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 Table of Contents
 Executive summary
 Introduction
 St. Croix
 St. Thomas






Title: Coral reef monitoring in St. Croix and St. Thomas, United States Virgin Islands
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Title: Coral reef monitoring in St. Croix and St. Thomas, United States Virgin Islands
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Language: English
Creator: University of the Virgin Islands.
Affiliation: University of the Virgin Islands -- Center for Marine and Environmental Studies
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Publication Date: 03/31/2004
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Table of Contents
    Title Page
        Page i
    Table of Contents
        Page ii
        Page iii
        Page iv
    Executive summary
        Page 1
    Introduction
        Page 2
        Objectives for monitoring coral reefs
            Page 3
    St. Croix
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
    St. Thomas
        Page 12
        Page 13
        Page 14
        Page 15
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        Page 17
        Page 18
        Page 19
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Full Text

















Coral Reef Monitoring
in St. Croix and St. Thomas,
United States Virgin Islands

Year Three Final Report
Submitted to
Department of Planning and Natural Resources

March 31, 2004




By

Richard S. Nemeth, Ph.D., Steve Herzlieb,
Elizabeth S. Kadison, Marcia Taylor, Paige Rothenberger
and Sera Harold

Center for Marine and Environmental Studies
University of the Virgin Islands
St. Thomas, USVI

and

Wesley Toller, Ph.D.

Division of Fish and Wildlife
Department of Planning and Natural Resources
US Virgin Islands








Table of Contents


Page

Executive Summary 1

Introduction 2
Objectives for Monitoring Coral Reefs 3

Section I: St. Croix
Methods
Benthic Assessments 4
Table 1. St. Croix site location information
Fish Census 5
Table 2. Summary of fish census effort, St. Croix

Results and Recommendations
Benthic Assessments 7
Fish Census 9
Table 3. Abundance of commercially important,
rare and/or vulnerable fish species, St. Croix

Section II: St. Thomas
Methods
Benthic Assessments and Abiotic Parameters 12
Table 4. St. Thomas site location information
Montastraea reefs 13
Table 5. Dates Aanderaa data recorders and
sediment traps deployed and retrieved
Acropora reefs 14

Fish Census 15

Results and Recommendations
Benthic Assessments and Abiotic Parameters
Montastraea reefs 15
Table 6. Sedimentation rates at Flat Cay and
the Red Hind Bank
Acropora reefs 17
Table 7. Acropora recruits at St. Thomas sites

Fish Census 19
Table 8. Summary of fish census effort on St. Thomas
Table 9. Comparison of Species Richness using
belt transect and RDS data
Table 10. Abundance of commercially important,
rare and/or vulnerable fish species, St. Thomas








Table of Contents (cont.)


Page

Summary and Discussion
St. Croix 24
St. Thomas 25

Acknowledgments 28

Literature Cited 29

Figures

Figure 1. Locations of monitoring sites, St. Croix. 31
Figure 2. Mean percent cover of scleractinian corals, 32 33
dead coral with turf algae, macroalgae,
sponges, gorgonians, and sand/Sediment
for years 1 -3, St. Croix.
Figure 3. Coral species composition, St. Croix 34
Figure 4. Percent of species composition of living coral cover 35 38
of the most common coral species, St. Croix.
Figure 5. Coral Diversity, St. Croix. 39
Figure 6. Mean percentage of coral colonies with disease and 40
bleaching by site, St. Croix.
Figure 7. Percentage diseased and bleached coral colonies 41
by species, St. Croix.
Figure 8. Reef fish community structure, St. Croix 42
Figure 9. Fish community similarity indices, St. Croix. 43
Figure 10. Fish abundance by family, St. Croix. 44 47
Figure 11. Locations of monitoring sites, St. Thomas. 48
Figure 12. Mean percent cover of scleractinian corals, 32 33
dead coral with turf algae, macroalgae,
sponges, gorgonians, and sand/Sediment, St. Thomas 49 50
Figure 13. Coral species composition, St. Thomas 51
Figure 14. Percent of species composition of living coral cover
of the most common coral species, St. Thomas 52 54
Figure 15. Coral Diversity, St. Thomas. 55
Figure 16. Mean percentage of coral colonies with disease and 56
bleaching by site, St. Thomas.
Figure 17. Percentage diseased and bleached coral colonies 57
by species, St. Thomas.
Figure 18. Current speed and direction Flat Cay 58 59
Figure 19. Current speed and direction Red Hind Bank 60 61
Figure 20. Daily mean temperature Flat Cay 62
Figure 21. Daily mean temperature Red Hind Bank 63








Table of Contents (cont.)


Page
Figures (cont.)

Figure 22. Percent cover of all Acropora species combined,
St. Thomas. 64
Figure 23. Percent cover of Acropora by site, St. Thomas. 65
Figure 24. Size distribution of A. cervicornis, St. Thomas. 66
Figure 25. Size distribution of A. palmata, St. Thomas. 67
Figure 26. Size distribution of A. prolifera, St. Thomas. 68
Figure 27. A. cervicornis tissue mortality, St. Thomas. 69
Figure 28. A. palmata tissue mortality, St. Thomas. 70
Figure 29. A. prolifera tissue mortality, St. Thomas. 71
Figure 30. Acropora predation, St. Thomas. 72
Figure 31. White band disease on Acropora, St. Thomas. 73
Figure 32. Reef fish community structure, St. Thomas 74
Figure 33. Fish community similarity indices, St. Thomas. 75
Figure 34. Fish abundance by family, St. Thomas. 76 79






Executive Summary


Coral reefs in the Caribbean are facing a dramatic decline. To effectively manage
and maintain these important ecosystems, the government of the Virgin Islands, in
coordination with federal agencies and the University of the Virgin Islands, has implemented
a long-term coral reef monitoring and assessment program. This program will help establish
a baseline condition of coral reefs and fish populations for determining the effectiveness of
various management initiatives on the sustainability of these important resources. This
program will also allow natural resource managers to gauge the impacts of natural
disturbances and human activities on coastal habitats and their rates of recovery. This report
presents results from the third year of monitoring in St. Croix, with comparisons to data
obtained in years one and two, and the first year of monitoring in St. Thomas. St. Thomas
monitoring and assessment employed a stratified design based upon the position of reefs
along the insular platform (near-shore, mid-shelf, and shelf-edge) to facilitate a systematic
evaluation of the effects of natural and human-induced stresses, as well as factors influencing
the decline or recovery of Caribbean coral reef systems.
Digital video and diver surveys were used to quantify coral diversity and the percent
cover of corals, algae and other organisms, incidence of coral bleaching and disease, sea
urchin density, and fish community structure at eight permanent sites surrounding the island
of St. Croix and six permanent sites surrounding the island of St. Thomas. Sedimentation
rates, current speed and direction, and temperature were assessed at two St. Thomas sites
using sediment traps and data recorders. In addition, digital video and diver surveys were
performed at six St. Thomas Acropora reefs to quantify percent cover, size distribution,
tissue mortality, predation, disease, and recruitment for all Acropora species at these reefs.
Assessment of these reefs provides a baseline to measure the recovery of Acropora corals,
which were once abundant, but have been decimated by disease and storm damage.
In St. Croix, turf algae covering dead coral was the predominant benthic cover at
most sites. Percent cover of living coral and other benthic organisms changed little over the
three years of monitoring. However, the relative abundance of stress tolerant coral species
increased at several sites, indicating a decrease in reef quality. Coral disease and bleaching
were variable between sites and years. Sea urchin densities were low and showed little
change between years. In 2003, fish diversity ranged from 47 to 61 species, while fish
abundance averaged 200 to 500 fish per census. The majority of observed fish were small
(J5 cm). Commercially important large groupers, snappers, and angelfishes were uncommon
to absent at all sites. Due to differing sampling methods between years, annual comparisons
of fish communities in St. Croix were not possible. Methodology is now standardized.
In St. Thomas, turf algae covering dead coral was the predominant substrate type at
three sites, macroalgae was predominant at two sites, and living coral had the highest percent
cover at one site. Near-shore reefs tended to have lower percent cover living coral and
higher percent cover dead coral covered with turf algae than mid-shelf and shelf-edge reefs.
Near-shore sites also tended to have higher relative abundances of stress tolerant corals than
the other reef systems. Coral disease and bleaching varied between sites. Sea urchins were
observed only at the two near-shore sites. Current patterns, temperature, and sedimentation
differed between the mid-shelf and shelf-edge sites. At the St. Thomas Acropora reefs, all
measured parameters varied between species and sites. No significant differences were
found between near-shore and mid-shelfAcropora reefs. St. Thomas fish diversity ranged
from 36 to 54 species, while fish abundance averaged 70 to 120 fish per census. The
majority of observed fish were small (5 10 cm). Commercially important large groupers,
snappers, angelfishes, and triggerfishes were observed at low densities, but were more
frequently observed at the mid-shelf and shelf-edge sites. Butterflyfish densities indicated
higher levels of reef health for mid-shelf and shelf-edge reef systems.








Introduction:


The U.S. Virgin Islands consists of three large islands, St. Thomas, St. John and St.
Croix, and numerous smaller islands surrounded by a diverse, tropical marine environment
that includes coral reefs, seagrass beds, and mangrove forests. The islands of St. Thomas and
St John are joined by an extensive shallow water platform that connects them to Puerto Rico
and the British Virgin Islands. Twenty-five kilometers to the south of St. Thomas and St.
John, St. Croix lies on a separate platform. St. Croix is separated from St. Thomas and St.
John by the Virgin Islands Trough (over 7,300 m deep).
Tourism drives the Virgin Islands economy. The marine environment with its clean,
clear water and fringing sandy beaches is our major tourist attraction. The waters of the
Virgin Islands are ideal for sailing because of the persistent trade winds and the numerous
bays that provide protected anchorages. The diverse marine life in the coral reefs and other
habitats attracts thousands of skin and scuba divers each year. Sport fishing also makes an
important contribution to the economy, especially on St. Thomas.
In addition to their tourist appeal, the coral reefs and other habitats in the Virgin
Islands are essential to the lives of hundreds of thousands of species including the
economically important queen conch, whelk, snapper and grouper. Over three hundred full-
time or part-time commercial fishermen fish in territorial and federal waters on all three
islands. In tough economic times, fishing is an important means of supplemental income for
many people.
Over the past 20 years, eight major hurricanes, numerous outbreaks of disease and
sporadic bleaching events have caused extensive coral mortality to the coral reefs
surrounding the Virgin Islands (Gladfelter, 1982: Edmunds and Witman, 1991; Rogers et al.,
1991; Causey et al., 2000). Recovery from these natural disturbances is hindered by a
multitude of human impacts that affect coral reefs such as overfishing, ship groundings,
anchor damage, and non-point source pollution (Roberts, 1993; Sebens, 1994; Rogers and
Garrison, 2001). Moreover, rapid development of inland and coastal areas has dramatically
increased soil erosion and sedimentation onto many of these coral reefs (Rogers, 1990;
MacDonald et al., 1997; Anderson and MacDonald, 1998). Chronic sedimentation may affect
the abundance and diversity of corals and other reef organisms, increase coral stress and
susceptibility to diseases and bleaching, and reduce the ability of corals and other reef
organisms to recover and regenerate after natural disturbances such as hurricanes (Acevedo
and Morelock, 1988; Rogers, 1990; Rice and Hunter, 1992). The cumulative effects of these
human impacts reduce coral abundance and larval recruitment and may make corals more
susceptible to disease and bleaching (Nemeth and Sladek Nowlis, 2001).
Most research around the Virgin Islands has focused on fringing reefs (5 30 m
depth) located along the shoreline of the three main islands, St. Thomas, St. John, and St.
Croix. In contrast, very little information exists for other reef systems, which can be quite
extensive. Surrounding St. Thomas and St. John, these other reef systems include the
shallow water Acroporapalmata reefs (<5 m depth), mid-shelf reefs (5 30 m depth) located
2 to 10 km from the shore of the main islands, and deep reefs (>30 m depth) located 10 to 15
km offshore along the edge of the insular platform. A more systematic approach to
investigating these cross-shelf coral reef systems will allow us to evaluate the variable
impacts and synergistic effects of natural impacts and human-induced stress as well as
factors influencing the decline or recovery of Caribbean coral reef systems. The first two
years of this project (2001 and 2002) concentrated on the fringing reefs surrounding St. Croix
(Nemeth et al., 2002; Nemeth et al., 2003). In 2003, monitoring continued at St. Croix reefs
and began at reef systems distributed across the insular platform surrounding St. Thomas.








The St. Thomas cross-shelf reef systems, with the exception of the shallow Acropora
reefs, are very similar in composition (i.e. dominated by the genus Montastraea) but differ in
a number of important ways. Because of the close proximity of near-shore fringing reefs to
human populations and their relatively shallow depths, these reefs are susceptible to both
harmful human activities (overfishing, sedimentation, nutrient enrichment, and physical
damage) and the effects of natural disturbances (storm wave damage, high sea surface
temperatures, high irradiance). The mid-shelf coral reefs, either fringing reefs associated
with offshore cays or non-emergent linear reefs on the insular platform, are less susceptible
to human induced stresses as described above, but are exposed to similar levels of natural
impacts. Thus, the mid-shelf reefs provide an ideal control for measuring the effects of
anthropogenic stresses on near-shore reefs due to their comparable depth but greater distance
from land-based sediments and pollutants. The deep reefs located along the edge of the
insular platform are largely free from human induced stresses (excluding fishing and
anchoring) and natural impacts due to their greater distance from human populations and
their greater depth, respectively. Since the shelf-edge deep reefs are quite extensive, but
largely unknown, studying these systems will greatly contribute to our understanding of the
coral reef resources in the Virgin Islands.
Acropora reefs occur in shallow waters adjacent to areas of high human population
density and on uninhabited off-shore cays in the Virgin Islands. Acropora palmata once
dominated the shallow water areas in the Virgin Islands and the Caribbean prior to the
devastating effects of white band disease (Gladfelter, 1982) and severe hurricanes (Woodley
etal., 1981; Rogers etal., 1982; Edmunds and Whitman, 1991; Hubbard etal., 1991; Rogers
et al., 1991; Bythell et al. 1993). However, recent observations indicate that this species may
be showing signs of recovery (C. Rogers personal communication; R. Nemeth, S. Herzlieb
personal observation). Monitoring stands of this major reef building species close to and far
from centers of human activity will allow us to determine the factors facilitating or hindering
its recovery.

