• TABLE OF CONTENTS
HIDE
 Front Cover
 Table of Contents
 Introduction
 Results
 Summary
 Recommendations
 Literature cited
 Appendix






Group Title: Virgin Islands of the United States. Division of Environmental Health. Water pollution report
Title: Water quality and environmental status of Benner Bay-Mangrove Lagoon, St. Thomas
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 Material Information
Title: Water quality and environmental status of Benner Bay-Mangrove Lagoon, St. Thomas
Series Title: Virgin Islands of the United States. Division of Environmental Health. Water pollution report
Physical Description: 42 ℓ. : ; 28 cm.
Language: English
Creator: Grigg, David I
VanEepoel, Robert P. ( joint author )
Brody, Robert W. ( joint author )
Caribbean Research Institute
Publisher: Caribbean Research Institute
Place of Publication: Christiansted, St. Croix, V.I.
Publication Date: 1971
Copyright Date: 1971
 Subjects
Subject: Water -- Pollution -- Virgin Islands of the United States -- Saint Thomas   ( lcsh )
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
Spatial Coverage: United States Virgin Islands
 Notes
Bibliography: Bibliography: p. 39-40.
General Note: At head of title: Contracted by: Caribbean Research Institute. College of the Virgin Islands.
Statement of Responsibility: By David I. Grigg, Robert P. VanEepoel and Robert W. Brody.
 Record Information
Bibliographic ID: UF00096176
Volume ID: VID00001
Source Institution: University of the Virgin Islands
Holding Location: University of the Virgin Islands
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 15863983

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Table of Contents
    Front Cover
        Front Cover 1
        Front Cover 2
    Table of Contents
        Table of Contents
    Introduction
        Page 1
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
    Results
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
        Page 25
        Page 26
        Page 27
    Summary
        Page 28
        Page 29
        Page 30
    Recommendations
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
        Page 36
        Page 37
        Page 38
    Literature cited
        Page 39
        Page 40
    Appendix
        Page 41
        Page 42
        Page 43
        Page 44
        Page 45
        Page 46
        Page 47
        Page 48
        Page 49
        Page 50
        Page 51
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Full Text





CARIBBEAN RESEARCH INSTITUTE


WATER POLLUTION REPORT NO. 10
WATiER QUALITY AND ENVIRONMENTAL STATUS
OF MBENNER BAV-MANGROV LAGOON, ST. THOMAS
David I. Grigg, Robert P. vanEepool and Robert W. Brody
(April, 1971)









GOVERNMENT OF THE VIRGIN ISLANDS

DEPARTMENT OF HEALTH, DIVISION OF ENVIRONMENTAL HEALTH


WATER POLLUTION REPORT NO. 10






CONTRACTED by:

CARIBBEAN RESEARCH INSTITUTE

COLLEGE OF THE VIRGIN ISLANDS








WATER QUALITY AND ENVIRONMENTAL STATUS

OF

BENNER BAY MANGROVE LAGOON

ST. THOMAS

David I. Grigg, Robert P. vanEepoel
Robert W. Brody

April, 1971







TABLE OF CONTENTS


Page

INTRODUCTION . . . . . . . . . 1

Statement and Purpose . . . . .. 1
Previous Work . . . . . . . 5
Description of the Study Area . . . .. 6


RESULTS . . . . 10

Temperature * * * * * * 10
Salinity . 11
Dissolved Oxygen .. 14
Water Clarity ............. 15
Diurnal Studies . . . . . . . .21


SUMMARY . . . . . . 28


RECOMMENDATIONS . . . . . . . .. 31

Recommendation I .. . .. 36:
Reoammendation II . . .. .. 36
Reeomaendation III . . . . . . 37
Recommendation IV . . . . . . 37
Reco-mendation V .. . . . . .. 38


LITERATURE CITED . .. .* . . . . . 39


APPENDIX . .. . . . . . . . 41

List of Figures . . . . . ..... .41
List of Tables . * * .......... 41








INTROD UCT 1ON


General Statement and Purpose
Development on the east end of St. Thomas is increas-

ingly geared toward water oriented facilities. The need

for boat anchorage and related service facilities on this

end of the island is being met in two places -- Red Hook/

Vessup Bay and, to a greater extent, Benner Bay (Figure 1)

where, within the past year the number of boats at anchor

or piered has more than doubled, due mainly to the opening

of a new facility (Antilles Yacht Services). There are

presently three bare-boat charter concerns operating out

of Benner Bay and plans for their expansion and for addi-

tional facilities will result in even higher boat densities

and traffic in the future. Construction has begun for the

Compass Point Club, a shoreline support facility for "Aqua-

miniums" -- ownership-lease properties similar to condoai-

niums but involving 46' powered houseboats as the property

unit; they are presently operating out of leased space on

the channel between Mangrove Lagoon and Banner Bay. Antilles

and a second charter sailboat facility, West Indies Yachts,

have docks on Benner Bay. Lagoon Fishing Center and Toby

Mann Mrine operate the remaining "public" dockage on

Benner Bay.

Benner Bay is relatively shallow, maximum depth is

about 2.5 meters, and deep draft or deep keeled boats


Paqe 1








regularly run aground, especially in the narrow passage

into the bay between Bovoni and Bird Cays (Figure 2).

Several requests have been made by boat owners and area

businessmen to dredge and deepen the channel.

Marinas and other good anchorages. which are used by

large numbers of boats are inevitably sites of extremely

poor water quality and an impoverished biota. Motor ves-

sels contribute appreciable quantities of various pollu-

tants to the water, especially when engines are running

slowly or at idle as they usually are within the anchorage.

Exhaust gases and unburned hydrocarbons are continuously

injected into the water at higher than ambient temperatures

and pressures. This material dissolves or is finely dis-

persed in the water and kills living things. In addition

to combustion products there is sewage (none of the marinas

on the island have pump-off facilities and very few craft

have holding tanks, in any case), other refuse and some un-

avoidable fuel and oil spillage. The significance of these

additions to the water can really be appreciated only if

other attendant facts are considered. The first is the

number, and, more important, the density of boats in most

anchorages where their combined effects are concentrated in

a relatively small area. The second factor is that places

best suited for docking and anchoring are usually least

capable of tolerating the ensuing stresses placed upon them.


P ae 2







Quiet, protected waters are often so because of very low

currents resulting in poor water exchange or flushing.

Pollutants added to such systems are not quickly removed

and their concentrations build up to very high levels.

These facts must be recognized and taken into account

whenever one is assessing the possible impact of boats and

boat traffic. This is not to say that marine oriented

coamsroe is undesirable -- without a doubt it is desirable,

and necessary, in an island setting -- but its consequences

must be recognized and admitted so that its proliferation

and development can be kept in proper perspective to other

requirements. One of the cardinal guidelines for insular

development should be to preserve as many varied natural

systems as possible. The tendency to convert natural

systems toward the economic end to which they can most

easily be converted cannot always be justified when weighed

against the rapidly deteriorating quality of man's environment.

During the past few years considerable controversy has

cantered around a proposal to fill most of the Mangrove Lagoon

for construction of a jet airport. Engineering proposals

for the airport provide for waterways under the runway de-

signed to maintain the present flow of water from the open

sea into the Lagoon. Such flow is essential to the proper

circulation and flushing of the Lagoon, but certainly is not

the only requirement for its preservation. Conservationists


Page 3








generally agree that, such structures notwithstanding, con-

struction of the jetport would destroy the Lagoon. Physi-

cally, it would occupy about two-thirds of the area, leaving

only the central shallow turtle grass area and part of one

mangrove islet. Additionally, it is anticipated that run-

off and siltation and other forms of pollution, during con-

struction and after development of the airport complex and

its satellite commercial facilities, will rapidly obliterate

these remaining portions of the Lagoon.

The Lagoon area now remains as the only extensive repre-

sentative of its kind in the U. S. Virgin Islands. Similar

areas on St. Croix have already been destroyed in the course

of industrial, tourist accommodating and housing developments.

While conservationists urge the protection of the St. Thomas

site, they are hard put to offer tangible evidence of its

value. It presently has no assessable economic value beyond

the price of the real estate. Its worth as a natural area

and recreation site and its potential for research and ar'aa-

culture have been described by conservationists and biologists

but have not been translated into terms most people can appre-

ciate, i.e. dollars and cents, or even been publicly acknowl-

edged by local agencies responsible for its disposition.

The purpose of this study was to describe the Benner Bay-

Lagoon environment, primarily the water quality. Field work


Pane 4








was conducted from February to July, 1970 by the authors

with the assistance of Lyn Slocum (Virgin Islands Ecologi-

cal Research Station) and several marine technology students

from Cape Fear Technical Institute. Other students who

assisted in the field and the laboratory were David Morris

(Fairleigh Dickenson University) and Laverne Ragater (Uni-

versity of Miami). Eileen Shatrosky, assisted by Sonya

Nelthropp of the College of the Virgin Islands, did most

of the laboratory analyses and Roosevelt Bryant and Lawrence

Lewie of the College of the Virgin Islands prepared the

figures. Jackie Thomas of the Caribbean Research Institute

and Paula Bailey deserve special thanks for the laborious

job of typing the report.


Previous Work

Several previous reports have covered various aspects

of the Lagoon biology and hydrography. All have acknowl-

edged the uniqueness and the natural value of the area. In

a survey of the biological aspects of water quality in the

three Virgin Islands, a Department of Interior, FWPCA, report

(1967) includes some data on sediment nutrients in the Lagoon.

