Fell (1974), but
there is much yet that is unknown about that process in
most species. A recent review by Simpson (1980)
pointed out the many areas open to research.
Larval ecology and behavior is fundamental to
the distribution of adult forms. Most sponges have sex-
ually produced larvae that are free-swimming, at least for
a short period, although some species have been shown
to produce larvae that do not swim but creep over the
substrate (Bergquist 1978). Three physical attributes
influence the swimming and settlement of sponge
larvae: light, gravity, and water turbulence. The com-
paritive morphology and behavior of some Demosponge
larvae have been reviewed by Bergquist et al. (1979).
Sponges are filter feeders and must take in great
quantities of water from which they remove plankton,
bacteria, organic, and other nutrients from the water
column. It has been estimated that the abundance and
pumping activity of sponges on the fore reef slope of
Discovery Bay, Jamaica, are such that a volume equiv-
alent to the entire water column passes through the
population every 24 hours (Reiswig 1974). Sponges are
capable of removing extremely small organic particles.
In a study by Reiswig (1971b), 80% of the organic
carbon removed by three species of sponges could


not be seen under an ordinary light microscope and was
thus postulated to be of colloidal (quasi-particulate)
nature. Many sponges depend on ambient currents to aid
in water transport through their tissues and to decrease
the amount of energy expended on pumping activities
(Vogel 1977). Thus, hydrodynamic regimes are impor-
tant in shaping sponge distributions. In tropical areas,
where reef boundary layers are typically low in nutrients
and organic particulate matter, increased water flow by
currents can be essential for the survival of many large
species.
Light intensity can be important in shaping
sponge communities for various reasons. In one respect,
reduced light intensity increases sponge abundance due
,to decreased competition from reef corals that depend
on light for survival of symbiotic zooxanthellae. Sponges
typically proliferate in deep fore reef areas below the
zone of maximum coral growth. Some sponges, however,
have been shown to contain species of symbiotic blue-
green algae (or Cyanobacteria) which have been impli-
cated in the distribution of those species, restricting
them to shallow areas where light is abundant (Wilkinson
1978).
For a good general review of sponge biology,
consult Bergquist (1978). Several recent collected works
have been compiled as the result of symposia on the
biology of sponges or in response to the need for cohe-
siveness in sponge research. These include Fry (1970),
Harrison and Cowden (1976), Levi and Boury-Esnault
(1979), and Hartman et al. (1980).
Quantitative ecological studies of sponges on
Caribbean reefs are few. The most complete series of
studies of Caribbean demosponges to date were those
carried out by Reiswig (1971a, 1971b, 1973, 1974) on
three common species found on Jamaican reefs. These
studies set the standard for ecological methodology of
sponges and their information is generally compatible
with Florida populations. His findings emphasized the
variability displayed by the different species in regard to
pumping activities, feeding, life history characteristics,
population dynamics, and respiration. Ecological studies
on entire sponge communities are rarer still. Alcolado
(1979) investigated the ecological structure of sponges
on a Cuban reef, and data were given in Wiedenmayer
(1977) stressing synecological relationships of sponges in
his Bahama sites. The difficulty of carrying out such
studies is reviewed by Rutzler (1978) who also gave
some methods for quantitative assessment of sponges
on coral reefs.
From these studies and from qualitative and
incidental observations, sponge communities are known
to be partitioned along habitat and depth gradients on
coral reefs. Habitat preference, reproductive strategies,
growth form, and competitive ability are important
biological agents that influence sponge distribution.
Abiotic factors, some linked directly or indirectly with
depth (e.g., light intensity, temperature, intensity of
wave and surge action, and sedimentation) are also major
controlling forces in shaping sponge assemblages.
Massive sponges are rare on reef flats where small
or low encrusting forms are predominant (Reiswig 1973;






Alcolado 1979), presumably because of the scouring
action of waves and the increased sediment load caused
by turbulence. Many species cannot tolerate high sedi-
ment loads. In Verongia lacunosa pumping rate is re-
duced under increased sediment conditions (Gerrodette
and Flechsig 1979). Species with high sediment toler-
ance, such as Tethya crypta, can be common on the reef
flat as are encrusting species such as Spirastrella cunc-
tatrix and Thalysias juniperina. Species of the genus
Cliona are also common, infesting dead coral skeletons
and other suitable substrate. In deeper areas (> 7 m),
where conditions are more predictable and favorable,
massive sponges increase in abundance. Common species
found on the outer reefs of the upper Florida Keys
include Amphimedon compressa, lotrochota birotu-
lata, Ulosa ruetzleri, Ircinia strobilina,' Ectypoplasia
ferox, Callyspongia vaginalis, Niphates erecta, N. digi-
talis, N. amorpha, Cliona deletrix, and Xestospongia
muta (name designations after van Soest 1978 and
1980, and Wiedenmayer 1977).

Synecology

Sponges are major competitors with other epi-
benthic organisms for space and other resources in reef
habitats. Sponges have the greatest overgrowth capa-
bility of the major groups of organisms encrusting
undersurfaces of foliaceous corals (cheilostome ectop-
rocts, crustose algae, and other algae). Results varied
with depth, but sponges were the superior overgrowth
competitors in 77% of the interactions monitored
(Jackson and Winston 1982). Overgrowth of Caribbean
corals by sponges has been observed for Chondrilla
nucula (Glynn 1973), Ectyoplasia sp., and Plakortis sp.
(Lang 1982), and has been demonstrated for Antho-
sigmella var. f. incrustans (Vicente 1978), which was
found to have a high level of competitive superiority
compared with corals and other sponges. Some sponge
species have been shown to exhibit toxicity to corals
which they overgrow, causing necrosis of the coral tissue
along the line of contact (Bryan 1973). Such a mech-
anism of competitive interaction presumably concerns
the production of species-specific allelochemicals (Jack-
son and Buss 1975; Buss 1976), which can lead to
intricate competitive networks and act to allow high
diversity in areas of low disturbance. Sponges have also
been shown to enter into complex epizoic relationships
(living on one another) with one another (Rutzler 1970)
which may be in response to competitive pressures.
Sponges are involved in symbiotic relationships
with other reel.organisms&Many-sponges-exisLin sym-
liQ.sis.wi.t-hlbluegree n-alga-e(or Cyanobacteria), which are
mostly free living within the mesophyll and may consti-
tute up to_52% of the cellular material of the sponge
(Rutzler 1981). Nutrient translocation of algal products
to coral reef spong~es-aiasleen demonstrated by Wilkin-
son (1979). Sponges can. therefore,,supplement their
energy requirements, through this relationship. Goreau
arid Hartman (1966) noted that the Caribbean sponge
Mycale laevis has a symbiotic relationship with some
stony corals. The sponge benefits from a protected and


enlarging coral base to grow on, while the coral is aided
by protection fyom borin-g_rg.anisns that usually gain
access throtLl h the cor.a's unidersurlace. The coral
possibly benefits also from greater access to hetero-
trophic energy sources carried in the sponge-created
water currents. An obvious symbiotic relationship in
Caribbean sponges involves species of Zoanthidea
(Anthozoa) which grow on the surface of some sponges.
Taxonomy of the sponge-associated zoanthids has been
given by West (1979). Aspects of the ecology of sponge-
zoanthid associations have been investigated by Crocker
and Reiswig (1981), who found a high specificity be-
tween species of host sponges and their associated
zoanthids. Lewis (1982) studied some functional aspects
of this relationship and suggested that the zoanthid
presence may have a deleterious effect by decreasing the
host sponge's pumping capabilities.
Another in!portantrole of -ponges in coral reef
ecosstems is thiatoLf-.proYiding.shelter for other reef
orgasms. Tyler and Bohlke (1972) listed 39 species of
fish that associate with sponges, at least 5 of which are
obligate sponge dwellers. The interior cav iies.fi.certain
sponges are inhabited by numerous invertebrates (Pearse
1932; Westinga and Hoetjes 1981), mostly crustaceans,
of which the alpheid_ hrim.saret thte nsti roninent.
The residents also include polychaete and annelid
worms. Reiswig (1973) reported that the sponge Veron-
gia gigantea supported large populations of Haplosyllis
spongicola in the canal system; densities of 50-100
polychaete individuals per ml of sponge were found.
Haplosyllis spongicola is also a frequent inhabitant of
the sponge Neofibularia nolitangere.
Sponges serve as a food source for other or-
ganisms, predominantly coraJ reef fish and some marine
turtles. In genernal,Jhowever, predation is not intense.
Only in 11 of 212 fish species (5%) studied by Randall
and Hartman (1968) did sponge remains comprise over
6% of stomach contents. Angelfish of the genera Holo-
canthus and Pomacanthus and the whitespotted filefish
(Cantherhines macrocerus) were the major sponge
predators. Abundance of mineralized sclerites, noxious
chemical substances, and tough fibrous components have
been identified as reasons for low predation pressure on
most coral reef sponges. The toxicity to fishes of many
common exposed (noncryptic) Caribbean sponges has
been shown by Green (1977) through forced feeding
experiments. He also noted that, in general, as latitude
decreases, the incidence of toxicity in sponges increases,
presumably in response to the high diversity and density
of associated fishes in the tropics. Predation, therefore,
is not usually considered a direct force limiting the
distribution of coral reef sponges. This is not true for all
sponge ecosystems, as was illustrated by Dayton et al.
(1974) in an Antarctic community.
Sponges have been regarded as a major force in
the bioerosional-procaessQocoral reefs (Goreau and
Hartman 1963; Rutzler 1975). The boring sponges are
classed mostly in the family Clionidae (genus Cliona),
but species of the Adocidae (Siphonodictyon) and the
Spirastrellidae (Spheciospongia, Anthosigmella) have
also been shown to excavate coral limestone skele-







tons. They weaken the substrate, causing the collapse
and dislodgement of some corals and creating cryptic
habitats in the interior of coral skeletons. In a study of
Cliona lampa in Bermuda, Neumann (1966) found that
as much as 6-7 kg of carbonate detritus could be gener-
ated from 1 m2 of sponge-infected substrate in 100
days. Hudson (1977) reported six species of boring
sponges that were principal in the bioerosion of Mon-
tastraea annularis (star coral) at Hens and Chickens Reef
in Florida.
In con tast-th-th ioa effect: of the boring
s5eciesmany other species contribute tothe_.stirtural
integrity of coral reefs by binding unconsolidated reef
frame material together and thereby increasing rates of
carbonate accrelion (Wulff and Buss 1979).
Sponggs _play .a m xaa-r rolein the ecologyof
FloridaraLxefs,-but have _begreatly jeg!.e.cted in


ecological stud.ies--As William Beebe (1928) wrote:
". ..when, in the Iliad, Homer described a sponge as 'full
of holes,' he expressed about all the knowledge which
mankind has possessed until comparatively recent
times." Although there have been some advances in
knowledge of sponge biology since 1928, there is still
much to be learned about the physiology, ecology, and
evolution of sponges.

4.4 CNIDARIA

The phylum Cnidaria (Table 24) includes jelly-
fish, sea anemones, corals, and hydrozoans. Although
extremely variable in appearance, all members have a
radially symmetrical body plan. The saclike body has
a central stomach cavity with a single opening that is
usually surrounded by food-capturing tentacles. Stinging


Table 24


Classification of major reef benthic Cnidaria.


PHYLUM CNIDARIA (COELENTERATA)

CLASS HYDROZOA

ORDER MILLEPORINA: fire corals

ORDER STYLASTERINA: hydrocorals

CLASS ANTHOZOA

SUBCLASS OCTOCORALLIA (ALCYONARIA) sensu Bayer 1961

ORDER STOLONIFERA

ORDER TELESTACEA

ORDER ALCYONACEA: fleshy soft corals

ORDER GORGONACEA: sea whips, sea feathers, sea fans, sea plumes, other gorgonian corals

ORDER PENNATULACEA: sea pens

SUBCLASS ZOANTHARIA (HEXACORALLIA)

ORDER ACTINIARIA: anemones

ORDER CORALLIMORPHARIA: false coral anemones

ORDER ZOANTHIDEA: carpet anemones

ORDER CERIANTHARIA: tube anemones, often parasitic in other organisms

ORDER SCLERACTINIA (MADREPORARIA): true stony corals

ORDER ANTIPATHARIA: black or thorny corals






capsules (nematocysts) on the tentacles narcotize prey
before they are drawn into the mouth, and sometimes
can inflict powerful stings on humans.
The two classes of Cnidaria in which major
colonial reef forms are found are the Hydrozoa and
Anthozoa. Within the Hydrozoa class is the order
Milleporina, containing the fire corals. The Anthozoa
class has two subclasses: (1) Octocorallia or soft corals,
including those in the order Gorgonacea (gorgonians),
and (2) Zoantharia, containing the order Scleractinia
or true stony corals. The following will describe the
fire corals; the soft corals, especially the gorgonians;
and the stony corals.

Milleporina

On Florida reefs, the Milleporina are represented
by a single genus, Millepora. These fire corals are quite
common throughout the western Atlantic tropical coral
reefs. A colony consists of a calcareous skeleton with an
internal meshwork and external pores through which the
polyps retract and expand. The two kinds of polyps are
the dactylozooid and the gastrozooid. The dactylozooid,
the defensive and food-collecting polyp, has potent
stinging apparatus, the nematocyst. The nematocyst
contains a small hypodermiclike structure. This is a
capsule with a coiled barb, flagella trigger, and a strong
neurotoxin. Upon stimulation the trigger releases the
barb that is shot into the prey or predator by hydraulic
pressure, and the poison is released. The gastrozooid
contains a mouth and digestive enzymes. Dactylozooids
and gastrozooids are distributed in cyclosystems of five
to seven dactylozooids around each gastrozooid.
Two species of Millepora are found in Florida. M.
alcicornis is a digitate branching form, and M. compla-
nata (Plate 3b) is a truncated bladed form. In many
cases, it is impossible to render a specific determination.
Thin encrusting veneers of reef rubble, the skeletons of
other organisms, and jetsam prevent recognition of the
specific characters. The western Atlantic species, M.
squarrosa, is a nominal species. Steam and Riding (1973)
and DeWeerdt (1981) showed that M. squarrosa was an
ecomorph of M. complanata. Boschma (1948, 1956) dis-
cussed the systematics and taxonomy of Millepora.
Millepora's life history reflects hydroid meta-
genesis or alternation of polyp and medusa generations.
The polyp represents the benthic stage. It asexually
produces planktonic medusae, which develop gametes
that, when fertilized, produce planktonic larvae. The
larvae settle and metamorphose into a juvenile Millepora
colony. Recruitment can also come from fragment
propagules. Following storms or physical impact, the
broken pieces have regenerative powers to grow into new
daughter colonies.
Millepora is a functional autotroph and hetero-
troph. It has very dense concentrations of zooxanthellae
(microscopic, symbiotic dinoflagellate algae) in its
endodermic tissues, discussed in detail in Chapter 7. The
zooxanthellae are autotrophic and provide the host
animal tissue with carbohydrates and some proteins.
Polyp nitrogenous wastes and CO2 are used by the


zooxanthellae in protein synthesis. The calcification rate
and colony growth are greatly enhanced by this sym-
biotic relationship. Plankton, captured by the dactylo-
zooids and digested by the gastrozooids, probably
provide the micronutrients to the polyps.
Growth rate data for Millepora are limited or
nonexistent. After settlement the growth seems to be
very rapid, probably upward growth approaches 10 cm
annually (author's subjective estimate). Encrusting forms
are transitory, instability of substratum usually leads to
early mortality for the colony.
Wahle (1980) reported that Millepora colonies
detect octocoral colonies from stimuli present in sur-
rounding seawater and redirect growth to reach the
octocoral colony. Millepora then grow over the surface
of the octocoral, thus gaining new space.
Millepora complanata has a limited bathymetric
distribution. It is generally restricted to the reef flat and
shallow spur and groove zones (0-5 m). On Looe Key
Reef (Table 23) it was second in abundance and frequen-
cy, with a mean density of slightly greater than three
colonies per square meter. Mergner (1977) reported that
M. complanata was an indicator species of photophilic
and rheophilic environments; its ecological niche is ap-
parently limited to the shallow, well-illuminated and tur-
bulent waters found in shallow windward reef communi-
ties.

Octocorallia (Soft Corals)

The Octocorallia, commonly called soft corals or
octocorals, are conspicuous in coral reef communities
off southeast Florida (Table 25). They have various
shapes ranging from inconspicuous encrusting mats to
large sea fans. Nearly all types possess calcareous spicules
embedded in an organic matrix. Specific species charac-
teristics include colonial morphology, branching pat-
terns, and morphology and configuration of the spicules.
The fundamental morphological character is the polyp,
which has eight pinnate tentacles.
The Gorgonacea (gorgonians) are the common-
est octocoral in southeast Florida reefs in depths less
than 30 m. They include the sea fans, sea plumes, sea
feathers, sea whips, and sea rods (Plate 4a), which are all
very flexible and attached by a holdfast or base to the
reef platform. Branches of gorgonians possess a horny,
solid center, while other groups have a solid or calcar-
eous axis.
The taxonomy of the major categories is cur-
rently being revised. Bayer (1961) is the most complete
single source for identification of the shallow water
octocorals found off southeast Florida, and Cairns
(1977) is a useful field guide. Deichmann (1936) report-
ed on the deep-water octocorals.
Octocoral autecology, including environmental
tolerances summarized by Bayer (1956), is similar to
that of the stony corals (see next section, Scleractinia).
Octocorals exhibit polytrophism, obtaining energy from
multiple sources; planktivory and autotrophism are the
two major sources.
Reproduction is generally dioecious. Colonies





Table 25

Octocoral fauna in shallow (<30 m) southeast Florida
reef communities (Bayer 1961; Opresko 1973;
Wheaton 1981, in preparation b).


Species Patch reef Bank reef


Briareum asbestinum
Iciligorgia schrammi
Erythropodium caribaeorum
Plexaura homomalla
P. flexuosa
Pseudoplexaura porosa
P. flagellosa
P. wagenaari
P. crucis
Eunicea palmer
E. pinta
E. mammosa
E. succinea
E. fusca
E. laciniata
E. tourneforti
E. asperula
E. clavigera
E. knight
E. calyculata
Muriceopsts flavida
Plexaurella dichotoma
P. nutans
P. grisea
P. fusifera
Muricea muricata
M. atlantica
M. laxa
M. elongata
Lophogorgia hebes
Pseudopterogorgia bipinnata
P. kallos
P. rigida
P. acerosa
P. americana
P. elisabethae
P. navia
Gorgonia ventalina
Pterogorgia citrina
P. anceps
P. guadalupensis
Nicella schmitti


(solid) substrate. Juvenile (sexually immature) character-
istics are not significantly different from the adult's.
Greatest mortality occurs during larval and juvenile
stages. Growth proceeds by asexual budding of polyps
and is determinant. Octocoral growth rates have not
been intensely studied. Kinzie (1974) reported that the
black sea rod (Plexaura homomalla) exhibited colony
growth of 10-40 mm annually. The study also noted that
sexually mature colonies were 25-35 mm in height.
Kinzie's study was in the Cayman Islands but would
generally apply to Florida populations.
Octocorals suffer high mortality from storms
when wave surge is too great for the holdfast or the sub-
strate itself becomes dislodged. The colony is often car-
ried off the reef proper and recovery after dislodgement
is frequently unsuccessful.
Density of octocorals ranges from very dense to
sparse, dependent upon the habitat; variability is quite
high. Work at Biscayne National Park, for example,
documented a range of 10-50 colonies within a square
meter. Both Wheaton (in preparation a) and Opresko
(1973) conducted studies in patch reef habitats. Domi-
nant species at Biscayne National Park were Plexaura
flexuosa, P. homomalla, Gorgonia ventalina, Eunicea
succinea, and Pseudopterogorgia americana. Opresko
reported mean densities of 6.9, 11.3, and 27.1 colonies/
m2 at three reefs.
The octocoral fauna from about Stuart-Palm
Beach to Dry Tortugas in depths to near 30 m is typical
Caribbean or Tropical Atlantic in species composition.
Local environmental conditions (depth, light, substrate,
and current) control community structure.
The octocoral fauna is an important component
of coral reef communities, principally as shelter and
refuge for numerous commensal and epibiotic species
important in the trophic structure of the reef commun-
ity ranging from bacteria to fish. Copepod, decapod,
amphipod crustaceans, barnacles, ophiuroids, gastropod
and pelecypod molluscs, and often small stony corals
attach to the central axis stem or holdfast. The fisheries
management plan for coral and coral reefs reported the
following predators and parasites of western Atlantic
octocorals:

1. Algae in Pseudoplexaura, Pseudo-
pterogorgia, Plexaurella, Plexaura,
and Muriceopsis are manifested in
abnormal growth (tumors) in the
branches.

2. Millepora (fire coral) overgrows the
octocoral.


release sperm into the water column; however, fertiliza-
tion and embryological development are internal. Plan-
ula larvae are released through the polyp mouth. Those
species studied spawn during the spring, summer, and
fall. Recruitment of new colonies results from larval
settlement following a brief planktonic period. Meta-
morphosis occurs after the larvae settle on appropriate


3. The fireworm Hermodice caruncu-
lata (Plate 18b) preys on many
corals including a number of reef
octocorals.

4. Cyphoma spp. gastropod molluscs
feed, sometimes in groups, on octo-
corals. Gorgonia ventalina is a
favored prey.





5. Numerous fish have been observed
feeding; however, they do not
appear to be obligate octocorali-
vores (Randall 1967).


Octocorals are increasingly harvested for human
purposes. Many octocorals contain pharmacologically
active compounds within their tissues. Medical-phar-
macological research requires harvest of prodigious
quantities of octocorals to isolate active compounds.
Bayer and Weinheimer (1974) reported on the prosta-
glandin compounds extracted from Plexaura homomalla.
Concern has been registered that this might eliminate a
species population over a wide area if harvest restrictions
were not instituted. Another exploitation of octocorals
within the area is for live aquaria. Information provided
to the Gulf of Mexico Fishery Management Council
reported 5,845 colonies of octocorals belonging to nine
species are harvested annually and sold as aquarium
specimens; several are nonreef species. Current State and
proposed Federal statutes only protect the sea fan, genus
Gorgonia.