Objectives for Monitoring Coral Reefs

In order to maintain the marine resources of the Virgin Islands in an ecologically and
economically sustainable manner, the territorial and federal waters of the Virgin Islands must
be effectively managed. By providing managers with fundamental information with which to
make and enforce decisions, monitoring programs are essential for successful management.
Monitoring establishes baseline data against which standards for resource protection can be
measured. Also, monitoring provides the means to assess the status and trends of ecological
resources, allowing managers to determine the effectiveness of current management plans
and to develop effective management for the future. The intent of this project is to monitor
the condition of coral reefs throughout the U.S. Virgin Islands to better manage these
ecosystems. This will be accomplished by continuing to monitor previously established reef
sites surrounding St. Croix and to begin monitoring reefs surrounding St. Thomas, comparing
biotic and abiotic parameters among the near-shore, mid-shelf, and shelf-edge Montastraea
reefs and biotic parameters among the near-shore and mid-shelfAcropora reefs.










Section I: St. Croix


Methods

Benthic Assessments:

In April 2001 (year one), the University of the Virgin Islands established permanent
video transects at eight long-term sites for annual monitoring (Nemeth et al. 2002). In 2002
(year two), two more long-term sites were added (Nemeth et al. 2003). To make more
efficient use of time and resources in 2003 (year three), monitoring was discontinued at two
of the long-term sites established in year one (Lang Bank and Salt River East Wall), bringing
the total number of long term monitoring sites in St. Croix to eight, two of which (Great
Pond and Jacks Bay) are within the East End Marine Park Boundary (Figure 1, Table 1).
Monitoring of Lang Bank was discontinued due do the low percent coral cover found in
years one and two and the logistic difficulty involved with reaching the site. Monitoring at
Salt River East Wall was discontinued due to the close geographic proximity to Salt River
West Wall and the similar benthic composition between the two sites (Nemeth et al., 2003).

Table 1. St. Croix site location information and number of benthic transects at each site.

Site Date Sampled GPS Coordinates Depth No. of Transects
Yr. 1 Yr. 2 Yr. 3 (ft.) Yr. 1 Yr. 2 Yr. 3
3/29, 5/2,
Buck Island 8/10/01 1/14/02 5/4, & N 17 47.122, W64 36.550 35 3 3 6
5/21/03
Cane Bay 4/25/01 5/29/02 4/21/03 N 17 46.433, W64 48.810 30 6 6 6
Great Pond 3/24/03 7/31/03 N 17 42.668, W64 39.148 14 6 6
Jacks/Isaac Bay 8/02/01 6/11/02 09/05/03 N 17 44.588, W 64 34.309 35 6 6 6
Lang Bank 8/01/01 5/29/02 N 17 44.443, W64 32.209 50 6 5
Long Reef/Eagle Ray 7/26/01 5/30/02 3/28/03 N 17 45.688, W64 41.929 30 6 6 6
Mutton Snapper 1/17/03 5/19/03 N 17 38.217, W64 51.683 75 5 6
Salt River East Wall 10/12/01 5/23/02 N 17 47.221, W 64 45.445 40 6 6
8/23/01
Salt River West Wall /2/01 5/22/02 4/08/03 N 17 47.116, W64 45.564 20 6 6 6
10/12/01
Sprat Hole 9/25/01 6/14/02 4/13/03 N 17 44.038, W64 53.722 40 6 5 6


At all sites except Buck Island and Mutton Snapper, all video, coral disease and
bleaching, and sea urchin density data were collected along six 10 m permanent transects
established in previous years. In years one and two, only three transects were sampled at
Buck Island. In year three, three more transects were established here by driving stakes 10 m
apart into non-living areas of the reef near the three existing transects. When sampling the
permanent sites, transect lines were stretched between the stakes, then removed after
sampling. For Mutton Snapper, transects were marked in year two and year three by
haphazardly laying 10 m transect lines on areas judged to be representative of the reef. Since
permanent transects were not established at this site, data from year three and year two do not
represent the exact same area of reef, but do correspond to the same general area. Video,
disease, bleaching, and urchin samplings for all sites except Buck Island were performed on
the same day. At Buck Island, video samplings for transects 1 3 and transects 4 6 were








performed on 3/29/03 and 5/04/03, respectively. Urchin/disease/bleaching transects were
performed for transects 1 3 and transects 4 6 on 5/21/03 and 5/2/03, respectively.
To video sample, one diver swam along each transect videotaping the benthic cover
using a Sony TRV-950 digital camcorder in a Light and Motion Stingray II underwater
housing. The diver swam at a uniform speed, pointing the camera down and keeping the lens
approximately 0.4 m above the substrate at all times. A guide wand attached to the camera
housing was used to help the diver maintain the camera a constant distance above the reef.
After taping, approximately 20 30 non-overlapping images per transect were captured and
saved as JPEG files on a computer using a Sony video capture card. Captured images
represented an area of reef approximately 0.31 m2 (0.64 m x 0.48 m). Microsoft Excel and
Adobe Photoshop were used to superimpose ten randomly located dots on each captured
image. The substrate type located under each of the dots was then identified to the most
descriptive level possible and entered into a database. For each transect, the percent cover of
coral, dead coral with turf algae, macroalgae, sponges, gorgonians, and sand/sediment were
calculated by dividing the number of random dots falling on that substrate type by the total
number of dots for that transect. Mean values for percent cover were calculated for each site
and coral diversity was measured by using the Shannon-Weaver diversity index.
Paired t-tests were performed to determine if there were significant differences in the percent
cover of these benthic categories at each site between years one, two and three. Since three
transects were added at Buck Island in year three transectss 4 6), significant differences at
Buck Island between years were tested using data from all sampled transects in year three as
well as means determined from transects 1 3, which were sampled in all years. This was
done to ensure that any differences found between years at Buck Island reflected temporal
changes in benthic composition at the site and were not the result of increasing the number of
sampled transects.

At all sites all coral colonies >0.1 m in diameter or height that were located directly
under the transect lines were measured for maximum width and height and assessed for signs
of disease or bleaching. Assessments of each coral colony were done by estimating the
percent surface area (planar view) appearing bleached and diseased for each colony. For
each site, the mean percent of coral colonies with disease was calculated by dividing the
number of colonies with disease by the total number of colonies assessed on each transect,
then determining the mean value among all six transects. The mean percent of bleached
colonies for each site was calculated in the same fashion. Paired t-tests were used to
determine if there were significant differences in the percent of diseased and bleached
colonies between years two and three. Since bleaching and disease data were collected by a
different method in year one, comparisons to year one were not possible.

Divers also counted the number ofDiadema antillarum sea urchins within 1 m on
either side of each transect at all long-term sites. The mean number of sea urchins per 10 m2
was calculated for each site and paired t-tests were performed to determine if there were
differences in the mean density of sea urchins at each site between years one, two, and three.

Fish Census:

For all years in St. Croix, fish surveys were performed at the same sites as the benthic
assessments (Figure 1). In 2003, methods for surveying fish communities on St. Croix were
modified from the previous year. In 2002, fish surveys were conducted using the stationary
point-count method (Bohnsack and Bannerot 1986). In 2003, belt transects were used instead








of point counts (except where noted) in order to maximize data compatibility with concurrent
studies in the USVI and elsewhere. This methodological change affects time-series
comparisons of St. Croix data sets but not those of St. Thomas, where surveys were being
conducted for the first time in 2003.
Belt transects 30 x 2 m (60 m2) followed the method of Brock (1954). In brief, each
diver affixed a transect tape to the seafloor at haphazardly chosen positions that were
sufficiently separated from other transects (>5 m) and slowly swam a straight distance
parallel to the reef profile. All fish observed within this swath or passing in front of (but not
behind) the diver were identified to species. Fish size (fork length) was estimated to the
nearest cm, and number of individuals was recorded into the following size categories:
<5 cm; 5-10 cm; 10-20 cm; 20-30 cm; 30-40 cm, and >40 cm. On St. Croix,
diminutive/cryptic fish species gobiess, blennies, apogonids) were excluded from fish counts.
At each site, ten replicate belt transects were conducted with the exception of Mutton
Snapper site (7 transects). An attempt was made to standardize the duration of each belt
transect to 20 minutes on St. Croix.
In 2003 roving diver surveys (RDS) were used in conjunction with belt transects. In
this method, divers swam a haphazard circuit in the immediate vicinity of the survey site
while listing all observed fish species into abundance categories as follows: 1 fish; 2-10 fish,
10-100 fish; 101-1000 fish; and >1000 fish. Observations were recorded onto pre-printed
forms (species lists). On St. Croix, one RDS was conducted at each site for 30 minutes.
Survey information and observations were recorded onto underwater data forms. In
the laboratory, data were entered into Microsoft Excel spreadsheets and analyzed for
descriptive statistics of reef fish community structure (average density, species richness,
Shannon Weaver Diversity (H'), etc). Jaccard's coefficient of similarity, based upon species
presence or absence, was calculated for all intra-island site comparisons. A summary offish
census effort for St. Croix is presented in Table 2.

Table 2. Summary of fish census effort, St. Croix.


Survey Survey Total No. of Total Survey Avg. Time per
Method Site Date Replicates Time (min) Transect (min)
Buck Island 9/16/03 10 198 19.8
Cane Bay 8/28/03 10 331 33.1
w Great Pond 9/19/03 10 190 19.0
S Jacks Bay 9/5/03 10 214 21.4
S Long Reef 9/8/03 10 221 22.1
Mutton Snapper 9/23/03 7 137 19.6
Sprat Hole 9/10/03 10 195 19.5
Salt River 8/26/03 10 251 25.1
Buck Island 5/4/03 1 30 na
Cane Bay 5/29/03 1 30 na
S Great Pond c.5/22/03 1 30 na
o Jacks Bay 9/5/03 1 30 na
Long Reef 06/03 1 30 na
o Mutton Snapper 5/21/03 1 30 na
Sprat Hole 9/10/03 3 90 30.0
Salt River c.5/22/03 1 30 na
Point Sprat Hole 9/10/03 6 232 38.7









Results and Recommendations


Benthic Assessments:

For year three, the percent cover of living coral at the St. Croix sites ranged from a
low of 6.6% at Long Reef/Eagle Ray to a high of 35.9% at Mutton Snapper. The percent
cover of living coral remained fairly constant at each site from year one to year three, with no
significant differences between years at any site (Figure 2A). For year three, turf algae
covering dead coral was the most dominant substrate type at all eight sites except for Jacks
Bay and Mutton Snapper, where macroalgae was the most abundant substrate type. Dead
coral with turf algae ranged from a low of 21.7% at the Mutton Snapper site to a high of
81.2% at Salt River. At most sites, dead coral covered with turf algae varied between years,
with significant differences at Buck Island for years one and two, Great Pond and Long
Reef/Eagle Ray for years two and three, and Sprat Hole for years one and two and two and
three (Figure 2B). In year three, macroalgae ranged from a low of 0.45% at Great Pond to a
high of 47.0% at Jacks Bay. Macroalgae varied between years with significant differences at
Buck Island between years one, two, and three, and Long Reef and Sprat Hole for years one
and two and two and three (Figure 2C). Since macroalgae can overgrow dead coral with turf
algae and macroalgal cover can vary seasonally, comparisons of algal cover between years
are difficult, as all sites with significant differences were sampled at different times of year.
We recommend future samplings be performed consistently in late spring/early summer each
year, when macroalgal cover is highest (R. Nemeth, unpublished data). Sponges and
gorgonians each comprised less than 10% of the benthic cover at all sites, with sponge cover
varying significantly at Buck Island between year three and years one and two (Figure 2D,
E). Sand/sediment was the only non-living substrate type found at the sites, ranging from 0%
at Great Pond to 6.2% at Buck Island. No significant differences were found for percent
cover of sand/sediment between years (Figure 2F). For all benthic categories, temporal
comparisons at Buck Island utilizing means from transects 1 6, as well as transects
1 3 in year three produced similar results, indicating that differences (or lack of) between
year three and previous years were the result of temporal changes at the site and not from the
addition of transects.

The coral reefs of St. Croix were generally dominated by coral species in the genus
Montastraea. For analysis purposes, corals within the Montastraea annularis complex (M
annularis, M. faveolata, and M. franksii) were grouped into a single MACX category (Figure
3, Figure 4A-H). In 2003, Montastraea corals were the most abundant corals at five of the
eight sites. Millepora alcicornis was most abundant at Great Pond and Jacks Bay and Porites
astreoides was most abundant at Long Reef. At all sites, species composition tended to
differ between years (Figure 4A-H). Buck Island, Cane Bay, and Salt River tended to show
decreases in the percent composition for corals in the M. annularis complex with increases in
the percent composition for P. astreoides and Siderastrea siderea. As was the case with the
percent cover, the addition of three transects at Buck Island had no effect on patterns of
species composition. Cane Bay showed increases in Diploria strigosa and
D. labyrinthiformis as well. Similarly, Sprat Hole showed a decrease from year one to three
for the M. annularis complex with an increase in the percent composition by P. astreoides.
These trends warrant special attention, as P. astreoides and S. siderea are especially stress
tolerant corals (Acevedo et al., 1989; Torres and Morelock, 2002). Increases in the relative
abundance of these stress tolerant species and decreases in the relative abundance of less








tolerant corals such as those within the M. annularis complex may indicate an overall
decrease of reef quality. At Jacks Bay, P. astreoides and S. siderea as well as the M
annularis complex tended to increase from year one to year three and the relative abundance
ofM. cavernosa and P. porites tended to decrease. Long Reef showed an increase of the M.
annularis complex, P. astreoides, and D. labyrinthiformis, with decreases of M cavernosa,
S. siderea, and Agaricia agaricites. Great Pond showed dramatic differences in relative
abundance ofM. cavernosa, P. astreoides, Millepora alcicornis, and Millepora complanata
between 2002 and 2003. These differences may be a reflection of the sites shallow depth
(- 3.5 m) and low percent coral cover. On shallow reefs, strong surge can move the transect
line marking the video transects, resulting in variation in the exact coral colonies videotaped
with each sampling. In cases of low percent total coral cover, small variations in the percent
cover of each species captured in the video transects can result in large differences the
relative abundance of each species. The Mutton Snapper site showed an increase in the
relative abundance of corals in the M annularis complex and decreases for M. cavernosa, P.
astreoides, and S. siderea. A decrease in the relative abundance of stress tolerant species and
an increase in the relative abundance of less stress tolerant species may reflect an
improvement of reef quality at this site, which is the deepest of the sampled St. Croix sites
(75 ft. depth).