McNulty, et al, (1968), in the most comprehensive study of

the Lagoon to date, divided the area into nine ecological

zones, presented data on its hydrography and wildlife and

called for several safeguards to be observed for the pro-

tection of the area if the airport is constructed. At the


Page 5








request of local government agencies, studies on biological
and engineering aspects of the proposed airport were made

(Tabb and Michel, 19689 Michel, 1970). These reports con-

tain information on the distribution of the major organism

in the area and on the importance of the existing unique

tidal and current regimes to the sustenance of the Lagoon.

Michel (1970) presents data on salinity distributions, tidal

cycles, and flushing rates of the Lagoon and proposes engi-

neering structures to be incorporated into the proposed runway

designs to maintain the critical water flow. Additional hydro-

graphic data are contained in Dammann (1970).

Description of the Study Area

The study was conducted in Benner Bay and Mangrove

Lagoon to the west. The area is on the southeast coast of

St. Thomas (Figure 1) and is open to the Caribbean Sea on

the south. Field work was confined to the area bounded by
Patricia and Cas Cays on the south and Coculus Rocks on the

east. Sampling stations are shown in Figure 3. Bovoni and

Patricia Cays, as well as the low land to the north and west

of the Lagoon are alluvial material (Donnelly & Whetten, 1968)

deposited by the Turpentine Run gut. This stream is pre-

sently the largest surface water producer remaining on
St. Thomas. Although it now runs into the Lagoon only after

very heavy rains, that portion of it below Mt. Zion, and


Pace 6








spots farther southeast, contain water the year round and

harbors an interesting but little known faunal assemblage

which includes at least two species of shrimp, several

species of fish, and an eel. The gut drains the entire

Tutu Valley plateau, about four square miles, which lies at

about 200 feet elevation and is fed by four tributary branches.

Much smaller guts drain the hills around Estate Nulliberg,

northwest of the Lagoon and Langmath and Benner on the north

and the northeast. The latter drains into a salt pond be-

hind the northeast shore of Banner Bay. The pond has been

partially filled as part of the area development already

mentioned.
The dominant terrestrial organism in the study area is

hiophor mangle (red mangrove). The entire shoreline of

the Lagoon and of Benner Bay was formerly fringed with red

mangrove, but much of the Benner Bay shoreline has been cut

and piers and bulkheads constructed. The remaining mangroves
along Benner Bay are in a belt usually one plant wide. Ex-

tensive growth of mangroves is responsible for the formation

of the many cays in the area.

The dominant marine feature of the area is an extensive

pasture of turtle grass, Thalassia testudintum the distribu-

tion of which has been mapped by Tabb and Michel (1968) and

McNulty, et al, (1968). Its density is sparser as one pro-

grasses into Benner Bay where all benthic plant growth


Paqe 7







disappears below 0.5 meter. Due to the dense boat anchor-

age, heavy traffic, increased runoff due to land clearing

and construction, great shoreline alteration and attendant

pollution, water quality in Benner Bay is extremely poor.

Although better, the water quality in the northern part of

the Lagoon is also reduced. The major part of the Lagoon,

however, contains clear water as does the outer portions

of Benner Bay and west Jersey Bay.

Other zones in the Laoon are characterized by various

algae, grass and coral assemblages (McNulty, 1968}) and con-

tribute to the habitat diversity which makes Mangrove Lagoon

possibly the most complex and varied natural system in the

islands. Not as obvious, but just as important to this eco-

system, is the reef on the south, dominated by Acropora

palate (elkhorn coral) which has been shown to be vitally

important to the Lagoon ecology (Tabb and Michel, 1968;

McNulty, 19609 Michel, 1970) by virtue of its effect on the

local water circulation. The present distribution of bottom

types is shown in Figure 16.

Benner Bay and the Lagoon are well protected from

strong seas by the reef and cays on the south and by the

eastern tip of St. Thomas and Great and Little St. James

islands to the east and southeast (Figure 1). Water moving

into the area northwesterly looses most of its energy where

the bottom shallows up rapidly between Potto and Cas Cays.


Page 8








Most waves are dissipated after moving across the shallows

of south Banner Day.

The north shore of Benner Bay is heavily developed.

Except for marinas along the northeast corner, most buildings

are private dwellings. North of the Lagoon in the Bovoni-

Nadir area, a fair-sized community is developing. Sewage

from this community is treated in a 70,000 gpd.plant (Figure 15)

located on the northwest shore of the Lagoon and the effluent

drained to the shore.

Long Point is undeveloped, although a small salt pond

on its west shore, south of Stalley Bay, has been dredged

open to the sea and a small beach area has been created by

dredging on the lee side of the southeast point. These

modifications are shown on Figure 2. The Cays and Compass

Point are also undeveloped, although the latter is soon to

be the site of extensive construction for another marina

facility. Land clearing, shoreline alteration and extensive

filling have already been accomplished.

Presently, most of the Lagoon's north shore is unde-

veloped. A horse racing track has been proposed for the flat,

formerly swampy, area west of the highway and some filling

and grading has been accomplished on that project.


Page 9








RESULTS


The raw data collected in this study is presented in

thirteen tables. Table 14 gives some mathematical qualities

for the data from two diurnal studies. Table 15 is a sum-

mary of the monthly averages of the raw data. Locations of

sampling stations are given in Figure 3; the mean depth at

each station can be found in Table 4.

Temperature

Temperature measurements were made from February to May

and are shown in Table 1 with the calculated monthly aver-

ages in Table 15.

Minimum and maximum temperatures were measured at

Station 10i 24.01C and 33.0*C. Temperatures of 24-C were

also encountered once each at Stations 6 and B. The aver-

age monthly temperatures for the period of study also exhi-

bits a wider range (4.7*C) at Station 10 than elsewhere.

The ranges of the monthly means are shown in Figure 4, and

give an indication of the relative thermal stability at

various points in the area. The shallow waters along the

north shore are not as well mixed and have higher and more

variable temperatures.
Temperatures are lower and exhibit less fluctuations

in the deeper and more exposed east and south parts of the


Page 10








area where good mixing with open sea water occurs. Aver-

age temperatures were lowest and very constant at Stations

1 and 2. The depth at these stations, 6.9 and 10.7 meters,

respectively, is, however, considerably greater than that

at other sample sites. The shallower more protected parts

of the area tend to be more sensitive to variations in air

temperature than are the deeper better flushed locations.

Thus, during cooler periods and at night, water temperatures

in the shallows fall below those at the deeper, exposed

stations; while during warmer weather or in the daytime,

water temperature in the shallows are higher than those at

deeper stations.

Salinity

Salinity varied widely, both spatially and temporally

(Table 1). Generally the shallow, more protected reaches

of Banner Bay and the Lagoon maintain a higher salinity than

do the more mobile waters to the south. However, during

Hay and June, 1970 unusually heavy rains caused considerable

flooding throughout the island. In May the study area and

its watershed received sone eight inches of rain, almost

half of it between May 9 and 10. Seven inches of rain fell

in June, about four inches from June 14 to 16.

In Benner Bay and especially the Lagoon, salinities

were depressed considerably; most notably at Station 10


Page 21








where a minimum salinity of 4.9 ppt. was recorded on

June 19. All stations showed some effects of the run-

off and the results are somewhat revealing of water circu-

lation in the area.

Before flooding, the highest salinity levels were at

Station 10; average for February and March were 37.5 and

37.8 ppt. During these months the average salinity at

individual stations ranged from 36.3 to 37.8 (Stations

11 and 10 respectively); a range of 1.5 ppt. During the

same period the range on any given day was from 0.7 ppt.

to 1.8 ppt. (mean, 1.2 ppt.). As might be expected, sali-

nity was most regular at Station 1, where the range of daily

values was 34.8 to 37.0 ppt. and of monthly averages from

February to June 35.2 to 37.0 ppt.

After flooding,the range increased to as much as 31.0

ppt. when, on June 19, 1970 salinities of 4.9 ppt. and 35.9 ppt.

were measured at Stations 10 and 4. Figure 5 shows the effects

of flooding in May and June on the average salinity based on

eleven sampling stations. The rank of stations in order of

increasing salinity reduction was, in May: 1, 3, 6, (2,7) 5,

8, 9, (4, 11) 10. In June the relative rank was the same,

with the exception that salinity was least affected at Sta-

tions 4 and 11. The relative ranking is as follows (4, 11) 1,

3, 6, (2, 7) 5, (8, 9) 10. The degree of salinity changes


Page 12









at various stations can be appreciated from the ranges of

the monthly averages shown in Figure 4 and Table 15.

The spatial distribution of salinity and its reduction

and recovery at each station following flooding can be seen

in Figure 6. The monthly salinity averages have been rounded

to the nearest 0.5 ppt. to facilitate comparisons. By the

beginning of July salinity at most stations was still below

normal and the range throughout Benner Bay and the Lagoon

was still 5 to 6 ppt.

Since Stations 4 and 11 are at the southern end of the

Lagoon and since the prevailing predominant water movement

is south to north and tends to oppose the southward spread

of flood water, these data indicated that very large amounts

of fresh water from Turpentine Run may reach as far south as

Patricia Cay. This may be aided if flooding occurs during

calm seas or very low tides at which times wave indicted

transport from south to north through the Lagoon is at a

minimum. (McNulty, at al, 1968; Michel, 1970).


Pace 13








Dissolved Oxygen

In general, waters throughout the area are well-

oxygenated (Table 2). Daytime levels below 5.0 mg./L

were measured only at Station 10. Mean oxygen content

for the study period was highest at Stations 3 and 4.