Scleractinia

The Scleractinia (stony corals) are a specialized
order of Zoantharia, distinguished by an aragonite
calcareous exoskeleton. The skeleton (Plate 9a) is
composed of a basal plate, external wall, and specialized
internal structures-the septa, pali, and columellae. The
group in general expresses radial symmetry set in a hexa-
merous mode. Yonge (1940, 1973) and Wells (1957b)
reviewed scleractinian biology, and Vaughan and Wells
(1943) and Wells (1956) provided a glossary of terms
and definitions.
The order Scleractinia is divided into five sub-
orders (Table 26)-Astrocoeniina, Fungiina, Faviina,
Caryophylliina, and Dendrophylliina. Most shallow-
water, reef-building corals are found in the first three
suborders, with the greatest number in the Faviina. With
few exceptions taxonomic characters are based on the
skeleton, especially the septa.
The fundamental unit of the coral colony is the
polyp (Plate 7b), a tiny mass of tissue with a set of
tentacles and a central mouth. The tentacles and adja-
cent connecting tissues are covered with cilia and ne-
matocysts. There are three tissue layers: ectoderm,
mesoglea, and endoderm or gastroderm. The endoderm
of reef Scleractinia is usually filled with dense concentra-
tions of zooxanthellae. The color of coral tissue, a com-
plex of plant and animal tissue, is mostly the result of
the plant pigments within the chloroplasts of these
zooxanthellae. Coral tissue covers only the very surface
of the limestone skeletal mass. McCloskey (in Muscatine
and Porter 1977) reported that this tissue complex was
45% plant and 55% animal by weight. Because coral
tissues contain the producer, and fixed carbon can be
passed directly to the coral animal tissues for utilization
without a herbivorous intermediary, the association of
coral and zooxanthellae is successful in nutrient-
impoverished tropical waters. To augment this ability,


Table 26


Southeast Florida reef Scleractinia.


ORDER SCLERACTINIA

SUBORDER ASTROCOENIINA (Vaughan and
Wells 1943)

Family Astrocoeniidae (Koby)

Stephanocoenia michelini (Milne, Edwards,
and Haime)

Family Pocilloporidae (Gray)

Madracis decactis (Lyman)
M. formosa (Wells)
M. mirabilis (sensu Wells)

Family Acroporidae (Verrill)

Acropora palmata (Lamarck) (Plate 5a)
A. cervicornis (Lamarck) (Plate 4b)
A. prolifera (Lamarck) (Plate 5a)

SUBORDER FUNGIINA (Verrill)

Family Agariciidae (Gray)

Agaricia agaricites (Linne')
A. agaricites agaricites (Linne')
A. agaricites danai (Milne, Edwards,
and Haime)
A. agaricites carinata (Wells)
A. agaricites purpurea (LeSueur)
A. lamarcki (Milne, Edwards, and Haime)
A. undata (Ellis and Solander)
A. fragilis (Dana)
Helioseris cucullata (Ellis and Solander)

Family Siderastreidae (Vaughan and Wells 1943)

Siderastrea radians (Pallas)
S. siderea (Ellis and Solander)

Superfamily Poritidae (Gray)

Family Poritidae (Gray)

Porites astreoides (Lamarck)
P. porites (Pallas)
P. porites divaricata (LeSueur)
P. porites furcata (Lamarck)
P. porites clavaria (Lamarck)
P. branneri (Rathbun)


(continued)






Table 26 (continued)


SUBORDER FAVIINA (Vaughan and Wells 1943)

Superfamily Faviidae (Gregory)

Family Faviidae (Gregory)

Favia fragum (Esper)
F. gravida (Verrill)
Diploria labyrinthiformis (Linne')
D. clivosa (Ellis and Solander)
D. strigosa (Dana) (Plate 6a)
Manicina areolata (Linne')
M. areolata mayor (Wells)
Colpophyllia natans (Houttyn)
C. amaranthus (Muller)
C. breviseralis (Milne, Edwards, and Haime)
Cladocora arbuscula (LeSueur)
Montastraea cavernosa (Linne') (Plate 6b)
M. annularis (Ellis and Solander) (Plate 5b)
Solenastrea hyades (Dana)
S. bournoni (Milne, Edwards, and Haime)

Family Rhizangiidae (d'Orbigny)

Astrangia astreiformis (Milne, Edwards,
and Haime)
A. solitaria (LeSueur)
Phyllangia americana (Milne, Edwards,
and Haime)

Family Oculinidae (Gray)

Oculina diffusa (Lamarck)
O. varicosa (LeSueur)
0. robusta (Pourtales)

Family Meandrinidae (Gray)

Meandrina meandrites (Linne')
M. meandrites braziliensis (Milne, Edwards,
and Haime)
Dichocoenia stellaris (Milne, Edwards,
and Haime)
D. stokesii (Milne, Edwards, and Haime)
Dendrogyra cylindrus (Ehrenberg) (Plate 7a)

Family Mussidae (Ortmann)

Mussa angulosa (Pallas)
Scolymia lacera (Pallas)
S. cubensis (Milne, Edwards, and Haime)
Isophyllia sinuosa (Ellis and Solander)
I. multiflora (Verrill)
Isophyllastraea rigida (Dana)
Mycetophyllia lamarckiana (Milne, Edwards,
and Haime)
M. danaana (Milne, Edwards, and Haime)
M. ferox (Wells)
M. aliciae (Wells) (continued)


Table 26 (continued)


SUBORDER CARYOPHYLLIINA (Vaughan and
Wells 1943)

Superfamily Caryophylliidae (Gray)

Family Caryophylliidae (Gray)

Eusmilia fastigiata (Pallas)
Paracyathus pulchellus (Philippi)

SUBORDER DENDROPHYLLIINA (Vaughan and
Wells 1943)

Family Dendrophylliidae (Gray)

Balanophyllia floridana (Pourtales)




corals have developed other methods to conserve and
recycle limiting resources such that high productivity is
maintained. Muscatine and Porter (1977) reported that
reef corals are primary producers, primary consumers,
secondary and tertiary consumers, deposit feeders, and
saprotrophs; different species have perfected different
strategies.
The most unusual and probably the most impor-
tant trophic strategy that is almost universal among
the reef-dwelling corals is the primary producer activity.
The autotroph or phototroph is carried within the coral
tissue as an endosymbiont. Hermatypic scleractinia
possess the dinoflagellate Zooxanthella microadriaticum
(Loeblich and Shirley 1979) (also reported as Symbio-
dinium or Gymnodinium) within their endodermic
tissues. The zooxanthellae complement the corals
by recycling nitrogen and phosphorus, fixing carbon
(lipids, amino acids, nonamino organic acids, glycerol,
organic phosphates, and glucose), producing oxygen,
enhancing calcification, and removing animal metabolic
products (CO2, nitrogenous wastes). Muscatine (1973),
Taylor (1973), and Muscatine and Porter (1977) review-
ed the coral host zooxanthellae symbiont relationship.
Muscatine and Porter (1977) reported that 30% of the
carbon fixed by the zooxanthellae on a clear day would
satisfy all of the coral's carbon needs.
Corals are suspension feeders. Several techniques
are used singularly or in combination to capture zoo-
plankton. The most common technique is to capture
drifting zooplankton by stunning the zooplanktors with
the nematocysts, a special poison organelle found in the
tentacles. (Although most polyp expansion for feeding
occurs nocturnally and the tentacles of most species are
retracted during the day, Dendrogyra cylindrus is an
exception (Plate 7a). Porter (1974) reported on polyp
expansion.) The captured zooplanktors are delivered to
the mouth by the tentacles or by reverse beating of the
cilia. In family Agariciidae small polyps generate water
currents with the cilia. Food caught in the current is





captured by the small tentacles and ingested. Some
observations of external digestion via mesenterial fila-
ments have also been reported (Yonge 1973). Plankton
can also be caught in mucus nets that are on the coral
surface or in the water column. The prey is brought to
the mouth for ingestion. Lewis and Price (1975) review-
ed coral feeding.
Digestion of animal material occurs in the region
of the mesenterial filaments; partially digested material
is translocated to the cells for final digestion. Transloca-
tion of food and wastes is by diffusion or wandering
cells (Yonge 1973). Cellular oxygen and carbon dioxide
exchange also occurs via diffusion. Muscatine and Porter
(1977) reported that most reef corals cannot receive
sufficient energy from planktivory to support their
energy requirements; they extrapolated that approxi-
mately 20% of energy needs could be met from zoo-
plankton. The role of zooplankton in the diet is sus-
pected to be one of providing critical minerals and
nutrients not gained via the autotrophic pathway. Other
sources of energy include bacteria, detritus, organic
dissolved in seawater, and external mesenterial feeding
of animal tissues adjacent to the colony. Wastes are
removed through the mouth.
The life history and autecology for many stony
coral species are incomplete or totally unknown and are
based on hypothesis and conjecture rather than fact.
Sexual reproduction includes gametogenesis (Plate 8a)
within the polyps near the base of the mesenteries. Some
species have separate sexes and some are hermaphroditic.
Fertilization occurs internally or externally. Some
species such as Acropora cervicornis and A. palmata
appear to be synchronous in development of gametes.
Embryology terminates with the development of plank-
tonic larvae, the planula. If there is larval brooding by
the species, the planula is released through the mouth
and has limited powers of locomotion by cilia. Kojis and
Quinn (1981) reported that several species of Pacific
Scleractinia had benthic swarming larvae. Lewis (1974)
noted that Favia fragum in the laboratory were bottom
swarming. Fadlallah (1983) reviewed scleractinian
reproductive larval biology. Upon proper stimulation,
the larvae settle on appropriate substrates. Negative
phototropism is partially responsible for settling. Initial
calcification ensues with the forming of the basal plate
and the initial protosepta, followed by the theca or wall
and axial skeletal members. Buds formed on the initial
corallite develop into daughter corallites.
Connell (1973) reviewed the population ecology
of reef-building corals. Two generalized contrasting life
history strategies are suggested; many species probably
fall between the extremes. Opportunistic or R strategists
attain small adult size, exhibit determinant growth,
reach sexual maturity at an early age, place a great deal
of available energies into reproduction, and produce
small eggs and sperm that are released into the water
column for fertilization. The lifespan of this type of
species is short; success is insured by the vast numbers of
progeny produced. These species may also be the more
eurytopic in environmental tolerances. They are able to
invade harsher reef habitats. Porites astreoides and F.


fragum are examples of this form of strategy.. Jaap (in
progress) studied populations of stony corals at 24 sites
(96 m2) at BNP (1978-81). He found that P. astreoides
was one of the most commonly recruited species in the
patch reef environments. The K strategist exhibits slow
growth and a long period before reaching sexual maturi-
ty. Most energy is expended toward growth and main-
tenance. Growth may be indeterminate. Apparently
little energy is diverted toward reproduction. These
species may live for hundreds or even thousands of years
and sexual reproduction may be a very rare event.
Montastraea annularis is the best example of this type of
life history. Some colonies are hundreds of years old.
Dustan (1977a) and Bak and Engel (1979) both reported
very low or no recruitment for M. annularis.
Growth in scleractinian corals involved asexual
tissue division and skeletogenesis (skeleton construc-
tion) (Barnes 1973). The two processes are highly inter-
dependent; imbalance of either causes change which
results in skeletal abnormalities. Growth in branching
species such as A. cervicornis and A. palmata is quite
rapid, while growth for the more massive star and brain
corals is relatively slow. Table 27 presents growth data
for several scleractinian species; many others have not
been studied. Hudson (1981) noted that certain cyclic
patterns appear over the 75-year growth period of the
corals he cored, slabbed, and x-rayed for growth-rate
skeletal density patterns. Buddemeir and Kinzie (1976)
reviewed coral growth.
Recruitment is critical to perpetuation of the
species and ultimately to the vitality of the coral reef
communities. Dustan (1977a) reported on stony coral
recruitment and mortality at Carysfort Reef (Figure 17)
off Key Largo. Because the duration of his study was
less than one year, the conclusions are qualified. The
study showed that Agaricia agaricites was the most
commonly recruited species. Bak and Engel (1979)
studied recruitment off Bonaire and Curacao, Nether-
lands Antilles. They also reported that A. agaricites was
the most commonly recruited species. Again, the one-
year time frame of this study is subject to some qualifi-
cations. The overall net recruitment comparison of
Dustan and Bak and Engel is difficult, since Dustan only
considered corals less than 15 cm to be juvenile recruits
and Bak and Engel considered colonies in the 2-40 cm
range as juveniles. Both of the studies were limited to
depths greater than 6.5 m. This is beyond the spur and
groove zone, hence it is most representative of the fore
reef or buttress zones.
As reported earlier, each reef has its own parti-
cular species composition of scleractinian corals. How-
ever, certain key framework species are fundamental to
the reef-building processes. In patch reefs M. annularis
(Plate 5b) is usually the most important species. Diploria
strigosa (Plate 6a), D. labyrinthiformis, Colpophyllia
natans, and Siderastrea siderea are also significant. The
remaining species are either in low abundances or
frequencies, or their biomass and framework building
capacity is low.
In the bank reef communities, different zones
manifest different species dominance. On reef flats with





Table 27


Growth rates of scleractinian species from Florida and the Bahamasa.

Growth rate
Species (mm/yr) Location Source


Acropora cervicornis 40.0 H Dry Tortugas Vaughan and Shaw 1916c
109.0 H Key Largo Dry Rocks Shinn 1966
115.0 H Eastern Sambo Jaap 1974
Acropora palmata 39.5 H Goulding Cay, Bahamas Vaughan and Shaw 1916
105.0 B Eastern Sambo Jaap 1974
Acropora prolifera 37.2 H Goulding Cay, Bahamas Vaughan and Shaw 1916
Agaricia agaricites 3.5 H Dry Tortugas Vaughan and Shaw 1916
Porites porites 17.9 H Dry Tortugas Vaughan and Shaw 1916
Porites astreoides 17.6 D Dry Tortugas Vaughan and Shaw 1916
Siderastrea radians 4.3 D Dry Tortugas Vaughan and Shaw 1916
Siderastrea siderea 6.3 D Dry Tortugas Vaughan and Shaw 1916
Favia fragum 4.9 D Dry Tortugas Vaughan and Shaw 1916
Diploria labyrinthiformis 7.8 D Dry Tortugas Vaughan and Shaw 1916
Diploria clivosa 17.3 D Dry Tortugas Vaughan and Shaw 1916
Diploria strigosa 6.9 H Dry Tortugas Vaughan and Shaw 1916
5.0 H Carysfort Shinn 1975
Manicina areolata 8.2 D Dry Tortugas Vaughan and Shaw 1916
Manicina areolata mayor 14.0 D Dry Tortugas Vaughan and Shaw 1916
Montastraea cavernosa 4.4 H Dry Tortugas Vaughan and Shaw 1916
Montastraea annularis 9.0 H Key West Agassiz 1890
5.0-6.8 H Dry Tortugas Vaughan and Shaw 1916
10.7 H Carysfort Hoffmeister and Multer 1964
8.4 H Carysfort Shinn 1975
8.0-9.7 H Key Largo area Hudson 1981
Oculina diffusa 14.3 H Dry Tortugas Vaughan and Shaw 1916
Dichocoenia stokesii 6.7 D Dry Tortugas Vaughan and Shaw 1916
Dendrogyra cylindrus 10.4 H Dry Tortugas Vaughan and Shaw 1916
Isophyllia sinuosa 5.1 D Goulding Cay, Bahamas Vaughan and Shaw 1916
Eusmilia fastigiata 5.8 H Dry Tortugas Vaughan and Shaw 1916

aGoulding Cay, Bahamas, data were only used when Tortugas information was unavailable.
bB = increase in branch length, D = increase in diameter, H = increase in height.
cVaughan and Shaw's multiple values were averaged.


high turbulence P. astreoides is dominant with D.
clivosa. In the spur and grooves, Acropora palmata (Plate
5a) is dominant (Table 18). In the buttress zone M.
annularis is most significant in the reef-building pro-
cesses. Tables 17, 19, and 20 present the species ranks,
abundance, densities, and dispersion patterns for a
number of reefs; note the high degree of variability
within and between reefs. In deep reef communities
(> 30 m) the species that dominate are Agaricia lam-
arcki, Madracis mirabilis, Stephanocoenia michelinii, A.
fragilis, and M. formosa.
Dynamic population changes affect the nature of
coral associations in shallower reef habitats. Colonies are
frequently relocated following storms. In many cases,
they do not die, but reestablish themselves in the new
habitat (Plate 10a). This makes it very difficult to
evaluate mortality in a time series within a sampling site.


Fragmentation also complicates the issue. During the
4-year BNP study, branching species (A. palmata, A. cer-
vicornis, and P. porites) were frequently fragmented and
scattered throughout the site causing major change in
abundance and dominance. What was originally a single
colony in some cases was broken into 10 or more living
fragments. The great variability over the period of this
study points out that shallow patch reefs are dynamic
and that physical controls are significant. Table 28
presents a time series of a representative 4-m2 plot at
Elkhorn Reef.
Biological interactions among the Scleractinia are
documented by Lang (1971, 1973, 1980); Jackson and
Buss (1975); Richardson et al. (1979); Wellington
(1980), and Sheppard (1981, 1982). These interactions
are mostly involved with maintaining and/or expanding
space, "lebensraum" in the reef where spatial resources





Table 28


Time series for abundance, density, and dispersion of stony corals at Elkhorn Reef
(one 4-m2 plot) (Jaap, unpublished).

Abundance
B. I.a (total no. Percent of Density
Species (ranking) of colonies) total colonies (-s) D.I.


.197!


Acropora cervicornis
Acrop6ra palmata
Porites porites
Porites astreoides
Siderastrea siderea
Millepora alcicornis
Favia fragum
Diploria clivosa
Yearly total


8

7 24.14 1.750.50 R
6 20.69 1.501.29 R
5 17.24 1.251.26 R
4 13.79 1.00-0.00 R
3 10.34 0.750.96 R
2 6.90 0.50+1.00 R
1 3.45 0.250.50 R
1 3.45 0.250.50 R
29

9


.197w


Acropora cervicornis
Acropora palmata
Siderastrea siderea
Porites astreoides
Diploria clivosa
Millepora alcicornis
Yearly total


9
6
4
4
1
1
25


36.00
24.00
16.00
16.00
4.00
4.00


1.750.96
1.501.29
1.001.15
1.000.82
0.250.50
0.25-0.50


i YO'


Acropora palmata
Acropora cervicornis
Siderastrea siderea
Porites astreoides
Yearly total


.198


Acropora palmata
Siderastrea siderea
Porites astreoides
Porites porites
Acropora cervicornis
Diploria clivosa
Millepora complanata


26 74.29 6.503.70 R
4 11.43 1.001.15 R
3 8.57 0.750.96 R
2 5.71 0.500.58 R
35

1


62.16
8.11
10.81
8.11
2.70
5.41
2.70


5.751.71
0.750.96
1.000.82
0.751.50
0.25-0.50
0.501.00
0.250.50


Yearly total 37


aB.I. = Biological Index, McCloskey (1970).
bD.I. = Dispersion Index, Elliott (1971): C= Contagious (clustered), R= Random, U= Uniform.
CNote that a storm during the winter of 1979-80 fragmented a large A. palmata colony. Survivors established a
new set of colonies, thus changing dominance and density.


,nonC


I







are often a limiting factor. Rapid growth among the
Acroporid species can shade out other slower growing
species (Shinn 1975). Some species have potent external
digestive mechanisms whereby the mesenterial filaments
are extended and kill the tissues of adjacent corals. Lang
(1971, 1973) documented this digestive mechanism as
hierarchical among the species of Atlantic Scleractinia.
Some species compete with this aggressive territorial
behavior through sweeper tentacles which keep the
mesenterial filaments away from the lower hierarchy
species. It is also probable that alleochemicals are
important in protecting space. Biological interactions are
probably more significant in deeper reef environments
where physical events are less frequent and of an inter-
mediate magnitude.
Coral pathology and disease is an infant research
area. Phenomena were reported by Preston (1950) and
Squires (1965). Laboratory experiments demonstrate
that bacteria cause morbidity and mortality in corals
(Mitchell and Chet 1975; Ducklow and Mitchell 1979a,
1979b). Antonius (1974b) reported that a blue-green
alga, Oscillatoria, was capable of killing corals under
certain (laboratory and field) conditions (Plate 19a). The
alga grew over the coral, killing it in a short period.
Gladfelter (1982) reported on an undetermined patho-
gen that caused epidemic mortality in A. palmata on a
reef off St. Croix, U.S. Virgin Islands. A similar condi-
tion is often seen on Florida reefs; Grecian Rocks
appears to be currently infested with this pathogen
(Plate 25a). Pathology and band diseases in corals were
reviewed by Antonius (1981a, 1981b).


4.5 OTHER BENTHIC GROUPS

The level of insight into many other coral reef
benthic groups is poor. Detailed examination will not be
attempted here. There are numerous diverse habitats
within a coral reef that provide niches to a multitude of
species belonging to nearly every phylum (Plate 8b).
Sedimentary deposits provide habitat for infaunal
organisms. Many mobile forms find refuge under the
sedimentary surface and forage for food at night. The
reef rock itself is a habitat for both epifauna and boring
and cryptic fauna. A single coral head weighing 4.7 kg at
Heron Island contained 1,441 polychaete individuals
(Grassle 1973); 67% of all organisms from the coral's
interior were polychaetes. Vittor and Johnson (1977)
studied polychaetes from Grand Bahama Island and
reported that 84 species were present. Robertson
(1963), Ebbs (1966), Hein and Risk (1975), and Hudson
(1977) reported on the boring fauna of Florida corals.
Specific references that deal with the other benthos
include the proceedings volumes from the past Inter-
national Coral Reef Symposia, the two volumes from the
Biology and Geology of Coral Reefs, Volumes 23 (1,2)
of Bulletin of Marine Science, Frost et al. (1977), Colin
(1978a), and Rutzler and Maclntyre (1982b). Voss et al.
(1969) provided a qualitative account of the biota found
within BNP prior to its becoming a national monument.
The study of most other benthic organisms, save certain
commercial species (e.g., spiny lobster), is for taxonomic
purposes. Decapod crustaceans were reported on by
Gore (1981). Lyons and Kennedy (1981) and Lyons et
al. (1981) reported on biological aspects of the spiny
lobster Panulirus argus. Work (1969) studied West Indian
mollusk communities. Kier and Grant (1965) and
Kissling and Taylor (1977) discussed echinoderms from
Florida reef communities.