For 2003, the Shannon Weaver Diversity Index (H') for coral ranged from a high of
2.28 at Long Reef to a low of 0.52 at Mutton Snapper. Coral diversity increased at most sites
from year one to year three, with the exceptions being Great Pond (decreasing slightly) and
Mutton Snapper (Figure 5). This is consistent with the increase of stress tolerant species at
most sites. The decrease of coral diversity at Mutton Snapper can be attributed to the
decrease in the relative abundance of stress tolerant species and the increase of the relative
abundance of the M. annularis complex.

In 2003, Salt River showed the highest incidence of both diseased and bleached coral
colonies, with diseased corals comprising 7.6% of the sampled colonies and bleached corals
comprising 14.0% of the colonies. Mutton Snapper and Sprat Hole were the only other sites
with disease, with 5.5% and 0.9%, respectively. Jacks Bay and Great Pond were the only
sites without bleaching in 2003. Sprat Hole had significantly less disease in 2003 than 2002
(P<0.01, Figure 6). In 2003, M.franksii was the most common coral with disease, while
S. siderea was the most common with bleaching (Figure 7). Divers observed white plague,
dark spots disease, and yellow blotch disease. In some instances, corals appeared diseased,
but could not be categorized as a specific disease. These were classified as 'unknown' and
included in counts of total disease. Since bleaching and disease vary seasonally in the Virgin
Islands (S. Herzlieb, unpublished data), and the sites were sampled at different times of year
in 2002 and 2003, comparisons between years are difficult. We recommend that future
samplings for disease and bleaching be performed at the same time of year.

No Diadema antillarum sea urchins were present at most sites in 2003, the exceptions
being Cane Bay (1.3 urchins/10 m2), Great Pond (6.5 urchins/10 m2), and Jacks Bay
(0.2 urchins/10 m2). No significant differences in urchin density were found between years.









Fish Census:


On St. Croix, a total of 25,473 fish representing 101 species were observed in 77 belt
transects at eight survey sites. Abundance was highly variable within and among sites
(Figure 8A). The highest densities were observed at CB, MS, and SR. Species richness was
also variable (Figure 8B), but generally high with between 19 species (at GP) and 30 species
(at CB) observed per transect. The greatest number of fish species was observed at CB
(61 species) and the fewest at GP (47 species). Reef fish diversity (Shannon Weaver H')
was less variable within and among sites (Figure 8C).

A comparison of belt transect data to Roving Diver Survey (RDS) data indicated that
the level of RDS replication on St. Croix (one per site) was insufficient to adequately
characterize the fish communities. Community richness as determined by RDS was, on
average, only 74% of estimates derived from belt transects (10 replicates per site). For
comparison, in St. Thomas where RDS was replicated 3 times per site, richness from RDS
was on average 165% of belt transect estimates. Therefore, in the following discussion, data
from belt transects are emphasized. We recommend increasing the number of RDS replicates
to three or more in future St. Croix surveys to adequately characterize fish communities.

Reef fish communities were compared among sites based upon taxonomic
composition (species presence or absence) using Jacaard's index of similarity (Figure 9).
Fish communities at CB, SR and SH shared relatively high similarity (0.65 to 0.67) and LR
was similar to JB (0.67). The fish community at GP was least similar to all other sites
(0.38 to 0.51).

The majority of fish observed in 2003 were small, with most fish (12,909 fish or
50.7%) falling into the smallest size category (<5 cm). An additional 7,012 fish (27.5%) fell
into the next smallest size category (<10 cm long). Intermediate size fish (10-20 cm and
20-30 cm) were less abundant, comprising 17.3% and 4.1% of observations, respectively.
Indeed, relatively few large fish (30-40 cm) were observed (67 fish or 0.3%) and fewer very
large fish (>40 cm) were observed (40 fish or 0.2%).

Reef fish communities among sites were compared based upon ten families (Figure
10A-J). Planktivorous labrids and pomacentrids predominated at all sites, with five species
accounting for 63% of all fish observed in belt transects: bluehead wrasse, Thalassoma
bifasciatum (19.5%); blue chromis, Chromis cyanea (18.2%); bicolor damselfish, Stegastes
partitus (10.4%); creole wrasse, Clepticusparrae (8.1%); and brown chromis, Chromis
multilineata (7.0%). Parrotfishes (Scaridae) and surgeonfishes (Acanthuridae), which
represent the most prominent group of herbivores, were the next most abundant families.
Scarids reached their highest densities at BI whereas acanthurids were most abundant at JB
and GP. Among acanthurids, the ocean surgeon (Acanthurus bahianus) was very common,
the blue tang (A. coeruleus) was common, and the doctorfish (A. chururgus) least common.
Among scarids, the redband (Sparisoma aurofrenatum), stoplight (Sp. viride), striped (Scarus
croicensis), and princess (Sc. taeniopterus) parrotfishes were very common. The herbivorous
pomacentrid, yellowtail damselfish (Microspathodon chrysurus), was exceptionally abundant
at GP, where it was observed at densities over 10-fold greater than all other sites.








The remaining families (Figure 10E-J) were observed at much lower densities at most
sites. Small serranids, such as hamletfish (Hypoplectrus sp.) and harlequin bass (Serranus
tigrinus) were relatively common, as were two small groupers, coney (Cephalopholisfulvus)
and graysby (C. cruentatus). Larger groupers were either rare (red hind, Ephinephelus
gattatus, and rock hind, E. adcensionis) or absent. Similarly, lutjanids were only observed at
low densities, with mahogany snapper (Lutjanus mahogani) and schoolmaster (L. apodus)
encountered frequently, yellowtail snapper (Ocyurus chrysurus) observed infrequently, and
mutton snapper (L. analis) observed rarely. Haemulids were observed at all reef sites, with
the French grunt (Haemulonflavolineatum) the most abundant and most common.
Butterflyfish were common at most sites, especially the foureye butterflyfish (Chaetodon
capistratus) and banded butterflyfish (C. striatus). Angelfishes were uncommon (SR,CB, JB,
LR, SH, MS) or absent (BI, GP) and represented primarily by a single species, the rock
beauty (Holacanthus tricolor) although one queen angelfish (H. ciliaris) was observed at JB,
LR and MS. The family Balistidae (triggerfishes) was moderately abundant but represented
by a single species, black durgon ( 7le/iL /d1/i niger) at all but one site (MS) where two queen
triggerfish (Balistes vetula) were seen.

In order to compare St. Croix fish census results from this year (using belt transects)
to the previous year (using stationary point counts), both methods were used at one reef site
(SH) on the same day. We used the same methods with the same level of replication and the
same observers as described here and previously in 2002. Under these conditions, the point
count and belt transect methods gave very similar results for most fish species in terms of
rank order of abundance and rank frequency of observation. Results from the methods
differed primarily in that belt transects identified a greater number of species (55 vs. 41) and
more individuals were observed per replicate (typically 1 4 times more). For the latter,
scaling of results to total area surveyed (dividing belt transect data by 2.93) did not
substantially improve agreement between methods. Many of the discrepancies appear to be
species-specific. In some cases, fish movement during the observation period may inflate
density estimates by belt transects (e.g. small scarids, acanthurids), while in other cases
topographic complexity may obstruct observation and therefore deflate density estimates by
point counts (e.g. fairy basslets, various recruits).

In the previous year (Toller 2002) it was noted that many of the larger, long-lived
resident reef fish were absent from St. Croix surveys. We combined results from RDS and
belt transects in an attempt to quantify the abundance of 12 commercially important, rare,
and/or vulnerable species (Table 3). From this list, only red hind (Epinephelus guttatus) and
mutton snapper (Lutjanus analis) were observed. Although the level of replication for roving
diver surveys was inadequate, the results nonetheless support direct observations of fish
communities at these reef sites, with the exception of the cubera snapper (L. cyanopterus),
which was occasionally encountered (Toller, personal observation).





















Table 3. Abundance of 12 commercially important, rare and/or vulnerable fish species on St. Croix.


Relative Fish Abundance*


RD0 S- O- -
2- 2 2


Total 0 I
Survey o = -2
0 -
Site Method (min)>
SaltRiver belt 251 -
RDS 30 2 -
Cane Bay belt 331 -
RDS 30 -
Isaac's Bay belt 214 4 -
RDS 30 2 2
Eagle Ray belt 221 -
RDS 30 2
Sprat Hole belt 195 2
RDS-1 110 0.3(1,0) 2
RDS-2 30 2 2
point 232 -
Buck Island belt 198 6 -
RDS 30 1 -
Great Pond belt 190 -
RDS 30 -
Mutton Snapper belt 137


* For belt transects, fish abundance is reported as the total number of individuals observed in ten transects. For RDS, abundance is reported as the mean
abundance index (maximum and minimum indices in parentheses) for 3 replicate surveys. Abundance indices were as follows: 0 = no fish, 1 = 1 fish,
2 = 2-10 fish, 3 = 11-100 fish.









Section II: St. Thomas

Methods

Benthic Assessments and Abiotic Parameters:

Between August 2002 and September 2003, the University of the Virgin Islands
assessed twelve sites in St. Thomas, USVI. Of these sites, six were reefs dominated by
corals in the genus Montastraea and six were reefs dominated by corals in the genus
Acropora. The Montastraea reefs were categorized into three reef types based upon their
location along the insular platform off the coast of St. Thomas: near-shore reefs (5 30 m
deep) located along the shoreline of St. Thomas, mid-shelf reefs (5 30 m deep) located 2 to
10 km offshore of St. Thomas, and shelf-edge reefs (>30 m deep) located 10 to 15 km
offshore St. Thomas along the edge of the insular platform. Since there are no shelf-edge
Acropora reefs, only near-shore and mid-shelfAcropora sites were sampled. Two
Montastraea and three Acropora sites were included in each category (Figure 11, Table 4).
Since most research and monitoring in the Virgin Islands in general has been concentrated on
near-shore fringing reefs along the three main islands of St. Thomas, St. John, and St. Croix,
these sites were chosen to fill gaps in the knowledge of other reef systems, as well as to
establish an experimental design to test hypotheses involving differences in biotic and abiotic
parameters of reefs located at different points along the insular platform off the coast of St.
Thomas.

Table 4. St. Thomas site location information.
Date Sampled
Site Disease, Predation, GPS Coordinates Depth
Video Bleaching, Disease, Size Fish Surveys (ft.)
Urchins Distribution
Montastraea reefs:
Benner Bay1 5/20/03 5/20/03 8/05/03 N 180 18.754, W 64 51.635 15-26
Black Point1 9/09/03 9/09 1 N 180 20.670, W 64 59.157 23 36
9/22/03 10/02/03
Flat Cay2 6/04/03 6/04/03 6/4/03 N 180 19.093, W 64 59.462 40 56
Seahorse Cottage 6/12/03
Seahose Cottage 6/12/03 03 6/12/03 N 180 17.680, W 64 52.050 61 -80
Shoal2 6/18/03 6/12/03
Grammanik Bank3 4/03/03 7/29/03 6/17/03 N 180 11.468, W640 57.019 126
Red Hind Bank3 1 3 8 3 N 180 12.130, W65 00.095 128 131
1/15/03 8/13/03 6/16/03
Acropora reefs:
Botany Bay' 6/25/03 7/09/03 N 180 21.507, W 650 01.998 3 12
Caret Bay1 9/04/02 8/12/03 N 180 22.318, W 640 59.320 8 20
Coculus Point1 7/01/03 8/05/03 N 180 18.554, W 64 53.951 3- 8
Flat Cay2 8/01/02 7/10/03 N 180 19.028, W 64 59.328 3 25
Hans Lollik2 8/07/03 8/07/03 N 180 24.278, W 64 54.182 8 20
Inner Brass2 9/09/02 8/11/03 N 180 22.650, W 64 57.859 6- 10
near-shore sites
2 mid-shelf sites
3 shelf-edge sites







Montastraea reefs:


Video transects, coral disease and bleaching assessments, and sea urchin counts were
all performed using the same methodology as previously described for the St. Croix sites. At
all St. Thomas sites except Black Point, Seahorse Cottage Shoal, the Grammanik Bank and
the Red Hind Bank, video, disease and bleaching, and urchin samplings were performed on
the same day. The greater depths of Seahorse Cottage Shoal and the shelf-edge sites limited
the amount of time the divers could safely stay at depth. Therefore, data collection at these
sites was performed over the course of several days. For the near-shore sites, permanent
transects were established by driving stakes 10 m apart into non-living areas of the reef. The
transects were placed in a linear fashion with a randomly generated distance between each
transect. For Flat Cay, non-permanent transects were marked by a diver haphazardly picking
a starting point, stretching a transect tape for 10 m in a randomly generated compass
direction, marking the end of the transect, then swimming a random distance in a random
direction to determine the starting point off the next transect and repeating the process. For
Seahorse Cottage Shoal and the shelf-edge sites, transects were marked by haphazardly
laying transect line on areas judged to be representative of the reef. For the sites sampled
over the course of several days, transect lines were laid each day. Thus, on occasions when
the disease, bleaching, and urchin surveys were not completed on the same day as the video
sampling, these data were not collected at the exact same locations sampled by video, but in
the same general area of the reef. After sampling, video, bleaching and disease, and sea
urchin data were analyzed using the same methodology as previously described for the St.
Croix sites. Significant differences in percent cover of the previously described benthic
categories, coral disease and bleaching, and sea urchin density between near-shore, mid-
shelf, and shelf-edge sites were determined by t-tests. At depths greater than 25 m (i.e. the
shelf-edge sites), coral species within the M. annularis complex appear very similar, making
identification to species difficult, especially from video images. In instances where corals
could not be reliably identified to species, they were classified as MACX, unidentified coral
within the M. annularis complex.