This is perhaps not surprising since both are located in

lush growths of Thalassia and other algae and, in addition,

have superb water clarity and good circulation due to their

positions near the periphery of the study area. The high-

est and the lowest levels of D.O. encountered were measured

on March 21; 8.2 no./L at Station 2 and 4, and 4.6 mg./L

at Station In (Table 9). Dissolved oxygen levels seemed

to be unaffected by flood run-off following the May rain-

storms. The data (Table 2) does not indicate any correla-

tive changes. Monthly averages for eaci station are given

in Table 15.


EH
The pH at all stations was usually between 8.2 and 8.4.

Of all the measurements made the lowest was 7.8 taken early

on the nornine of April 21 at Station 10. It will he shown

later, during analysis of the diurnal studies, that night-

time pH values can fall below 9.0. However, the lowest mid-

day value was 8.0. Like other variables measured, pl was

more chanaeable at shallower or more polluted spots. The


Pace 14








range of values measured was 8.2 8.4 at all stations

except Stations 6 10. At Stations 6 and 8 the range

was from 8.1 to 8.4; at Station 9, 8.1 to 8.5 and at

Station 10, 8.0 to 8.4.

Water Clarity

Water clarity is the single most variable water quality

indicator in the Benner Ray-Lagoon area. Basically, all of

Benner Bay, and to a lesser extent the channels from Benner

Bay weRt to the Lagoon and southeast to Jersey Bay, have

poor water clarity and color. In these areas the bottom is

typically not visible. Secchi depth is as little as 0.25

meters, the water contains dispersed fine particulate matter.

and the color is brown, greyish brown or greenish brown.

Quantitative data for water clarity and color are in

Tables 4, 5, 6, 7 and 14.

The bottom is never visible at Stations 6, 7, 0 and

9 in Denner Bay even though the depth at all these points

is less than 2.5 meters. In contrast, the bottom could

always be seen at Stations 3 and 5 and it was (except

following mud-laden flood run-off) always visible at

Stations 1, 4, 10 and 11 (Figure 4).

Following flooding on May 9th to 10th, Secchi depths

were first reduced at those stations nearest the sites of


Page 15








input: the northern Lagoon and the heavily developed Benner

Bay Marine basin. Secchi depth reduction was not noted at

Station 11 until five to seven days later and the bottom

was again visible here after another three or four days.

At Stations 1 and 2 more than a week passed before turbidity

reached levels high enough to obscure the bottom. At Sta-

tions 3, 4 and 5 turbidity, while increased, was usually not

severe enough to obscure the bottom.

The relative transparency of water at various points

is shown in Table 5. These data do not indicate optimum

or usual water clarity because the area was still suffer-

ing some effects of the early May flooding when the measure-

ments were made. In particular, the data from Station 11

greatly underrated the clarity of this water which, under

normal conditions, is probably the best in the whole area.

It will be noted that the extinction rates given in

Table 5 relate well to the Secchi Depth measured on the

same day (Table 4). If one divides the amount of available

light (surface light) in Table 5 by the extinction rate at

each station, it will be seen that this theoretical limit

of visibility approximates very closely the Secchi Depth

actually recorded. At Stations 2 and 9 these calculated

depths of visibility are greater than the depth to the bottom

(which is visible from the surface at these locations),


NPa- 16








indicating that the water is of a clarity sufficient to allow

greater visibility; that is, the Secchi Depths at these

stations are limited by the bottom and not by the clarity

of the water. This close correlation between Secchi Depths

and light transmittance in coastal waters has also been re-

cently reported by Holmes (1970).

The amount of suspended matter (Table 7) in the water

varies throughout the study area, as is obvious on visual

inspection. Further, those sites which routinely have high

turbidity are also most heavily affected during periodic

flooding. of interest is the observation that, following

the initial drop in concentration of suspended solids, con-

tributed by flooding on May 9th to 10th, there was a second

slighter increase about a week later (Figure 7). This in-

crease is attributed to organic debris from organisms dam-

aged or killed by the suddenly lowered salinity. Beginning

on May 18th, when enough mud had cleared from the water to

make a noticeable improvement in clarity, large amounts of

floating material was noted throughout the Lagoon. Most ot

it was recognized as fragments of Thalassia, various fila-

mentous algae, and hydroids which are abundant on the mangrove

roots.

On Hay 11, after the storm, the entire area was heavily

silted and visibility was poor everywhere. The plume of muddy


Page 17








water extended as far south as the reef and, at that time,

as far east as Bird Cay and out to a line running to the

eastern tip of Cas Cay. The area around Station 3, south of

Compass Point, was not noticeably affected at that time. The

turbidity was highest, of course, in the northern reaches of

the Lagoon proper and throughout the channel north of Bovoni

Cay. The bottom was visible at Stations 2 and 3 and points

southeast and the surf cresting over the reef to the south

presented an effective barrier to the further southward spread

of the plume. Besides the considerable amounts of mud still

in suspension, quite a lot had already settled and was dis-

turbed by the boat's prop. At approximately 4:30 p.m. on

May 11, with the tide at or near low slac; there was good

flow of very turbid water from at least two points on the

north shore, one adjacent to Station 10, the other farther

west.

On May 13 little improvement was noted. A traverse

from Station 10 to 11 stirred up large amounts of brown mud.

By May 18 there was improvement in some areas, most notably

at Station 11 and southward, where clean, sandy bottom with

open worm holes was visible. Clearing to a lesser extent

was noted north of Station 11 with increasing amounts of

settled clay and turbidity toward the shore where there was

still no evidence of improvement. By May 20, however, the


Paae 10








bottom was again visible where it usually was, except still

along the north shore of the north shore of the Lagoon.

From October 3 to 11 rainstorms again produced consider-

able run-off, but the effects this time were confined to

Benner Bay and the north shore of the Lagoon.

As far as we can tell the water quality and the bottom

biota have not yet returned to normal everywhere. Along the

north shore of the Mangrove Lagoon and throughout the channel

from Benner Bay into Jersey Bay, turbidity has remained higher

than it was before flooding. A distinct brown plume extend-

ing from Henner Bay into Jersey nay well southeast of Cas Cay

is visible from the air. The shallows over the grass flats

northwest of Cas Cay to Bovoni Cay are not noticeably affected,

however. This continued turbidity is believed to be maintained

by periodic clay contributions caused by rain showers and, in

Benner Bay, aided by boat traffic which keeps silt suspended.

Water color also, because of increased turbidity in these

quarters, is poor.

Estimates of shallow water color are greatly subject to

the character of the bottom. The color estimate may, barring

large amounts of suspended matter, be the color of the bottom.

The apparent color of the waters in the study area falls into

four broad categories:

1. Brown, opaque water of Benner Bay and the north

shores of the Mangrove Lagoon (Forel-Ule colors ranging from


Pa,.,, 1









XVIII-XXI) contains large amounts of suspended and dissolved

materials.

2. Green or bluish-green water is relatively clear,

low in suspended matter and transmits light reflected from

plant cover on the bottom. In deeper water the blue com-

ponent is heightened as the longer wave lengths are selec-

tively absorbed by the water, giving colors from bluish

green (IV), tending toward blue (I), which is characteristic

of clear, deep offshore water.

3. Apparently green water (VI-XII) contains some sus-

pended matter, but it primarily reflects the color of the

grass and algal cover of the bottom. The largest portion

of the area falls into this range, including the grass beds

between Bovoni and Cas Cays and most of the Mangrove Lagoon

proper west of Bovoni Cay.

4. Clear, essentially colorless water which is not

really embraced by the Forel-Ule scale, is found over clean,

current-swept sand in the channels and northof Patricia Cay.


I'ae 20








Diurnal Studies

This section presents the results of two twenty-four hour

studies of the fluctuations of temperature, salinity, pH, and

dissolved oxygen at six sites in Benner Bay and the Lagoon.

Measurements and water samples were taken at each station at

three hour intervals. Data were also taken periodically on

sunlight intensity, air temperature, wind, sea and tide state.

Diurnal fluctuations of water quality parameters in

Banner Bay and the Lagoon are the result of physical and bio-

logical dynamics which are extremely variable from site to

site. Tidal effects on salinity, temperature, etc. vary de-

pending on the site, because of the peculiar combination of

wave and tidal forces throughout the area and fluctuations

of these parameters follow an unusual spatial sequence dic-

tated by the local bathymetry and shoreline irregularities.

Besides the familiar pumping effect of tidal action on

water movement, the state of the tide is also critical to

water movement induced by wind and waves offshore of the

Lagoon. The offshore currents south of the cays have a

westerly set with velocities, varying with the tide, from

2.4 to 28.8 ft./min. (McNulty, 1960; Michel, 1970).

McNulty's group found that at slack tides the drift was in-

terupted and either no current was measured or there was a

weak easterly current.


Page 21









North of the reefs, inside the Lagoon, Michel and

Tabb (1968) found that water movement was always northerly.

Their measurements were made north of Bovoni Cay, between

Long Point and Patricia Cay and between Patricia and

Cas Cays.

Tidal Variation along the southern coast of St. Thomas

is of mixed character (both diurnal and semidiurnal) although

it is primarily diurnal, i.e. one high and one low per day

(McNulty, at al, 19608 Michel, 19701 U. S. Dept. of Commerce,

ESSA, 1970). The average tidal range is about 0.8 feet.

McNulty (1968) and Michel (1970) both found that the

amount of water entering over the reefs to the south of the

Lagoon depends on the height of the tide and is modified by

the state of the offshore seas. This circulation, which is

generally quite good, tends to increase on the high tide and

is enhanced by strong wind and wave activity. According to

McNulty, et al, (1968) the general wind and surf induced

circulation through the Lagoon is north, northwest into the

Lagoon from the reefs which run from Long Point to Cas Cay;

water then moves easterly from the Lagoon into Benner Bay

via the channel north of Bovoni Cay, and then south, southeast

into Jersey Bay. Circulation in the northwestern Lagoon and

in the head of Benner Bay is usually somewhat retarded. Our

observations support this description.