CHAPTER 5


PLANKTON

by J. O. Roger Johansson
Tampa Bay Study Group
City of Tampa, Florida


5.1 INTRODUCTION

Coral reefs are highly productive marine ecosys-
tems with a great abundance-a-nd diversity of organisms.
They are generally surrounded by waters with small
plankton standing stocks. Most studies describing coral
reef plankton communities have investigated the impor-
tance of zooplankton in coral nutrition. The results of
these studies have been somewhat contradictory.
The early studies (Yonge 1930 and others)
generally indicated that there was not a sufficient
amount of zooplankton in the water column around the
reef to support the corals. Recent studies of coral reef
zooplankton (Emery 1968; Porter 1974; Sale et al.
1976; Alldredge and King 1977; Porter et al. 1977;
Hobson and Chess 1978; Hamner and Carleton 1979;
Hobson and Chess 1979; Rutzler et al. 1980; Hamner
and Hauri 1981; McWilliams et al. 1981; and Ohlhorst
1982) have shown that methods used in the earlier
studies for capturing the reef zooplankton were not
adequate to describe the zooplankton community most
nutritionally important to the corals. These plankton
live in close association with the corals, sometimes
within the reef itself.
The earlier collections used nets which were
towed or drifted above and sometimes away from the
reefs. The recent studies, using an array of different
collection and observation methods such as stationary
nets, diver-controlled nets, plankton pumps, diver-
operated suction devices, emergence traps, light traps,
and diver visual and photographic observations (see
Porter et al. 1978; Hamner and Carleton 1979; and
Youngbluth 1982 for discussion of sampling tech-
niques), have found that coral reefs, worldwide, have an
abundant and diverse resident near-reef zooplankton
community different from the oceanic forms in the
surrounding ocean. Porter et al. (1978), summarizing
iiiformation from mostly Indo-Pacific reefs, estimated
that 75%.of the reef zooplankton standing stock was of
benthic origin and that 85% of the biomass was of local
origin. Parts of this community are, therefore, often not
considered as truly planktonic, but rather as epibenthic
or demersal. Many organisms in the resident community
are only found in the water column at night and spend
daylight hours on the sediment or within the reef itself
(see Section 5.3).
It is still not. 1learl demonstrated_ however,
what importance zooplankton play in coral nutrition.
EiM-ry (I9bb) states that plankton represent a major
source of food to the reef, while Muscatine and Porter
(1977) suggest that zooplankton feeding 'does not
contribute a majority of either calories or carbon re-
quired for reef corals. Hamner and Carleton (1979)


summarize and critique studies of reef zooplankton and
find that, due to often questionable methodologies used,
no conclusive data on the relative importance of zoo-
plankton to coral reef nutrition have yet been published.
Few studies have been conducted describing the
free living phytoplankton community in the vicinity
of coral reefs. Researchers generally agree that phyto-
plankton's contribution to the primary productivity of
the coral reef ecosystem is small (e.g., Hargraves 1982).
Further, Wood (1954) suggested that the waters of the
Great Barrier Reef might have a distinctive reef phyto-
plankton community. Subsequent studies (Jeffrey 1968;
Revelante et al. 1982), however, found a reef commun-
ity similar to the nearby ocean phytoplankton com-
munity. The following discussion of coral reef plankton
will, therefore, mainly be concerned with the zoo-
plankton community.

5.2 TAXONOMIC COMPOSITION AND SPATIAL
DISTRIBUTION

As discussed above, several researchers have
described coral reef zooplankton communities in great
detail. However, due to geographical considerations, the
following discussion will generally be limited to observa-
tions of Alligator and Looe Key Reefs in Florida by
Emery (1968). The information obtained in these
studies is somewhat limited due to the lack of quantita-
tive abundance measurements; however, the report gives
a detailed account of the spatial and temporal distribu-
tion of the different zooplankton taxa found on the
reefs. Emery used several different collection methods,
including boat- and swimmer-towed nets, suction
devices, light traps, and diver observations, in order to
reduce sampling errors of zooplankton living near or
within the reefs. Further, he made collections and
observations during both day and night. He also subdi-
vided the study areas into several habitats such as grass
beds, lagoons, patch reef, reef tops, caves, and deep
reefs. Visual observations by divers, swimmer-towed
nets, and suction devices produced the most interesting
information about the zooplankton on and in close
vicinity of the reefs.
Close to the water surface of all areas of the
reefs, Emery found a typical offshore zooplankton com-
munity, consisting mostly of free living copepods and
larvaceans. Visual observations deeper in the water
column and just above the bottom often found the reef
plankton in close and dense aggregations or swarms. The
swarms tended to hold together and move as a unit, and
they also maintained their position against the current
and the surge. Emery found four species of copepods in
these swarms: Acartia tonsa, A. spinata, Oithona nana,





and 0. oculata. He estimated that one swarm of A. were most often captured at night included: fish larvae;
spinata contained 110,000 copepods/m3. Hamner and large copepods; crab larvae; chaetognaths; ostracods; and
Carleton (1979) also reported extremely dense swarms shrimp larvae. Ohlhorst (1982) found that the zooplank-
of copepods (max. 3,320,000/m3) on Australian reefs, ton emerged from the substrate of Discovery Bay,
Swarming species of copepods, in the Emery study, were Jamaica, at variable rates throughout the night. The peak
most often found on the grass beds and reef tops. activity was usually two hours after sunset. However,
Monospecific schools of mysids, of one size class, were smaller species of copepods and juvenile members of
also found on the the reef tops often inside caves and large species migrated into the water column during the
along coral faces. Schooling implies a stronger social day and were least abundant in the water column during
behavior than swarming since the individuals that belong the night. She suggested that the reasons for dielertical
to one size class are longitudinally aligned and move as a migration are many and varied They include: feeding;
unit. Schooling behavior of mysids has also been re- repro uc ion; escape from predation; and dispersal.
ported by other investigators of Alligator Reef (Randall Porter et al. (1977) studied reefs in the Pacific Ocean
et al. 1964). On the deep reefs and the patch reefs of and found that the volume of emerging plankton was
both Alligator and Looe Key Reefs, close aggregations of greatest over branching coral and least over sand and
the plankton did not appear as important. Copepods and rubble. Alldredge and King (1977) and McWilliams et al.
mysids were found individually or in looser aggregations. (1981), sampling different reefs of the Great Barrier
Emery also observed that the swarming and schooling Reef, also found a positive relationship between the
behavior of these organisms was mostly a daytime structural heterogeneity of the substrate and the amount
phenomenon. They were often found individually at of epibenthic plankton emerging at dark. The composi-
night. Hobson and Chess (1979), reporting on resident tion of the community Alldredge and King found was
reef plankton of Hawaiian atolls, found a similar diurnal similar to the one described by Emery (1968), and they
pattern for swarms of copepods, mysids, and larval estimated that an average of 2,510 zooplankton emerged
fishes. per m2 of the reef substrate. McWilliams et al. (1981),
Swarming and schooling in dense aggregates are conducting a more detailed study, found not only a
important examples of behavior adaptation by resident greater volume of plankton emerging from the coral than
reef plankton, which differentiates them from pelagic from the sand but also that the composition of the rising
forms. Hamner and Carleton (1979) stated that at least communities were different. The reef bases were transi-
seven species of copepods, and probably more, engage in tional zones with a mixture of "coral" and "sand"
swarming behavior at coral reefs in three of the world's communities. These authors further found that more
oceans. The same authors have suggested that swarming plankton emerged during the summer than during the
not only reduces predatory pressure, but also facilitates winter. The annual range of the "coral" fauna was
reproduction and permits the plankton to cluster in local 5,030-2,350 animals/m2 and the "sand" fauna 2,720-
eddies to maintain a favorable feeding position with 1,150 animals/m2. Also, the plankton samples collected
minimum energy cost. In a subsequent paper, Hamner during the summer were generally more diverse in
and Hauri (1981) related the resident reef zooplank- taxa than winter samples. Hobson and Chess (1979),
ton distribution to the reef configuration and the local collecting emerging plankton from the lagoon substrata
water motion. They found swarms of copepods and of atolls in the Pacific Ocean, found a considerably less
chaetognaths directly upcurrent of the reef face in an abundant plankton community in their traps than
entrained water mass, which was subject to less removal reported by Alldrege and King (1977) and McWilliams et
than downstream waters. This accumulation of biomass al. (1981). Hobson and Chess (1979) suggested that the
and increased primary productivity in areas upstream of use of different types of traps may account for some of
reefs is one aspect of the well-known "island mass the variations reported between study areas. Youngbluth
effect" phenomenon. (1982) tested three types of emergence traps and found
that both density and diversity of the zooplankton
5.3 DIURNAL MIGRATIONS collected were affected by the trap design and sampling
procedures. He concluded that different mesh size
Investigators of coral reef zooplankton who have netting in the traps alone could probably account for
taken care to sample the populations near the substrate much of the variability in plankton abundance and
and on a diurnal schedule have found the plankton different study areas.
community undergoes drastic daily changes. Emery -'- )
(1968) found that nighttime collections contained four 5.4 SUMMARY
times greater volume than daytime collections. A suction
device with a light close to its mouth to attract the The coral reef plankton community can be
plankton was used for these collections, and therefore, characterized as follows:
quantitative comparisons are not in order. Emery did,
however, find a very different composition of the 1. A highly abundant and diverse
plankton at night. Many forms, such as polychaetes, zooplankton community is
cumaceans, and zoea, which he observed living in caves found on the reefs. It is in
and crevices during the day, were swimming outside the striking contrast to the open
reef in great abundance at night. Other forms which water community nearby.







2. Most of the reef zooplank-
ton belong to a resident com-
munity, which is able to main-
tain position on the reef.
3. The community consists partly
of true planktonic forms living
in dense aggregates and using the
reef configuration and water cur-
rents to maintain position.


4. The major portion of the resi-
dent plankton community con-
sists of epibenthic forms. This
community generally migrates
from the substrate to the water
column at dark.
5. Phytoplankton communities
found over the reefs appear to
be little different from open
ocean assemblages.







CHAPTER 6


REEF FISH

by James T. Tilmant
U.S. National Park Service
South Florida Regional Research Center


Tropical coral reefs are richer in fish species than
any other habitat (Marshal 1965; Emery 1973). The fish
fauna of the Florida reef tract is wholly tropical
with only seven species that have not been recorded else-
where in the West Indies. Thus, although the study of
coral reef fishes in south Florida has not been extensive,
considerable information concerning their biology and
ecology has been developed through studies elsewhere in
the Caribbean.
The most complete studies conducted in the
Florida Keys are those by Longley and Hildebrand
(1941) for the Dry Tortugas, and Starck (1968) for Alli-
gator Reef. Field guides to Florida reef fish include
Chaplin and Scott (1972); Greenberg (1977); Stokes
and Stokes (1980); and Kaplan (1982).
Three major reviews concerning the general
ecology of coral reef fish on a worldwide basis are
Ehrlich (1975), Goldman and Talbot (1976), and Sale
(1980b).

6.1 REPRODUCTION AND RECRUITMENT

Most coral reef fish spawn in the water column
above the reef, and their eggs remain in the plankton
during development. A few species either lay their
eggs demersally and attend to them or they brood
them by mouth (Smith 1982; Colin 1982). Breed-
ing aggregations are common to most reef species. These
serve to increase egg fertilization and release of egg and
sperm in the lee of the reef, thereby increasing disper-
sion and reducing predation (Colin 1982). Coral reef
fishes typically produce large numbers of offspring
which are then dispersed by means of a pelagic larval
stage (Breder and Rosen 1966; Ehrlich 1975; Johannes
1978; Sale 1980b). The timing of egg release (or hatch-
ing for those families with dermersal eggs) is often
triggered by dusk, night, or the tides, increasing the
ability of newly spawned or hatched eggs to elude
predators (Myrberg 1972; Robertson and Choat 1974;
Warner et al. 1975; Bell 1976; Colin 1976, 1978b,
1982; Moyer and Bell 1976; Johannes 1978; Lobel
1978; Moyer and Nakazono 1978).
Most species of reef fish spawn several times
during their spawning season. Spawning may be daily,
biweekly, or monthly (Robertson 1972; Holzberg
1973; Warner et al. 1975; Moyer and Nakazono 1978;
Lobel 1978; Ross 1978). These multiple spawnings
have been explained as a method of ensuring a wide
dispersal of offspring (Sale 1978).
Sex reversal is also common in many reef species.
Often the adult populations are largely females (with
only a small but sufficient percentage of males). If the
number of males in the population becomes reduced,


new males are rapidly developed from female stock by
some individuals undergoing a protogynous sex reversal.
Egg production is maximized by this mechanism and a
greater proportion of energy channeled into population
maintenance (Goldman and Talbot 1976; Smith 1982).
Florida reef species known to undergo sex reversal
include most (if not all) parrotfish (Scaridae), many
wrasses (Labridae), and some groupers (Serranidae).
A pelagic larval stage is almost universal among
coral reef fish species. Little detailed information is
known about the life of larval reef fish while in the
pelagic phase, although they are frequently taken in off-
shore plankton tows. Studies in which the time of
spawning and time of period of peak recruitment of
juveniles from the plankton have been correlated indi-
cate that the larval stage varies from a few weeks to
months depending on the species (Randall 1961a; Moran
and Sale 1977). Aging of larvae or newly transformed
juveniles by counting daily growth increments on the
otoliths has revealed that pomacentrids, gobiids, and
blenniids have larval lives of about 21 days. The larval
stage of siganids, acanthurids, chaetodontids, and labrids
is 30 or more days (Sale 1980b). As is common among
many marine invertebrates, many species can probably
extend their larval life until suitable settlement habitat is
found (Randall 1961a; Johannes 1978; Sale 1980b).
The methods by which larval fish are returned to
a reef environment have been mostly hypothesized from
circumstantial evidence. Generally, it is believed that
current gyres that form in the lee of islands and reefs act
as traps to prevent the loss of larvae downstream and,
through their rotation, return the larvae to the reef
(Munro et al. 1973; Leis and Miller 1976; Johannes
1978). Johannes (1978) reported that the spawning
migrations, which bring some species to particular sites
at precise times, release the gametes into a mass of water
that is most likely to return them to the same reef at the
end of their pelagic existence. He cited the variability in
spawning peaks between various locations, often within
the same region, as possible evidence that spawning
patterns have arisen as responses to a variable pattern of
water circulation. The season in which spawning occurs
is not well known for many coral reef species, but it is
known some species spawn on a regular basis all year
(Colin 1982). For most species that have been studied,
spawning peaks in the late afternoon and may last from
a few minutes to an hour or more depending on the
species (Colin 1982). Present knowledge concerning the
reproductive behavior of coral reef fishes in the Carib-
bean has been summarized in papers by Smith (1982)
and Colin (1982).
Seagrass beds are important to the reproduction
of coral reef fishes in that they act as nurseries for some







species. Ogden and Zieman (1977) reported that at
Tague Bay, St. Croix, juvenile spiny puffer (Diodon),
squirrelfish (Holocentrus), yellowtail snapper (Ocyurus
chrysurus), surgeonfishes (Acanthurus), and numerous
wrasses (Halichoeres) were commonly present within the
grassbed. The spotted goatfish (Pseudupeneus macu-
latus) and the yellow goatfish (Mulloidicthys martinicus)
occur as juveniles in grassbeds off the Florida Keys
(Springer and McErlean 1962a; Munro 1976). Springer
and McErlean reported capturing eight species of juve-
nile scarids in Thalassia beds off Matecumbe Key; all but
one, Sparisoma radians, are considered reef species as
adults. These fish remain in the seagrass habitat until
they become too large (> 20 cm) to hide among the
blades (Ogden and Zieman 1977) and presumably mi-
grate to the reef.

6.2 FOOD HABITS AND TROPHIC STRUCTURE

Fish constitute a major portion of the animal
biomass on a coral reef, and they are an important com-
ponent of the overall trophic structure. Most reef fish
are carnivores and many studies have shown that carniv-
orous fishes normally represent three to four times the
biomass of herbivorous fishes (Bakus 1969; Goldman
and Talbot 1976; Parrish and Zimmerman 1977). This
reversal of the_-"traditinnal"_iomas pyramid results
from many carnivorous fishes feeding on invertebrates
that form the largest portion of lower trophic levels on
reefs. Benthic invertebrates are of considerable impor-
tance to reef fish populations as energy assimilators at
the planktivore, herbivore, and detrital levels (Vivien
and Peyrot-Clausade 1974).
Herbivorous reef fish are sustained primarily by
low algal turfs and low-growing filamentous algae and
diatoms (Goldman and Talbot 1976). No phytoplankton
feeders have been identified in any of the reported
studies of reef fish food habits (Hiatt and Strasberg
1960; Randall 1967; Bakus 1969; Hobson 1974; Gold-
man and Talbot 1976; Parrish and Zimmerman 1977;
Hobson and Chess 1978). This is in contrast to fish
populations in temperate regions where up to 6% of the
species may consume phytoplankton (Davies 1957).
Benthic algal feeders include most parrot fish (Scaridae)
and surgeonfishes (Acanthuridae) and some blennies
(Blennidae), damselfish (Pomacentridae), butterfly fishes
(Chaetodontidae), and filefish (Balistidae). A number of
studies have shown that the herbivorous reef fish have a
marked effect on the distribution and abundance of
algae present on a reef. When protected from grazing by
exclosures, algal communities will rapidly increase in
standing crop (Stephenson and Searles 1960; Randall
196 la; Earle 1972a; Montgomery 1980; Montgomery et
al. 1980; Hixon and Brostoff 1981).
The extent to which zooxanthellae is eaten by
reef fish has been disputed (Randall 1974). Parrotfishes
(Scaridae) have been reported to scrape coral in a feed-
ing manner by Hiatt and Strasberg (1960) in the Mar-
shall Islands; Motoda (1940) in the Palao Islands; Talbot
(1965) off East Africa; Al-Hussaini (1947) in the Red
Sea; and Bakus (1969) along the Pacific coast of Panama


and Costa Rica. This habit was not observed by Randall
(1967) during extensive studies in the Caribbean; Finckh
(1904) in the Ellice Islands; Wood-Jones (1910) at Cross-
Keeling Island; or Choat (1969, cited in Goldman and
Talbot 1976) on the Great Barrier Reef. Randall (1974)
did observe coral feeding by scarids in some areas of the
Pacific, however, and discussed how this habit appears to
vary among the same species of fish at different loca-
tions. Scraping of massive (head) corals by parrotfish
does occur at least occasionally on Floridareefs (W.A.
Starck II, personal comment in Randall 1974; J.T.
Tilmant, personal observation). The amount of food
taken in this way may be insignificant compared to algae
ingested by grazing.
There are few true omnivores among most reef
fishes. The majority of species tend to be substantially
more carnivorous than herbivorous. Most herbivorous
fishes have been found to take only a small amount of
animal matter. Among the Caribbean species reported
as omnivorous are the damselfish (beaugregory and the
threespot damselfish); the grey angelfish and French
angelfish; the scrawled filefish, orangespotted filefish,
and fringed filefish; and the sharpnose puffer (Randall
1967).
Schools of small zooplankton-feeding fishes are
common on coral reefs and zooplankton is an important
energy source for larval stages of most reef species.
Among adult zooplankton feeders commonly schooling
on reefs are the herring genera Harengula, Opisthonema,
Sardinella, and Jenkinsia; the anchovies (Anchoa); and
silversides (Atherinomorus and Allanetta). Basslets
(Grammidae), cardinalfish (Apogonidae), glassy sweepers
(Pempheridae), and chromis (Chromis spp.) also typi-
cally occur in relatively large schools among reef crevices
where they feed on plankton. In addition to these adult
planktivores, dense schools of minute larval grunts
(Haemulidae), snappers (Lutjanidae), and wrasses (Labri-
dae) are often quite common hanging above coral heads
or among branches of Acropora where plankton and
coral mucus are the only available food.
Most of the carnivorous reef fish appear oppor-
tunistic, taking whatever is of the right size and is catch-
able within their habitat (Goldman and Talbot 1976).
This conclusion is based primarily on the variety of food
items observed within the same species at various loca-
tions. Only a few studies of reef fish species have evalu-
ated food consumption in relation to what was actually
available: Jones (1968); Vivien and Peyrot-Clausade
(1974); and Hobson and Chess (1978).
Some carnivorous reef fish are highly specialized
in their feeding habits. Among these are the parasite
pickers or cleaners (Labroides spp.), juvenile bluehead
wrasse, and neon gobies (Gobiosoma spp.), and several
sponge feeders. Caribbean reef fish reported to feed on
sponges include butterfly fish (Chaetodontidae), spade-
fish (Ephippidae), puffers (Tetraodontidae), and' box-
fishes (Ostraciidae) (Menzel 1959; Bakus 1964; Randall
and Hartman 1968).
Few, if any, reef fish have been classified as detri-
tal feeders and theutfilization and turnover of detritus
on coral reefs appear to be left primarily to inverte-






rates. Only a few blennies (none occurring in Florida)
have been reported to be primary detritivores (Goldman
and Talbot 1976). This number may increase as more
food studies for the numerous smaller blennies and
gobies become available. Also much detrital material is
ingested by those fish classified__as herbivores, and
determining actual material being foraged is often
difficult (Randall 1967).
Many ie- -ize-t reef oly as a refuge.
They use adjacent seagrass beds and sand flats as feeding
grounds (Longley and Hildebrand 1941; Randall 1963;
Starck and Davis 1966; Davis 1967; Ogden and Ehrlich
1977; Ogden and Zieman 1977). Randall (1963) report-
ed that grunts and snappers were so abundant on patch
reefs :n the Flonda Keys that it was obvious thatthe
reefs couJ -nt provide food and possibly not even
shelter for all of them. Both the abundance and diversity
o haemulids and lutjanids have been reported to be re-
duced on reefs where adequate off-reef forage areas are
unavailable (Starck and Davis 1966; Robins 1971; Ale-
vizon and Brooks 1975; Gladfelter et al. 1980). Simi-
larly, when reef shelter is lacking,what appears to be
suitable grassbed forage areas maygo unused (Starck and
Davis 1966; Ogden and Zieman 1977).
In Tague Bay, St. Croix, Virgin Islands, 79.4% of
the fishes actively feeding in the grassbeds at night were
species that sought shelter on adjacent coral reefs during
the day (Robblee and Zieman, in preparation). Starck
and Davis (1966) listed species of the Holocentridae,
Lutjanidae, and Haemulidae families as occurring diur-
nally on Alligator Reef and feeding nocturnally in adja-
cent seagrass beds. Typically both juvenile and adult
haemulids and lutjanids form heterotypic resting schools
over prominent coral heads (most commonly Acropora
palmata and Porites porites) or in caves or crevices of the
reef (Ehrlich and Ehrlich 1973; Ogden and Ehrlich
1977). At dusk these fishes move off the reef into
adjacent seagrass beds and sand flats where they feed on
available invertebrates (Randall 1967; Ogden and Ehrlich
1977; McFarland et al. 1979). At dawn they return to
the reef.
Starck and Davis (1966) reported that 11 of 15
species of haemulids found in diurnal resting schools on
Alligator Reef dispersed at night to feed. The lighter
colored grunts (seven species) generally distributed
themselves along sandy to thin-grass areas of the back
reef zone. Snappers (Lutjanidae) followed a similar pat-
tern with L. griseus and L. synagris in sparse grass to
back reef habitat. At Tague Bay, St. Croix, the nocturnal
distribution of grunts over the grass beds was quite simi-
lar to that reported in the Florida Keys. The French
grunt was most abundant over thin grass or bare sand
while white grunts were almost always observed by Rob-
blee (in preparation), in thick grass. He also found the
number of coral reef fishes feeding nocturnally over a
particular area was positively correlated with a measure
of habitat complexity, implying some form of organi-
zation of the fish assemblage while active over the
feeding ground.
It has been hypothesized by Billings and Munro
(1974) and Ogden and Zieman (1977) that migrating


nocturnal feeders may contribute significantly to the
energy budget of the coral reef through the import of
organic matter in the form of feces. If so, their contribu-
tion to reef nutrient levels and maintenance of more
sedentary fish abundance may also be important. Meyer
et al. (1983) found what appeared to be higher nutrient
levels and coral growth rates associated with diurnal
resting schools of grunts. Verification of these links,
however, requires further investigation.
Use of adjacent grass and sand flats by reef fish
is not strictly a nocturnal phenomenon, but seems to be
the dominant pattern. Only quite large herbivores, such
as the rainbow parrotfish (Scarus guacamaia), venture far
into the grass bed away from the shelter of the reef. Mid-
sized herbivores are apparently excluded by predators
and feed only near the reef (Ogden and Zieman 1977).
Randall (1965) reported parrotfishes (Scarus and Spari-
soma) and surgeonfishes (Acanthurus) feeding on sea-
grasses (Thalassia and Syringodium) closely adjacent to
patch reefs in the Virgin Islands during the day. He
attributed the formation of halos around patch reefs in
St. John, Virgin Islands, to this grazing.