To measure abiotic factors, two sediment traps and one Aanderaa RCM 9 MkII data
recorder were installed at the Flat Cay and Red Hind Bank sites, respectively (Table 5). This
mid-shelf and shelf-edge site were chosen as abiotic stations to complement oceanographic
data that will be collected by the NOAA CREWS station to be placed at the near-shore reef
in Brewer's Bay. The data recorders were installed according to the manufacturer's
instructions in small sand patches within the reef in the same general area where the benthic
transects were assessed. The data recorders were set to record temperature and current speed
and direction at hourly intervals. The sediment traps were constructed of PVC tubing 20 cm
long and 5 cm internal diameter. At each site, the traps were mounted 10 m apart on stakes
driven into non-living areas of the reef with the top of each trap 0.5 m above the substrate.
The traps were placed such that one trap was within 2 m of the data recorder at each site.

Table 5. Dates Aanderaa data recorders and sediment traps deployed and retrieved.
Set 1 Set 2 Set 3 Set 4
Data recorders: Deployed Retrieved Deployed Retrieved Deployed Retrieved Deployed Retrieved
Flat Cay 4/8/03 7/25/03 7/29/03 10/29/03 11/4/03 2/12/04
Red Hind Bank 4/10/03 8/13/03 8/15/03 10/28/03 10/31/03 2/27/04
Sediment traps:
Flat Cay 7/08/03 8/15/03 8/15/03 9/10/03 9/10/03 10/29/03 10/29/03 11/20/03
Red Hind Bank 7/15/03 8/15/03 8/15/03 9/10/03 9/10/03 10/28/03 10/29/03 11/26/03








After retrieval, data from the data recorders were downloaded into a personal
computer according to the manufacturer's instructions using software supplied by Aandera
instruments. Since there were small amounts of sediment in all the traps (i.e. the total
sediment did not completely cover the bottom of the trap), glass fiber filters were used to
process the sediment. The glass fiber filters were first rinsed with distilled water while
installed in a vacuum pump manifold, then oven dried, placed in a desiccator for 15 minutes,
then weighed. After filter preparation, the filters were placed on the vacuum pump manifold
and the contents of the sediment trap were poured onto the filter, using distilled water to rinse
all sediment from the trap. The vacuum pump was then turned on and the samples were
rinsed with distilled water. The sediment and filters where then placed in a drying oven for
1 hr. at 100 C. Finally, the weight of the sediment sample was determined by weighing the
dried sediment and glass filter and subtracting the filter weight. In all cases, the rate of
sediment accumulation (g/cm2/d) was determined by dividing the weight of the dried
sediment by the area of the cross section of the sediment trap, then by the number of days the
traps were on the reef (soak time).

Acropora reefs:

Digital video transects and diver surveys were used to assess all Acropora sites. Due
to the nature of the structure of Acropora reefs, video transect methodology differed from
that used at the Montastraea sites. At each Acropora site, five 30 m transect lines were
haphazardly laid on areas judged to be representative of the reef. A diver videotaped the
benthic cover along each transect in the same fashion used on the Montastraea reefs. We
determined that video images recorded at a distance of 0.4 m are 0.64 m in width. Therefore,
a 30 m video transect defines an area of 19.2 m2. After taping, video images containing
Acropora colonies were captured as still images to a personal computer. For each image, an
analyst measured the surface area of living Acropora colonies using ImagePro image analysis
software. The percent cover of live coral for each transect was then determined by dividing
the digitally measured areas by 19.2 m2, and the mean percent cover was calculated for each
site. Percent cover was determined for each Acropora species: A. palmata, A. cervicornis,
and A. prolifera. Significant differences in percent cover of Acropora between near-shore
and mid-shelf reefs were determined by t-tests. During the diver surveys, each diver chose a
species to sample (A. palmata, A. cervicornis, or A. prolifera) then swam (snorkel or
SCUBA) in a randomly determined direction over the reef. The divers assessed every colony
of their chosen species that they came across while swimming along this line until they
assessed 25 colonies of their chosen species, or until they reached the end of the reef. In
cases where divers failed to see 25 colonies before reaching the end of the reef, the divers
swam in another randomly chosen direction until they assessed 25 colonies, or until it
became apparent that the diver would be unable to locate any more colonies of the given
species. For each colony, divers measured the maximum length, width, and height, estimated
percent tissue mortality (planar view total dead and recent dead), and noted the presence of
Coralliophila snails (predators of Acropora corals) and white band disease. The length,
width, and height were then multiplied together to determine a representative volume for
each colony and the colonies were categorized into the following size classes (cm3): <1000;
>1000 < 15,625; >15,625 < 125,000; >125,000 < 1 x 106; and >1 x 106. Divers also counted
the number of Acropora sexual recruits in each of 10 haphazardly placed 1 m2 quadrats at
each site. Recruits were defined as colonies <10 cm in maximum dimension that appeared to
be established from settled larvae, as opposed to fragmentation. Typically, these recruits
were too small and amorphic to be reliably identified to species. Significant differences







between near-shore and mid-shelf reefs for tissue mortality, number of coral colonies
infested with Coralliophila snails, incidence of white band disease, and recruitment were
determined by t-tests. At all sites except Hans Lollik, video samplings and diver surveys
took place on separate occasions.

Fish Census:

On St. Thomas, fish surveys were conducted on the six Montastraea dominated reefs
where video benthic assessments were performed. No fish surveys were conducted on the
Acropora dominated reefs. Methods used to survey fish communities were similar to those
for St. Croix with the following modifications: on each site, ten replicate belt transects were
completed with the exception of Seahorse Cottage Shoal, where 7 were completed. No
attempt was made to standardize the duration of the belt transects, but transect times
averaged 7.5 minutes. Three roving diver survey (RDS) replicates were completed at each
site except on the two shelf-edge sites, where 4 replicates per site were completed. Roving
diver surveys were 60 minutes in duration or the highest quarter hour of that time possible
within time limitations imposed by depth. On the inshore sites (Benner Bay and Black Point),
RDS replicates lasted the entire 60 minutes, on mid-shelf sites (Seahorse Cottage Shoal and
Flat Cay) they were 45 minutes, and on shelf-edge sites (Grammanik Bank and Red Hind
Bank) survey replicates were 15 minutes. All species of fish observed were recorded during
both survey types (belt transect and RDS) with the exception of the glass goby
(Coryphopteruspersonatus). Survey data were recorded, managed and analyzed using the
same software and descriptive statistics as that for St Croix.

Results and Recommendations

Benthic Assessments and Abiotic Parameters:

Montastraea reefs:

For the St. Thomas sites, percent cover of living coral ranged from a low of 8.3% at
Benner Bay to a high of 42.0% at the Grammanik Bank. The percent cover of dead coral
covered with turf algae ranged from 15.0% at Seahorse Cottage Shoal to 45.6% at Benner
Bay. The percent cover of macroalgae ranged from 13.8% at Black Point to 42.7% at
Seahorse Cottage Shoal (Figure 12A-C). Sponges and gorgonians each comprised less than
10% of the benthic cover at all sites. No gorgonians were observed on the shelf-edge sites.
The percent cover of sand/sediment ranged from 3.0% at the Grammanik Bank to 28.0% at
Black Point. For this category, Black Point was predominately sediment covering the entire
substrate, while the other sights were predominately sandy areas in between vertical reef
structures (Figure 12D-F). Near-shore reefs tended to have lower percent cover of living
coral and higher percent cover of dead coral covered with turf algae than mid-shelf and shelf-
edge reefs, but there were no significant differences in percent cover of any benthic category
between near-shore, mid-shelf, and shelf-edge sites. Given the small sample size of n = 2 for
each reef type and the high variation between reefs within each category, comparisons
between reef types are difficult. We recommend sampling a greater number of reefs of each
type to make comparisons more statistically robust. We also recommend further stratifying
site selection for the mid-shelf reef systems, distinguishing between shallower mid-shelf
reefs associated with small islands or cays and the deeper mid-shelf reefs that are not. In this
study, we found the reefs at the two mid-shelf sites to differ dramatically.







Seahorse Cottage Shoal had significantly higher percent cover of living coral and
significantly lower percent cover of dead coral covered with turf algae and percent cover
sponges than Flat Cay (t-tests, P = 0.003, P = 0.006, and P = 0.002, respectively). It is
difficult to attribute these differences to a specific cause. The reef at Flat Cay is associated
with a small island, while Seahorse Cottage Shoal is not and Seahorse Cottage Shoal is at a
greater depth than Flat Cay (Table 4). Also, Flat Cay is frequently visited by recreational
divers, while Seahorse Cottage Shoal is not. Finally, current direction data collected at Flat
Cay indicate that despite this reef s location on the insular platform, this site may still be
considerably impacted by terrigenous stresses from St. Thomas (see subsequent paragraph
regarding abiotic parameters). Sampling a greater number of mid-shelf reefs both associated
and unassociated with cays will help to elucidate the effects of natural and anthropogenic
stresses on these as well as near-shore reef systems.

The coral reefs of St. Thomas were generally dominated by coral species in the genus
Montastraea. Near-shore sites tended to have lower percent composition of corals within the
M. annularis complex and higher percent composition of the stress tolerant corals P.
astreoides and S. siderea than mid-shelf and shelf-edge sites (Figure 13). Corals within the
M. annularis complex were the most abundant corals at all sites except Benner Bay, where
M. cavernosa was most abundant (Figure 14A-F).

The Shannon Weaver Diversity Index (H') for coral ranged from a high of 2.26 at
Flat Cay to a low of 1.20 at the Grammanik Bank. In general, the deeper sites (SC, GB, RH)
had lower diversity than the shallow sites (Figure 15). This supports the recommendation of
stratifying the mid-shelf sites into shallower sites associated with cays and deeper mid-shelf
reefs not associated with cays or islands.

Benner Bay showed the highest incidence of both diseased and bleached coral
colonies, with diseased corals comprising 17.4% of the sampled colonies and bleached corals
comprising 47.8% of the sampled colonies. The Red Hind Bank showed the lowest
incidence of diseased corals (1.4%) and Flat Cay showed the lowest incidence of bleached
corals (0%). Near-shore sites tended to have a higher incidence of bleaching than mid-shelf
and shelf-edge sites, but there were no significant differences in incidence of disease or
bleaching between near-shore, mid-shelf, and shelf-edge sites (Figure 16). Once again, the
small sample size of n = 2 for each reef type and the high variation within each category
made comparisons between reef types difficult. M. cavernosa and S. siderea were the most
common corals with disease, while S. siderea was the most common coral with bleaching
(Figure 17). Divers observed black band disease, dark spots disease, yellow blotch disease
and white plague. In some instances, corals appeared diseased, but could not be categorized
as a specific disease. These were classified as 'unknown' and included in counts of total
disease.

D. antillarum sea urchins were observed only at the two near-shore sites, with 0.5
urchins/10 m2 at Benner Bay and 0.3 urchins/10 m2 at Black Point. No significant
differences in sea urchin density were found between near-shore, mid-shelf, and shelf-edge
sites.







Abiotic Parameters:


At Flat Cay, current direction headed just west of south throughout the course of the
deployment of the data recorder (Figure 18). Given the position of Flat Cay southwest of
heavily developed and industrial areas of St. Thomas (Charlotte Amalie, Krum Bay,
Lindbergh Bay, and the Cyril E. King Airport) and differences in percent coral and algal
cover between Flat Cay and Seahorse Cottage Shoal, Flat Cay may still be considerably
impacted by terrigenous stresses despite the reef's mid-shelf location. This supports the
recommendation of further data collection at mid-shelf reefs to elucidate the relative effects
of terrigenous stresses. Current at the Red Hind Bank headed predominantly both north and
south with higher current speeds occurring from late summer to early winter (Figure 19).
Daily mean temperature at Flat Cay tended to be higher than the Red Hind Bank, with the
highest temperatures in September and October at both sites (Figure 20, Figure 21).
Sedimentation rates were higher at Flat Cay than the Red Hind Bank for all periods of
deployment except Set 4 (Table 6).

Table 6. Sedimentation rates (g/cm2/day x 10-4) at Flat Cay and the Red Hind Bank.

Flat Cay Set 1 Set 2 Set 3 Set 4
(Jul. Aug.) (Aug. Sep.) (Sep. Oct.) (Oct. Nov.)
Trap 1 7.55 6.76 6.35 1.07
Trap 2 5.94 5.88 2.88 3.45
Mean + SD 6.74 + 1.14 6.32 + 0.62 4.62 + 2.46 2.26 + 1.69
Red Hind Bank
Trap 1 0.30 4.06 1.42 4.06
Trap 2 2.83 7.82 0.86 1.36
Mean + SD 1.56 + 1.79 5.94 + 2.66 1.14 + 0.40 2.71 + 1.90

Acropora reefs:

Average percent cover of all Acropora species combined (A. cervicornis, A. palmata,
and A. prolifera) for the sampled St. Thomas sites ranged from a low of 5.8% at Caret Bay to
a high of 13.0% at Hans Lollik. Percent cover of Acropora was not significantly different
between near-shore and mid-shelf sites (Figure 22). Percent cover ofA. cervicornis ranged
from a low of 0.3% at Hans Lollik to a high of 6.1% at Botany Bay. Percent cover of A.
palmata ranged from a low of 1.6% at Botany Bay to a high of 12.6% at Hans Lollik.
Percent cover ofA. prolifera ranged from 0% at Botany Bay, Caret Bay, and Inner Brass
Island to 6.4% at Coculus Point. No significant differences were found between near-shore
and mid-shelf reefs for percent cover of any Acropora species (Figure 23). For A.
cervicornis, colonies with an estimated volume between 15,626 cm3 and 125,000 cm3 were
the most common size class at all sites. Caret Bay had the greatest number of colonies with
an estimated volume <1000 cm3 and Flat Cay was the only site that had colonies with an
estimated volume >1 x 106 cm3 (Figure 24). For A. palmata, colonies with an estimated
volume between 125,000 cm3 and 1 x 106 cm3 were the most common size class at all sites,
except for Coculus Point, where colonies with an estimated volume between 1,000 cm3 and
15,626 cm3 were the most common size class and Inner Brass Island, where colonies with an
estimated volume between 15,626 cm3 and 125,000 cm3 were the most common size class.
Inner Brass Island was the only site with colonies with an estimated volume <1000 cm3 and
Coculus Point and Inner Brass Island were the only sites without colonies with an estimated
volume >1 x 106 cm3 (Figure 25). A. prolifera was the least abundant of the Acropora
species at all sites. No colonies were observed at Caret Bay, and only five colonies were
observed at Inner Brass Island. Divers were able to find and assess 25 colonies at all other







sites, but this required more time and effort than for the other Acropora species. Colonies
with an estimated volume between 15,626 cm3 and 125,000 cm3 were the most common size
class at most sites with A. prolifera, the exceptions being Hans Lollik, where colonies with
an estimated volume between 1,000 cm3 and 15,626 cm3 were the most common and Inner
Brass Island, where colonies <1,000 cm3 and between 1,000 cm3 and 15,626 cm3 were the
most common size classes. No A. prolifera colonies with an estimated volume >1 x 106 cm3
were observed at any of the sites (Figure 26).