Page 22








During times of extremely low tides, however, we have

observed the tops of the Acropora reef protruding from the

water, exposure of the Porites-Penicillus back-reef flats,

and apparent cessation of water movement in the Lagoon.

Both McNulty (1968) and Michel (1970) also observed simi-

lar periodic loss of circulation. At such times, with calm

weather, the southerly movement of Lagoon water is unopposed

by the usual wind driven waves from the reefs, and hyper-

saline or storm water may move south from the northwest

Lagoon into the channels around Patricia and Bovoni Cays.

This rather unique interaction of waves and tides and

its effects on circulation and flushing of the Lagoon is

crucial to the hydrography and ecology of the area. One

of the most obvious of these effects is that increased

circulation causes the water in Benner Bay and the Lagoon

to become more homogenous, generally reflected by a reduc-

tion of the usually higher salinities in northeast Benner

Bay and northwest Lagoon to levels closer to those of the open

sea to the south. This effect is less marked at deeper more

exposed stations (2, 4, 11) which normally maintain salini-

ties close to open sea values, and, as a consequence, the

range of salinity throughout the area is compressed.

On the other hand, during periods of poor circulation

evaporation increases salinity in the more remote areas and

distinct spatial heterogeneity develops.


Page 23








Air and water temperatures were higher in April than in

March but at most stations dissolved oxygen reached higher

levels in March. In March pH was lower, especially at night,

possibly the result of higher metabolic activity associated

with the higher water temperatures. Diurnal oxygen curves,

although markedly different among stations, were similar

at each site on both occasions.

These pictures of the diurnal changes in dissolved

oxygen are useful in assessing the health and productivity

of an area.

Under purely physical forces, dissolved oxygen in sur-

face waters tends to equilibrate at 100 per cent of satura-

tion. The analysis of diurnal oxygen curves for their fluc-

tuation around the saturation point can be used to assess

the metabolic activity of an area and to estimate changes

in photosynthesis and respiration and the relative balance

between the two. Dissolved oxygen levels beyond saturation

indicate net photosynthetic activity while concentrations

below saturation reflect relatively greater respiration than

photosynthesis and, therefore, a net consumption of oxygen.

Station 2 (Figure 9) was the deepest of the diurnal

stations and on both occasions maintained supersaturated oxy-

gen levels well into the night. Dissolved oxygen never fell

far below saturation. The surface water here is well mixed,


Page 24








not heavily taxed by the benthos and probably equilibrates

to near the saturation point at night more as a result of

diffusion across a concentration gradient at the air-sea

interface than as a result if respiratory depletion which

would be expected to cause a continued fall in the dissolved

oxygen curve to levels further Below the saturation point

than were actually encountered. In fact, the curves show

a definite leveling off just at or below the saturation

levels.

A similar situation is indicated at Station 11

(Figure 14) where, however, daytime levels do not reach as

high and there is a greater depletion at night. The depth

here is only one-fifth that at Station 2, the bottom is clear

white sand with a rich infauna, but practically no grass or

algae.

Oxygen curves from Station 4 (Figure 10) are closest

to a simple diurnal pattern and indicate an extremely pro-

ductive area where photosynthesis rapidly builds up dissolved

oxygen during the daytime, where this production ceases and

a net respiratory depletion begins in the evening and where

nighttime demands continue to reduce dissolved oxygen levels.

Station 4 is characterized by an extremely rich algal-

grass community, very good water clarity and almost continuous

water movement from the reef northward. In such clear waters

over Thalassia beds we have observed thousands of small oxy-

gen bubbles rising to the surface from the grass leaves.


Page 25








Diurnal oxygen changes at Station 7 (Figure 11) are

similar to those at Station 9 and indicate maintenance of

nocturnal oxygen concentrations by transport associated

with the tides. Oxygen concentrations were least dynamic

that is, showed the least degree of change, at Station 9

(Figure 12). Changes in concentration follow gentle slopes

and the dissolved oxygen is, except for a few hours during

the day, near or below saturation. The maximum concentra-

tion attained during the day was the lowest for all stations

studied. On the other hand, nighttime minima were not as

low as at Station 10, probably because of the greater volume

of water and apparently lower benthic biomass at Station 9

(the bottom here is patchy Thalassia, as opposed to a dense

cover at Station 10). Oxygen curves at Station 9 are very

similar to the salinity curves which may indicate that oxy-

gen changes here are due mainly to transport. This interpre-

tation is supported by the fact that nighttime concentrations,

on both occasions, did not fall steadily, but were supported

during the flood and high tide (2000-2400 hours). In fact,

there is bulge or "knee" in both curves during this period.

The greatest diurnal oxygen consumption is indicated at

Station 10 (Figure 13) where dissolved oxygen is far below

saturation for all but six hours during the day.. In addi-

tion, there is a considerable lag in oxygen buildup in the


Page 26







early morning following very low levels (4.6 mg./L) to which

it falls at night. The nighttime depletion of dissolved

oxygen is extremely rapid, due most likely to the respiratory

demands of the bottom fauna. It should also be remembered

that the water is very shallow here (average O.Sm.) and so

the volume overlying a given area of bottom and the total

amounted oxygen it carried is not great. The result is that

the small oxygen reserve produced during daylight is rapidly

used up at night. The dominant benthic organism here is

dense Thalassia, so that the aereal potential for oxygen

production is great and once production commences the con-

centration raises quickly to high levels (7.8 to 8.0 mg./L).

However, because of the shallow water column and the generally

higher temperatures and salinity, there is little storage

capacity for oxygen and on both occasions levels fell rapidly

after about 3 p.m. Recovery from nocturnal low begins only

after an early morning lag, but is relatively rapid.


Page 27








SUMMARY

This study and the available literature reveals that

the Benner Bay-Mangrove Lagoon area is one of diversity;

diversity not only of habitat types but in the degree of

anthropogenic destruction throughout the area. Benner Bay,

as a result of concentrated development for marine faci-

lities, is biologically devastated. Water color and clarity

are extremely poor because of an extremely high loading of

various dissolved and suspended pollutants, including clay,

organic matter and hydrocarbons. The visibility is so poor

that the bottom cannot be seen anywhere in the Bay even

though the maximum depth is only about 2.5 meters. Diur-

nal oxygen balance indicates an excess of respiration over
photosynthesis. In addition, the Bay is well protected

and, while perhaps desirable for marina facilities, is

incapable of handling the present pollution load because

the rate of addition is greater than the rate of removal.

It is expected that the Benner Bay environment and water

quality will continue to deteriorate, although further

changes will, relatively speaking, be of no great import.

Water quality and natural systems are less affected to

the west along the northern fringe of the study area and

improve rapidly toward the south. There is an obvious plume


Page 28







of turbid water which extends from a focus in Benner Day south

into Jersey Bay along the navigable channel east of Bird Cay.

Environmental stresses on the Lagoon are increasing from ex-

panding development in Nadir and Bovoni and as far away as

Tutu which contribute increasing amounts of silt and fresh

water during storms. Sewage eutrophication and pollution

from the Nadir plant will increase and there are signs that

the ability of the receiving water to absorb these wastes is

waning. Foam from the plant is frequently piled up along the

northwest shore.

In addition, previous studies (Michel and Tabb, 1968;

Michel 1970; McNulty, 1970) have shown that this corner of the

Lagoon is one of the most poorly flushed reaches of the area.

It is, therefore, probably the least suitable to receive sew-

age effluent. The ability of the system to absorb this waste

in the past is testimony to the healthy and productive nature

of this environment. However, this ability to assimilate

organic and inorganic nutrients is not infinite and with the

increasing pressures of other ecological modifications (silta-

tion, fresh water, turbidity), the productivity and assimila-

tion potential of the Lagoon nay be declining. At any rate,

conditions are presently less normal in this quarter than they

are elsewhere in the Lagoon. All of the lagoon, however,

still appears highly productive even though siltation on

Thalassia, resulting from floods a year ago, still persists.


Pace 2"








The southern section of the Lagoon, the reefs and the

grass flats northeast of Cas Cay remain superb examples of

shallow tropical reef and marine pasture systems. They re-

main so because of the unique northerly flow of clean water

from the open sea, because they are not subject to heavy

boat usage and because Long Point and the cays are undeveloped.

The data collected in this study indicate this area is one

of very high net productivity.


Page 30







RECOMMENDATIONS


We strongly urge that the local government come to a

decision on the use to which the Mangrove Lagoon is to be

put. The present course of development in and around the

area increases pressures daily on this unique ecosystem.

Because of the lack of a stated objective for the area,

continuing development and shoreline alteration is destroy-

ing this area as a basic production, prime recreational and

as a research site. Its value for these purposes is being

lost by default.

The uniqueness of this environment on the island,with

its presently healthy and varied complex of habitats,pro-

vides a site of significant natural value for which esti-

mates of the esthetic and economic worth have not yet been

constructed. Its destruction, however, can have decisive

and far-reaching effects, many of which cannot be predicted

and some of which are likely unimagined.