6.3 MOVEMENT

Most reef fish seldom change their residence once
they have settled onto a reef and some become quite
sedentary (Thresher 1977). Many smaller species, such as
gobies (Gobiidae), blennies (Blenniidae), and damselfish
(Pomacentridae), maintain relatively small territories
which they vigorously defend (Salmon et al. 1968;
Rasa 1969; Low 1971; Myrberg 1972; Vine 1974). Tag-
ging studies have shown that even those larger, wider
ranging species, such as serranids, lutjanids, haemulids,
chaetodontids, and acanthurids, remain, at least diur-
nally, in a fairly circumscribed place on a reef (Bardach
1958; Randall 1961b, 1962; Springer and McErlean
1962a). Randall (1962) recaptured some serranids and
lutjanids at their initial place of capture up to 3 years
after their release. Tagged Haemulon plumieri were
repeatedly captured on the same reef by Springer and
McErlean (1962a). When the H. plumieri were trans-
planted, they exhibited a tendency to home (Springer
and McErlean 1962a). Ogden and Ehrlich (1977) re-
ported on the successful homing of H. plumieri and H.
flavolineatum to original patch reefs over distances as
great as 2.7 km in the U.S. Virgin Islands.
Only a small amount of information is available
on the usual extent of nocturnal movements of reef
fishes that feed on adjacent grass beds. As indicated
above, these fishes potentially can range quite far from
their diurnal resting sites. Lutjanus griseus and Haemu-
ion flavolineatum ranged as far as 1.6 km from Alligator
Reef (Starck and Davis 1966), while H. plumieri and
H. flavolineatum typically migrated distances greater
than 100 m over the grass beds in Tague Bay, St. Croix
(Ogden and Ehrlich 1977; Ogden and Zieman 1977).
The migrating schools follow a linear path for 20-40 m
from the reef, and then begin to break up into smaller
and smaller groups in a dendritic pattern (Ogden and
Zieman 1977). The distance traveled to feed is undoubt-







edly related to the abundance and quality of food avail-
able within the seagrass bed and can be expected to vary
considerably among locations.

6.4 SOCIAL ORGANIZATION

Literature on the social behavior and organiza-
tion of reef fish assemblages is extensive (see Ehrlich
1975; Goldman and Talbot 1976; Sale 1977, 1980a;
Thresher 1977; and Emery 1978 for reviews). It has
been conclusively shown that individuals or groups of
individuals are not scattered randomly about the reef.
Rather, their distribution reflects topographic and
biologic features of the environment as well as behav-
ioral adaptations to disperse (Thresher 1977). The
interaction of ecologically evolved behavior and the
availability of existing resources largely determine the
social organization within a given reef fish community.
Most smaller reef species are either herbivorous
or planktivorous and are territorial to varying degrees.
The size of territory and the extent to which it is de-
fended is a function of resource availability for many
species (Low 1971; Thresher 1977; Sale 1980a). Thresh-
er (1976) found that the size of area defended by the
threespot damselfish (Pomacentrus planifrons = Eupo-
mancentrus planifrons) on Florida reefs varied with
the type of resource secured and further that the size of
the area defended against a given intruder was deter-
mined by the threatened severity of the intrusion. The
size of territory defended against other families, for
example, correlated with the amount of benthic algae in
the diet of each species. Thresher (1977) reported that
the threespot damselfish in the northern portions of its
range generally defended larger territories than those in
the southern portion, where thicker algal lawns develop-
ed within their territories.
Differences in social structure have been ob-
served within a single species at different locations.
Itzkowitz (1978) and Williams (1978), working at differ-
ent sites in Jamaica, reported different social organiza-
tions for Pomacentrus planifrons. Itzkowitz found
males and females occurring together as neighbor-
ing territory holders in the same habitat, while Williams
reported the use of different habitats by the sexes. In
other regions, Robertson (1972) at Heron Reef (Great
Barrier Reef) and Potts (1973) at Aldabra Atoll reported
Labroides dimidiatus occurring as males with harems
and as mated pairs, respectively. Barlow (1974) found a
correlation between the social structure exhibited by
Acanthurus triostegus and the presence or absence of
various other territorial acanthurid species. The extent
to which the nature and distribution of food resources
can predict the form of space and resulting social organi-
zation used by territorial species was demonstrated by
Thresher (1977) for five species of pomacentrids com-
mon on Florida reefs. Invariably, the organization pre-
dicted closely matched that observed in the field.
The large reef fish species require a greater food
supply and, therefore, tend to range over a larger area of
the reef. These species, although often having distinct
ranges, are less territorial and frequently form foraging


groups (Buckman and Ogden 1973; Ogden and Buckman
1973; Alevizon 1976; Itzkowitz 1977).

6.5 ECOLOGICAL ASPECTS OF REEF FISH
DIVERSITY

Only two studies have attempted to fully define
the diversity of fish species on selected Florida reefs:
Longley and Hildebrand (1941) and Starck (1968).
Longley and Hildebrand provided a systematic account
of all fishes they captured or observed during 25 years of
investigations at the Dry Tortugas, and Starck listed
fishes collected and observed during 9 years of study at
Alligator Reef. Longley and Hildebrand listed 442
species, 300 of which are closely associated with coral
reefs. Starck listed 517 species, 389 of which he con-
sidered reef species. The remaining species were either
offshore pelagic forms, demersal species from deeper
water, or strays from adjacent inshore areas. Both lists
are from single reef areas and, therefore, probably under-
represent the actual diversity of fish species on Florida's
reefs.
Bohlke and Chaplin (1968) identified 496 fish
species within the Bahamas and adjacent waters. About
450 of these species are known to occur on coral reefs
and probably approximate Florida's total diversity.
Several less extensive surveys of fish on Florida
reefs involved visual census, filming, or limited collect-
ing techniques. One of the earliest surveys was done by
Jordan and Thompson (1904), who identified 218 spe-
cies inhabiting the reefs at the Dry Tortugas by using
baited lines and various nets.
The high diversity of fish on Florida's tropical
coral reefs is exemplified by a few studies which report-
ed the number of species observed within a given limited
area. Bohnsack (1979) recorded a mean number of
species ranging from 10 to 23 on isolated natural coral
heads less than 330 x 210 x 150 cm in size off Big Pine
Key, Florida, and 13 to 20 species on small artificial
reefs (160 x 60 x 80 cm) that he established. Alevizon
and Brooks (1975) observed an average of 14.7 fish
species during 2.75-min samplings during which scuba
divers took color movies. During the sample period the
diver panned the camera to include most or all fishes
sighted within 4-5 m (Alevizon and Brooks 1975).
At present, there appears to be only six or seven
species of reef fish that might be considered endemic to
the U.S. continental reefs. Two of these, Lythrypnus
phorellus and Gobiosoma oceanops, are small gobies; the
latter (neon goby) is common. The purple reef fish
(Chromis scotti) is also known to occur only within U.S.
waters, although the genus is well represented by at least
three other species throughout the West Indies. Ophi-
dion selenops, the mooneye cusk eel, is a species report-
ed by Starck (1968) to occur occasionally within the
area of Alligator Reef (near Matecumbe Key), but has
not been reported elsewhere. Cusk eels are curious elong-
ate fishes, highly nocturnal and burrowing into mud
during the day. At least five species of cusk eels, repre-
senting two genera, are known to occur along the
southeastern United States, but the taxonomy of this







group is not entirely clear. Two small tropical serranids
have also been considered endemic to the continental
United States. One of these, the blue hamlet (Hypoplec-
trus gemma), may only be one of many color morphs of
a single species, H. unicolor, which is common through-
out the Caribbean (Thresher 1978; Graves and Rosen-
blatt 1980). The other serranid is the wrasse bass (Lio-
propoma eukrines), which ranges northward along the
continental shelf, but is not known to occur elsewhere in
the Caribbean. The remaining possible endemic species is
the cubbyu (Equetus umbrosus), but its distinction from
E. acuminatus, found elsewhere in the Caribbean, is
questionable (Robins et al. 1980).
The reason forhigh diversity of fish species on
coral reefs is frequently dbehated and may he-elated to a
number offactors-(Sanders 1968; Goldman and Talbot
197 7Smith 1978; Talbot et al. 1978). All biological
communities tend to diversify through colonization over
time, and coral reefs exist in an environment generally
without major perturbations or great temperature
change. Most coral reefs have had long and relatively
sAtble periods to develop. Within this overall long-range
stability of the tropics, intermittent moderate disturb-
ances from _weather events occur. Although we are just
beginning to understand the effects of disturbance
events (Endean 1976; Bradbury and Young 1981;
Pearson 1981; Woodley et al. 1981; Davis 1982; Porter
et al. 1982; Roberts et al. 1982), the ayh olp-to
maintain a higher diversity by preventing a resource-
imited equi~librhum an d the competitive exclusion of
some species (Connell 1978).
Coral reefs generally include a variety of micro-
habitats related to zones of coral growth, wave exposure,
and reef structure (Wells 1957a; Maxwell 1968; Stoddart
1969). This diversity of habitat types allows for an
increased diversity of fish species. Although- habitat
relationships have not been extensively studied on
Florida reefs, few reef fish have been found to be cosmo-
politan over all available habitats. At One Tree Island
Reef, Australia, 49% of all species collected were re-
stricted to one or another of five major habitats (Gold-
man and Talbot 1976). Similar faunal differences among
habitats have been reported by Gosline (1965) for the
Hawaiian Islands; Chave and Eckert (1974), Fanning
Island, South Pacific; Jones and Chase (1975), Guam;
Harmelin-Vivien (1977), Tulear Reef, Madagascar; and
Williams (1982), the Great Barrier Reef.
The coexistence of a high-numberofJfish species
on coral reefs also implies either-that-these-species are
highly specialized (occupy finely partitioned niches) or
'that there is considerable overlap ui resource utilization.
Predators are generally food limited and tend to have
more clearly separated niches (Hairston et al. 1960;
Paine 1966). Reef herbivores such as parrotfishes, dam-
selfishes, gobies, and angelfishes are generally believed to
use many of the same food resources (Randall 1967;
Smith and Tyler 1972; Hobson 1974). Both specializa-
tion and resource-sharing appear to occur among various
reef fish groups and at various life stages within some
species.
Recruitment of juvenile 'fish to coral reefs may


also influence species diversity, although this is hotly
contested (Sale 1976, 1980a; Sale and Dybdahl 1978;
Smith 1978; Talbot et al. 1978; Brock et al. 1979;
Ogden and Ebersole 1981; Sale and Williams 1982). The
controversy centers around whether reef communities
have an ordered structure with predictable species re-
cruitment to vacant niches or an unpredictable chance
species recruitment. An unpredictable larval recruitment
would increase local variation in the species present and
might well contribute to a higher overall diversity (Gold-
man and Talbot 1976). Recently some investigators have
suggested that differences in recruitment and communi-
ty structure may be a result of the size of the reef area
considered (Ogden and Ebersole 1981) or of the time
interval between which samples have been taken (Bohn-
sack, in preparation).

6.6 COMMUNITY DESCRIPTIONS

Although fish diversity is usually high on coral
reefs, fewer number of species will appear abundant or
highly obvious to the average reef diver at any one
location. Reef fish, like most organisms, have depth
and habitat preferences where they can typically be
seen. Many are active only nocturnally or diurnally, and
some species, such as yellowtail snapper and gag grouper
(Mycteroperca microlepis), are abundant only season-
ally.
A comparison of three Florida reef studies, all of
which used the same 50-min visual census technique,
shows significant differences in reef fish communities at
each study location (Thompson and Schmidt 1977;
Jones and Thompson 1978; Tilmant et al. 1979). Al-
though the top six families comprising the fish com-
munity in terms of abundance were the same, their rela-
tive ranking and individual species members varied
(Table 29). Damselfish (Pomacentridae) were the most
common family at Tortugas while ranking third at
John Pennekamp Coral Reef State Park (JPCRSP) and
second at Biscayne National Park (BNP). Parrotfish
(Scaridae) were the most common community member
at BNP but were second at JPCRSP and the Dry Tor-
tugas. Grunts (Haemulidae) were particularly abundant
at JPCRSP (most common family) but were third at
BNP and the Tortugas. Of the 165 species observed
between JPCRSP and the Dry Tortugas, 115 were shared
in common. Thirty-one species were seen only in
JPCRSP and 19 were observed only in the Tortugas
study areas (Jones and Thompson 1978). Overall, fish
communities at John Pennekamp Coral Reef State Park
were found to be more diverse and abundant than at the
Dry Tortugas.
Seven of the top 10 reef fish species at Biscayne
National Park were also within the 10 most common
species in John Pennekamp Coral Reef State Park.
However, only 10 of BNP's top 20 species were repre-
sented in the 20 most common species at JPCRSP.
Three major types of coral reefs are recognized
along the Florida reef tracts: patch reefs, hardground
live bottom, and bank reefs. Each general reef type
supports a characteristic fish fauna (Table 30). General







Table 29

Comparison of the most abundant reef fish families among three Florida coral reef
areas as indicated by Jones and Thompson (1978) visual census methods.


Ranking Pennekamp Tortugas Tortugas Biscayne National Park
1975a 1975a 1976 1979c



1 Haemulidae Pomacentridae Pomacentridae Scaridae

2 Scaridae Serranidae Scaridae Pomacentridae

3 Pomacentridae Haemulidae Haemulidae Haemulidae

4 Labridae Scaridae Labridae Labridae

5 Serranidae Chaetodontidae Serranidae Chaetodontidae

6 Chaetodontidae Labridae Chaetodontidae Serranidae



aJones and Thompson 1978.
bThompson and Schmidt 1977.
CTilmant et al 1979.



Table 30

Coral reef fish most commonly observed by divers on reefs.
The list is based on summary ratings of the average length of time a diver
must spend before observing the species.
Species averaging less than 30 minutes to observe are listed
(Thompson and Schmidt 1977; Jones and Thompson 1978; Tilmant et al. in press).

Reef types and zones

Patch Livebottom Bank
Species Top Outer Shallow Deep
Fringe


Ocean surgeon Acanthurus bahianus

Doctorfish Achirurgus

Blue tang A. coeruleus

Barred cardinalfish Apogon binotatus

Flamefish A. maculatus

Belted cardinalfish A. townsendi

Trumpetfish Aulostomus maculatus


(continued)
57







Table 30 (continued)
Reef types and zones

Patch Livebottom Bank
Species Top Outer Shallow Deep
Fringe


Orangespotted filefish Cantherhines pullus *

Scrawled filefish Aluterus scriptus

Slender filefish Monacanthus tucker *

Bar jack Caranx ruber *

Queen angelfish Holacanthus ciliaris *

Gray angelfish Pomacanthus arcuatus *

French angelfish P. paru *

Rock beauty Holacanthus tricolor *

Reef butterfly Chaetodon sedentarius *

Foureye butterfly C. capistratus *

Spotfin butterfly C. ocellatus

Saddled blenny Malacoctenus triangulatus

Roughhead blenny Acanthemblemaria aspera *

Wrasse blenny Hemiemblemaria simulus *

Redlip blenny Ophioblennius atlanticus

Neon goby Gobiosoma oceanops *

Bridled goby Coryphopterus glaucofraenum *

Masked goby C. personatus *

Goldspot goby Gnatholepis thompsoni *

Hovering goby loglossus helenae *

Herrings Clupeidae *

Bermuda chub Kyphosus sectatrix *

Spanish hofish Bodianus rufus *

Slippery dick Halichoeres bivittatus *

Yellowhead wrasse H. garnoti *

Creole wrasse Clepticus parrai *

(continued)
58







Table 30 (continued)
Reef types and zones

Patch Livebottom Bank
Species Top Outer Shallow Deep
Fringe


Hogfish Lachnolaimus maximus *

Clown wrasse H. maculipinna *

Blackear wrasse H. poeyi *

Puddingwife H. radiatus *

Bluehead wrasse Thalassoma bifasciatum *

Schoolmaster snapper Lutjanus apodus *

Mutton snapper L. anelis *

Gray snapper L. griseus *

Mahogany snapper L. mahogoni *

Yellowtail snapper Ocyurus chrysurus *

Yellow goatfish Mulloidichthys martinicus *

Spotted goatfish Pseudupeneus maculatus *

Glassy sweeper Pempheris schomburoki *

Sergeant major Abudefdufsaxatilis *

Blue chromis Chromis cyaneus *

Brown chromis C. multilineatus *

Yellowtail damselfish Microspathodon chrysurus *

Dusky damselfish Pomacentrus fuscus *

Beaugregory P. leucostictus *

Bicolor damselfish P. partitus *

Threespot damselfish P. planifrons *

Cocoa damselfish P. variabilis *

Black margate Anisotremus surinamensis *

Porkfish A. virginicus *

Tomtate Haemulon aurolineatum *

Caesar grunt H. carbonarium *
(continued)
59







Table 30 (continued)
Reef types and zones

Patch Livebottom Bank
Species Top Outer Shallow Deep
Fringe


Smallmouth grunt H. chrysargyreum *

French grunt H. flavolineatum *

Spanish grunt H. macrostomum *

White grunt H. plumieri *

Bluestriped grunt H. sciurus *

Bluelip parrotfish Cryptotomus roseus *

Midnight parrotfish Scarus coelestinus *

Princess parrotfish S. taeniopterus

Blue parrotfish S. coeruleus *

Striped parrotfish S. croicensis *

Rainbow parrotfish S. guacamaia *

Queen parrotfish S. vetula *

Redband parrotfish Sparisoma aurofrenatum *

Redtail parrotfish S. chrysopterum *

Redfin parrotfish S. rubripinne *

Bucktooth parrotfish S. radians *

Stoplight parrotfish S. viride *

Jackknife-fish Equetus lanceolatus *

Cubbyu E. umbrosus *

Reef croaker Odontoscion dentex *

Blue hamlet Hypoplectrus gemma *

Barred hamlet H. puella *

Butter hamlet H. unicolor *

Graysby Epinephelus cruentatus *

Red grouper E. morio *

Nassau grouper E. atriatus *

(continued)
60







Table 30 (continued)
Reef types and zones

Patch Livebottom Bank
Species Top Outer Shallow Deep
Fringe


Black grouper Mycteroperca bonaci *

Harlequin bass Serranus tigrinus *

Lantern bass S. baldwini *

Saucereye porgy Calamus calamus *

Jolthead porgy C. bajonado *

Great barracuda Sphyraena barracuda *

Sharpnose puffer Canthigaster rostrata *


descriptions of some of the most common fish species
follow.

Patch Reefs

On most patch reefs, fish occur in two distinct
zones: top and outer. Species commonly seen over the
coral rubble substrate of the reef top are bluehead and
clown wrasses, the puddingwife, the slippery dick, and
bicolor damselfish. The dusky and threespot damselfish
staunchly defend small territories of algae-covered rocks.
The cocoa damselfish is also abundant at some localities.
Resting on coral rubble close to a crevice into which
they can dart for cover are redlip blennies, the only
species of combtooth blenny (Blenniidae) commonly
found on Florida's coral reefs. Also near protective
crevices are hamlets (Hypoplectrus spp.) of various
colors. Scorpion fish (Scorpaenidae) can also be found
frequently blending with coral rubble over the top of the
patch reefs.
Wider ranging species typically seen moving
among the corals within the top zone are the surgeon-
fish (Acanthurus spp.); gray, French, and queen angel-
fish, white grunts, and striped, stoplight, and redband
parrotfish. Frequently blue tang, ocean surgeons, and
parrotfish (particularly the midnight parrot) will form
large mixed or monospecific schools while ranging about
the reef top. Common fish species typically found near
coral heads, branching corals, or other outcrops on the
top of patch reefs are the bluehead wrasse, sergeant
major, tomtate, Caesar grunt, and Spanish grunt. The
vertical standing trumpetfish and the slender filefish can
usually be seen among the branches of the octocorals.
Around the outer edges of the patch reefs, the
water depth is greater (8-10 m), and larger coral heads


provide a varied and cavernous habitat. Along this outer
zone larger predators such as grouper, particularly black
grouper, red grouper, and Nassau grouper, mutton and
gray snapper, and hogfish can be found. Close inspection
of crevices and holes will commonly reveal sharpnose
puffers, squirrelfish (Holocentrus spp.), small cardinal
and flamefish (Apogon spp.), soapfish (Rypticus spp.),
glassy sweepers, and, possibly, the green moray (Gymno-
thorax funebris). Clinging to coral heads are small neon
and masked gobies. The neon goby is noted for its func-
tion as a parasite and mucus picker, or "cleaner," on
large fish species. Gobies frequently establish "cleaning
stations" into which larger fish will move, become quies-
cent, spread their opercula, and allow the cleaner fish to
work freely through the gills and about the head. Juve-
nile angelfish and the juvenile Spanish hogfish have also
been observed functioning as cleaners of larger fish on
the reef (Thresher 1980).
Close to the bottom, among the corals along the
outer edge of the patch reefs, the.puddingwife and yel-
lowhead wrasses become more abundant. Feeding more
in the open along the reef edge are typically saucereye
and jolthead porgies, spotted and yellow goatfish, redtail
parrotfish, and angelfish. Close inspection along grassy
areas will frequently reveal the small bucktooth parrot-
fish, blackear wrasse, and lizardfish (Synodus spp.). At
the base of the corals on sandy substrate, nearly trans-
parent bridled and goldspot gobies can be seen, as well as
the harlequin bass. In open sandy areas immediately
adjacent to the patch reef (but not on it), hovering
gobies and yellowhead jawfish (Opistognathus aurifrons)
can usually be seen protruding from their burrows.
The water column over the patch reefs usually
does not support a large number of fish, but barracuda,
bar jack (Caranx ruber), yellow jack (C. bartholomaei),







and Mojarras (Gerreidae) are among the most commonly
observed species. Ballyhoo (Hemiramphus brasiliensis)
can often be seen moving about just under the surface.
In the quieter waters of the back reef, schools of small
herring (Harengula spp.) are common.