Inner Brass Island had the lowest A. cervicornis tissue mortality of all the sites, with a
mean of 8.4% surface area of each colony comprised of dead coral skeleton. Hans Lollik had
the highest A. cervicornis tissue mortality, with a mean of 30.4% of the surface area of each
colony comprised of dead coral skeleton (Figure 27). A. palmata tissue mortality ranged
from a low of 11.0% at Inner Brass Island to a high of 37.0% at Caret Bay (Figure 28).
A. prolifera tissue mortality ranged from a low of 8.4% at Inner Brass Island to a high of
19.2% at Hans Lollik (Figure 29). No significant differences were found for both total and
recent tissue mortality for any Acropora species between near-shore and mid-shelf sites.
Coralliophila snail infestation was most common on A. palmata at Caret Bay, where snails
were observed on 72.0% of the sampled colonies. Snail infestation was lowest on A.
cervicornis and A. palmata at Botany Bay, where no snails were observed on assessed corals
(Figure 30). No significant differences in snail infestation were found for any Acropora
species or all species combined between near-shore and mid-shelf sites. Incidence of white
band disease was highest on A. palmata at Caret Bay, where 28.0% of the assessed colonies
were infected. No white band disease was observed on any Acropora species at Botany Bay
and no white band disease was observed on A. cervicornis and A. prolifera at Coculus Point
and A. cervicornis and A. palmata at Flat Cay (Figure 31). No significant differences in the
percent of colonies infected with white band disease were found for any Acropora species or
all species combined between near-shore and mid-shelf sites.

Recruitment density ranged from 0.1 recruits/m2 at Caret Bay to 1.3 recruits/m2 at
Coculus Point (Table 7). No significant differences in density of Acropora recruits were
found between near-shore and mid-shelf sites.

Table 7. Acropora recruits at St. Thomas sites (n = 10 quadrats for each site).


Site No. of Recruits/m + SD
Botany Bay 0.5 + 0.71
Caret Bay 0.1 + 0.32
Coculus Point 0.9 + 1.29
Flat Cay 0.1 + 0.32
Hans Lollik 0.6 + 0.52
Inner Brass 0.4 + 0.70







Fish Census:


A summary offish survey effort is presented in Table 8 for St. Thomas. Because no
attempt was made to standardize or record belt transect duration, effort by survey type can
only be estimated. We recommend that belt transect duration be recorded and standardized
when possible in future St. Thomas samplings. Due to the time constraints imposed by the
depths of the mid-shelf and shelf-edge sites in St. Thomas, RDS duration cannot be
standardized for all sites, but only for sites of similar depths. Therefore, the resulting species
richness values can only be compared between sites within the same depth ranges.

Table 8. Summary of fish census effort on St. Thomas.

Survey Site Survey Total No. Total Survey Ave. Time per
Method Date of Replicates Time (min) Replicate (min)
Benner Bay 8/5/03 10 NR -7.5
SBlack Point 10/2/03 10 NR -7.5
U Seahorse Cottage Shoal 6/12/03 7 NR -7.5
SFlat Cay 6/4/03 10 NR -7.5
Grammanik Bank 6/17/03 10 NR 7.5
Red Hind Bank 6/16/03 10 NR 7.5
Benner Bay 8/5/03 3 180 60
SBlack Point 9/11/03 3 180 60
o Seahorse Cottage Shoal 6/18/03 3 135 45
Flat Cay 6/4/03 3 135 45
o Grammanik Bank 6/18/3 4 60 15
Red Hind Bank 6/16/03 4 60 15


A total of 5,117 fish representing 87 species and 22 families were observed in 67 belt
transects. Fish abundance was variable within and between sites (Figure 32A). The highest
densities of fish were observed at FC and SC, both mid-shelf reef sites. Species richness was
variable within and between sites, but was again highest on the mid-shelf reefs (Figure 32B).
The site with the greatest number of fish species observed on belt transects was FC (54
species) and the site with the fewest was BP (36 species). Community diversity was less
variable between sites, but was slightly lower on the shelf-edge sites, GB and RH
(Figure 32C).

On roving diver surveys a total of 125 species representing 35 families were
observed. Table 9 presents a summary of the total number of species observed and species
richness values for each site, using both belt transects and RDS. Species richness values were
higher on RDS than belt transects at all sites. Values for RDS were not comparable across
reef sites due to differences in the duration of the surveys.







Table 9. Comparison of Species Richness across sites off St. Thomas, using belt transect data
and roving diver survey (RDS) data.
Belt Transects RDS
Site Total Survey Total No. Ave. Species Total Survey Total No. Ave. Species
Time (min) Species Richness (St. Dev.) Time (min) Species Richness (St. Dev.)

BB -75 38 16.3 (1.9) 180 83 59.7 (2.9)
BP -75 36 15.6 (3.3) 180 64 47.3 (4.0)
SC -75 49 18.0 (5.6) 135 72 57.7 (2.1)
FC -75 54 22.7 (3.2) 135 84 60.7 (1.5)
GB -75 43 15.4 (3.2) 45 58 36.8 (2.5)
RH -75 42 13.6 (2.9) 45 68 39.5 (6.4)

Reef fish communities were compared among sites based on taxonomic composition
(species presence or absence) using Jaccard's index of similarity. This was done separately
for belt transects and RDS (Figure 33). Jaccard's indices computed with data from belt
transects indicated that fish communities at BP, SC and FC shared relatively high similarity
(0.47 to 0.56) and GB was similar to RH (0.50). The fish community at the two shelf-edge
sites, GB and RH, were most dissimilar to the two near-shore sites, BB and BP (0.31 to
0.40). Similarity indices for roving dives were highest between the near-shore and mid-shelf
sites (0.51 to 0.64), and between shelf-edge sites (0.58). The most dissimilar site was GB,
which produced relatively low similarity indices (0.35 to 0.44) when compared to all sites
except RH.

The majority of fish observed in 2003 were small or intermediate in size, with most (2,748
fish or 54.1%) falling into the second smallest size category (5-10 cm). Fish in the next larger
size category (10-20 cm) made up an additional 22.8% (1159 fish) of the individuals seen.
Very small fish (<5 cm) were recorded in less abundance (716 fish or 14.1%) and individuals
in the largest size categories (20-30 cm, 30-40 cm and >40 cm) were less abundant still,
comprising 5.2%, 3.1% and 0.7% of the observations respectively.

Reef fish communities among sites were compared based upon ten families (Figure
34). Planktivorous pomacentrids predominated at all sites except BB and RH, which were
dominated by invertebrate-feeding labrids and planktivorous labrids respectively. Labrids
were fairly evenly distributed on BB between yellowhead wrasse (Halichoeres garnoti),
clown wrasse (H. maculipinna) and slippery dicks (H. bivittatus). On RH, labrids were
almost exclusively represented by the creole wrasse (Clepicusparrae). The highest densities
of pomacentrids were observed on FC, where blue chromis (Chromis cyanea) and brown
chromis (Chromis multilineata) represented 78% of that family observed. Parrotfishes
(Scaridae), which represent the most prominent group of herbivores, had the highest densities
at BP, SC and FC. They were most commonly represented by the princess parrotfish (Scarus
taeniopterus) and striped parrotfish (Sc. iserti). Stoplight parrotfish (Sparisoma viride) and
redband parrotfish (Sp. aurofrenatum) were also relatively common on the near-shore sites,
BB and BP. The more rare scarid species observed on some sites were the redtail parrotfish
(Sp. chrysopterum), the yellowtail parrotfish (Sp. rupripinne) and the queen parrotfish
(Sc. vetula). Acanthurids (tangs) were observed most frequently at BB. Among acanthurids,
blue tangs (Acanthurus coeruleus) and the ocean surgeons (A. bahianus) were the most
common. Acanthurid and scarid relative densities were reciprocal on sites BB, BP and SC







(Figure 34C and 34D). This pattern is found in fish surveys off St. Croix as well, both in the
present study, and in 2002 (Toller).

The remaining families (Figure 34E-J) were observed at much lower densities at most
sites. Figure 34E represents the commercially important serranids, the groupers. These were
uncommon at all sites but were most frequently encountered on the shelf-edge sites, GB and
RH. Graysby (Cephalopholis cruentatus), the smallest and most common grouper, were
observed on all sites. Red hind (Epinephelus guttatus) and Nassau grouper (E. striatus) were
uncommon to rare, but were observed on nearshore (BP) mid-shelf (FC) and shelf-edge sites
(GB, HB). Yellowfin (Mycteroperca venenosa) and tiger groupers (M tigris) in contrast,
were only observed on the offshore sites, GB and RH. Lutjanids (snappers) were also
observed at low densities. Only the yellowtail snapper (Ocyurus chrysurus) was encountered
relatively frequently and on all sites. Schoolmaster snapper (Lutjanus apodus) were observed
infrequently on mid-shelf (SC) and shelf-edge reefs (GB, HB). Mutton snapper (L. analis),
cubera snapper (L. cyanopterus), gray snapper (L. griseus), dog snapper (L. jocu), mahogany
snapper (L. mahogoni) and lane snapper (L. synagris) were observed rarely. The greatest
number and variety of snappers was seen at SC, with six species observed. Fish surveys at
Seahorse Cottage Shoal took place two days prior to the full moon in June. During the full
moon in May, large numbers of Lane and Gray snappers were observed during a concurrent
UVI study. Collected snappers possessed hydrated oocytes, indicating imminent spawning
and confirming Seahorse Cottage Shoal as a snapper spawning aggregation site. Continued
monitoring at this site is essential, especially as Seahorse Cottage Shoal is under no fisheries
protection. We recommend future samplings at Seahorse Cottage Shoal be performed near
the full moon in May during snapper spawning aggregations. Relatively high snapper
densities at BP represented only one species, the yellowtail snapper (0. chrysurus).
Haemulids (grunts) were again most common and most diverse at the mid-shelf site, SC,
followed by one of the shelf-edge sites, RH. The French grunt (Haemulonflavolineatum) was
the most abundant of the family and occurred at all six reef sites. Chaetodontids
(butterflyfish) were common on the mid-shelf reef sites (SC, FC) and the shelf-edge sites
(GB, RH). Foureye butterflyfish (Chaetodon capistratus) were by far the most common of
the chaetodontids and occurred on all reef sites. Banded butterflyfish (C. striatus) were less
common, but were observed on five of six sites. Longsnout butterflyfish were observed only
on the shelf-edge sites (GB, RH). Chaetodontid densities have been suggested to indicate
levels of reef health (Crosby and Reese, 1996). In our study, on both belt transects and RDS,
chaetodontid observations were highest on mid-shelf and shelf-edge reef sites. The increased
distance from shore and decreased effects of land based runoff and pollution may be reflected
in densities of these fish. The commercially exploited angelfishes were very uncommon but
were present on all sites. They were most common and most diverse on HB (5 species) and
FC (4 species). The rock beauty (Holacanthus tricolor) occurred on all sites and was the only
representative of the family on BB and GB. The family Balistidae (triggerfishes) was rare to
absent on all sites except GB. Balistids were represented by a single species, the black
durgon (1 Al' hi/ly\ niger) at GB, by queen triggerfish (Balistes vetula) at FC and SC, and by
one orangespotted filefish (Ct/he, ii', pullus) at BP.








As with the St. Croix fish data, results from RDS and belt transects were combined in
an attempt to quantify the relative abundance of 12 commercially important, rare and/or
vulnerable species on the St. Thomas reef sites (Table 10). Of those species, the red hind
(E. guttatus) was seen on all sites, and the three largest groupers, the Nassau (E. striatus),
yellowfin (M venenosa) and tiger (M. tigris) were observed on both shelf-edge reefs (GB
and HB). The most rare snappers, dog (L. jocu) and cubera (L. cyanopterus) were observed
on the shelf-edge sites as well, and the mutton snapper (L. analis) was seen on one near-shore
site (BB), one mid-shelf site (SC) and one shelf-edge site (RH). Hogfish (Lachnolaimus
maximus) were observed on only one site (SC) and the rainbow parrotfish (Scarus
guacamacia) on another (BB).













Table 10. Abundance of 12 commercially important, rare and/or vulnerable fish species on St. Thomas.