In recent years detailed productivity studies and va. te

analyses have been accomplished for particular open coastal

submerged lands, mangrove swamps, and river swamps, and for

the first time a total resource worth has been described

for some of the coastal zones of the states of Florida and

Georgia. These value estimates range from $300 per acre


Page 31








per year for fish production alone on the coastal sub-

merged lands, to over $3,000 per acre per year total value

for the highly productive protected marshes. The present

worth of an asset yielding $3,000 per year over a long term

at nominal interest rates would be listed at a surprising

figure in the hundreds of thousands of dollars; thus, if the

worth of protected lagoons and marshlands is computed in

terms of the 100-year asset value, a not worth in the range

of $200,000 to $300,0n0 per acre would be realized.

The island has several marine facilities and other bays

which could be used for additional anchorage. There is no

other good representative of the mangrove ecosystem in the

Virgin Islands. Sube (19F8), in a survey of island resources,

said:

"The beach vegetation, mangrove and rain forest

areas are important vegetation types because of

their relative scarcity compared to other types.

They are also important as. natural features which

contribute to the diversity of the scenery. There

is only one remaining mangrove lagoon of size in

the U. S. Virgin Islands. It is located on the

southeast shore of St. Thomas. . Decisions on

the allocation of this resource should be withheld

until comprehensive scientific investigations have


Page 32







been completed and its intrinsic natural values

have been more clearly delineated."

Housing, horseracing and commercial establishments

could be planned in the Bovoni-Nadir area in a manner con-

sistent with the continued healthy existence of the Mangrove

Lagoon -- if its preservation were deemed desirable govern-

ment policy. Me cannot justify destruction of the Mangrove

Lagoon by over-developnment deemed necessary to accomplish

alternate critical land or water user and with the possible

exception of the proposed jetport, none of the existing or

proposed land use schemes is absolutely essential at the

site. Whether the jetport is built or not, the Mangrove

Lagoon will be lost -- is presently being lost -- by de-

fault because the appropriate policies and priorities have

not been yet assigned.

If there is a decision to preserve the area in a state

close to the natural, then immediate action is needed to

develop a management plan to ensure proper protection and

preservation. In some instances, remedial action may he

necessary. It cannot be too strongly emphasized that the

present course of development in the Nadir and Bovoni area

is inconsistent with the maintenance of the Mangrove Lagoon

in the natural state.

Decisive planning for use of the Lagoon itself is just

as important, although less pressing, or the area,too, will


Page 33








be committed to further marina and other shoreline develop-

ment. Because of its predominantly shallow depth and rela-

tively small water volume, the Lagoon is unsuited for sewage

outfall or navigation. If development and pollution pressures

continue to increasethe natural cleansing abilities of the

system will be overloaded and the Lagoon will succumb and

eutrophy to a much less desirable state.

Several recommendations are here offered to serve as

a basis for action in Benner Bay and the Lagoon as well as

to indicate some of the problems which we feel require atten-

tion. These recommendations are built around the following

assumptions:

1. The proposed airport will not be built.

2. The Mangrove Lagoon is a valuable resource
and should be so treated.

3. Banner Bay has been committed to use as a
commercial marina area.

4. Planning for the beast use of the territory's
resources requires the maintenance of a diver-
sity of ecosystems, particularly those which
are unique because of their rarity or because
they are representative segments of local resources.

The recommendations build the framework for planning

and establishing a Virgin Islands Coastal Zone Preserve

which, besides its aesthetic worth, will continue to be

of value as a recreation site for fishing, sightseeing

and swimming; an educational resource for use as a living

laboratory; a research asset which can play a significant


Page 34








part in the development of the Islands' economic future

and a nursery for the fishery of the northern Virgin Islands.

The suggested houndries of the preserve in minimum area

form and references to the recommendations are shown in

Figure 15.

In May, 1970, by letter to the Department of Conser-

vation and Cultural Affairs, Caribbean Research Institute

recommended designation of the area as a territorial natural

preserve, protected by legislation and warden policing. Areal

extent recommended was "all of the peninsula west of the la-

goon, Patricia Cay, Cas Cay, Bovoni Cay and all of the smaller

mangrove islands; all of the enclosed submerged lands and

enclosed waters, the grass/sand flats east of Bovoni Cay and

north of Cas Cay, and the marine waters and submerged lands

offshore to the south to a water depth of ten fathoms."

The area outlined in the 1970 recommendation included

more land area on the peninsula west of the Lagoon (the

western slopes), but did not include Bird and Rotto Caya.

This investigation does not support need for inclusion of

the western slopes for adequate protection of the Mangrove

Lagoon itself, but does suggest need to isolate the flats

east of Dovoni Cay from heavy boat traffic hence, relo-

cation of the channel into Renner Ray if the traffic to the

existing commercial marinas is allowed at the present level.

The land on the western slope of the Long Point peninsula


Page 35








should still be considered for inclusion in a Coastal Zone

Preserve to be set up in more than minimum area form.


Recommendation I:

Marina development should be confined to Benner Bay

and any extension should be east rather than westward. No

further development should be allowed on the shoreline north

of Bovoni Cay. Additional commercial marine activity should

be shifted to the Red Hook area (see Grigg, et al, 1970).

All activity allowed under an area use and development

plan must be closely monitored and strictly controlled. Sub-

merged land permits, zoning exceptions and building plans

must be complete in detail and exact in scope. All applica-

tions need to be reviewed with consideration of possible

leechings and discharges and direct disposal of effluents

prohibited.


Recommendation II:

No dredging should he allowed outside of Benner Bays

except if channel deepening is allowed in the development

plan, it should not be allowed in the present channel west

of Bird Cay. Necessary access channel improvement should

be made around Compass Point north of Bird and Rotto Cays

(as shown in Figure 15).


Page 36








Recommendation IIIs

The government should acquire the necessary land on

Long Point (or institute restrictive zoning to ensure its

use in a compatible manner), to include at least all of

the eastern slopes and designate the area generally within

the suggested boundaries shown on Figure 15 as a Virgin

Islands Coastal Zone Preserve.

Well planned, limited access to scenic and recreation

points would allow public use of swimming and fishing areas.

General motor boat traffic within the preserve should be

prohibited or strictly regulated. The area would be made

available for educational use by local and visiting students

and teachers and could be used for a wide variety of research

and development programs.

As such, it could become an outstanding example of

multiple resource use, which is particularly suited to small

island settings which have limited resources.


Recommendation IV,

The Nadir sewage treatment plant should be made to

operate closer to optimal. Eventually, the effluent should

be piped to an outfall point which is better situated to

provide rapid diffusion and dilution of the effluent.

There is need for buffering the Lagoon from the pre-

sent effects of the effluent now discharged; thus,


Page 37









construction of a polishing pond for further reduction of

the effluent strength is recommended. Additionally, eco-

nomic feasibility of reuse of the polishing pond effluent

should be studied -- as in flushing/irrigation systems in

the new housing development constructions.


Recommendation Vi

The proposed horse race track should not be placed

close to the shore, but should be located far enough west

to allow for a green belt between it and the shore to act

as an ecological buffer zone. Design proposals for this

facility should include features necessary to minimize

runoff and other pollution of the Lagoon. Use of a race

track-park area here will have to he continually regulated

and policed as are the other sections of the preserve.


Page 36








LITERATURE CITED


Dammann, A. E. 1969. Study of the fisheries potential of

the Virgin Islands. Contrib. #1, Virgin Islands

Ecological Research Station, College of the Virgin

Islands.

Donnelly, T. 01. and J. Whetten 1968. Field guides to the

geology of St. Thomas, St. John and St. Croix,

Virgin Islands, Fifth Caribbean Geol. Conference.

Grigg, D. I., R. P. vanEepoel and R. W. Brody 1970. Water

quality and marine environment of Vessup Bay,

St. Thomas. Water Pollution Report No. 8,

Caribbean Research Institute.

Holmes, R. W. 1970. The Secchi disk in turbid coastal

waters. Limnol. and Oceanogr. 15(5):688-694.

McNulty, J. K., W. B. Robertson and B. F. Horton 1968.

Departmental study team report and recommendations

on proposed now jet airport, St. Thomas, Virgin

Islands, U. S. Dept. of Interior.

Michel, J. F. and D. C. Tabb 1968. A study of the biolo-

gical and coastal engineering aspects of the pro-

posed jet airstrip at Jersey Bay, St. Thomas,

II. S. Virgin Islands; Part II, Coastal engineering

considerations, Institute of Marine Sci., University

of 'aTi.a.


Page 39









Michel, J. F. 1970. A study of the hydrodynamic effects

of the proposed airport at Long Beach Point,

St. Thomas, Virgin Islands. Univ. of Miami,

School of Marine and Atmospheric Sciences. Rpt.

to the Virgin Islands Port Authority.

Tabb, D. C. and J. F. Michel 1968. A study of the biolo-

gical and coastal engineering aspects of the pro-

posed jet airstrip at Jersey Bay, St. Thomas,

U. S. Virgin Islands, Part I. Biological considera-

tions. Institute of Marine Sciences, University of

Miami.

U. S. Dept. of Commerce, E.S.S.A. 1970. Tide tables.

East coast North and South America. U. S. Govt.

Printing Office, Washington, D. C.

U. S. Dept. of Interior, F.W.P.C.A. 1967. Biological

aspects of marine water quality, St. Thomas,

St. Croix and St. John, U. S. Virgin Islands.

F.W.P.C.A., Tech. Advisory and Investigations

Branch, U. S. Dept. of Interior.