Live Bottom

Live bottom communities are formed on broad
areas of limestone outcrops occurring in relatively shal-
low water (2 m or less) within the protected reef zone.
Coral growth may vary greatly in density over the area
and often is mixed with seagrasses. The habitat generally
has little relief or structure and is composed largely of
octocorals, sponges, and small scleractinian corals.
Only occasionally are large colonies of stony corals
found and these often form an independent cluster.
Fish fauna of the live bottom is generally similar
to that found on the top zone of patch reefs. A few not-
able differences include an increased tendency for tangs
and surgeonfish to form large wide-ranging schools, an
increased abundance of the large rainbow parrotfish, and
frequently larger schools of white, Spanish, and Caesar
grunts. An interesting species increase over live bottoms
is that of the lantern bass. This small bottom-dwelling
bass appears to prefer the broad rocky flats around
turtlegrass beds and, occasionally, replaces the similar
harlequin bass found more frequently on patch reefs.

Bank Reefs

Bank reefs (Figure 18) form elongated discon-
tinuous structures along the seaward edge of the reef
tract. They rise to within a meter or less of the surface
and have extensive reef flats supporting only sparse
encrusting corals over their shallow zones. Seaward,
they slope rapidly to depths exceeding 20 m.
Redlip and saddled blennies, small gobies, and
other small bottom-dwelling species dominate the reef
flat. Within the shallow spur and groove zone branched
and fan octocorals become much more prevalent.
Among dense branches of staghorn or elkhorn coral
(Acropora spp.) are dusky and threespot damselfish,
many species of grunts (Haemulon spp.), black margates,
gray and schoolmaster snapper, sergeant majors, and
Bermuda chub. Within the water column over the reef,
bar jack, barracuda, and yellowtail snapper are easily
seen.
The fish fauna of the deep spur and groove zone
can be highly varied depending on depth and the amount
of reef structure. Below the Acropora coral zone (deep
spur and groove zone), however, the following become
more prevalent: yellowtail damselfish, the rock beauty,
butterfly fish, small groupers (i.e., hamlets, hinds, and
graysby), yellowtail and redtail parrotfish, large pudding-
wives, and large scrawled filefish. With increasing depth,
there is a distinct increase in Chromis (Chromis cyaneus
and C. multilineatus), the longsnout butterfly fish (C.
aculeatus), triggerfish (Balistes spp. and Canthidermis
sufflamen), filefish (Aluterus spp.), jackknife-fish,
schools of creole wrasse, and the blue parrotfish. Along


the outer base (mixed hardgrounds) of the bank reefs
(usually at depths of 20-30 m), large mutton snapper,
grouper, and porgies (Sparidae) become more abundant.
The tobaccofish (Serranus tabacarus) and sand tilefish
(Malacanthus plumieri) can easily be found resting
openly on the flat calcareous silt bottom in the mixed
hardground and sediment zone.
In the deep reef zone the bigeye (Priacanthus
arenatus) tends to replace the glasseye snapper (P.
cruentatus) commonly found on the shallower reefs.
Similarly, the cubbyu is replaced by the jackknife-fish,
and hinds and graysby (Epinephelus adscensionis, E.
guttatus, and E. cruentatus) are replaced by the coney
(E. fulvus). The snowy grouper (E. niveatus) becomes
prevalent at depths greater than 30 m. Over these deep
reefs, the number of species of jacks (Carangidae) and
mackerels (Scombridae) greatly increases. Also com-
monly seen are the large bar jack (C. ruber), rainbow
runner (Elagatis bipinnulata), amber jack (Seriola
dumerili), black jack (Caranx lugubris), bonita (Sarda
sarda), and cero mackerel (Scomberomorus regalis).
Cloud-forming schools of small herrings (Jenkinsia and
Sardinella) are seen over the reefs at depths greater than
20 m during the day. At depths greater than 30 m, a
third species of Serranus, similar in appearance to the
tobaccofish, becomes common. The chalk bass (S. tor-
tugarum) is found around small rubble mounds, coral
outcrops, and rocks near the base of the reef. At this
depth, a short search over the sand plain next to or be-
tween reefs will usually reveal a colony of garden eels
(Nystactichtys halls). They have long, slender bodies
and are found in large colonies where, each protruding
vertically from its burrow, they form "gardens" of wav-
ing heads while feeding on plankton carried by the
current.
The number of species described above in no way
approximates the total number found within the coral
reef habitats of Florida.

6.7 REEF FISH MANAGEMENT

Fish resources on the coral reefs of Florida and
elsewhere are highly prized economically and are exten-
sively utilized. Reef-fishing activities commonly include
commercial hook-and-line harvest, commercial trapping,
sport angling, spearfishing, tropical fish collecting, and
scientific collecting. The importance of reef fish re-
sources and their economic potential have been describ-
ed in a number of summary reports (Camber 1955; Stru-
saker 1969; Swingle et al. 1970; Stevenson and Marshall
1974; Bullis and Jones 1976; Klima 1976). In addition
to descriptive reports of fishing activities, a number of
exploratory studies and fishing development projects
have been completed for reef fish resources (Brownwell
and Rainey 1971; Munro et al. 1971; Kawaguchi 1974;
Wolf and Rathjen 1974; Stevenson 1978). Little infor-
mation, however, is available concerning the impact of
commercial or recreational use on reef fish populations
or on reef fish management. Fairly substantial sections
of Florida's coral reefs are now designated as local,
State, or National preserves and are being managed for







the protection and conservation of their resources.
The impetus to preserve coral reef resources
stems largely from their recognized economic value
through tourist attraction and recreational opportuni-
ties. But the negative impact of recreational use (i.e.,
snorkeling, diving, boating, and fishing) on coral reefs
has not been extensively investigated. Interestingly,
although the taking of tropical fish for aquarium pur-
poses is prohibited in all coral reef preserves, spearfishing
is permitted in at least one and hook-and-line fishing is
permitted in all. Impacts to fish population through
disturbance by boating and diving alone could become
significant. On extremely popular reefs, such as Molasses
Reef in the Key Largo National Marine Sanctuary, as
many as 20-30 boats with divers are often anchored at
one time within a 4-5 ha area (NOAA-OCZM 1979).
Specific studies at locations with such an extremely high
level of use are not available. However, within Biscayne
National Park, a 5-year study of eight selected patch
reefs revealed little disturbance to fish populations
where maximum annual use per reef ranged from 3,400-
3,600 persons diving or snorkeling (Tilmant et al., in
preparation).
Past research on exploitation of reef fish stocks
can best be described as gaining basic information on life
histories, food habits, growth rates, and basic biology of
important species, and on developing harvest techniques.
Only recently have studies evaluating the ecological
impacts of fishing activities begun to be reported (Camp-
bell 1977; Davis 1977b; Tilmant 1981; Katnik, in press;
Pauly and Ingles, in press; Bohnsack 1982).
The few studies available show that a limited
number of reef fish are actually sought and comprise
most of the sport and commercial harvest. Austin et al.
(1977), after interviewing 4,275 recreational fishermen,
reported that only four species groups (grunts, snappers,
dolphin, and grouper) constituted almost the entire
catch. Within the groups, gray snapper and yellowtail
snapper accounted for 85% of the harvested snapper;
white and bluestriped grunt, 97% of the grunts; and red
and black grouper, 82% of the grouper. Thus, only six
species made up about 80% of the total recreational
catch. The National Park Service has recorded over 120
species of reef fish caught within Biscayne National Park
(Dade County, Florida); however, 10 species accounted
for more than 80% of the harvest.
The commercial harvest of fish from coral reef
areas is almost entirely directed toward snappers (Lutja-


nidae) and groupers (Serranidae), although some tilefish
(Branchiostegidae), jacks (Carangidae), and triggerfish
(Balistidae) are harvested. A complete listing of commer-
cially important reef species can be found in the U.S.
Fishery Management Council's management plans for
these fish in the Gulf of Mexico (Florida Sea Grant
College 1979) and South Atlantic (South Atlantic
Fishery Management Council 1982).
Within Biscayne National Park, a limited assess-
ment of fishing impacts on reef fish populations was
conducted by underwater visual surveys concurrently
with fishermen's creel census (Tilmant 1981). During a
3-year period, fish catch rates varied inversely with the
number of fishermen using park waters while reef fish
populations remained relatively stable. Katnik (1981)
found that of the reef flats surrounding the Pacific island
of Guam, those with the highest fishing pressures
showed a marked reduction in the large size classes of
the most prized species. Also, some fishes of less eco-
nomic importance were more abundant on heavily fished
reefs than on reefs lightly fished (Katnik 1981). Bohn-
sack (1982) reported that he found significantly smaller
piscivorous predator populations on Looe Key Reef
(near Big Pine Key, Monroe County, Florida) than on
either of the two similar reefs within the Key Largo
National Marine Sanctuary. He attributed these differ-
ences to spearfishing on Looe Key and believed that the
abundance of some remaining species on Looe Key Reef
was affected by the larger predator loss.
In 1977 the United States passed the Fishery
Conservation and Management Act, which extended
jurisdiction over fisheries to 200 mi and called for estab-
lishing regional fishery management councils to develop
specific long-range management plans for each coastal
fishery resource within the Fishery Conservation Zone.
In response to this legislation, the coral reef fishery
resources within U.S. territorial waters are receiving
much greater attention, and management plans for their
conservation are being developed. The status of biologi-
cal knowledge and application of fishery management
principles to coral reef fish stocks was reviewed at a
workshop on reef fishery management sponsored by the
National Marine Fishery Service in October 1980
(Huntsman et al. 1982). The workshop proceedings
succinctly summarized the requirements for such
management. It is widely recognized that before coral
reef ecosystems can be effectively managed, much basic
data and many larger-scale multidisciplinary studies are
required.






CHAPTER 7


CORAL REEF ECOLOGY


7.1 INTRODUCTION


Wells (1957a) succinctly defined the nature of
the coral reef as a deterministicc phenomenon of seden-
tary organisms with high metabolism living in warm
marine waters within the zone of strong illumination.
They are constructional physiographic features of
tropical seas consisting fundamentally of a rigid calcar-
eous framework made up mainly of interlocked and
encrusted skeletons of reef-building (hermatypic) corals
and calcareous algae. The framework controls the
accumulation of sediments on, in, and around itself.
These sediments are derived from organic and physical
degradation of the frame and organisms associated with
the reef constructors and have bulk ten or more times as
great as the frame itself. The coral reef biotope is a faces
of the marine tropical biochore, and its essential fauna
and flora consists of corals and calcareous algae, which
dominate in numbers and volume and provide the
ecological niches essential to the existence of all other
reef-dwelling animals and plants. In addition, there is an
associated fauna and flora of other sedentary organisms
which may be represented by relatively few species, and
there is also the epifauna and epiflora of associated
commensals, symbionts, and parasites living on and
within the essential and associated organisms, and
finally, the mobile fauna of benthic and nektonic
species. Both physically and organically, reefs are
complicated structures and are the result of a near
balance of constructive and destructive forces. The
constructional forces are largely organic, the accumula-
tion of the calcareous skeletons of corals, calcareous
algae, foraminifera, mollusks, etc., roughly in that order
of importance. . Destructive and degradational forces
tending to break down the stout framework of reefs are
exemplified in the ceaseless breakdown of coral, algal,
and molluscan skeletons and reef rock by the normal life
activities of a wide variety of perforating, boring, and
dissolving algae, sponges, mollusks, worms, and echi-
noids . . A more obvious, but no more important,
destructive agency is wave action . [including] wind-
driven waves, which during hurricanes strike prodigious
hammer blows on reefs."
That which Wells (1957a) reported is still valid.
Detailed investigations into various ecological functions
have increased our understanding and appreciation of
the coral reefs in general. Today, Florida's coral reefs are
probably one of the most visited reef systems in the
world, yet the life history of many species is still poorly
understood. The recent increase in coastal development
and sport diving has generated concern about the vitality
of the coral reefs. Since very little early baseline ecologi-
cal information is available for comparison, qualitative
subjective statements are often offered in support that
the reefs are deteriorating. The most significant impacts
on the Florida coral reefs are, however, caused by natu-
ral events over which man has no control.


7.2 PHYSICAL-CHEMICAL ENVIRONMENT

The substratum for establishment of a coral reef
must be rock or consolidated materials. Shinn et al.
(1977) reported that the reefs they cored in Florida
were established on a basement of Pleistocene reef fa-
cies, fossil mangrove, and lithified cross-beaded quartz
(old sand dunes). The initial settlement of pioneering
species is followed by successional stages during which
the genesis for creation of the reef is established. Shep-
pard (1982) discussed the evolution of reefs based on
data from the Red Sea and Hawaii and noted that about
a 50-year period was required for a coral reef commun-
ity to attain the fourth (final stage) or binding-of-
sediment phase. Florida reefs are in various phases of
development; some have reached considerable develop-
ment while others are either juvenile or have suffered
impacts denying them full development.
Most coral reefs off southeast Florida are found
in depths of <43 m. Beyond these depths the substra-
tum and physical environments are unfavorable to the
existence of hermatypic reef-building Scleractinia. It
should be noted that where the physical environment is
favorable in other areas of the Caribbean (Bahamas,
Belize, Jamaica), a set of deep reef Scleractinia are found
colonizing the escarpment faces. These communities are
found as deep as 70-80 m. Off southeast Florida this
type of environment is, for the most part, nonexistent.
A deep reef was recently found in 60- to 90-m depths
west of the Dry Tortugas. Few details are available at
this time. Sclerosponges are also a conspicuous element
of deep reef communities; these are not reported from
Florida reefs. Dustan et al. (1976) discussed the factors
limiting sclerosponges from Florida.
Light is probably one of the most significant
environmental considerations controlling coral reef de-
velopment in general. Light is necessary for the symbio-
tic relationship between the coral and zooxanthellae.
Any factor which reduces the amount of solar radiation
impinging on the coral surface will affect growth and
nutrition. Reef corals are almost universally phototropic.
Wells (1957a) reported that species richness at Bikini
Atoll was closely controlled by solar illumination and
indirectly influenced by temperature and oxygen. Gene-
ral solar radiation characteristics in Florida were discus-
sed in Chapter 2. The nature of light is significant. Jokiel
and York (1982) reported that specialized pigments in
coral tissues filter the potentially dangerous ultraviolet
portions of the spectrum, thus allowing the corals to
occupy the shallow waters without being harmed. The
zooxanthellae are able to compensate for changes in
radiation quality and quantity through changes in their
pigments. Wethey and Porter (1967) reported that reef
corals were able to compensate to a depth of 25 m
without loss of autotrophic efficiency. Kanwisher and
Wainwright (1967) reported on respiration and produc-
tivity in Florida reef corals from a study at Hens and






Chickens Reef. Wells et al. (1973) reported that some
corals were best classified as producers based on P/R
(productivity/respiration) ratios being greater than one.
Temperature is related to solar radiation impin-
ging on the water column and the influence of the Gulf
Stream or Florida Current. While reef corals have been
described as stenothermic (Wells 1957b), many species
are very tolerant of temperature variation (Mayer 1914,
1916, 1918). Reef corals flourish (optimum physiologi-
cal conditions) best between 250 and 290 C. Coral reef
development is reported to be limited by low tempera-
tures. This was proposed by Vaughan (1919) for Florida.
He reported that corals did not build reefs where tem-
peratures fell below the 180 C minimum for prolonged
periods. The growth and demise of staghorn reefs at the
Dry Tortugas are related to temperature control. During
favorable periods these populations proliferate, but
occasionally a cold winter reduces temperature below
tolerance levels and mass mortality occurs (Porter et al.
1982). Within a decade, if mild conditions prevail, the
populations recover. Temperature data in Figures 6-11
compared recent data with that from the early part of
this century. The data imply no major change in climate.
It is apparent that temperature is one of the
major controls of reef development off southeast Florida
(Roberts et al. 1982). Another source of coldwater stress
is from occasional upwelling from sources beneath the
Florida Current. These stratified layers occasionally
cause localized fish kills. Heat-related stresses in summer
usually occur during midday when spring low tides
coincide with calm wind conditions (Plate 24b). The
shallow reef flats suffer from thermal stresses manifested
in zooxanthellae expulsion. Ultraviolet light may also be
involved with this phenomenon. As water depth is
reduced, the UV light may have sufficient strength to be
toxic and physically burn the tissues (Jokiel and York
1982).
Salinity is controlled by precipitation, evapora-
tion, and runoff after major rainfall over adjacent land
areas. Salinities are usually in the oceanic range. Table 9
reported ranges from 33.1 to 38.6 ppt. Jones (1963)
reported some diurnal changes in a time series from
Margot Fish Shoal off Elliott Key. Salinity does not
normally pose a threat to the reefs. After hurricane
rains, however, there is a potential for dilution due to
runoff. The only reported possible salinity-related
phenomenon was the 1878 Tortugas "blackwater,"
which was reported to have killed significant populations
of corals. Mayer (1902) reported that a great number of
the Acropora reefs were devastated by this event. It is
suggested that this was a glut of freshwater runoff from
the Everglades or a toxic phytoplankton bloom. There is
no documented evidence to sustain either hypothesis. In
other parts of the Caribbean, particularly the Greater
Antilles and other high islands (e.g., Roatan) with
mountain ranges, freshwater runoff is a significant threat
to nearshore coral reefs. Goreau (1964) reported that
freshwater runoff killed corals in Jamaica following a
hurricane.. Wells (1956, 1957a) reported that reef
corals tolerated 27-40 ppt, and that optimal limits were
34-36 ppt.


Tidal conditions off the southeast coast of
Florida were presented in Table 8. All ranges are less
than 1 m. Tidal conditions only pose a threat to the
shallower portions of the reef flat and spur and groove
zones. Reef emergence rarely occurs except under
synergistic meteorological influences. When spring low
tides occur at or near midday during the summer,
thermal heating can occur (Plate 24b).
Dissolved oxygen is dependent upon photosyn-
thesis and respiration of benthic organisms. Temperature
and salinity control the saturation level of oxygen in the
water. Studies by Vaughan (1914d), Mayer (1918),
Yonge and Nicholls (1931), Smith et al. (1950), and
Jones (1963) reported that oxygen is not truly a limiting
factor for corals under most circumstances. Oxygen
remains in supersaturation during most of the day. Jones
(1963) reported that the diurnal range was from 90% to
125% saturation during the summer.
Water column pH is influenced by organic
metabolism. Studies by Jones (1963) and Jaap and
Wheaton (1975) reported pH values of near 9. It is not a
limiting factor under most circumstances.

7.3 COMMUNITY STRUCTURE

Coral reefs off southeast Florida have developed
over the past 5,000-7,000 years. It is presumed that
"survival stocks" living in what is now deeper water
during the Wisconsin ice age were the seed populations
for replenishment of the reefs as the sea level rose during
the Holocene transgression. Some evidence for this is
found in terraces seaward of some of the major reefs
(Middle Sambo and Sand Key Reefs). These were
probably active constructional reefs during a lower sea
level stand which were drowned as sea level rose rapidly.
The fossil barrier reef off Broward and Palm Beach
Counties also provides credibility to this theory (Lighty
1977). Since the origin of the recent reefs, organisms
have had sufficient time to develop into complex com-
munities. They display all levels of complexity in their
structure, diversity, interactions, competition, and
trophic relationships.
In terms of abundance, dominance, and diversity,
various elements display certain characteristic patterns.
The sessile benthos is the most stable and best suited for
time series studies. The mobile benthos, plankton, and
nekton exhibit properties that make it difficult to make
time series comparisons. The significance is that al-
though some organisms are essential to the reef, others
may be important, but have not been studied or have
such radical seasonal variability that they are not a good
indicator of reef vitality. Most of the primary framework
coral species have a relatively long lifespan and, once
established, are successful in competing for resources.
These are keystone species in that they build the reef
and create many niches for other biota. Table 29 details
abundance measurements conducted at Elkhorn Reef.
Additional information on the abundance and densities
of stony corals at a number of coral reefs from the reef
tract appears in Tables 11, 13-15, 17, and 19. In the
patch reef it is apparent that Montastraea annularis is a







dominant keystone species. Siderastrea siderea, Diploria
spp., and Colpophyllia natans are also important. On the
bank reefs, dominance and importance varies among reef
zones with great variability between reefs. On reef flats
Porites astreoides and Diploria clivosa are dominant;
Porites porites and Acropora cervicornis are also impor-
tant. Temporal stability in this zone is poor; hence, the
existence of the arborescent species is often transitory.
The shallow spur and groove zones are dominated by
Millepora complanata and the zoanthid Palythoa sp.
These species thrive in the turbulent conditions around
this zone. In deeper spur and groove areas Acropora
palmata is found to be the dominant and keystone
species. Occasionally on some reefs the A. palmata zone
extends onto the reef flat. This is especially true where
the reef flat is deeper than 1-2 m.
On the flanks of the spurs a set of species that
favor vertical orientation is conspicuous. This includes
several species of Mycetophyllia and Agaricia agaricites..
In the buttress-forereef zone the seaward portion of the
spur and groove formation often continues as low relief
features into deeper water. Montastraea annularis is of
prime importance. Other important species include
Acropora cervicornis, Diploria spp., Colpophyllia natans,
Agaricia agaricites, and Meandrina meandrites. The
diversity in this zone is often high. The physical ex-
tremes are moderated by depth, and biological interac-
tion is much more significant in affecting community
structure.
In the general sense the structure of the entire
community can be envisioned, but in fact there is no
field study that has quantitatively defined all the biota
from a coral reef community. The autotrophic elements
are represented by calcareous, crustose coralline, fleshy
algae, and the other benthic organisms that contain
producer organisms (zooxanthellae) within their tissues:
corals, anemones, zoanthids, and sponges. The producers
are also represented by a blue-green endolithic algae
within the upper levels of living Scleractinia skeletons.
All of the above have the function to fix carbon on the
reef. The phytopglnktorn prr.idce limited input, adjacent
seagrass and benthic algae add to the carbon budget.
Production is portioned into a number of categories. The
carbon fixed within the zooxanthellae is conserved
within the host or exported as a secretary product:
mucus that is an energy source. The herbivore or pri-
mary consumer category is complex. Some of the
better known herbivores include parrotfish (Scaridae),
surgeonfish, tangs (Acanthuridae), and the sea urchins
(Diadema antillarum and Eucidaris tribuloides). Various
other organisms also are herbivores. Secondary con-
sumers include those organisms that feed primarily on
herbivore consumers. This includes a wide range of fish
and invertebrates. There may not be great discrimination
by the carnivore on prey selection; they may indiscrimi-
nately feed on carnivore, omnivore, and herbivore
elements. Some known secondary consumers include the
butterfly fish (Chaetodontidae) and fireworm (Hermo-
dice carunculata; Plate 18b), which are obligate coral
predators. Higher level consumers include larger preda-
tory fishes: grouper (Plate 23b), jewfish, and barracuda.