Relative Fish Abundance*

0 C 0 0


Survey z .
e M d T
RDS*** 60






Black Point belt 75 1 4
Seahorse Cottage belt 53
RD 45 E 0.7(1,0) 2.7(3,2) 1.0(2,1
Total 0.3(1,0) 0 0.
Survey z E *
Site Method Time (min)
Benner Bay belt* 75**- -
RDS*** 60 1 1.7(2,) 0.7(2,0) 1.3(2,0)
Black Point belt 75 1 -
RDS 60 2.0(2,2) 0.7(1,0) -
Seahorse Cottage belt 53 -
RDS 45 0.7(1,0) 2.7(3,2) 1.0(2,1)
Flat Cay belt 75 1 2 -
RDS 45 0.3(1,0) 0.7(1,0) -
Grammanik Bank belt 75 1 3 5 4 -
RDS 15 0.5(2,0) 1.0(2,0) 0.5(2,0) 1.0(2,0) 3.0(3,3) -
Red Hind Bank belt 75 1 3 5 3 -
RDS 15 0.5(2,0) 0.8(3,0) 0.5(2,0) 1.0(2,0) 0.8(2,0) 0.8(2,0)
* belt transect occurence reported as total number of fish observed over 10 repetitive surveys (except SC with 7 repetitive surveys).
**Belt transect survey time was estimated to average 7.5 minutes/survey
***RDS occurances reported as mean Abundance Index (Al) over 3 or 4 repetitive surveys with maximum and minimum Al in parentheses.
Al: 0=no fish, 1=1fish, 2=2-10 fish, 3=11-100 fish, 4=101-1000 fish








Summary and Discussion


St. Croix

On St. Croix, turf algae covering dead coral was the dominant substrate at most
sampled sites, comprising greater than 50% of the substrata at six of the eight sites. The
percent cover of other benthic organisms ranged from 6.6% to 35.9% for living hard coral,
0.45% to 47.0% for macroalgae, 0.22% to 3.63% for sponges, and 0% to 5.62% for
gorgonians. Coral species composition was similar between most sites, with twelve coral
species representing 98% of the coral community. Coral diversity (H') varied between 0.52
and 2.28 between sites. Coral condition varied between sites with incidence of coral disease
and bleaching ranging from 0% to 7.6% and 0% to 14.0%, respectively. Diadema sea
urchins were uncommon and observed on transects at only three of the eight sites.

Annual comparisons showed little change in percent cover of live coral. However,
species composition tended to differ between years at all sites. Half of the sampled sites
showed increases in the relative abundance of stress tolerant coral species and decreases in
the relative abundance of less stress tolerant species, indicating a possible decrease in overall
reef quality at these sites. One site (Mutton Snapper) showed a decrease in stress tolerant
species and an increase in less stress tolerant species, indicating a possible increase in reef
quality at this site. Coral diversity increased at most sites from year one to year three.
Percent cover of sponges, gorgonians and sand remained fairly constant between years, with
only one site (Buck Island) showing significant changes in percent sponge cover in year
three. Due to variations in sampling time, annual comparisons of percent cover turf algae,
macroalgae, and disease and bleaching are difficult due to seasonal fluctuations in
macroalgal cover and levels of coral disease and bleaching. Percent cover dead coral
covered with turf algae showed significant changes in 2003 at three sites (Great Pond, Long
Reef, and Sprat Hole) and percent cover of macroalgae also showed significant changes in
2003 at three sites (Buck Island, Long Reef, and Sprat Hole). Sprat Hole showed a
significantly lower incidence of disease in year three than in year two. No significant annual
differences in bleaching were found. Based upon recommendations from year two, efforts
were made to sample all St. Croix sites within the same time period in late spring and early
summer. This goal was partially met in year three. Five of the sites were sampled in April
and May, while the remaining three sites were sampled in March, July, and September,
respectively. Future monitoring efforts will attempt to refine sampling effort further and
sample all sites in late May and early June, making temporal comparisons for percent cover
turf and macroalgae and disease and bleaching assessments more robust. No significant
annual differences in sea urchin density were found.

Fish abundance averaged from approximately 200 to 500 fish per census. The
number of fish species observed at the St. Croix sites ranged from 47 to 61 species. The
St. Croix fish fauna was numerically dominated by planktivorous wrasses and damselfishes.
Parrotfishes and surgeonfishes were the next most abundant families. The commercially
important large groupers, snappers, and angelfishes were uncommon to absent at all sites.
Triggerfishes were moderately abundant, but dominated by a singe species, the black durgon.
The commercially important queen triggerfish was absent at most sites, with only two queen
triggerfish observed at Mutton Snapper. The majority of fish observed in year three were
small, with most fish <5 cm. Relatively few large fish (30 40 cm) and very few larger fish
(>40 cm) were observed.









Due to differing methods utilized for fish censuses between years (point counts and
belt transects), annual comparisons of fish surveys are difficult. Also, previous surveys
utilizing point counts and belt transects determined that accurate assessments of
commercially important fish species, such as groupers and snappers, are difficult because
these fish are typically rare at monitoring sites. In year three, Roving Diver Surveys (RDS)
were performed to attempt to more accurately characterize fish communities, but it was
determined that the level of RDS replication was insufficient. To better facilitate annual
comparisons and characterize St. Croix fish communities, future monitoring efforts will
consistently utilize belt transects and increased replication of RDS at all sites.

While no attempt was made to stratify the St. Croix sites based upon depth or distance
from shore, the deepest of the sites, Mutton Snapper had the highest fish abundance of all the
St. Croix sampled sites. In addition, Mutton Snapper had the highest percent living coral
cover and the lowest percent cover of dead coral with turf algae. This site was also the only
site that showed decreases in the relative abundance of stress tolerant coral species and an
increase in the relative abundance of less stress tolerant corals (i.e. corals within the
Montastraea annularis complex). While continued monitoring of the established St. Croix
sites is vital (especially Jacks Bay and Great Pond, which are within the East End Marine
Park) stratification of St. Croix sites based upon such factors as distance from shore and
fishing pressure would facilitate the attribution of causal factors to observed changes in reef
communities.

St. Thomas

On St. Thomas Montastraea reefs, turf algae covering dead coral was the
predominant substrate type at three of the six sites, ranging from a percent cover of 15.0% to
45.6% across all sites. Macroalgae was the predominant substrate at two of the sites, ranging
from 13.8% to 42.7% across all sites, and living coral was the predominant substrate at one
site ranging from 8.3% to 42.0% across all sites. The percent cover of sponges ranged from
2.8% to 9.9% and the percent cover of gorgonians ranged from 0% to 4.0%. There were no
significant differences in percent cover for any benthic category between near-shore, mid-
shelf, and shelf-edge reefs, but near-shore reefs tended to have lower percent cover of living
coral and higher percent cover of dead coral covered with turf algae than both mid-shelf and
shelf-edge reefs. The coral reefs of St. Thomas were generally dominated by coral species in
the genus Montastraea. Near-shore sites tended to have higher percent composition of stress
tolerant corals and lower percent composition of less stress tolerant species than the mid-
shelf and shelf-edge sites. Coral diversity (H') ranged between 1.20 and 2.26, with deeper
sites tending to have lower diversity than shallow sites. Coral condition varied between sites,
with incidence of coral disease and bleaching ranging from 1.39% to 17.36% and 0% to
47.78%, respectively. Diadema sea urchins were uncommon and observed only at the two
near-shore sites. No significant differences in incidence of disease or bleaching and sea
urchin density were found between reef systems.

Abiotic factors at the St. Thomas Montastraea reefs tended to differ between the
sampled mid-shelf site (Flat Cay) and the shelf-edge site (the Red Hind Bank). Current
headed predominantly just west of south at Flat Cay and predominantly both north and south
at the Red Hind Bank. Current direction at Flat Cay indicated that this reef may be
significantly affected by terrigenous stresses, despite the reef s mid-shelf location. Daily








mean temperature at Flat Cay tended to be higher than the Red Hind Bank. Higher current
speeds occurred from late summer to early winter at both sites and the highest temperatures
occurred in September and October at both sites. Sedimentation rates were higher at Flat
Cay than the Red Hind Bank for the majority of the study. Abiotic data collected in this
study can be used to complement data from the NOAA CREWS station, to be placed at the
near-shore reef in Brewer's Bay, St. Thomas.

At the St. Thomas Acropora reefs, percent cover of all Acropora species combined
ranged from 5.8% to 13.0%. Percent cover ofA. cervicornis ranged from 0.3% to 6.1%,
percent cover of A. palmata ranged from 1.6% to 12.6%, and percent cover of A. prolifera
ranged from 0% to 6.4%. Size distribution of colonies of all Acropora species varied within
and between sites. Tissue mortality ranged from 8.4% to 30.4% of the surface area of each
colony comprised of dead coral skeleton for A. cervicornis, 11.0% to 37.0% for A. palmata,
and 8.4% to 19.2% for A. prolifera across all sites. Coralliophila snail infestation varied
within and between Acropora species and sites. For A. cervicornis, occurrence of white band
disease ranged from 0% at Botany Bay, Coculus Point, and Flat Cay to 28.0% at Caret Bay
and Inner Brass Island. White band disease on A. palmata ranged from 0% at Botany Bay
and Flat Cay to 28% at Caret Bay. White band disease on A. prolifera ranged from 0% at
Coculus Point to 20% at Inner Brass Island. Recruitment density ranged from 0.1 recruits/m2
to 1.3 recruits/m2. No significant differences for percent cover, tissue mortality, snail
infestation, white band disease, and recruitment density were found between near-shore and
mid-shelf Acropora reefs.

Fish surveys concentrated on Montastraea reefs. No censuses were performed at
Acropora reefs. Fish abundance averaged from approximately 70 to 120 fish per census.
The number of fish species observed at the St. Thomas sites ranged from 36 to 54 species.
The St. Thomas fish fauna was numerically dominated by planktivorous damselfishes at all
sites except Benner Bay and the Red Hind Bank, which were dominated by wrasses.
Parrotfishes and surgeonfishes were also abundant on the sampled St. Thomas reefs. The
commercially important large groupers, snappers, angelfishes, and triggerfishes were
observed at much lower densities at all sites, but were most frequently encountered on the
mid-shelf and shelf-edge sites. Butterflyfish densities were higher at mid-shelf and shelf-
edge reefs than at near-shore reefs, indicating higher levels of reef health for mid-shelf and
shelf-edge reef systems. The majority of fish observed in 2003 were small or intermediate in
size, with most falling into the 5 10 cm size category. Relatively few large fish were
observed, but were most common at the mid-shelf and shelf-edge sites. Three of the St.
Thomas sites monitored in this study have been determined as spawning aggregation areas
for grouper (Red Hind Bank, Grammanik Bank) and snapper (Seahorse Cottage Shoal,
Grammanik Bank). The Red Hind Bank is within a marine protected area (Red Hind Bank
Marine Conservation District), while Seahorse Cottage Shoal and the Grammanik Bank are
currently unprotected. Continued monitoring at these sites is vital to detect changes in these
ecologically important areas.








Since only two Montastraea reefs of each type were sampled in this study,
comparisons between near-shore, mid-shelf, and shelf-edge reefs are difficult. We
recommend that future monitoring efforts incorporate more replicates of each reef system as
resources become available. Also, characteristics of the two sampled mid-shelf reefs (Flat
Cay and Seahorse Cottage Shoal) varied significantly, supporting the recommendation that
mid-shelf reefs be stratified into two types: shallow mid-shelf reefs associated with cays, and
deep mid-shelf reefs not associated with cays. Since other monitoring efforts performed by
the University of the Virgin Islands are concentrating on shallow mid-shelf reefs associated
with cays, we recommend that future monitoring efforts for this study concentrate on deep
mid-shelf reefs not associated with cays. This will allow concurrent monitoring efforts to
complement each other to provide a greater understanding of Virgin Islands reef systems.









Acknowledgments


This study was funded by grant NA03NOS4260004 from the National Oceanic and
Atmospheric Administration awarded to the Division of Coastal Zone Management,
Department of Planning and Natural Resources, U.S. Virgin Islands. WT wishes to thank the
participation of St. Croix fish counters Diane "Dee Skylan" Osinski, Robert Daniel Stone,
and Brooke Morton. William Tobias provided valuable assistance with fish counts and his
innumerable insights into St. Croix reef fish ecology. Willy Ventura weathered the seas for
the cause. UVI CMES wishes to thank Elizabeth Whiteman, Jeremiah Blondeau, Alkin Paul,
Daya Stridiron, and Devon Tyson for valuable assistance with data collection and analysis, as
well as Marilyn Henderson for providing smiles and administrative support.









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--
!'''" '~~



^|3.
i ~ i''l~ r~


\


Lcr,3 ReEr.-ragie Pay
S a ...-..*,
,,; -


St. Croix


5km 0 5 km


Jack. BEay






-"


- East End Marine Park
Boundary


Fig. 1 Locations of monitoring sites in St. Croix, USVI.
Great Pond and Jacks Bay are located within the
East End Marine Park. Buck Island is located within the
Buck Island Reef National Monument.


Canle ba -.


Salt Rwer4

v- *j


a
Sprat Ials


Mutton Snapper
Spawning Site
A


-,,-


















A. Coral


I CB GP JB LR MS SR SH
BI CB GP JB LR MS SR SH


100

80

S 60-
--
O
0
p 40-

20

0-


100

80

60 -
O
0
p 40-

20

0


100

80

60 -
0
0
p 40-

20 -

0


BI CB GP JB LR MS SR SH
2001
S2002
2003
Fig. 2A, B, C Mean percent cover of A. Scleractinian corals, B. Dead coral with turf algae, and C. Macroalgae
for the year one, year two, and year three sampling periods at eight monitored sites:
BI Buck Island; CB Cane Bay; GP Great Pond; JB Jacks Bay; LR Long Reef/Eagle Ray;
MS Mutton Snapper; SR Salt River; SH Sprat Hole.
GP and MS sampling began in 2002. n = 6 transects for all sites, except for n = 3 transects for
BI in 2001 and 2002 and n = 5 transects for MS and SH in 2002.
Error bars represent standard deviation. Asterisks denote significant differences:
= P < 0.05; ** = P < 0.01;*** = P < 0.001


BI CB GP JB LR MS SR SH
C. Macroalgae


**


LI I I


***




I II ,n,


















D. Sponges














BI CB GP JB LR MS SR SH

E. Gorqonians














BI CB GP JB LR MS SR SH


BI CB GP JB LR MS SR SH
2001
2002
2003

Fig. 2D, E, F Mean percent cover of D. Sponges, E. Gorgonians, and F. Sand/Sediment
for the year one, year two, and year three sampling periods at eight monitored sites:
BI Buck Island; CB Cane Bay; GP Great Pond; JB Jacks Bay; LR Long Reef/Eagle Ray;
MS Mutton Snapper; SRW Salt River; SH Sprat Hole.
GP and MS sampling began in 2002. n = 6 transects for all sites, except for n = 3 transects for
BI in 2001 and 2002 and n = 5 transects for MS and SH in 2002.
Error bars represent standard deviation. Asterisk denotes significant difference: = P < 0.05


















DL
2.3%
AA
2.5%
DS
4.0%

PP
4.1%
MILCO
4.1%

SS
6.2%
PA
10.7%


MME MILA
0.9%, 0.9%


CN
0.6% Other

1.9%






MACX
52.0%


MC
9.9%


Fig. 3 Percentage coral species composition at all sampled sites in St. Croix, USVI.
MACX Montastraea annularis complex; MC Montastraea cavernosa;
PA Porites astreoides; SS Siderastea siderea; MILC Millepora complanata;
PP Porites porites; DS Diploria strigosa; AA Agaricia agaricites; DL Diploria labyrinthiformes;
MME Meandrina meandrites; MILA Millepora Alcicoris; CN Colpophyllia natans.
Other denotes percent of all other coral species combined and includes:
Acropora palmata, Agaricia fragilis, Agaricia lamarcki, Eusmilia fastigiata,
Madracis mirabilis, Mycetophyllia ferox, Mycetophyllia lamarckiana, and
Stephanocoenia michelinii.

