Zube, E. H. 1968. The islands. Selected resources of the

U. S. Virgin Islands. U. S. Dept. of Interior.


Page 40








APPENDIX


Figure;

1. Location Map

2. Study area and watershed

3. Sampling stations

4. Panges of monthly averages of temperature
and salinity

5. Salinity changes during study period

6. Monthly averages of salinity to nearest
0.5 ppt.

7. Suspended solids changes during study period

8. Air temperature and sunlight during diurnal
studies

9. Diurnal variables at Station 2

10. Diurnal variables at Station 4

11. Diurnal variables at Station 7

12. Diurnal variables at Station 9

13. Diurnal variables at Station 10

14. Diurnal variables at Station 11

15. Suggested land usage

16. Distribution of benthic communities


Table:

1. Temperature and salinity

2. Dissolved oxygen

3. pH


Page 41









4. Secchi depth and average water depth

5. Submarine illumination

6. Water color

7. Suspended solids

8. March diurnal temperature and salinity

9. March diurnal dissolved oxygen

10. March diurnal pH

11. April diurnal temperature and salinity

12. April diurnal dissolved oxygen

13. April diurnal pH

14. Means, maxima, minima and ranges of
diurnal data

15. Monthly averages for water quality
parameters


Pace 42









TABLE I
BENNER BAY MANGROVE LAGOON
TEMPERATURE (C) AND SALINITY (PPT.)


STA T I ON
DATE
1 2 3 4 5 6 8 9 10 11
T S T 6 T 8 T S T 8 T S T T S S T 8 T S
2/12/70 27.1 36.5 27.4 36.9 27.7 36.9 27.9 36.8 28.8 37.0 28.6 37.2 28.5 37.2 28.2 37.2 28.3 36.9 --
2/17/70 28.8 36.8 26.8 37.7 26.9 36.4 28.0 36.6 27.6 38.2 27.5 37.0 27.5 37.0 27,6 37.2 27.2 38.1 ---- -----
2/19/70 26.8 36.6 26.9 37.0 27.3 36.6 27.5 36.5 28.1 36.6 27.9 37.1 27.& 37.1 27.9 37.2 27.7 37.5 -- --
2/24/70 26. 36.5 26.3 36.5 27.0 36.5 26.4 36.3 27.5 36.8 27.3 36.8 27.0 37.1 27.5 36.8 27.0 36.8 27.5 37.5 26.5 36.3
2/26/70 26.7 -- 27.2 -- 27.5 27.7 -- 28.1 28. -- 27.5 -- 28.0 -- 28.0 -- 27.0 26.9 --
)3/4/70 26.3 37.0 25.0 37.0 25.2 36.5 24.8 36.8 24.4 37.0 24.0 37.5 24.2 37.0 24.0 37.3 24.2 37.2 24.0 37.8 24.4 36.6
3/10/70 27.5 -- 28.0 29.5 1 28.0 -- 28.0 -- 29.0 -- 30.0 -- 29.0 -- 29.0 28.0 28.0 --
6/11/70 27.0 36.6 -- 35.7 -- 28.0 30.1 -- 33.2 35.8 -- 353.5 35.7 -- 31.6 29.0 10.8 29.0 22.4
5/13/70 27.0 37.0 27.0 36.9 26.5 36.8 26.2 34.8 28.0 35.8 28.0 36.1 28.0 36.2 28.0 36.1 29.5 33.6 31.2 14.0 27.8 27.3
5/15/70 -- 37.0 -- 36.9 -- 37.3 -- 32.7 -- 35.7 37.1 -- 36.9 -- 36.8 -- 34.4 -- 13.7 31.1
5/18/70 36.5 -- 3.4 -- 36.6 -- 36.3 -- 36.8 -- 36.0 -- 3.3 -- 36.3 -- 36.5-- 32.2 34.0
5/20/70 29.4 -- 27.5 16.6 28.0 29.0 35.5 29.5 35.9 29.5 2 3.6 29.5 36.8 29. -- 30.0 35.5 32.0 34.0 30.0 37.0
5/23/70 28.2 36.9 29.4 37.3 29.5 36.9 30.5 37.1 31.1 36.9 30.6 36.9 31.0 37.0 30.5 37.2 31.0 36.2 33.0 33.1 31.2 35.7
5/25/70 27.2 36.8 27.4 36.9 27.4 36.9 27.6 37.2 28.5 36.7 28.4 37.0 29.2 37.4 29.0 37.1 28.3 36.9 29.6 33.4 28.6 36.A
5/29/70 28.7 -- 28.1 37.5 29.5 -- 28.0 37.4 28.8 37.3 29.0 37.3 29.2 37.4 28.9 37.3 29.2 29.2 36.1 28.8 37.3
6/19/70 35.5 -- 32.4 -- 34.9 -- 39 31.0 34.7 31.9 30.1 -- 24.8 -- 4.9 -- 35.6
6/23/70 34.8 -- 3350 -- 34.6 -- 36.3 -- 33.6 33.4 33.7 -- 33.7 -- 26.7 -- 34.
6/25/70 -- 34.7 -- 35.2 -- 34. -- 34.4 -- 34.6 -- 35.1 -- 4.1 -- 26.3 35.4
6/29/70 35.7 -- 35.9 -- 35.3 -- 35.1 -- 34.7 -- 3 .3 34.3 30.6 -- 35.
7/1/70 -- 32. -- 32J -- 330. .61 3 .0 32.7 -- 32.7 29.8 35.-




TABLE 2

BENNER BAY MANGROVE LAGOON
DISSOLVED OXYGEN (mg/L) AND % SATURATION


__________________________________STATION _______________
1 2 a 4 5 6 7 8 a 9 100

DATE D. % 1Sat. D.O %Sat.D.O. %Sat. D.O. % Sat. D.O. %Sat. D.O. at D.O. 1%Sat D.O. %sat. D.O. J%Sat. D.O.at. D.OSat.


5.2 80 15.4 84 I6.3


5.7 90 S.6


87 I I -


2/12/70

2/17/70

2/19/70

2/24/70

2/26/70

3/04/70

3/10/70

5/11/70

5/13/70

5/20/70

5/23/70

5/25/70

5/29/70








TABLE 3

BENNER BAY MANGROVE LAGOON

PH


STATION


1970 1 2 3 4 5


8.4 8.4 8.3

8.2 8.3 8.2 8.2

8.3 8.4 8.4 8.3

8.4 8.4 8.4 8.4

8.4 8.4 8.4 8.4

8.3 8.3 8.3 8.3

8.2 8.4 8.2 8.2

8.4 8.4 8.3 8.4

8.2 8.2 8.3 8.2

8.4 8.4 8.4 8.4

8.4 8.4 8.4 8.4

U.2 8.3 8.3 -

8.2 8.2 8.2 8.2


8 7 8 9 10 11

8.2 8.2 8.2 8.3 -

8.1 8.1 8.0 8.1 -

8.2 8.2 8.1 8.3 -

8.3 8.4 8.4 8.3 8.4

8.4 8.2 8.2 8.3 8.1 8.2

8.3 8.2 8.2 8.3 8.3 8.2

8.3 8.4 8.3 8.2 8.2 8.2

8.3 8.3 8.3 8.2 8.4 8.3

8.4 8.4 8.2 8.5 8.2 8.3

8.4 8.4 8.3 8.4 -

8.4 8.4 8.4 8.4 8.2 -

- 8.4 8.2 -

8.3 8.2 8.1 8.2 8.0 8.2







TABLE 4

BENNEK BAY MANGROVE LAGOON

SECCHI DEPTH AND AVERAGE WATER DEPTII (METERS)







DATE STATION

1970 1 2 3 4 5 8 7 8 9 10 11

2/12 B 2.8 B B B 1.5 0.8 0.8 1.5 -

2/17 B B B B B 1.3 1.0 1.5 -

2/19 B 4.8 I! B B 1.3 1.0 1.0 1.3 -

2/24 B B B B B 1.0 1.0 1.0 1.0 B B

2/26 B 6.5 B B B 1.5 1.3 1.0 1.3 B B

3/04 B B B B B 1.3 1.0 1.3 B B B

3/10 B 4.5 B B B 1.0 1.0 1.3 1.8 B B

5/13 B D B B B 1.3 0.8 0.8 B 0.5 1.0

5/15 B B B 1.0 B 1.2 1.0 1.0 0.5 0.5

5 18 B B B B B 0.7 0.8 0.6 B 0.4 B

5/20 10.5 5.0 B B B 0.8 0.6 0.6 B 0.4 B

5/23 9.3 0,3 B D B 0.8 0.5 0.8 1.3 0.3 B

5/25 7.0 5.5 B B B 1.3 0.8 0.8 B 0.8 B

5/29 B 2.5 B B B 1.0 0.8 1.0 1.5 0.5 B
Average
Water 10.7 6.9 1.9 2.0 1.0 1.9 1.5 2.3 1.5 0.8 1.3
Depth

B= Visibility to bottom








TABLE 5

BENNER BAY MANGROVE LAGOON

SUBMARINE ILLUMINATION
Noon, May 13, 1970

0. 5 METER 1 METER 4 METERS 9 METERS
Extinction
Surface Rate
Ft. Ft- Pt. t,- Pet. Ft.- Pet. Ft.- Pet. Ft. -Cand.
STATION Cand. Cancd Loss and. Los Cand. Loss Cand. Loss per metel

2 8,700 7,900 9 5,200 40 3,300 62 780


4 11,700 5,700 51 6,000


7 9,500 1,.900 80 7.600


9 8, 700 7,300 16 2.800


10 8,700 1,700 81 14,000


11 8,700 3,300 51 8,800







TABIE 6

BENNEIt RAY MANGROVE LAGOON

WATER COLOR (FOREI. ULE)


DATE

1970 1 7


STATION

d s. K


2/12 IV V VI

2/17 IV VII VI

2/19 IV VI VI

2/24 mI VI VIII

2/26 IV VI VI

3/04 IV V VI

3/10 Iv VIII VI

5/11 m -

5/13 IV VI V

5/15 IV IV V

5/18 mI V V

5/20 m VIII V

5/23 m VI V

5/2b5 m VI IV

5/29 mI VI V


XIV XIV

xny xvi



XV -

XVII XIX
xvn xix

xv xvi

XV XVII



XV XVI
xv xvi

XIV XV

VIII XIX

XVI XIX

XVI XVI


XVI XV
XVI XVmI


XVII XVII -

XVI XIV -

xvI XVIII xv -

XVI XV XVII XII

XIX XX XVII XVII XV

xvi xvi xv] xvn xn

XVII XVm XVI XVII VI

- xx XVII

XVI xVI xvm xx XVII

XV XVI XVIII XVm XVII

XIX XVIII XVI XXT XVI

xvm xvm xix xxi xvi
XVIII XVII XIX XI XVI

XVI XVI XVI XVm XIV



XIX XIX XIV XXI VII


i970 1 2 3 4 5 6 7 8 9 io 11.