These fishes tend to range widely over numerous reef
habitats and forage on prey as opportunity occurs. The
omnivores include a number of crustaceans and echino-
derms that scavenge plant and animal material. Plankti-
vores include the corals, zoanthids, polychaetes (Spiro-
branchus giganteus; Plate 8b) and basket star (Astrophy-
ton muricatum). The corals, as noted in Chapter 4, have
a trophic structure that is species dependent. Other
organisms are presumably more dependent upon a single
resource, e.g., the basket starfish feeds exclusively on
plankton.
Community structure of the corals appears to be
physically controlled by depth, light, substrate, wave
forces, sediment, and temperature. In a dendrogram
(Figure 20) of Bird Key Reef (Figure 19), Dry Tortugas,
the pattern is consistent with a change of species asso-
ciations of a few opportunistic species that settle and
exploit this region; but the physical extremes often
make this area unsuitable for coral habitation. The
dendrogram displays low similarity and weak linkage in
this portion of the reef. In the moderate depths is a set
of species that displays a wide range of distribution, but
localized abundance patterns. This is presumably the
result of microhabitat preferences, larval settlement, and
competition among the other community elements.
The similarity found in the dendrogram indicates that
these species groups are bound together in a more
organized manner than those species found in the
shallower portions of the reef. The deepest portion of
Bird Key Reef exhibited a unique set of species not
found in any other portion of the reef; hence, the
dendrogram set this coral association off by itself. The
pattern displayed in patch reef communities is much less
defined, and depth differences are moderate; hence, the
random spatial dispersion usually makes the patch reef a
community of greater similarity than that found in the
bank reef.

7.4 DIVERSITY

Species diversity of the coral reef communities
found off southeast Florida is a difficult parameter to
estimate. Coral reefs in general have been described as
the most diverse marine biological entities in the bio-
sphere. They have been likened to the tropical rain
forest with its multi-canopy of producers: high biomass,
rapid turnover, and recycling of limiting nutrients.
Physiography is often multilayered, e.g., in the Acropora
palmata community (Plate 16a) the branches form
layers, while smaller corals and other benthos live in the
shadow of the elkhorn coral. Numerous other organisms
live on, within, or under this coral association. Glynn
(1964) reported that six species of crustaceans and
echinoderms lived in or around the A. palmata com-
munity in Puerto Rico (Gonodactylus oerstedii, Dome-
cia acanthophora, Petrolisthes galathinus, Echinometra
lucunter, Holothuria parvula, and Ophiothrix angulata).
The diversity of a community is related to the
complexity of the trophic relationships of the habitat
(Hutchinson 1959; Paine 1966). Species diversity has
developed into polarized theology. Pielou (1966) advo-































































I I I I I
100. 75. 50. 25. 0.
LEVEL OF SIMILARITY
Figure 20. Classification of Bird Key Reef and Dry Tortugas based on abundance of stony corals using
group average sorting and Czekanowski's coefficient.








cated use of information theory to study species diver-
sity, and Hurlburt (1971) responded that species diver-
sity was a nonconcept. Species diversity has been mea-
sured in many ways. Some reef workers have favored
using plotless sampling techniques and computing
diversity with the Shannon Wiener Index H' and its
evenness component, J', as well as reporting the number
of species (species richness). Sampling adequacy is
usually determined by the asymptote of a species area
curve. The most striking finding in relation to stony
corals is the matter of sample size. In the Red Sea (Loya
1972) and Panama (Porter 1972) the minimum accept-
able transect length was 10 m; in Florida reef communi-
ties, a 25-m length is necessary to insure adequate
sampling. This implies that the reefs off southeast
Florida are less diverse in their stony coral fauna than
those from other more tropical regions. If one studies
the species found on any given reef, however, one will
find almost all the species reported from other Carib-
bean areas. They may be quite rare, but present never-
theless. Table 27 presents the Scleractinia found
throughout the Florida Reef Tract, and Figure 21 shows




BIRD KEY REEF


7.-
ELKHORN REEF, BNP





10.
DOME REEF, BNP




uj,
D
W SCHOONER REEF, BNP
0
oa

S SAJAX REEF, BNP
w




o
U


Z0.
z CARYSFORT REEF


MOLASSES REEF

3.
FRENCH REEF

2.
ELBOW REEF


I .I ,- I I I *


o00.


5o.
LEVEL OF SIMILARITY


Figure 21. Similarity of coral fauna on Florida reefs
using group average sorting and Czekanowski's coeffi-
cient.


similarity of coral fauna at various reefs. Some reefs have
received much more intensive study than others; there-
fore, inter-reef comparisons cannot be drawn. For
example, in Table 17 sampling was restricted to a
specific site within a narrow depth range; hence, species
diversity is limited. On the other hand, work at Bird Key
Reef, Dry Tortugas, was intensive over a wide area and
more than 50 species were identified (Jaap, in prepara-
tion). The same holds true for many other reef taxa.
Small-scale studies report fewer species while large-scale
(spatial and temporal) studies present long species lists.
In some groups the species are so poorly known or so
many species remain undescribed that it is truly impos-
sible to evaluate total community species diversity.

7.5 SYMBIOSIS

Coral reefs exhibit a high level of species inter-
action; symbiosis contributes to the high diversity and
productivity. There are many scales of symbiosis ranging
from the microscopic (zooxanthellae-coral) (Figures 22
and 23) to macroscopic (cleaner shrimp-anemones-fish).
It also includes commensalism, mutualism, and parasi-
tism. Numerous organisms display some form of sym-
biotic relationship in coral reefs. One of the most
dramatic forms of symbiosis is the fish-cleaning station.
Several associations have developed to take advantage of
this resource. One example is the cleaner shrimp, Pericli-
menes pedersoni (Chase). The shrimp lives in a host
anemone; various anemones may serve as host, and the
shrimp may move from one anemone species to another.
Condylactis gigantea (Weinland) and Bartholomea
annulata (LeSueur) are common hosts to P. pedersoni.
The shrimp attract fish to clean by waving their anten-
nae. The fish come to the anemone, and the shrimp
swim to the fish and clean the mouth and gills. Another
cleaning relationship involves the cleaning gobies Elac-
tinus oceanops and Gobiosoma genie. These small gobies
establish cleaning stations, usually around a specific
coral, but sometimes a few fish form a collective station
and cooperate in the cleaning. A fish requesting a
cleaning approaches the station and displays a particular
behavior to receive cleaning. Upon the displayed signal,
the goby swims into the mouth, gill chamber, and
around the fish body to remove parasites, fungi, algae,
and necrotic tissue. Limbaugh (1961) reported that
cleaning symbiosis was very important in coral reef
communities. Bruce (1976) and Patton (1976) reported
on associations of living corals and crustacean commen-
salism in coral reefs with most of the emphasis on Pacific
reefs.
Organism interactions in a coral reef are also
complex and highly developed. Some are obligate while
others are mostly by chance. Patton (1976) wrote,
"Corals exceed all other invertebrate groups in the
diversity of forms and numbers of species to which they
play host." Food and shelter are the major factors
attractive to associates. The coral skeleton offers an
especially good niche for smaller organisms to escape
predation. Numerous sponges, polychaetes, bivalves, and
sipunculids find habitat in the base of corals. Other













t$>t


~-ZrJK4 j -l.. .~ :-y K .


x A

Coral nucleus

Coral mitochrondria

Figure 22. Electron micrograph of Agaricia fragilis zooxanthella, 6590 magnification.













Starch grain

C Chloroplast

Accumulation body

"Calcium oxalate


- Coral nucleus


- Chromosome

SZooxanthellae nucleus


*-


S

Figure 23. Electron micrograph of Agaricia fragilis zooxanthella, 14,660 magnification.


if


A'
/9


.4


Ce
'
411- 10


'SH
IqP


, *


0








organisms live successfully on the coral's upper surface.
Some, such as copepods, have developed specialized
forms to live in the coral polyps; they are more worm-
like than crustacean (Patton 1976). Some organisms
have developed unique ways to modify the coral skele-
ton. The subfamily Pyrogomatinae (barnacles) and the
decapod crustacean Domecia acanthophora are able to
modify the Scleractinian skeleton. Domecia acantho-
phora lives on A. palmata branches (Patton 1967) and is
able to influence calcification such that the coral builds
a skeletal structure around the crab. The process initiates
when a crab seeks a position on the branch margins
where bifurcation has begun; the crab maintains its
position, and the skeleton grows around its den. In time
the area resembles a small pit or cave. Domecia acantho-
phora has modified second maxillipeds that allow the
crab to feed on suspended material. In this case, the
relationship is both shelter- and food-related. Patton
(1976) reported that mobile crustaceans living in close
association with corals feed on the sediment and detritus
from the water column and that which settles on the
coral surface. Corals also release energy sustaining
materials that other organisms may utilize, e.g, mucus,
fecal detritus, zooxanthellae, and metabolic wastes.
Competitive interactions are important in deter-
mining community structure on a coral reef. The major
area of interaction is in the competition to acquire
spatial territory. Successful organisms can defend
their territory against intruders. They are also able to
expand into the adjacent region at the expense of
organisms that are less able to maintain their territory.
An example of local habitat manipulation is the effect of
the threespot damselfish (Pomacentrus planifrons) on
the corals Acropora cervicornis and Montastraea an-
nularis. Kaufman (1977) and Potts (1977) reported that
the threespot damselfish was able to garden small areas
of reef by killing the corals and defending the area from
herbivorous fish, thus allowing a crop of filamentous
algae to grow on the dead corals. These small fish are
territorial and defend the area against fish, invertebrates,
and divers. As a result, the area has an abnormally high
algal cover. This result is short term in A. cervicornis
habitats. Since this species grows rather rapidly, it can
grow away from the damselfish territory and develop a
new area. In the case of M. annularis where growth is
slow and propagation is mostly by larval recruitment,
the damselfish may have a more significant negative
impact on the affected coral colony.
A number of authors have reported on the effect
of the black-spined sea urchin, Diadema antillarum, on
coral reefs. Sammarco et al. (1974) reported that D.
antillarum controlled coral community structure; Bak
and Van Eys (1975) reported that the urchin fed on
coral; and Sammarco (1980) reported that D. antillarum
was important in providing microhabitats for coral larvae
to settle. Diadema antillarum is a common resident on
most coral reefs; hence, its control is probably signifi-
cant.
Another form of interaction that has been
mentioned earlier is the ability of the corals themselves
to maintain or advance territorial superiority by extra-


coelentric feeding behavior with the extension of mesen-
terial filaments. The more "aggressive" species have the
ability to digest the tissues of less "aggressive" adjacent
species. Lang (1973) described this form of interaction.
It is not a rapid phenomenon; in some cases it may take
months for the interaction to be noticed.

7.6 PREDATOR-PREY RELATIONS

Predator-prey relationships are far too great and
complex to detail here. One of the more well-known
corallivores is the polychaete Hermodice carunculata
(Plate 18b), a large marine worm that is documented to
feed on a number of coral species (Marsden 1960, 1962;
Glynn 1962; Ebbs 1966; Antonius 1974b; Lizama and
Blanquet 1975. Glynn (1973) reviewed western Atlantic
coral predators. Some organisms such as the gastropods
Coralliophila abbreviata, Calliostoma javanicum, and
Cyphoma gibbosum are mobile species that move to and
from the coral. They feed on the coral, but apparently
do not receive protective shelter. Fish within the families
Scaridae, Ephippidae, and Pomacentridae feed on coral
(Glynn 1973). They are not obligate to a particular coral
species; this major difference between Pacific and
Atlantic corallivores (lack of obligate species relation-
ships in the Atlantic) may reflect that the time of
development for Atlantic reefs and coral species has
been relatively short. (Atlantic Scleractinia are only ca.
one million years old; Pacific reefs have a much older
fauna.) Predation may directly cause mortality and
morbidity. Injury caused by predation may lead to the
invasion of boring and rasping biota. When the coral is
damaged, recovery may occur by regeneration of tissue;
but regeneration may be prevented by successful coloni-
zation of the injured area by other organisms (filamen-
tous algae, diatoms, sponges, Millepora, and zoanthids).
This alien growth is detrimental to the coral, which may
succumb to the secondary invasion.
Rapidly growing species may grow over and
shade out other organisms, denying them resources.
There is also evidence that some reef organisms are able
to maintain and advance spatial resources through the
secretion of toxic chemicals (Jackson and Buss 1975).
Figures 24-27 show the cumulative effect of
these interactions through time for a small area on
Elkhorn Reef.

7.7 PRODUCTIVITY

The earliest study of overall productivity of a
small coral reef was Odum and Odum (1955) at Eniwe-
tok, a Pacific atoll. The comparability with Florida is
poor; however, the concept of high productivity is valid.
Odum and Odum (1955) reported that mean annual
production was 846 gm dry biomass/m2. On a 24-hour
basis there was a net gain of 2 gm C/m2. Sournia (1977)
reviewed coral reef primary production and concluded
that gross production in coral reefs yielded the highest
productivity of any ecosystem on earth. The magnitude
of gross production ranged from 2-10 gm C/m2/day;
however, net production may, in some cases, be negli-
















0 o

S Aeropor cerviorni

Acropora palmata







Diploria clivosa
O SE
Figure 24. Time series of a 2x2 meter area of Elkhorn
Reef, 1978.


Figure 25. Time series of a 2x2 meter area of Elkhorn
Reef, 1979.


I pora cerviLornls

- Acropora palmata





-p: : H


4Sideroltroa ;


CC


Diploria cllvose


Figure 26. Time series of a 2x2 meter area of Elkhorn
Reef, 1980.



gible. Much of this research was accomplished in the
Pacific; extrapolation to Florida reefs must be qualified
by several facts. The Pacific reefs are usually set in more
benign or predictable environments, with negligible
seasonal variation in temperature. Because of the diffi-
culty in evaluating community productivity and respira-
tion, few studies have considered total community
metabolic budgets. By far, the greatest research emphasis
has been on the zooxanthellae and the symbiotic rela-
tionship with coral. Trench (1979) and Schoenberg and
Trench (1980a, 1980b, 1980c) reviewed the cellular
biology of this aspect. Rodgers (1979) studied two 10 x


Figure 27. Time series of a 2x2 meter area of Elkhorn
Reef, 1981.



1 m reef sections at San Cristobal Reef, Puerto Rico; net
productivity ranged from 0.03 to 1.85 g 02/m2/hr. A
recent summary-review of coral reef physiology is found
in Gladfelter (1983).

7.8 CORAL REEF MODELS

Conceptual models were proposed by Dahl et al.
(1974) and improved upon by Smith (1978). The Dahl
et al. (1974) model included organism processing units
(similar functional elements), pathways, and external
driving forces. The following outline is taken from Dahl


4


r~~-s
.2~
..~.
. :
~






et al. (1974), with some modification in terminology.

1. Benthic Plants
a. Nitrogen-fixing algae, nutrient recycling
function
b. Crustose coralline algae, framework or-
ganism, cementing function
c. Benthic microalgae, primary producer
d. Turf algae, <2 cm high, autotroph
e. Carbonate producing macroalgae,
sediment production
f. Boring algae (Ostreobium), filamentous,
within the carbonate frame
g. Detached macroalgae, Sargassum,
floating autotrophs
h. Marine grasses, blades, adjacent to
the reef
i. Marine grasses, roots, alter sediment
characteristics

2. Plankton
a. Heterotrophic phytoplankton, <10
microns
b. Autotrophic phytoplankton, <10
microns
c. Autotrophic phytoplankton, 10-100
microns
d. Autotrophic phytoplankton, >100
microns
e. Microholoplanktonic omnivores,
<200 microns
f. Mesoholoplanktonic omnivores,
200-500 microns
g. Macroholoplanktonic omnivores,
>500 microns
h. Neuston omnivores, all sizes
i. Microepibenthic omnivores, <200
microns
j. Mesoepibenthic omnivores, 200-500
microns
k. Macroepibenthic omnivores, > 500
microns
1. Mesoholoplanktonic carnivores,
200-500 microns
m. Macroholoplanktonic carnivores, > 500
microns
n. Neuston carnivores, all sizes
o. Mesoepibenthic carnivores, 200-500
microns
p. Macroepibenthic carnivores, >500
microns
q. Microholoplanktonic detritivores,
< 200 microns
r. Mesoholoplanktonic detritivores,
200-500 microns
s. Macroholoplanktonic detritivores,
>500 microns
t. Neuston detritivores, all sizes
u. Microepibenthic detritivores, <200
microns


v. Mesoepibenthic detritivores, 200-500
microns
w. Macroepibenthic detritivores, > 500
microns

3. Benthos, Invertebrates
a. Animal-plant symbionts, energetic sup-
port from autotrophs
b. Invertebrate "scrapers," remove sub-
stratum with food
c. Invertebrate browsers, do not remove
substratum
d. Passive suspension feeders, collect nu-
trients from water column without
physical action on the part of the
organism
e. Active suspension feeders, actively col-
lect nutrients from the water column
by creating currents or selective pre-
dation
f. Microbrowsers (meiofauna), nutrition
gained from material in sediments,
<2 mm
g. Macro-deposit feeders, nutrition gained
from larger (> 2 mm) sedimentary
fraction
h. Sedentary micropredators, selectively
capture water column prey
i. Small predators, motile organisms that
harvest invertebrates and vertebrates
j. Medium predators, mobile organisms
that harvest medium-sized invertebrates
or vertebrates
k. Meiofauna predators, live in the sedi-
ment, harvest meiofauna
1. Parasites and pathogens, very selective
predator that gains nutrients from a
limited number of host organisms
m. Parasite cleaners, mobile organisms,
specializing in removing parasites
from other organisms
n. Attached eggs

4. Nekton, Vertebrates
a. Grazers, also remove a portion of the
substrate, i.e., parrotfish
b. Browsers, do not affect substrate
c. Bottom feeding planktivores, feed on
epibenthic plankton
d. Midwater feeding planktivores, feed on
holoplankton and neuston
e. Small predators, <50 mm standard
length (SL)
f. Medium predators, 50-250 mm SL
g. Large predators, 250-500 mm SL
h. Top predators, >500 mm
i. Parasite pickers, feed on vertebrate
ectoparasites
j. Detritus feeders
k. Attached eggs







5. Detritus/Nutrient
a. Nitrate, NO3 dissolved
b. Nitrite, NO2 dissolved
c. Ammonia, NH3 dissolved
d. Organic carbon, C dissolved
e. Suspended detritus, <10 microns
f. Suspended detritus, 10-100 microns
g. Suspended detritus, > 100 microns
h. Trapped detritus
i. Organic nitrogen, N dissolved
j. Inorganic phosphate, PO4
k. Organic phosphorus, P dissolved
1. Oxygen, 02
m. Interstitial NO3, dissolved
n. Interstitial NO2, dissolved
o. Interstitial NH4, dissolved
p. Interstitial C, dissolved
q. Interstitial particulate organic C (dead)
r. Interstitial organic N, dissolved
s. Interstitial organic P, dissolved
t. Interstitial P04, dissolved
u. Interstitial 02, dissolved

6. Geology
a. Dissolved inorganic C (CO2, HCO3, and
CO3)
b. Suspended inorganic C (fine CaCO3)
c. Bedload inorganic C (coarse CaCO3
sediments on the sea floor)
d. Frame inorganic C (reef frame)
e. Organism inorganic C (CaCO3 in living
non-frame organisms)
f. Rubble inorganic C (large talus)
g. Inorganic C in sand (CaCO3, 62 mic-
rons-4 mm)
h. Inorganic C in mud (CaCO3, <62
microns)
i. Interstitial dissolved C (CO2, HCO3,
and CO3 dissolved in interstitial sedi-
ment water)

7. Input From Outside the Reef Community
a. Autotrophic plants, C
b. Nitrogen-fixing plants, N
c. Nitrogen-transforming plants, oxidize
and reduce N compounds
d. Decomposing plants, convert organism
biomass to simpler organic material,
nutrients, CO2, and water
e. Birds, remove fish and invertebrates,
contribute feces containing N and P
compounds
f. Decomposing organisms, contribute to
organic and inorganic chemical pool
g. Sea turtles, feed on benthos and float-
ing organisms, contribute chemicals
from feces
h. Talus islands adjacent to the reefs, may
contribute organic and inorganic chemi-
cals and sediments to the reef.


The Dahl et al. model contained 104 compart-
ments. A matrix of the interrelationships implied about
2,000 of the 10,816 potential interactions were active,
and a material and energy flow exists between these
categories. In terms of modeling coral reefs, Smith et al.
(1978) reported that until the modeling technique
advances to the point that it is realistic, the budget
analysis method offers better insight into ecosystem
dynamics by focusing on an element within the ecosys-
tem (e.g., carbon budget, nitrogen budget). Smith et al.
(1978) reported on several budgets from a hypothetical
atoll in the Pacific. Figure 15 provided a qualitative
graphic representation of a calcium carbonate budget
from Barbados.