A. Buck Island


MACX MC PA SS MILC DS PP AA DL MME MILA CN



B. Cane Bay


MACX MC PA SS MILC DS PP AA DL MME MILA CN

2001
I 2002
S2003

Fig. 4A, B Percent of species composition of living coral cover of the most common coral species at
A. Buck Island and B. Cane Bay for years 2001, 2002, and 2003.
Percent composition calculated by dividing the number of random dots falling on each coral species
by the total number of dots on all living coral at each site.
MACX Montastraea annularis complex; MC M. cavernosa; PA Porites astreoides; SS Siderastrea siderea;
MILC Millepora complanata; DS Diploria strigosa; PP P. porites; AA Agaricia agaricites;
DL D. labyrinthiformis; MME Meandrina meandrites; MILA Millepora alcicornis; CN Colpophylia natans.
n = 6 transects for all samplings, except n = 3 transects for Buck Island in 2001 and 2002.


0 11 a


-M r-











C. Great Pond


MACX MC PA SS MILC DS PP AA DL MME MILA CN


D. Jacks Bay


4U -1


20 -



MACX MC PA SS MILC DS PP AA DL MME MILA CN

M 2001
II 2002
m 2003



Fig. 4C, D Percent of species composition of living coral cover of the most common coral species at
C. Great Pond and D. Jacks Bay for years 2001, 2002, and 2003.
MACX Montastraea annularis complex; MC Montastraea cavernosa; PA Porites astreoides;
SS Siderastrea siderea; MILC Millepora complanata; DS Diploria strigosa; PP Porites porites;
AA Agaricia agaricites; DL Diploria labyrinthiformis; MME Meandrina meandrites;
MI LA Millepora alcicornis; CN Colpophylia natans.
n = 6 transects for all samplings. Sampling of GP began in 2002.









E. Long Reef


i Nd


]L r11


U I
MACX MC PA SS MILC DS PP AA DL MME MILA CN


F. Mutton Snapper
00

80

60

40

20 -


MACX MC PA SS MILC DS PP AA DL MME MILA CN

S2001
[I 2002
S2003


Fig. 4E, F Percent of species composition of living coral cover of the most common coral species at
E. Long Reef and F. Mutton Snapper for years 2001, 2002, and 2003.
MACX Montastraea annularis complex; MC Montastraea cavernosa; PA Porites astreoides;
SS Siderastrea siderea; MILC Millepora complanata; DS Diploria strigosa; PP Porites porites;
AA Agaricia agaricites; DL Diploria labyrinthiformis; MME Meandrina meandrites;
MILA Millepora alcicornis; CN Colpophylia natans.
Sampling of MS began in 2002.
n = 6 transects, except for n = 5 transects at MS in 2002.








G. Salt River


MACX MC PA SS MILC DS PP AA DL MME MILA CN


H. Sprat Hole



i 171 rI -i I7 Ii_


MACX MC PA SS MILC


DS PP AA DL MME MILA CN


S2001
II 2002
I 2003

Fig. 4G, H Percent of species composition of living coral cover of the most common coral species at
G. Salt River and H. Sprat Hole for years 2001, 2002, and 2003.
MACX Montastraea annularis complex; MC Montastraea cavernosa; PA Porites astreoides;
SS Siderastrea siderea; MILC Millepora complanata; DS Diploria strigosa; PP Porites porites;
AA Agaricia agaricites; DL Diploria labyrinthiformis; MME Meandrina meandrites;
MI LA Millepora alcicornis; CN Colpophylia natans.
n = 6 transects for all samplings, except n = 5 transects for SH in 2002.


[i


II


h d ll























Coral Diversity


3.0


2.5


2.0


I 1.5


1.0


0.5


0.0


BI CB GP JB LR MS SR SH


2001
II 2002
2003




Fig. 5 Shannon Weaver Diversity Index (H') for corals at eight monitored sites in St. Croix, USVI
for years 2001, 2002, and 2003.
BI Buck Island; CB Cane Bay; GP Great Pond; JB Jacks Bay; LR Long Reef/Eagle Ray;
MS Mutton Snapper; SR Salt River; SH Sprat Hole
Sampling for Great Pond and Mutton Snapper began in 2002.















A. Coral Disease


8i 30


v 25
t-

2 20











E 0
a-






BI CB GP JB LR MS SR SH

B. Coral Bleaching




o 30

25 -

20 -
20

Q 15

8 10 -
0
5-

S, ,
E
BI CB GP JB LR MS SR SH
02002


















MS Mutton Snapper; SR Salt River; SH Sprat Hole
n = 6 transects for all sites, except for n = 3 transects for BI in 2001 and 2002 and n = 5 transects
for MS in 2002. Asterisk denotes significant difference: = P < 0.01
| 25


























for MS in 2002. Asterisk denotes significant difference: = P < 0.01














A. Coral Disease


80



o 60
0

0
0











60











o
0


20
AA MA MACX MC MFAV MFR A SS

B. Coral Bleaching


1002


E 80
0
-5 6
0

40









S2003
AA DL DS MA MC MFAV MFRA PA SS








Fig. 7 Percentage of A. diseased colonies and B. bleached colonies of all coral species with disease
and bleaching sampled at each St. Croix monitoring site (n = 8).
Percentage calculated by dividing the number of diseased and bleached colonies of each species
by the total number of diseased and bleached coral colonies, respectively.
AA Agaricea agaricites; DL Diploria labyrinthiformis; DS Diploria strigosa; MA Montastraea annularis;
MACX unidentified species belonging to the M. annularis complex; MC M. cavernosa; MFAV M. faveolata;
MFRA M. franksii; PA Porites astreoides; SS Siderastrea siderea













A. Fish Abundance St. Croix


SR CB IB ER SH BI GP MS


B. Fish Species Richness St. Croix


SR CB IB ER SH BI GP MS

C. Fish Community Diversity (H')








T t tTht


SR CB IB ER SH BI GP MS



Fig. 8 Reef fish community structure across eight St. Croix reef sites.
A. average abundance; B. average species richness;
C. average Shannon-Weaver diversity (H').


800



' 600



* 400

0
O
T 200
6
z

0































CB 0.67 79(19,18) 72(18,11) 70(15,9) 72(18,11) 78(31,17) 75(22,14)

IB 0.48 0.53 68(14,8) 73(18,13) 74(20,14) 71 (24,11) 77(24,17)

ER 0.62 0.60 0.68 67(12,13) 70(16,16) 70(23,16) 73(20,19)

SH 0.66 0.66 0.58 0.63 68(14,13) 69(22,14) 68(15,13)

BI 0.50 0.60 0.54 0.54 0.61 70(23,16) 75(22,21)

GP 0.42 0.39 0.51 0.44 0.48 0.44 70 (17,23)


0.60


0.52


0.47


0.47


0.59


0.43


0.43


Above diagonal: Total No. of fish taxa observed at both sites combined,
(No. of unique taxa, site 1, site 2)
Below diagonal: Jacaard's Community Similarity Index



Fig. 9 Fish community similarity indices for St. Croix sites.


67 (6,16)


75 (15,24)


65 (11,14)


(9,13)


70 (16,19)


69 (6,18)


65 (12,14)














A. Labridae
400




300




S200


0

U 100
o




z

0
< o^J-- _----- LU------

SR CB IB ER SH BI GP MS




B. Pomacentridae
400

a


300




" 200


0


0o



0-
SR CB IB ER SH BI GP MS




C. Acanthuridae
80


60








0




z
40

U 20


SR CB


IB ER SH BI GP MS


Fig. 10 Fish abundance by family across eight St. Croix reef sites.







D. Scaridae


SR CB IB ER SH BI GP MS
E. Serranidae


SR CB IB ER SH BI GP MS
F. Lutjanidae
10


I 7 I


I r


I 7 ^


SR CB IB ER SH BI GP MS


Fig. 10 (cont.) Fish abundance by family across eight St. Croix reef sites.


7 r








G. Haemulidae


*nF .


I-


7


SR CB IB ER SH BI GP MS
H. Chaetodontidae
lB -----------------------


5


SR CB IB ER SH BI GP MS

1. Pomacanthidae
in


0 -I I -- ---------
SR CB IB ER SH BI GP MS

Fig. 10 (cont.) Fish abundance by family across eight St. Croix reef sites.


T ~1


r + rI


F-k Fk r-






















J. Balistidae


Sn 4mrfl fl


SR CB IB


ER SH


BI GP MS


Fig. 10 (cont.) Fish abundance by family across eight St. Croix reef sites.















SHan s Lollick


Inner


-';:2 ED


D


AM
Seahorse Cottage Shoal


+


5 km


5 km


Red Hind Bank
,.- '" AM Grammanik
Bank ,-.
MA,'
s. -* .


4,


. ', -


Fig. 11 Locations of monitoring sites in St. Thomas, USVI.
M denotes Montastraea reefs, A denotes Acropora reefs.
The Red Hind Bank is located within the Red Hind Bank Marine Conservation
District. Botany Bay and Benner Bay are designated Areas of Particular Concern.
















48


C


. f











A. Coral

T





BB BP SC FC GB RH

B. Dead Coral with Turf Algae





^LLT


BB BP


SC FC


GB RH


C. Macroalgae


BB BP SC FC GB RH
Near-shore Mid-shelf Shelf-edge


Fig. 12A, B, C Mean percent cover of A. Scleractinian corals, B. Dead coral with turf algae,
and C. Macroalgae for St. Thomas monitored sites:
BB Benner Bay; BP Black Point; SC Seahorse Cottage Shoal; FC Flat Cay;
GB Grammanik Bank; RH Red Hind Bank.
BB and BP are near-shore sites, SC and FC are mid-shelf sites, and GB and RH are shelf-edge sites.
n = 6 transects for all sites. Error bars represent standard deviation.














D. Sponges











BB BP SC FC GB RH

E. Gorgonians











BB BP SC FC GB RH

F. Sand/Sediment

^ 1


BB BP
Near-shore


SC FC
Mid-shelf


GB RH
Shelf-edge


Mean percent cover of D. Sponges, E. Gorgonians,
and F. Sand/Sediment for St. Thomas monitored sites:
BB Benner Bay; BP Black Point; SC Seahorse Cottage Shoal; FC Flat Cay;
GB Grammanik Bank; RH Red Hind Bank.
BB and BP are near-shore sites, SC and FC are mid-shelf sites, and GB and RH are shelf-edge sites.
n = 6 transects for all sites. Error bars represent standard deviation.


Fig. 12D, E, F










MME
AA -1.4%
2.0%


DS
1.4%
MME
2.3%
MILA
2.9%


B. Mid-Shelf
PF Other
\1.4% 3.0%


I


ss
10.7% PA
12.8%


C. Shelf-Edge

AL CN Other
1 3% 1 1% F 1.8%


D. Combined


AC PF AL


MACX
85.0%


Fig. 13 Percentage coral species composition at A. Near-shore sites, B. Mid-shelf sites, C. Shelf-
edge sites and D. all sites combined for St. Thomas, USVI.
MACX Montastraea annularis complex; MC M. cavernosa; PA Porites astreoides;
SS Siderastrea siderea; PP P. porites; AA Agaricia agaricites; CN Colpophyllia natans;
MME Meandrina meandrites; AC Acropora cervicornis; PF P. furcata; AL Agaricia lamarcki;
MILA Millepora alcicornis; DS Diploria strigosa; SR S. radians. Other denotes percent of all
other coral species combined and includes: Agaricia grahamae, A. humilis, Dendrogyra
cylindrus, Diploria clivosa, D. labyrinthiformis, Eusmilia fastigiata, Manicina areolata,
Mycetophyllia aliciae, My. danaana, My. lamarckiana, P. divaricata, Solenastrea bournoni,
S. hyades, and Stephanocoenia michelinii.


A. Near-Shore


PF
1.4%


SR
1.4%


Other
4.3%


2.2%
PP
2.3%
PA
2.3%
AC
2.3%
SS
4.1%
MC
18.0%


MACX
33.6%


AA
6.4%


MC
10.1%


MACX
61.0%















A. Benner Bay


m


I I I I


MACX MC PP PA SS AA MILA MME DS PF SR


B. Black Point




















MACX MC PP PA SS AA MILA MME DS PF SR


Fig. 14A, B Percent of species composition of living coral cover of the most common coral species at
St. Thomas near-shore sites: A. Benner Bay and B. Black Point.
Percent composition calculated by dividing the number of random dots falling on each coral species
by the total number of doats on all living coral at each site.
MACX Montastraea annularis complex; MC M. cavernosa; PP Porites porites; PA P.astreoides;
SS Siderastrea siderea; AA Agaricia agaricites; MILA Millepora alcicornis; MME Meandrina meandrites;
DS Diploria strigosa; PF P. furcata; SR S. radians












C. Seahorse Cottage Shoal


I I I I = == z I I
MACX MC SS AC PA PP CN AA MME PF


D. Flat Cay


















MACX MC SS AC PA PP CN AA MME PF


Fig. 14C, D Percent of species composition of living coral cover of the most common coral species at
St. Thomas mid-shelf sites:C. Seahorse Cottage Shoal and D. Flat Cay.
Percent composition calculated by dividing the number of random dots falling on each coral species
by the total number of doats on all living coral at each site.
MACX Montastraea annularis complex; MC M. cavernosa; SS Siderastrea siderea;
AC Acropora cervicornis; PA Porites astreoides; PP P. porites; CN Colpophylia natans;
AA Agaricia agaricites; MME Meandrina meandrites; PF P. furcata.