TRain1t







TABLE 7

BENNER BAY MANGROVE LAGOON

NON-FILTERABLE SUSPENDED SOLIDS (mg./l)
(greater than 0.45 micron)


DATE STATION

1970 1 2 3 4 5 6 7 8 9 10 11

5/11 102.6 93.2 20.2 68.8 170.0 93.5 31.0 106.0 695.5 26.8

5/13 10.5 13.6 11.7 17.4 12.6 21.7 19.1 15.3 57.9 21.4

5/15 22.7 22.9 20.0 25.1 18.4 29.1 22.4 27.3 24.4 31.3 31.9

5/18 27.1 43.3 48.6 7.9 36.8 83.3 71.8 71.0 39.6

5/20 64.4 14.3 14.2 8.2 16.3 22.9 24.4 77.9 9.7 8.9 12.4

5/23 29.9 22.8 16.5 29.7 22.4 24.4 25.0 30.6 19.5 16.6

5/25 21.2 12.9 20.0 20.4 19.5 5.5 25.1 32.8 32.9 26.2 20.3

5/29 10.6 15.8 14.6 17.7 33.8 32.8 19.6

6/19 20.9 34.8 27.7 29.5 24.7 31.3 25.6 19.5 17.5 107.2 20.8

6/23 6.5 22.2 23.9 21.3 17.6 26.0 19.1 24.4 17.8

6/25 34.5 15.0 20.4 22.5 19.6 15.6 16.2 21.7 13.3

6/29 2.1 13.-4 8.1 28.8 14.3 22.2 22.9 8.8

7/01 21.6 22.9 12.6 22.6 23.5 0.4 25.9 20.9 2.5







TABLE 8

BENNER BAY MANGROVE LAGOON

DIURNAL STUDY, MARCH 21-22, 1970
Temperature (C), Salinity (%o)


8 T A T I O N

TIME 2 4 7 in 11
3T T S T S T 8 T S T S

0630 26.0 37.6 24.8 37.9 26.0 38.6 25.0 38.1 25.5 38.6 25.0 38.2

0930 26.0 38.3 25.8 37.1 26.0 38.5 26.0 38.3 25.5 38.7 25.0 37.1

1230 26.0 38.3 27.0 37.0 27.0 38.9 26.0 38.3 26.0 41.0 25,.7 37.9

1530 26.5 38.3 27.0 37.3 27.0 38.9 27.0 39.1 27.5 39.7 27.0 38.0

1830 28.5 37.9 26.5 37.2 27.0 39.5 26.0 38.1 26.5 39.3 27.0 38.1

2130 26.0 36.6 25.0 36.6 26.0 37.4 26.0 38.3 26.0 37.6 26.0 36.8

0030 26.0 36.5 25.0 36.5 26.0 38.7 26.0 38.5 26.0 40.1 25.5 37.9

0330 26.0 37.9 25.0 37.0 26.0 37.8 26.0 37.2 25.5 38.6 25.0 36.9

0630 2-.5 38.0 25.0 38.3 26.0 39.1 26.0 38.3 25.0 38.0 25.0 41.0







TABLE 9

BENNER BAY MANGROVE LAGOON

DIURNAL STUDY, MARCH 21-22, 1970
Dissolved Oxygen (mg. /1) and' % Saturation


A T A T I n N


%S t DO %Bt


0630 6.3 97 5.3 80 6.1 94 5.6 85 4.7 70 5.4 82

0930 6.3 97 7.0 106 6.5 100 5.9 91 4.6 69 5.6 84

1230 6.3 97 7.9 122 6.8 106 6.7 103 5.5 86 6.1 94

1530 7.8 122 8.1 126 7.5 117 7.3 114 7.8 124 7.6 119

130 8.2 128 7.8 120 7.8 122 6.8 105 7.1 111 7.4 115

2130 7.5 114 5.9 88 7.1 107 6.7 103 6.5 99 7.3 110

0030 6.7 102 5.7 85 6.9 106 5.8 89 5.4 83 6.5 100

0330 6.3 100 5.5 82 6.3 97 6.1 92 4.7 70 5.4 81

0630 6.5 100 5.7 87 5.5 1 85 5.7 88 5.4 82 5.5 85


I tl17 I~0R.y IflAIrLy.,I el


f
L-








TABLE 10

BENNER BAY MANGROVE LAGOON

DIURNAL STUDY, MARCH 21-22, 1970
pH


STATION

'lIME 2 4 7 9 10 1

0630 8.4 8.3 8.2 8.4 8.4 8.4

0930 8.4 8.:; 8.2 8.4 8.1 8.2

1230 8.3 8.4 8.2 8.3 8.2 8.2

1530 8.4 8.4 8.4 8.3 8.2 8.2

1830 8.3 8.5 8.2 8.3 8.4 8.4

2130 8.2 8.2 8.1 8.2 8.2 8.2

0030 8.4 8.4 8.2 8.2 8.2 8.4

0330 8.4 8.4 8.2 8.3 8.3 8.4

0630 8.4 8.4 8.4 8.4 8.4 8.4







TABLE 11

BENNER BAY MANGROVE LAGOON

DIURNAI. STUDY, APRIL 20-21.1970
Temperature (C), Salinity (%o)


TIME


11 S T AT T N


2 4 7 9 10


TI S


T S


T S


T S


0600 26.5 37.1 25.5 37.1 29.5 38.4 28.0 38.4 27.0 Q 9.Z 7.9 38.9

0900 26.5 36.9 26.5 37.9 28.5 38.6 28.0 38.8 27.0 39.6 27.5 37.1

1200 26.5 38.4 28.0 38.9 28.5 37.9 27.5 38.1 27.5 39.6 27.0 37.3

1500 27.0 37.3 29.0 38.6 129.0 38.9 28.5 39.2 28.0 39.5 28.0 38.8

1800 27.4 38.9 28.0 37.3 28.1 38.6 28.0 37.7 28.0 39.9 28.8 -

2100 27.5 36.9 27.0 37.7 28.3 38.4 27.4 37.9 27.5 39.8 28.5 36.9

2400 26.2 37.1 26.5 36.1 28.0 38.4 27.5 37.5 27.5 39.8 27.5 36.3

0300 27.0 16.5 26.3 36.6 28.0 37.9 27.4 38.4 27.0 39.4 26.5 37.9

0600 26.2 .35.5 26.2 36.9 26.0 39.1 27.0 38.6 26.5 39.6 26.0 37.9








TABLE 12

BENNER BAY MANGROVE LAGOON

DIURNAL STUDY, APRIL 20-21, 1970
Dissolved Oxygen (mg. /I) and % Saturation


STATI ON

TIME 2 7 9 10 11

- .O. %Sat. .O. at. D.O. Sat. D.O. %Sat D.O. %Sat D.O. %Sat.

0600 6.5 99 4.9 73 5.7 92 5.1 81 4.5 70 6.0 94

0900 6.5 97 6.2 94 5.6 88 5.8 92 5.2 81 6.4 102

1200 6.6 102 7.3 116 6.6 103 6.1 97 6.7 106 5.2 80

1500 6.5 100 7.5 119 7.1 114 6.9 111 8.0 127 6.8 10B

1800 7.7 117 7.3 116 6.7 106 6.2 98 6.7 108 7.0 113

2100 7.4 112 6.5 102 6.2 98 6.2 97 5.7 92 7.0 113

2400 7.4 112 0.0 91 6.2 98 6.1 97 5.6 90 6.7 105

0300 6.3 97 6.2 93 5.7 90 5.9 92 5.3 83 5.5 86

0600 0.1 92 0.1 92 5.8 89 5.4 84 4.5 70 5.5 85
I I- -I






TABlIJ 13

BIINNI:R BAY MANGROVE [AGOON

DIURNAL STUDY, APRIL 20-21, 1970
pH


8 TA T ION 0


0900 8.4 8.3 8.2 8.2 8.1 8.4

1200 8.4 8.5 8.3 8.2 8.4 8.4

1500 8.2 8.2 8.0 8.1 8.2 8.1

1800 8.3 8.4 8.1 8.2 8.1 8.3

2100 8.3 8.3 8.1 8.1 8.1 8.3

2400 8.2 8.0 8.0 8.0 7.9 8.2

0300 8.1 8.0 7.9 7.9 7.9 8.0

0600 8.0 8.0 7.9 7.9 7.8 8.0


9


4 7 9 10 11







TABLE 14
BENNER BAY-MANGROVE lAGOON
MEANS. MINIMA. MAXIMA. AND RANGES OF VARIABLES
MEASURED DURING DIURNAL STUDIES


Air


Water Tem
o
C


y tinilaS t


STATION STATION
2 4 7 9 10 11 2 4 7 9 10 11
1970
22.0 25.5 24.8 26.0 25.0 25.0 25.0 36.5 36.5 37.4 37.2 37.6 36.8
28.0 26.5 27.0 27.0 27.0 27.5 27.0 38.3 38.5 39.5 39.1 41.0 41.0
24.1 26.1 25.7 26.3 26.0 25.8 25.7 37.7 37.2 38.6 38.2 39.1 38.0
6.0 1.0 2.2 1.0 2.0 2.5 2.0 1.8 2.0 2.1 1.9 3.4 4.2