7.9 NATURAL IMPACTS

Hurricanes are the most severe natural impact
faced by coral reef communities. Mega-hurricanes (those
with 200-mi/hr or greater winds) have devastated reef
areas, and either recovery has been slow or the coral reef
community has been replaced by another community.
Stoddart (1962, 1963, 1974) reported that Hurricane
Hattie destroyed reefs off the coast of British Honduras
(Belize) and that recovery was negligible. Woodley et al.
(1981) reported that Hurricane David decimated shallow
reefs near Discovery Bay, Jamaica, and post-hurricane
mortality of damaged organisms was significant (Knowl-
ton et al. 1981).
In considering the effect of hurricanes, two
major areas of negative impact are reported. Physical
damage occurs as a result of the huge seas generated by
the hurricane winds. Shallow reef zones bear the brunt
of the wave forces as they are expended on the spur and
groove and reef flat. Smaller corals and other attached
organisms are often dislodged, fragmented, and abraded
by the severe physical pounding. The other major impact
concerns dilution of salinity caused by torrential rains.
In regions where mountainous terrestrial land masses
abut the coral-lined coast, severe runoff may turn coastal
waters hyposaline (Goreau 1964). Erosion of soil and
transport by the runoff is also credited with causing
coral mortality. Goreau (1964) reported shallow reef
mortalities due to salinity stress as well as to burial by
terrigenous silt. The passage of the storm also causes
churning of the bottom sediments increasing turbidity
within the water column.
Hurricane damage to Florida reefs reported from
the literature are of a lesser magnitude, and in some
respects could be considered beneficial. Springer and
McErlean (1962a) reported negative impact on patch
reefs off Key Largo from Hurricane Donna. The storm
crossed the reef tract about 40 km south of Key Largo,
9-10 September 1960. Windspeed was approximately
161 km/hr, with gusts approaching 242 km/hr (Shinn
1975). High seas dislodged and redistributed corals in
the adjacent area of Key Largo Dry Rocks (Shinn 1975).
Hurricane Betsy passed within 16 km of Key Largo Dry
Rocks on 8 September 1967, with a windspeed of
approximately 193 km/hr. Shinn reported that hurricane
damage was not evident 5 years following Donna and 2







years after the passing of Betsy. Ball et al. (1967) and
Perkins and Enos (1968) also discussed the effect
Hurricanes Donna and Betsy had on the reefs from a
geological standpoint. Jindrich (1972) postulated
that hurricanes were one of the controls on reef develop-
ment at Dry Tortugas.
The nature of hurricane impact has several
interesting aspects. First, the hurricane causes consider-
able physical alteration of habitat. Sessile biota are often
dislodged and transported considerable distances from
their original growth positions. Fish are dislocated some
distance from the resident reefs (Springer and McErlean
1962a). Smaller cryptic organisms are often left home-
less, the resident coral or sponge being fragmented or
possibly destroyed. When the mobile organism is an
obligate commensal (having specialized niche require-
ments), it is quite likely that it will be difficult for it to
locate alternative housing. Following the initial impact,
turbidity may remain high for a week or more before
water column transparency returns to normal condi-
tions. After several more weeks, those corals that did
survive will either exhibit growth over the scars and
lesions and reattach to the bottom or they will die.
Several recent reports described in detail the process of
healing and secondary mortality. Highsmith et al.
(1980), Woodley et al. (1981), and Rodgers et al. (1982)
reported on the effects of several Caribbean hurricanes.
Acropora cervicornis and A. palmata displayed impres-
sive recovery in Belize and the U.S. Virgin Islands
(Highsmith et al. 1980; Rodgers et al. 1982); however,
these same species displayed considerable secondary
mortality in Jamaica (Woodley et al. 1981). In Florida
rapid recovery was reported following Hurricanes Donna
and Betsy (Shinn 1975). The differences relate to the
magnitude of impact; those reefs exposed to major
hurricanes that pass close to the reef will suffer severe
impact, while hurricanes that are of lesser magnitude or
a greater distance from the reef are a lesser threat.
Pearson (1981) reviewed coral reef recovery; he reported
that following severe impact, it requires several decades
for recovery. Pearson also reported that larval recruit-
ment was much more significant than fragment propaga-
tion in the reef recovery process. This finding reflects
recovery of Pacific reefs following the plaguelike preda-
tion by Acanthaster planci (crown-of-thorns starfish)
more than recovery from natural physical impacts. It
appears that following major storm damage Acropora
palmata and A. cervicornis may benefit from fragment
propagation. In Discovery Bay, Jamaica, however, the
few fragments of A. cervicornis alive 5 months after the
storm still suffered heavy mortality from surviving coral
predators (Knowlton et al. 1981). Plate 10b shows
fragments of an A. palmata colony that has been over-
turned and is now sprouting new branches. Highsmith
(1982) reviewed propagation recruitment.
The other major natural impact on coral reefs is
thermal stress. This can occur on either end of the spec-
trum; both heat and cold stress are reported to cause
negative impact. Jaap (1979) reported on a zooxanthel-


lae expulsion (Plate 24b) at Middle Sambo Reef (off
Boca Chica Key) related to elevated water temperature
that was created by synergistic meteorological and tidal
conditions. The overall impact was not significant in that
recovery took approximately 6 weeks. Vaughan (1911),
Mayer (1918), Porter et al. (1982), and Hudson (in
press) reported thermal stress damaged or killed reef
biota at Dry Tortugas.
Heat-related stress usually occurs in late summer
during solar noon to mid-afternoon. It is usually low
tide, and the sea state is calm. Under these conditions,
shallow reefs heat rather rapidly. Ambient temperatures
are already 300-310 C. Since the upper lethal tempera-
ture for Acropora palmata is 35.80 C (Mayer 1914), it
does not take a great deal of heatingto create stressful
temperature levels. Shinn (1966) reported that trans-
planted A. cervicornis expelled zooxanthellae at or near
33.80 C. In contrast to cold stress, most heat stress is
localized and is not a transported water mass phenome-
non.
Cold stress was discussed in Chapter 2 under
seawater temperature. The basic geographic configura-
tion lends itself to the creation of cold water masses in
shallow embayments, especially Florida Bay during the
passage of winter cold fronts. The shallow bay allows the
water mass maximum surface exposure to the polar air
mass. After cooling, the water is moved to the Atlantic
by tidal pumping, density gradients, and winds. The
water mass moves through the passes and across the shelf
and into the reef communities. Reef development
requires no prolonged exposure to 180 C; however,
individual species can tolerate significantly lower tem-
perature (Mayer 1914, 1918). Most reef corals are
severely stressed at or near 140 C. Shinn (1975), Hudson
et al. (1976), and Roberts et al. (1982) reported that
cold water masses originating in Florida Bay caused coral
mortality to patch reefs adjacent to the passes. Most
major offshore reefs do not suffer due to mixing of the
cold water with resident water masses and the modera-
ting effect of the Florida Current. Dry Tortugas has
suffered significant mortality of staghorn coral popula-
tions as reported earlier due to cold stress.
Red tide (toxic phytoplankton blooms) are not
common off the east coast, but entrained water masses
occasionally carry a red tide into the Atlantic.
Natural events are a major factor controlling
coral reef development, community structure, and
species diversity. Connell (1978) reported that high
diversity in tropical rain forests and coral reefs was
related to intermediate frequency and magnitude of
interference by natural events. Without negative impact
by these agents, dominant organisms outcompete other
organisms for resources, and species diversity is reduced.
The hurricane or other natural agent opens new spatial
habitat to pioneering organisms that can successfully
exploit new territories. In a benign environment, one or
a few species can potentially dominate, thus reducing
diversity and the overall ability of the community to
respond to outside stress.







CHAPTER 8


MANAGEMENT


8.1 HUMAN IMPACTS

Coral reefs off southeast Florida are multi-user
resources, experiencing increased exploitation that
results in some negative human impact on the resource.
Although natural events are far more severe than man's
individual acts, human impact on the reefs must be
multiplied by the number and the frequency of occur-
rence, which in total may not allow the reef resources
sufficient time for recovery. Some negative impact is
focused on spatially small areas and is chronic. In recent
years a number of publications dealing with coral reef
pollution, stress, and death have documented or por-
trayed these subjects in some detail. Loftas (1970),
McCloskey and Chesher (1971), Smith et al. (1973),
Johannes (1975), Endean (1976), and Weiss and
Goddard (1977) detailed pollution and human impact
on coral reef communities. Voss (1973) and Dustan
(1977b) reviewed problems in Florida reefs. Currently
a number of controls are in force to mitigate human
impact. In some cases controls have worked; in others,
the negative impact has continued, and increased damage
has occurred. Mitigation is difficult because activities are
continuous and human impact on coral reefs is contro-
versial. User groups are often polarized, frequently
making the possibility of compromise or acceptance
of alternative viewpoints difficult.

Dredging and Treasure Salvage

In terms of severity, dredging is the most damag-
ing human activity in and around coral reefs. Poorly
planned and mnijge dr-dgmng operations have caused
the demise of many reefs. The physical impact of dredge
gear (anchors, cables, chains, pipes, suction and cutting
heads) dislodge corals or cause lesions or scars that lead
to infection and mortality. Reef organisms increase
respiration to remove silt resultingin reduced dissolved
oxygen levels. Coupled with increased respiration is
reduced photosynthesis and oxygen production due
to lowered light levelsMHigh turbidity generated by
dredging reduces light penetration through the water
column (Johannes 1975). Sediments excavated by
dredging are often anaerobic and bind up available
dissolved oxygen. Silt created by dredging remains in the
local area for long periods and is resuspended during
storms. Johannes (1975), Levin (1970), Endean (1976),
and Bright et al. (1981) reviewed dredging impacts on
coral reefs. A coral's ability to remove sediments was
reported by Hubbard and Pocock (1972) and Hubbard
(1973). Bak (1978) reported on lethal and sublethal
effects of dredging on reef corals in Curacao, Nether-
lands West Indies. Corals that were poor sediment
removers expelled zooxanthellae and died. Two species
had extremely reduced calcification rates (Bak 1978).
Two types of dredging occur off southeast
Florida; most of this activity is located from Miami


northward. One kind results in spoil from deepening and
maintenance dredging of navigational channels; it is
disposed of on land and at sea. When disposed at sea
there is potential for reef burial and increased turbidity.
Occasionally, dredging operations will cut through living
reefs. Sewage outfall pipe burial has also cut through
reefs (Shinn et al. 1977). The other form of dredging
off the southeast coast is done for beach renourishment.
Sedimentary deposits are mined and brought ashore by
pipes or barges and deposited on the beach. The material
is a slurry; the silty runoff leaches back to sea causing
increased sediment loading of the water column. During
the fall of 1981, a beach renourishment project on
South Miami Beach threatened a small linear hardground
community composed of significant numbers of octo-
corals and stony corals. Dade County Pollution Control,
Dade County Marine Institute, U.S. Geological Survey,
and Florida DNR personnel transplanted about 200
stony coral colonies that were threatened by burial.
A critical part of all dredging activities should be
a coherent field study to insure that reef communities
are not endangered by dredging. Occasionally tradeoffs
must be made, but should be minimized. Straughan
(1972) condemned dredging for the demise of Florida
Keys reefs. Courtney et al. (1974) documented reef
burial and water quality problems at a beach renour-
ishment dredging project off Hallendale; poor planning
resulted in reef burial. Griffin (1974) studied a dredge
operation on coastal Key Largo, and reported localized
water quality problems. Aller and Dodge (1974), Dodge
et al. (1974), and Dodge and Vaisnys (1977) reported
that coral growth was retarded by dredge-created sedi-
ments. Loya (1976b) reported that Puerto Rican coral
reefs impacted naturally by heavy sedimentation had
lower species diversity than protected reefs.
Griffin (1974) and Courtney et al. (1974)
recommended that all dredge operations in the vicinity
of coral reef communities be closely monitored to insure
that the community's vitality was not adversely affected.
Specifically, Griffin proposed the following guidelines. A
buffer zone of at least 0.5 nmi should separate the coral
reef community from dredge operations. The magnitude
of the buffer zone should be determined by local hydro-
graphic conditions (wave and current patterns). Water
column turbidity and sedimentation rates should be
closely monitored. The water column sediment load
deposition rate should not exceed 200 mg/cm2/day,
averaged over a 7-day period; if fall out exceeds this rate,
a pause in dredging should be imposed to allow the
benthic community to adjust. Because coral trans-
planting is a time consuming, labor intensive activity, it
should not be considered a routine technique for res-
toration or mitigation. Natural stocks must be used;
hence it becomes a matter of removing corals from an
existing reef to restore a damaged reef. Survival of
transplants may or may not be successful. Insufficient
research has been accomplished to rationally judge this.







Another activity affecting reefs that is somewhat
similar to dredging is salvaging of ancient shipwrecks for
treasure and artifacts. If the activity is near a coral reef,
turbidity may increase. Many of these salvage operations
employ the "mailbox" technique. A tubular elbow-
shaped device surrounding a propeller forces the thrust
downward to remove overburden from the shipwreck.
Air lifts used to vacuum up material from the bottom
for shipboard inspection also increase turbidity. A
sufficient buffer zone should be established to protect
any reef from the impacts of this activity. Restraints
similar to dredging recommendations should be en-
forced.

Anchor Damage

Anchor damage was a significant negative human
impact on coral reefs at Dry Tortugas (Davis 1977a).
Carelessly deployed anchors break fragile corals, dislodge
reef framework, and scar corals, opening lesions for
infection (Plate 27b). Increased visits increase the
number of anchorings and the potential for impact.
Anchor ground tackle, lines, and chains also are docu-
mented as destructive agents (Davis 1977a). Anchor
buoys were established at Biscayne National Park in
1977 as a means of mitigating this negative impact on
four reefs. During the summer of 1981 anchor buoys
were established at French Reef, JPCRSP-KLNMS, as a
test (Plate 28b; also see Plate 28a). Anchor buoys,
designated anchorages, and better public education are
the best way to mitigate this problem. Halas (in prepara-
tion) documents the techniques for installing anchorless
mooring buoys in the JPCRSP-KLNMS.


Groundings and Shipwrecks

Since the time of the Spanish and English explor-
ations along the Florida coast, shipwrecks and ground-
ings on reefs have been common. As reported in Chapter
1, luring ships onto a reef was a major economic enter-
prise during the 19th century, a practice that ended with
the building of lighthouses. In the recent past small boat
shipwrecks and groundings have increased. Table 31
summarizes recent reef shipwrecks. Pleasure and com-
mercial craft of < 100-ft (< 30-m) length have run
aground or sunk on many reefs. These occurrences are
the result of poor navigational skills, accidents, drug-
related incidents, and in some cases, purposeful ground-
ing to avoid sinking. Whatever the reason, the vessels
cause physical damage to the reef. In some cases the
negative impact is very severe; corals and other orga-
nisms are dislodged from the reef platform.
The greatest potential for groundings and ship-
wrecks is on the reef flat and in barely submerged patch
reefs. It would be impossible to buoy all the reefs that
are potentially threatened. While conducting research
in Biscayne National Park (BNP) during 1979, the
author witnessed the grounding of a motor yacht High
Life on Elkhorn Reef. The vessel captain was confused
by the anchor buoy and ran hard aground on the reef
flat. The vessel's path was strewn with broken fragments
of elkhorn and staghorn coral (Plate 29a). Toxic anti-
fouling paint was driven into several heads of Siderastrea
siderea. Another patch reef in BNP suffered when a boat
struck a large buttress of Montastraea annularis, splitting
and toppling the coral. Toxic antifouling paint was
again driven into the corallites.


Table 31


Recent reef shipwrecks.

Size
Vessel (ft) Date Location Impact


Ice Fog and 70 1973 Molasses Reef Tug sank in deep water; barge grounded on
barge reef; both salvaged.

Capt. Allen 60 1973-1974 Middle Sambo Abandoned on reef flat.
(Plate 26a)

Lola 110 1976 Looe Key Aground on a spur for 18 days.
(Plate 26b and 27a)

Robby Dale 60-75 1977 Looe Key Aground; spilled fuel.

Morania 1979 Fort Lauderdale Damaged 5,600 m2 of live bottom.

2 shrimp boats November Looe Key Reef Extensive damage to a spur.
1982

Wellwood 397 August Molasses Reef 18.6 acres impacted.
1984







The threat of a major shipwreck is quite real.
Much of the ship traffic into and out of the Gulf of
Mexico is concentrated just seaward of the reef tract.
Traffic into the gulf is between the coral reefs and the
Gulf Stream; outbound vessels travel inside the Gulf
Stream to take advantage of the current. Large tankers
or freighters grounded on a reef because of mechanical
difficulties or navigational errors would cause greater
damage than small vessels. The 400-ft vessel MV Well-
wood grounded on Molasses Reef on 5 August 1984,
causing severe damage to the reef.
The collisions of large vessels is like a bulldozer
blade leveling the top of the reef. Other negative effects
of shipwrecks and groundings include fuel leakage and
cargo and other materials lost or thrown overboard. An
example of a vessel grounding incident was the wreck of
the 110-ft motor vessel Lola on Looe Key Reef on 5
January 1976 (Plates 26b and 27a). The vessel was
loaded with construction steel when it began taking on
water. The captain ran the ship aground to avoid sinking.
The vessel ended up on a spur and remained aground on
the reef for 18 days. Approximately 344 m2 of reef
were impacted. The crew remained aboard ship while the
vessel was aground and disposed of garbage, sewage,
damaged steel cargo, and other junk including batteries
and tools onto the reef. Several weeks after grounding,
the ship was lightened by the removal of cargo onto a
barge and towed to Key West for repairs. The Lola was
foreign owned, and no legal action was taken.
Salvage operations pose a threat when they occur
around a coral reef. Techniques used to free grounded
or sunken vessels are often counter to reef conservation.
Explosives, large anchors, and ground tackle pose a
threat to the reef. In 1976 the Robby Dale carrying
contraband drugs was wrecked at Looe Key Reef. A
salvager used explosives to remove the ship from the
reef, despite warnings by the Bureau of Land Manage-
ment that unwarranted reef damage would result in legal
prosecution under the Outer Continental Shelf Lands
Act. The salvage firm of Alexander was brought to
court and found guilty on two accounts. However,
the Fifth Circuit Court of Appeals ruled that the Outer
Continental Shelf Lands Act could only be invoked in
cases where mineral or petroleum exploration or produc-
tion activities were threatening coral reefs.
In cases where tugboats are used to tow the
grounded vessel off the reef, care should be exercised to
keep towing cables off the bottom. During the Wellwood
salvage, towing cables caused a great deal of damage to
the reef (corals were turned over, broken, and abraded
by the towing cables). This could have been avoided.
More stringent regulations should be enforced when
salvage operations are close to coral reef habitats. Coast
Guard cooperation and reef scientists' advice would aid
in moderating the severity of negative impacts.
Numerous other incidents could be cited. The
results have a general pattern that includes initial dam-
age; sinking or salvaging of vessel; and development of
successional communities in the disturbed area. If the
structural integrity of the reef platform is not adversely
affected, the community will recover; after 5-10 years or


more the impact will be unnoticeable (Pearson 1981).

Fishing

Coral reefs concentrate marine protein in a
localized area, attracting both commercial and sport
fishing interests that use various techniques to harvest
fish and invertebrate stocks. Negative impacts occur as a
result of gear deployment and harvesting.
Lobster fishing is the largest commercial fishery
located in and adjacent to the coral reef habitat area.
This fishery was worth over $10 million in 1980 (Table
1). The commercial fishery uses traps or pots to harvest
the spiny lobster Panulirus argus. Traps are set in waters
inshore and offshore of the reefs, and on occasion close
to the reefs. Damage occurs when the traps are set on
corals, as well as during recovery. Trap recovery takes

place while the boat is underway; the hydraulic puller
retrieves the trap while the boat motors to the next
trap. The trap is pulled along the bottom for a short
distance before it clears the bottom. When the lobster
trap is on coral, the sliding trap breaks and damages
coral and other sessile benthos. Large numbers of traps
are lost when buoy lines are cut by boat propellers. Lost
lobster traps decompose in time, but cement bottoms do
not rapidly degrade. To eliminate this negative impact,
fishermen should be required to keep their traps out of
the reef environment proper.
Sport divers who harvest lobster damage the reef
through their efforts to dislodge lobsters from ledges and
caves. The author has seen moderately large (1.5-m
diameter) brain coral heads (D. strigosa) dislodged and
turned over by enthusiastic lobster divers. Smaller fragile
corals and other benthic organisms are damaged in the
process of lobster hunting. The lobster divers often
become so engrossed in their quest to obtain lobster that
they break off coral that is in their way to get at the
lobster.
Hook-and-line fishing methods are employed by
commercial and sportfishermen in the coral reef habitat.
There is considerable loss of line, leaders, hooks, sinkers,
lures, and other paraphernalia on the reefs. When diving
on any reef, it is common to find line, hooks, etc.,
caught in the coral. The hooks and line impact when the
hook is dragged across the coral face, causing lesions or
scars. Monofilament line wraps around corals and other
organisms, often causing abnormal growth. Net fishing is
not common around coral reef habitats; however the
author found a net entangled in the coral at Eastern
Sambo reef in 1973. Shrimp vessels anchoring at Pulaski
Shoal near Dry Tortugas have made a habit of disposing
junk on the reef. The area resembles a garbage dump,
with all manner of fishing-related gear on the bottom.
Fish traps are a controversial issue with polarized
constituents expounding their viewpoint. Traps are not
selective, but catch all manner of biota, much of which
is not consumed because of cultural biases or lack of a
market. The trap is made of steel mesh and is marked
with a buoy. If the buoy is lost, the trap continues to
harvest fish, many of which die in the trap (Plate 29b).
The fish trap, like the lobster trap, can damage the coral






by physical impact during setting and recovery. National
Marine Fisheries Service laboratory studies show that
some reef fish species can enter and escape from fish
traps at will.
Spearfishing is the major means divers employ to
harvest finfish. Spearpoints damage coral if they are
fired into the reef. Some divers use a "bangstick" (explo-
sive head on the end of a spear or a stick) to harvest
large fish or for confidence. When exploded on the
surface of a stony coral, it creates a concave crater
about 0.5 ft in diameter and of equal depth. It is illegal
to use spearguns in several of the marine parks, and
within much of Monroe County.

Diving Activities

Diving as a sport and hobby has increased and
developed into a major industry in the Keys area. As
reported earlier, it is a major economic contributor in
some parts of Monroe County. With the numbers of
persons involved, it is not surprising that negative im-
pacts occur. Unskilled divers grab coral for stabilization.
The dive guides try to enforce and instill an axiom of
don't touch or collect anything. The efforts are for the
most part successful; however, there are so many people
to monitor that it is difficult to police everyone. Those
persons who visit the reefs in private boats are not
governed by similar restraint. A small number of coral
collection violations occur within the parks and sanctu-
aries. Enforcement is spread very thinly; hence many
persons probably do collect coral as a souvenir.
Marine collecting as a hobby includes both live
and dead material for aquariums. Some individuals
harvest mollusk shells and other curio items for collec-
tions. For the most part, these specimens are dead;
however, some live material is taken. Collection pressure
is quite heavy on colorful and distinctive species such
as helmet shells (Cassis spp.), thorny oyster (Spondylus
spp.), and the flamingo tongue (Cyphoma gibbosum).
Queen conch (Strombus gigas) is harvested for food
and for its shell.
Live marine specimen collecting has developed as
a minor industry and popular hobby in southeast Flor-
ida. The collection of attractive fish and invertebrates is
focused in the coral reef areas primarily between Palm
Beach and Key West. Brightly colored fish, crustaceans,
mollusks, and other species are collected and sold
to pet shops and aquarium stores.
Specimens are collected by divers using various
techniques and transported in tanks aboard their boats.
Professional collectors use nets, traps, and in some cases
narcotizing chemicals to collect target species. Damage is
inevitable; in the quest to harvest illusive fish and
invertebrates, certain amounts of physical damage are
bound to occur. Frequency and magnitude of damage
are correlated with the experience and conservation
ethic of the collector. Part-time amateur and hobby
collectors with limited experience and time pose a
greater threat than a professional collector with several
years of experience.
Chemical collecting agents threaten corals if used


indiscriminately or in strong concentration (Plate 25b).
The most frequently employed chemical is Quinaldine
(Jaap and Wheaton 1975). The State of Florida requires
a permit for its use. When used in a restrained manner, it
poses a minimal threat to corals. In strong concentration
it may cause zooxanthellae expulsion and stun cryptic
microfauna which are rapidly consumed by certain
fish (e.g., the bluehead wrasse) that are immune to the
chemical. The use of Quinaldine is minimal; hence, it
does not pose a great threat. Other chemicals cited as
major threats to coral reef communities include a great
list of materials (Johannes 1975). The use of commercial
laundry bleach (sodium hypochlorite) is a potential
threat. It has been cited as a fish and invertebrate
collecting chemical, but it also does severe damage
(mortality) to sessile benthic invertebrates (Johannes
1975).