E. Grammanik Bank


0 1 I I I I
MACX MC PA AA SS AL CN


F. Red Hind Bank


100


80 -


60 -
80


E
o

0
o 40


20 -


0
MACX MC PA AA SS AL CN





Fig. 14E, F Percent of species composition of living coral cover of the most common coral species at
St. Thomas shelf-edge sites: E. Grammanik Bank and F. Red Hind Bank.
Percent composition calculated by dividing the number of random dots falling on each coral species
by the total number of doats on all living coral at each site.
MACX Montastraea annularis complex; MC M. cavernosa; PA Porites astreoides;
AA Agaricia agaricites; SS Siderastrea siderea; AL A. lamarcki; CN Colpophylia natans.























Coral Diversity


2.5




2.0 -




1.5 -




1.0 -




0.5 -




0.0


BB BP


Near-shore


SC FC
Mid-shelf


GB RH


Shelf-edge


Fig. 15 Shannon Weaver Diversity Index (H') for corals at eight monitored sites in St. Thomas, USVI.
BB Benner Bay; BP Black Point; SC Seahorse Cottage Shoal; FC Flat Cay; GB Grammanik Bank
RH Red Hind Bank. BB and BP are near-shore sites, SC and FC are mid-shelf sites,
and GB and RH are shelf-edge sites. n = 6 transects for all sites.


I











A. Coral Disease


BB BP SC FC GB RH


B. Coral Bleaching


BB BP SC FC GB RH
Near-shore Mid-shelf Shelf-edge


Fig. 16 Mean percentage of A. colonies with disease and B. colonies with bleaching of all coral colonies
sampled at each monitoring site. Percentage calculated by dividing the number of diseased
and bleached colonies on each transect by the total number of colonies sampled on each transect
for each site.
BB Benner Bay; BP Black Point; SC Seahorse Cottage Shoal; FC Flat Cay; GB Grammanik Bank;
RH Red Hind Bank. n = 6 transects for all sites. Error bars represent standard deviation.











A. Coral Disease


AA DL DS MA MACX MC MFAV MFRA PA SS


B. Coral Bleaching


MACX


MC MFRA


Fig. 17 Percentage of A. diseased colonies and B. bleached colonies of all coral species with disease
and bleaching sampled at each St. Thomas monitoring site (n = 6).
Percentage calculated by dividing the number of diseased and bleached colonies of each species
by the total number of diseased and bleached coral colonies, respectively.
AA Agaricea agaricites; DL Diploria labyrinthiformis; DS Diploria strigosa; MA Montastraea annularis;
MACX unidentified species belonging to the M. annularis complex; MC M. cavernosa; MFAV M. faveolata;
MFRA M. franksii; PA Porites astreoides; SS Siderastrea siderea


F-


n














Current Speed and Direction Flat Cay


May 2003


n
~-
s-
4
'II
I(-


5:"^
1; -







J.

sr


July 2003


?r, i1 4 1ljl l


September


7'~f~j


Fig. 18 Current speed and direction at Flat Cay, St. Thomas, USVI by month. Individual points
represent hourly readings throughout each respective month.


April 2003


A1


June 2003


August 2003


1-



s,






.., ~

..

",


-9N ~ rV ~~ -1) d11"1"~*11 IllllalUNg*IN9
~~~m~~~~.. rcru -~n~


.-m-s~. c~rl ~n~e~


-'-'----"-I-" -~PL~


-u-


---- ~~-~~---- ~--~


I





11 --


C -


.~.,., ~


- --- ~-e --- -- -~~~~


a a a Ir rr a to r


------ ---------


_ ;1 -


d.




-W- X t -^ < a- <


;; ;~;


. . .












Current Speed and Direction Flat Cay


October 2003


December 2003




















February 2004 -


February 2004


January 2004






'-

4 -



1-
S-
nS
*0 3


Fig. 18 (cont.) Current speed and direction at Flat Cay, St. Thomas, USVI by month. Individual points
represent hourly readings throughout each respective month.


November 2003




B -

12-



10 -
i "






,, i
1D -
-1S -


MI 1B .I -11 iS .10 -B


1





i'


*'V'


rul*l~ls~n~nsl8*l


~-d
381
9~1
a~i ~ st .ls .In s*


I I I b I 1 r I I
















Current Speed and Direction Red Hind Bank


May 2003


July 2003


August 2003 September


"'
''"
"';L


~1~s~
,,
.

ai:a r:


Fig. 19 Current speed and direction at the Red Hind Bank, St. Thomas, USVI by month. Individual points
represent hourly readings throughout each respective month.













60


June 2003


9--


..



,
.U.
r
ld~~l~~*~ulr


u-..nlm~-.u.ln~ 1-Ir4


.-
-:

ri .


~~



















Current Speed and Direction Red Hind Bank


November 2003


December 2003


January 2004


E A!,


Fig. 19 (cont.) Current speed and direction at the Red Hind Bank, St. Thomas, USVI by month.

Individual points represent hourly readings throughout each respective month.


October 2003










vlii

\-{










o. -*>



m~d I..d ..-< .f
'-


February 2004


I I


I~
rU*T~r

r i
1;


;r


I I


"'1 I


t -


>ia


*K -

*s*

>ia
hr

HIa Wl a ;f Ilr t Bfl.


ill II ~ IIL 9 P~ ~1~411
I~Llm*l *IUI1II


g.
fil
I
iii
U

lli
II);
Ir
Ilr

:,



H:-

la::
bl
Q1
IB 1
11
'1
I)`
11-
h)
II

a~a~-
19~

PI~B P I~ I~ If 86~


I I I I I
111 11 U II Is ~ n n 2~ la a
rapMI ,,..,,,




-*^-
v. ?.



'..^














30


29.5


29


28.5


28


27.5


27


26.5


26


25.5


25

a. oo 9, oo 7 C ,




Fig. 20 Daily mean temperature (C) recorded at Flat Gay, St. Thomas USVI, between 8 April 2003 and 12 February 2004.












29


28.5


28


27.5


27


26.5


26


25.5


25


24.5

So % %9o 9 7 % o < 7 %


Fig. 21 Daily mean temperature (C) at the Hind Bank between 10 April 2003 and 27 February 2003.























Percent Cover of Acropora spp.


BT CT CP FC HL IB


Near-shore


Mid-shelf


Fig. 22 Percent cover of all Acropora corals combined (A. cervicornis, A. palmata, and A. prolifera)
for St. Thomas sites: BT Botany Bay; CT Caret Bay; CP Coculus Point;
FC Flat Cay; HL Hans Lollik; IB Inner Brass Island.
BT, CT, and CP are near-shore sites. FC, HL, and IB are mid-shelf sites.
n = 5 transects for all sites. Error bars represent standard deviation.



















Percent Cover of Acropora spp.


BT CT CP FC HL IB


SA. cervicornis
S A. palmata
A. prolifera


Fig. 23 Percent cover of A. cervicornis, A. palmata, and A. prolifera for all St. Thomas sites.
BT Botany Bay; CT Caret Bay; CP Coculus Point;
FC Flat Cay; HL Hans Lollik; IB Inner Brass Island.
BT, CT, and CP are near-shore sites. FC, HL, and IB are mid-shelf sites.
n = 5 transects for all sites. Error bars represent standard deviation.
















Size Distribution of Acropora cervicornis


S0 100 j00 0 0 0 00
BT CT CP FC HL IB


Fig. 24 Size distribution for Acropora cervicornis at St. Thomas sites.
BT Botany Bay; CT Caret Bay; CP Coculus Point; FC Flat Cay; HL Hans Lollik; IB Inner Brass Island
n = 25 colonies at all sites.


S<1,000 cm3
I >1,000<15,626 cm3
>15,626<125,000 cm3
I >125,000<1x106 cm3
S>1x106 cm3















Size Distribution of Acropora palmata


u oo l oo I ol II
0BT CT CP FC HL I
BT CT CP FC HL IB


Fig. 25 Size distribution for Acropora palmata at St. Thomas sites.
BT Botany Bay; CT Caret Bay; CP Coculus Point; FC Flat Cay; HL Hans Lollik; IB Inner Brass Island
n = 25 colonies at all sites.


S<1,000 cm3
I >1,000<15,626 cm3
>15,6265125,000 cm3
I >125,000<1x106 cm3
S>1x106 cm3


I













Size Distribution of Acropora prolifera


BT CT CP FC HL IB

<1,000 cm3
I >1,000<15,626 cm3
>15,626<125,000 cm3
I >125,000<1x106 cm3
>1x106 cm3


Fig. 26 Size distribution for Acropora prolifera at St. Thomas sites.
BT Botany Bay; CT Caret Bay; CP Coculus Point; FC Flat Cay; HL Hans Lollik; IB Inner Brass Island
n = 25 colonies at all sites, except for n = 0 colonies at CT and n = 5 colonies at IB.


o0 0000 1100 oo o oo

















Acropora cervicoris mortality


40




30



-o

o 20 -




10










m Total % dead
I I Recent % dead






Fig. 27 Mean percent dead tissue on Acropora cervicornis colonies at all St. Thomas sites.
n = 25 colonies at all sites. Error bars represent standard error.















Acropora palmata mortality


ledm ee eM ? GO^ leo` \ VO


Total % dead
I I Recent % dead




Fig. 28 Mean percent dead tissue on Acropora palmata colonies at all St. Thomas sites.
n = 25 colonies at all sites. Error bars represent standard error.


















Acropora prolifera mortality


02 \ ye


Total % dead
I I Recent % dead



Fig. 29 Mean percent dead tissue on Acropora prolifera colonies at all St. Thomas sites.
n = 25 colonies at all sites, except n = 5 colonies at Inner Brass Island.
Error bars represent standard error.



















Acropora predation


0
V


~,00


A. cervicornis
I I A. palmata
A. prolifera



Fig. 30 Percentage of Acropora colonies infested with Coralliophila snails at all St. Thomas sites.
n = 25 colonies for all Acropora species at all sites, except for n = 0 for A. prolifera at Caret Bay
and n = 5 for A. prolifera at Inner Brass Island.


!0S


,c""~




















White Band Disease


V"


0"


00j


A. cervicornis
I I A. palmata
A. prolifera



Fig. 31 Percentage of Acropora colonies with white band disease at all St. Thomas sites.
n = 25 colonies for all Acropora species at all sites, except for n = 0 for A. prolifera at Caret Bay
and n = 5 for A. prolifera at Inner Brass Island.






A. Fish Abundance-St. Thomas


BB BP SC FC GB HB


B. Species Richness-St. Thomas


BB BP SC FC GB HB


C. Fish Community Diversity (H') St. Thomas


BB BP SC FC GB HB



Fig. 32 Reef fish community structure across six St. Thomas reef sites.
A. average abundance; B. average species richness;
C. average Shannon-Weaver diversity (H').










A. Belt Transects
2.
BB BP SC FC GB RH

BB 54 (18,16) 55 (15,17) 65 (11,27) 57 (10,27) 61 (19,23)

BP 0.37 51 (11,15) 57(4,21) 60(14,22) 57(15,21)

SC 0.42 0.49 64 (10,24) 59 (17,19) 58 (16,18)
1.
FC 0.42 0.56 0.47 68 (26, 14) 66 (24,12)

GB 0.35 0.40 0.39 0.45 56 (14,14)

RH 0.31 0.37 0.41 0.45 0.50


Above diagonal: Total No. of fish taxa observed at both sites combined,
(No. of unique taxa, site, site 2)
Below diagonal: Jaccard's Community Similarity Index




B. Roving Diver
2.
BB BP SC FC GB RH

BB 95 (31, 13) 98 (26,21) 106 (21,24) 104 (46,22) 105 (37, 23)

BP 0.54 92 (16,29) 91 (6, 27) 85 (27, 21) 88 (20, 24)

SC 0.54 0.51 101 (16,25) 97 (39,19) 97 (29,21)
1 -------
FC 0.58 0.64 0.59 101 (43,16) 104 (36,19)

GB 0.35 0.44 0.40 0.42 80 (12,22)

HB 0.43 0.50 0.48 0.47 0.58


Above diagonal: Total No. of fish taxa observed at both sites combined,
(No. of unique taxa, site, site 2)
Below diagonal: Jaccard's Community Similarity Index





Fig. 33 Fish community similarity across six St. Thomas reef sites calculated using:
A. belt transects and B. roving diver surveys.














A. Labridae


B. Pomacentridae


BB BP SC FC GB RH





C. Scaridae


Fig. 34 Fish abundance by family across six St. Thomas reef sites.


100


t 80
i


c 60
Io

i 40

z
~ 20


35


30

25






t 15


6 10
z


5


0










D. Acanthuridae


g 20


15

I-
c

S10

6
z
> 5


0





45

40

1 35

30

g 25




6)
!- 20

- 15
z
10

05

00






7

6

5

i4

2




1


0


-


-


-


BB BP SC FC GB RH



E. Serranidae




















BB BP SC FC GB RH




F. Lutjanidae


Fig. 34 (cont.) Fish abundance by family across six St. Thomas reef sites.


r


+t


-






-






-


Ffi


m








G. Haemulidae


H. Chaetondontidae


BB BP SC FC GB RH


I. Pomacanthidae


BB BP SC FC GB HB


Fig. 34 (cont.) Fish abundance by family across six St. Thomas reef sites.


TI


30

25
a

S20

215

IL
- 1 0
0
z
>05


r4 th














































J. Balistidae
45

40

3 35
30
30

2 25

20

. 15 5
6
z


05


Fig. 34 (cont.) Fish abundance by family across six St. Thomas reef sites.




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