1970
24.0 26.2 25.5 28.0 27.0 26.5 26.0 35.5 36.1 37.9 37.5 39.2 36.3
29.5 27.5 29.0 29.5 28.5 28.0 28.5 38.4 38.6 39.1 39.2 39.9 38.8
26.4 26.8 27.0 28.2 27.4 27.3 27.6 37.0 37.2 38.5 38.9 39.6 37.9
5.5 1.3 3.5 0.5 1.5 1.5 2.5 2.9 2.5 1.2 1.7 0.7 2.5

D.O. mIg/, p-H
STATION STATION
2 4 7 9 10 11 2 4 7 9 10 11
1970
6.3 5.3 5.5 5.6 4.6 5.4 8.2 8.2 8.1 8.2 8.1 8.2
8.2 8.1 7.8 7.3 7.8 7.8 8.4 8.5 8.4 8.4 8.4 8.4
6.9 6.5 6.7 6.3 5.7 6.3 8.4 8.4 8.2 8.3 8.3 8.3
1.9 2.8 2.3 1.7 3.2 2.2 0.2 0.3 0.3 0.2 0.3 0.2


1970
6.1 4.9 5.0 5.1 4.5 5.2 8.0 8.0 7.9 7.9 7.8 8.0
7.7 7.5 7.1 6.9 8.0 7.0 8.4 8.5 8.3 8.2 8.4 8.4
6.8 6.4 6.2 6.0 5.9 6.2 8.2 8.2 8.1 8.1 8.1 8.2
1.6 2.6 1.5 1.8 3.6 1.8 0.4 0.5 0.4 0.3 0.6 0.4


3/21-2:',
Min.
Max.
MeRan
Range


"/21-22,
Mim.
Max.
Mean
Range


1/20-21,
1 in.
Max.
Mean
lange





TABLE 15

BENNER BAY MANGROVE LAGOON
MONTHLY AVERAGES FOR WATER
QUALITY PARAMETERS


STATION
1 2 1 3 1 4 5 6 7 8 9 10 Ii

2S. 2. 6.9 27.3 1 21.5 28.1 27.5 k 27.7 27.8 27.6 27.3 26.7


.viamcn 1. 26.5 1 2T.4 26.3 .. .e 26.5 1 27.1 1 20.5 1126.6 1 26.0 26.2
May 27.9 27.9 28.2 28.2 29.2 29.1 29.4 29.2 29.6 30.7 29.2

F 2b. 36.6 37.0 36.6 3&.6 37.2 37.0 37.1 37.1 37.3 37.5 36.3
March 37,0 37.0 36.5 36.8 37.0 27.5 37.0 37.3 37.2 37.8 36.8
May 36.8 36.8 36.9 35.1 36.0 36.6 3 36.7 36.6 35.0 25.9 32.6
June 35.2 33.7 35,0 35.8 33.6 34.4 33.7 33.6 31.7 22.1 35.3
July 32.8 32.7 33.0 32.6 33.0 32.7 32.7 29.8 35.9

Ceb. 8.3 6.4 7.2 6.7 6.3 6.1 6.2 5.8 6.3 6.1 6.4
March 6.5 6.4 6.8 6.6 6.6 6.5 6.6 6.0 6.7 6.0 6,3
May 6.3 6.1 6.5 6.5 6.1 6.0 6.0 6.0 6.8 5.8 6.5

Yob. 8.3 8.3 8.4 8.4 8.3 8.2 8.2 8.1 9.3 8.2 8.3
Ma rch .3 _8.4 8. .--8 T3 8.3 3.3 8.2 a. -
May 8.4 8.3 8.3 8.3 8.3 8.4 8.3 8.3 8.4 8.2 8.3

Feb. 10.7 5.6 1.9 2.0 1.0 1.3 1.0 0.9 1.3 0.8 1.3
iMarh 10.7 5.7 1.9 2.0 1.0 12 1.0 1.3 1.7 0.8 1.3
ay a 9.9 5.7 1.9 1. 1.0 1. 0 0. 0.8 1.4 0.5 1.1

Feb. IV I V VIII XIV XVI XVII XV XVI XVIII IV
a .rh .1 ...V. xv i.I


41.9 27.2 21.0 24.0 23.2 39.9 41.2 41.5 39.8 142.1 23.6
13.7 28.5 22.1 19.6 11.7 27.1 119.8 19.1 19.4 50.6 15.2


21.6


22.9


12.6 22.6 1 23.5


0.4 1| 25.9 || 20.9 2.5


-* ____ B ____ ~ ____ ~l ____ 99 ____ 99 ____ 19


Temp.
C



SlBnity
PPt.




D. 0.
mg1 I


PH


Secchl Depth
Meters


Suspended
Solids
mg/1


1970


- ILL -V


A VI XVU I| AX








S T TIO0MAAS


Ha2mLoilik [S

















Al.1

lit'.
44






AQ1M Al





























FIGURE 3

Sompla "s toti..:,


















f+.: .~.5


FIGURE 4
Benner Bay-Mangrove Lagoon
Ranges of monthly averages
for Temp.(Feb.-May) and Sal.
(Feb.-Jul.) rt'c/r y,






I I . I I I I. I I I I I I I I


38




37



36



35








33



32 r




31




30


2/12.17 19 24 26 3/4 10 5/11 15 18 20 23 25 29 6/19 25 29 7/1
13 23

Figure 5. Salinity changes during study period in Benner
Bay Mangrovo Lagoon. Average for 11 stations.














0 *












e-f - -r -e -d o3

meag .... ri''"" FIGURE 6
li.salt pond 4 Benner Bay-Mangrove Lagoon
salt n>d Monthly averages of salinity
s nd luvisum Feb. to July. 1970
SIto nearest 05 esa





r- U


STA.
140 1
2
a
A4

120 .
XA 7

S}* 10
100 *11




gso



60
60 .
IA




S* A


20 A


D I o


5/11 13 15 I8 20 23 25 29 6/19 ?k 25 29 7/1 .9

Figure 7. Suspended solids following flooding, Benner Bay Mangrove
Lagoon. Line is plot of average values. Particle size greater than
0.45 micron.























































6 9 12 15 19 21 24 3

Figure 8. Air temperature and sunlight intensity during
diurnal studies. Solid lines March 21-22, broken lines
April 20-21, 1970









9.0 -


7.0 -




0 5.0


4.0 -


41


40


' 39




37 -_.e --




9.0


8.0 - -


29


28-




27



6 9 12 15 10 21 24 3 6h

Figure 9. Sttion 2. Diurnal variables measured at Benner
Bay Mangrove Lagoon. Solid lines March 21-22, 1970, broken
lines April 20-21, 1970. O indicates n.0 saturation points,









8.0 -



Q~ ~ -. -^
7.0 -





4.0 -

41 -

40 -

39


S 38 ..

37

" 5- -
36 -

9.0 -

8.0 -

ou 29

28 40


. 27-





6 9 12 15 18 21 24 3

Figure 10. Station 4. Diurnal variables measured at Benner
Bay Mangrove Lagoon. Solid lines March 21-22, 1970, broken
lines April 20-21, 1970 0 indicates n.0 saturation points.






II I I I I I I















41 -









3S
3. "



31

9. -





8.



23-
S --- --- -- --- | -- 1 --- --- ---- [












6 9 12 15 18 21 24 3 6h

Figure 11. Station 7. Diurnal variables measured at Benner
Bay Mangrove Lagoon. Solid lines March 21-22, 1970, broken
lines April 20-21, 1971. 0 indicates D.0 saturation points.






II i I I i I




78.


6.0 .


N. %


9. 0


- -
-


- --. -


- -


6



6 9 12 15 1B 21 24 3 6h

Pigure 12. Station 9. Diurnal variables measured at Benner
Bay Mangrove Lagoon. Solid lines March 21-22, 1970, broken
lines April 20-21, 1970. O indicates D.0 saturation points


4.d-












7.0-


6.0 -




4.0 -


41




39 -


38-


37-


36-


9.0-


8.0-


29-


2 -



2-




6 9 12 15 18 21 24 3

Figure 13. Station 10. Diurnal variables measured at Benner
Bay Mangrove Ligoon. Solid lines March 21-22, 1970, broken
lines April 20-21, 1970. 0 indicates D.0 saturation points.

















S5.0 -


4.0 -


41 -


40 -


39 -







36 -


9.0 -

8.0 -


29 -


S28-


27





S 9 12 15 21 24 3

Figure 14. Station 11. Diurnal variables measured at Benner
Bay Mangrove agoon. Solid lines March 21-22 1970 broken
lines April 20-21, 1970. 0 indicates M .o saturation points.








RACE ~g








*5
















M~mangrove .9FIGURE15
Ij.IJJ~t pond B nlhO BaV-Mangrove Lagoon

saiidv allu~ir .-10A Suggested Land Us.










- - rrnr-r -


nreAcyp dom..c




~masngrove !2
IO atpond
sandy alluvium


FIGURE 16
Bonner Bay-Mangrove Lagoon
Distribution of
Benthic Communities


AL




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