Pollution

General reviews of the effects of pollution on
coral reefs are Johannes (1975) and Endean (1976).
Weiss and Goddard (1977) reviewed a case history of
coastal pollution and its effect on coral reefs off the
coast of Venezuela. Bright et al. (1981) added additional
references on the subject. Loftas (1970), McCloskey and
Chesher (1971) and Smith et al. (1973) documented the
effects of pollution on coral reefs. Many of the previous
studies were either unrealistic field and laboratory
experiments or from Kaneeohe Bay, Hawaii. Certainly
there is cause for concern in Florida coastal waters as the
population continues to grow and municipal sanitary
sewage systems use ocean outfalls as an expedient means
of disposal of sewage effluent. Kaneeohe Bay, Hawaii, is
a classic case of what can go wrong when untreated
sewage and siltation from poor land management impact
a semi-closed ecosystem. Eutrophication and siltation of
the sea bottom extirpated a large number of the reefs
(Smith et al. 1973). Florida coral reefs represent an open
ecosystem where eutrophication is less likely to occur.
Much of urban Monroe County uses septic tank
sewage disposal; therefore, input into the marine envi-
ronment is likely. Bright et al. (1981) reported that the
porous limestone strata in the Florida Keys did not
retain the sewage effluent for sufficient time to allow for
decompositon. The aforementioned article also reported
on the massive amount of liquid wastes pumped into the
ocean by southeast Florida coastal communities. As
growth in coastal southeast Florida continues, potential
for pollution impact on coral reef communities also
increases. Dilution in the ocean is not the solution for
sewage disposal.
Manker (1975) reported on heavy metal accumu-
lations in the sediments and corals off southeast Florida;
he noted higher concentrations of mercury, zinc, lead,
and cobalt adjacent to population centers.
Disposal of wastes from existing lighthouse
navigational aids may be a minor problem, yet is clearly
a cause for concern. Plate 30b shows batteries and other
refuse disposed of on the reef flat at Carysfort light-
house. Coast Guard maintenance crews have, over a







period of years, disposed of spent batteries by throwing
them into the sea; subsequently, acids are released into
the area.
Southeastern Florida is a major truck farm area
for vegetables and fruit. Use of agricultural chemicals
(fertilizers, herbicides, pesticides, etc.) is intense. Porous
soils, canal systems leading to the bays, and rapid runoff
of surface materials following rains and irrigation are
causes for concern. McCloskey and Chesher (1971)
reported that organochloride compounds reduced
productivity (photosynthesis:respiration ratios) in Acro-
pora cervicornis. The methodology and concentrations
of the study were not realistic compared to what is the
normal concentration of such compounds in the reef
environment. The effect of chronic low level concentra-
tions over a long period has not been studied. Pollution
research into chronic low level concentrations of hydro-
carbon pollutants documents that reproduction is the
most severely affected biological process (Loya and
Rinkevich 1980).

Petroleum Hydrocarbons

The effect of petroleum hydrocarbons (PHC)on
coral reefs is po:,ri\ underrst.,od Reviews summarizing
the information include Johannes (1975), Loya and
Rinkevich (1980), Ray (1981), and Bright et al. (1981).
Gunkel and Gassmann (1980) reviewed oil pollution in
the marine environment.
A diversity of methods has been used to evaluate
the effects of PHC on corals; many of the procedures
used represent exposures or concentrations that are
difficult to relate to field conditions. Some situations on
a coral reef tend to magnify exposure, while others
would lessen impact; laboratory tests often are unrealis-
tic compared with the actual environment. Shallow reef
flats, lagoons, and other reef environments with poor
circulation expose organisms to higher concentrations
than open ocean conditions, while spur and groove
formations with high turbulence probably reduce
exposure. Experiments have documented response of
coral tissue to coating by PHC. Static and flow through
bioassay tests are poor because of prolonged exposure,
unrealistic concentrations, and unknown real concentra-
tion of PHC (detailed as oil added with unknown solu-
bility). Quantitative field research has advanced knowl-
edge on the ecological consequences of PHC in coral
reef communities (Loya 1972, 1975, 1976b; Loya and
Rinkevich 1980). Quantitative chemical data on uptake,
as well as flux between organisms, water column, and
sediments are presently the missing links in field studies.
Recent studies documented that detrimental
effects of PHC on corals included feeding, reproduction,
recruitment,-and-gr.w-th. The environmental parameters
make each oil_ s pillaniqtl gi ibnter per-
ature, wind, tide, etc., all contribute to overall conse-
quinces Heavier grades of oil that float are less likely to
cause negative impact. Jaap (1975, unpublished) and
Chan (1976) reported on the 1975 oil spill in the Florida
Keys. The spill was of an estimated magnitude of
20,000-50,000 gallons. Diving observations and histo-


pathology revealed little or no damage to the reefs or
corals. Lighter fraction PHC that has high solubility
poses a greater threat.
Rinkevich and Loya (1977) reported damage to
gonadal tissues and no coral recruitment in shallow reef
areas off Eilat, Israel, that were chronically polluted by
PHC. Other field observations reported that Acropora
spp. possessed a greater affinity for oil than Agaricia
(Lewis 1971). Oil mixed with sediments also caused
morbidity in corals (Bak and Elgershuzen 1976). Oil
dispersant in concentrations of 100-500 ppm was
harmful to corals (Lewis 1971). Oil and its effect on
reproduction is of prime concern. Recent studies by
Rinkevich and Loya (1977) show a strong relationship
between reduced coral fecundity and PHC exposure.
Lewis (1971) reported reduced feeding responses in
corals exposed to PHC.
Corals respond or protect themselves from
foreign materials by secretion.of mucus, ciliary water
currents, and pulsation. Growth and calcification studies
indicate various responses to PHC exposure. Neff (1981)
tested several species and found both increased and
decreased calcification rates.
At this point the evidence indicates that chronic
PHC pollution is harmful to coral reef communities. The
stenotopic nature of many reef dwelling organisms, and
the fact that many are sessile, leads to the conclusion
that while most of the research in coral reefs on PHC
pollution has dealt with corals, chronic or massive
concentrations of PHC would also harm the other
organisms._Population dynamics. (reproduction, develop-
ment, larval recruitment, settlement, and juvenile
growth) appears to be the biological process most
affected by PHC pollution.
Potential oil pollution sources include tanker
cleaniing _nd cargo discharge, vessel sinkings and acci-
dents, and accidental discharges from petroleum produc-
tion and transportation activities. The Minerals Manage-
ment Service (MMS) (Department of the Interior)
controls leasing and operational aspects of offshore oil
exploration and development in federal waters.
Although there are numerous reports of other
acts that have damaged coral reefs in other areas of the
world, they are not germane to Florida at this time;
hence, the reader is referred to Johannes (1975) and
Bright et al. (1981) for documentation.

Coral Collection

Collection, damage, or sale of stony corals
(Millepora spp. and Scleractinia) and two species of sea
fan (Gorgonia ventalina and G. flabellum) in Florida
waters is prohibited by Florida statute 370.110. Florida
waters extend to 3 nmi on the Atlantic and approxi-
mately 10.3 nmi on the gulf coast. Corals and other
biota within specially designated parks, marine monu-
ments, and sanctuaries are protected by special Federal
and State regulations. The area under Federal regulation
is currently without protection. However, at the time of
this writing the Gulf of Mexico and South Atlantic
Fishery Management Councils are developing a fishery







management plan for the coral reefs and corals from
North Carolina to Texas. The coral reef fishery manage-
ment plan will be effective as of August 22, 1984. This
would extend to all the coral species found within the
Federal jurisdiction (the 200-mi zone). Proposed Federal
regulations would parallel Florida statutes. There would
be allowable bycatch in certain fishing activities. Some
areas would receive special considerations as Habitat
Areas of Particular Concern (HAPC). Limitations on
fishing gear and anchoring are proposed to conserve
habitat (Gulf of Mexico and South Atlantic Fishery
Management Councils 1981).

8.2 CORAL REEF RESOURCE MANAGEMENT

Coral reef parks and other sanctuaries represent
a unique management for subsea resources.

Parks, Sanctuaries, and Monuments

Biscayne National Park (BNP) (70,822 ha;
Figure 1). Located off southeast Florida, including
nonreef areas in Biscayne Bay. Reef areas are seaward of
Elliott and the Ragged Keys to a 60-ft (18.3-m) depth.
To the southwest this park adjoins John Pennekamp
Coral Reef State Park and Key Largo National' Marine
Sanctuary. To the north the BNP adjoins Biscayne Bay.
The park is administered by the U.S. National Park
Service with headquarters at Convoy Point. All coral is
protected. Rangers enforce regulations.
John Pennekamp Coral Reef State Park
(JPCRSP) (21,741 ha; Figure 1). Located off north and
central Key Largo. It includes the mangrove communi-
ties to the 3-nmi limit. It is administered by the Florida
Department of Natural Resources (FDNR) with head-
quarters located on Key Largo. Park rangers and the
Florida Marine Patrol enforce statutes that protect coral
and other living resources.
Key Largo National Marine Sanctuary (KLNMS)
(25,901 ha; Figure 1). Continues from the seaward
boundary of John Pennekamp Coral Reef State Park to
the 300-ft (91-m) isobath. It is administered, by special
agreement with the National Oceanic and Atmospheric
Administration (NOAA). On site inspection is by the
Florida Department of Natural Resources (DNR).
Enforcement is by park rangers, U.S. Coast Guard, and
Florida Marine Patrol.
Looe Key National Marine Sanctuary (LKNMS)
(11,144 ha; Figure 1 and Plate 2). Recently established;
located seaward of Big Pine Key. Unlike the previously
mentioned parks, it does not include any coastal seafloor
in its boundaries but is a discrete area of reef. Adminis-
tration is by NOAA, with the Florida DNR rangers and
Marine Patrol enforcing regulatory statutes on-site.
Dry Tortugas, Ft. Jefferson National Monument
(19,021 ha). Located in the Dry Tortugas, 60 mi west
of Key West. It is administered by U.S. National Park
Service with headquarters on Garden Key, Dry Tortugas.
Park rangers enforce regulations.
The following summarizes the various county,
State, and Federal regulations governing portions of the


resource. Shinn (1979) detailed permitting regulations
and agency responsibility for collecting biological and
geological specimens. In the coral reef environments a
patchwork of regulations and jurisdiction exists that is
inefficient and often a duplication of effort. It is beyond
the scope of this treatise to review and offer ways to
correct this problem. The reader may use the following
outline to determine jurisdiction and enforcement
responsibilities. Damage mitigation and management
recommendations will be presented in 8.3.

Monroe County

Monroe County prohibits use of spearguns for
the harvesting of marine protein in and around bridges
and piers and in State waters from the Dade County
border to Long Key.

State of Florida

Department of Natural Resources (DNR). DNR
is responsible for management of all marine fisheries and
resources in State waters. In the area of consideration,
this includes lobster, snook, snapper, grouper, other
commercial and sport species, mangrove, seagrass, and
coral reef communities. DNR has specific police powers
through the Florida Marine Patrol to enforce State and
some Federal statutes. In the area of specific regulations
for reef management, the department enforces statute
370.110 (prohibition of harvest, damage, or sale of fire
coral, sea fans, and the true stony corals), 370.114
(protection of all corals in John Pennekamp Coral Reef
State Park), 370.08 (management of fish collecting
chemicals), and 370.15 (fishery gear regulation). The
Division of Recreation and Parks manages and operates
State parks and Federal marine sanctuaries through
agreements with NOAA. The Division of Marine Re-
search conducts scientific research to support manage-
ment in the areas of coral reef ecology and fisheries.
Department of Environmental Regulation
(DER). Within State waters DER has management
powers over environmental change caused by human
activity. All major engineering projects must be reviewed
prior to permitting. Both environmental monitoring and
research are conducted. In the area of permitting, DER
reviews permits for any human activity that affects the
marine environment. Coastal dredging is managed
through statute 370.03 and marine pollution under
statute 370.09.
Department of Administration (DOA). Under
special powers the DOA can enact "State Areas of
Critical Concern" and decree special regulations for
indefinite periods if growth or other activities overload
the capacity of local government to adequately manage
the resources.
Department of State (DOS). DOS manages
salvage of historical artifacts in State waters. In the Keys
area this includes numerous vessels sunk offshore. The
activity is managed through the licensing of salvagers and
monitoring of operations. Many historical artifacts are
recovered for the State. These are archived in museums







and displayed for public benefit.

Federal

Office of Coastal Zone Management, Marine
Sanctuaries Program, NOAA. Specifically, this program
manages and funds the program at KLNMS and LKNMS.
On-site management and enforcement are delegated to
DNR through special agreements. Funding for research
and management is arranged through grants. A manage-
ment plan for KLNMS was published in 1979; the
management plan for LKNMS was published in 1984.
National Marine Fisheries Service (NMFS),
NOAA. The enactment of the Fishery Management Act
of 1976 (P. L. 94-265) provides for exclusive manage-
ment of fisheries seaward of State jurisdiction. This
includes both specific fishery stocks and habitat. The
process for developing "fishery management plans"
(FMP) is highly complex. It includes plan development
by various procedures through a fisheries management
council. NMFS implements approved plans. The Coast
Guard, NMFS, and Florida Marine Patrol enforce reef
related FMP's. Presently, FMP's for corals and coral
reefs, reef fish, grouper and snapper, and spiny lobster
are in the developmental stages or already in force.
National Park Service (NPS), Department of the
Interior (DOI). National parks and monuments, includ-
ing Biscayne National Park and Ft. Jefferson National
Monument, are under the jurisdiction of NPS. Manage-
ment, enforcement, and research are accomplished
in-house. In some cases research projects are contracted
out or made through interagency agreements.
Minerals Management Service (MMS), DOI. This
agency has jurisdiction over mineral and petroleum
resources on the continental shelf. Management has
included specific lease regulations and mitigation of
exploration and production activities in areas where
coral resources are known to exist. Specifically, the
agency helped to fund a coral reef mapping project from
Miami to Key West.
Fish and Wildlife Service (FWS), DOI. FWS
assists with environmental impact review, develops
biological resource evaluations, and administers the
endangered species program. In the Keys area the FWS
manages several national refuges for wildlife. The Great
White Heron and Key West Refuges include Sand Key
Reef off Key West. Importing of exotic biota is moni-
tored and controlled by FWS. The Lacey Act was
amended in 1981 to include all coral. This should
curtail all commercial imports.
Geological Survey (GS), DOI. In the coral reef
areas GS has conducted considerable reef research and
assisted or cooperated with other institutions and
agencies to facilitate logistics and support of coral reef
research. The mapping program was partially supported
through GS funding.
Coast Guard (CG), Department of Transporta-
tion. The 1978 Waterways Safety Act charges the CG
with marine environmental protection. The CG is the
general enforcement agency for il! marine activity in the
Federal zone. Among the duties are enforcement of


sanctuary and fishery management regulations, managing
vessel salvage, coordinating oil spill cleanup operations at
sea and search and rescue operations, interdicting illegal
alien and drug traffic, and maintenance of navigational
aids such as buoys and lighthouses.
U.S. Army Corps of Engineers (USACE). USACE
contracts and regulates coastal engineering projects,
particularly harbor dredging and beach renourishment
projects. USACE also reviews and is the permitting
agency for coastal development projects and artificial
reefs.
Environmental Protection Agency (EPA). This
agency has a general responsibility in the air and water
pollution area. Disposal of hazardous wastes and sewage
plant outfall permitting are EPA functions. Certain
mineral and petroleum exploration and production
activities are managed by EPA. Environmental research
germane to waste disposal and pollution are funded by
EPA.

8.3 MANAGEMENT AND MITIGATION RECOMMEN-
DATIONS

This document has detailed the complexity of
coral reef communities: their biota, their physical and
chemical determinants, the multi-user nature of their
resources, their significance as fishery and aesthetic-
tourist resources to southeast Florida and the United
States, and the conflicts and human impact problems
that currently exist. The wisdom of Solomon would be
put to the test to devise a management plan for these
resources that would satisfy all the users and manage-
ment and enforcement agencies. Decisions will have to
be made that do not satisfy some users. The main
criteria that should be used in judging any particular
decision should be: (1) does it significantly impact the
resource and/or (2) will it cause undue economic hard-
ship on a large segment of the population. It is literally
impossible not to cause some impact and some economic
hardship. Overall, the goal should be prudent steward-
ship of the coral reef resources.
While we can do nothing to mitigate natural
events, we should make every effort to minimize human
insults. Major emphasis toward achieving this goal should
include improved communication between the various
responsible State and Federal agencies, improved en-
forcement, and a meaningful public information and
education program. Since it is impossible to place
enforcement officers on every reef, public education is
the most efficient way to obtain cooperation, especially
in terms of chronic boating and diving accidents. Signs,
brochures, television, and user group workshops are
ways to get the message across.
In terms of specific recommendations, the age-
old adage that a gram of prevention is worth a kilogram
of cure holds true in coral reef communities. It is far
easier to prevent most human interference beforehand
than to correct the damage after it occurs. This is
particularly true in the case of major coastal engineering
projects (e.g., dredging, pipeline excavation) in southeast
Florida. Any proposed project should be required to






complete an in-depth field study (not a literature survey)
in the preparation of an environmental impact state-
ment. Field scientists should have local experience in the
area and know the biota. All coral reef communities
within 1 nmi of the proposed project should be identi-
fied and documented so that monitoring can be accom-
plished. Dredging operations close to a coral reef should
be required to use turbidity curtains. Turbidity and
sediment fallout should be monitored; the overall rate
should not exceed 200 g/cm2/day (Griffin 1974).
Mechanical dredging equipment should not come in
physical contact with the reef. Dredged spoils should not
be disposed of on or near reef communities.
Oil spills, vessel groundings, shipwrecks, and
sinkings are the responsibility of the Marine Patrol in
Florida waters and the Coast Guard in Federal waters.
There should be rapid resource evaluation and analysis
by competent reef scientists shortly after such accidents.
The enforcement agencies should call in reef scientists as
soon as possible to evaluate and to offer advice to
minimize resource damage in the salvaging efforts.
Each oil spill incident must be evaluated on its
own merits. General guidelines are offered here, but
local conditions may require taking alternative measures.
When major damage occurs, the most expedient way to
promote recover is to let natural recruitment of reef
biota recolo.niZe the arei. Remedial action should only
be taken after it becomes evident that natural recruit-
ment is not occurring or is very slow. Transplanting
corals is a slow and costly activity. If it is done, it should
be supervised by reef scientists. Hydraulic cement should
be used to attach the organisms to the bottom. It will
require permits to harvest stock to transplant.
In the case of vessel groundings, if the vessel is
afloat or aground it should be removed from the reef as
soon as possible in a manner that minimizes reef impact.
Explosives should not be used. If the vessel is sunk in


depths of less than 5 m, it should be salvaged. Sinkings
in deeper water should be evaluated to see what sort of
potential harm might occur. They might be left in place
if they have no salvage value. In all vessel accidents, care
should be taken to minimize fuel and cargo discharge.
Fishing-related problems are the responsibility of
DNR in State waters and NMFS in the Federal zone.
These agencies should take necessary action to minimize
habitat destruction by sport or commercial fishing activi-
ties. Action is being taken in some fisheries at the
present time. In some areas between Miami and Dry
Tortugas it would be beneficial to prohibit the harvest of
all fish and invertebrates. This would provide a refuge
for those species under intense fishing pressure; in many
cases they are harvested before they attain sexual
maturity. These refuges would increase reproductive
potential and return communities to a more natural
state. Several existing marine parks should consider this
possibility on an experimental basis for all or por-
tions of their reef areas.
Coral reef communities found off southeast
Florida are the northernmost distribution of shallow
coral reefs within the tropical Atlantic biogeographical
region (exception being Bermuda). Located this far
north, they endure natural physical stresses not encoun-
tered in more southerly Caribbean areas. Human inter-
ferences, as noted, are not individually as harmful to the
reef community as natural events (hurricanes); however,
it is the chronic and synergistic effect of the human
impact that causes problems. These coral reefs are a
natural resource similar to California's redwood forests
or the Grand Canyon, and they should be viewed as a
national treasure worth conserving for future genera-
tions. Their fisheries resources are significant and yields
could be increased with better management. The eco-
nomics are very important to southeast Florida. Fishing,
diving, boating, and tourism in general are dependent on
the vitality of these coral reefs.









COLOR PLATES


Plate la. Satellite photograph of southeast Florida. Note large passes between islands
in the middle Keys. Florida Bay lies between the mainland and the Keys.


Plate lb. French Reef off Key Largo. Waves breaking on the reef flat; dive boats an-
chored on the deeper spur and groove zone.






































Plate 2a. Looe Key National Marine Sanctuary viewed from seaward to landward. The
western area has deep reef development. Photo: Bill Becker, Newfound Harbor Marine
Institute.


Plate 2b. Looe Key spur and groove zone; boats are between 20 and 30 ft long. White
area (mid left of photograph) is where the M/V Lola was aground. Photo: Bill Becker,
Newfound Harbor Marine Institute.






































Plate 3a. Grecian Rocks Reef, Key Largo National Marine Sanctuary. The dense cover
of coral is mostly Acropora spp. (brown color).


Plate 3b. Fire coral Millepora complanata Middle Sambo Reef.




































Plate 4a. Octocoral Pseudopterogorgia acerosa hardgrounds off Soldier Key.


Plate 4b. Staghorn coral (Acropora cervicornis) Eastern Sambo Reef.






































Plate 5a. Elkhorn or moosehorn coral (Acropora palmata) (heavy blades) and fused
staghorn coral (A. prolifera) (right).


Plate 5b. Star coral Montastraea annularis at Elkhorn Reef, Biscayne National Park.




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