Oyster Bed Distribution as a Long Term

;;;;;
;;;;;
;;;;;
;;;;;
;;;;;
;;;;;
;;;;;
;;;;;
;;;;;
;;;;;
;;;;;
;;;;;
;;;;;
;;;;;
MARINE
TECHNICAL
REPORT
NUMBER 01-1
Oyster Bed
Distribution
as a Long Term
Environmental
Indicator for the
Duplin River,
Sapelo Island
National Estuarine
Research Reserve
Randal L. Walker
and Charles Cotton
I785
School of Marine Programs
Athens, Georgia
Oyster Bed Distribution as a Long Term Environmental Indicator for the Duplin River, Sapelo Island National Estuarine Research Reserve
Randal L. Walker
and
Charles Cotton
The Technical Report Series is issued by The University of Georgia. It was established to provide
dissemination of technical information and progress reports resulting from marine studies and
investigations mainly by staff and faculty of the University System of Georgia. In addition, it is
intended for the presentation of techniques and methods, reduced data, and general information
of interest to the industry, local, regional, and state governments and the public. Information
contained in these reports is in the public domain. If this pre-publication copy is cited it should
be cited as an unpublished manuscript.
Acknowledgments
The authors would like to thank the following people for their aid in determining field estimates
of oyster bed size within the Duplin River: A. Mellor, T. Recicar, M. Sweeney-Reeves, and
Dodie Thompson. We also acknowledge Dr. A. Chalmers’ help in developing the GIS database.
The manuscript was reviewed by C. Belcher, K. Gates, and M. Thoresen and their efforts to
improve the manuscript are appreciated. The efforts of the Georgia Sea Grant Communicators,
David Bryant, George Davidson, and Charlotte Ingram in editing and producing the final report
are appreciated. This work was made possible by funding from the Sapelo Island National
Estuarine Research Reserve Program under Coastal Resources Division NOAA Grant 87 OZ
0115 with support from the Turner Foundation and the Sapelo Foundation.
Abstract
A survey of the Duplin River oyster resource within the Sapelo Island National Estuarine
Research Reserve yielded 209 oyster beds covering a total area of 43,567 m2 or 4.4 ha. Beds
ranged in size from 3,555 m2 to 3.2 m2 with a mean size of 208.5 ± 33.7 (SE) m2. Within the total
area of beds, live oysters covered 13,124 m2 or 1.3 ha. Of the 209 beds, 12 beds had no live
oysters (range from 10 to 2,268 m2, mean = 249 ± 177 m2), while other beds had from 1% to
100% coverage by live oysters. Overall coverage by live oysters within beds in the Duplin River
was 30.1%. The mean coverage by live oysters was 62.8 ± 6.9 m2 with areas of live oysters
ranging in size from 0.56 to 677.7 m2. Comparison of this data to previous oyster surveys is
difficult because of different sampling methods and incomplete data reporting. Drake (1891)
reported 8.9 ha of oyster beds within the Duplin River. According to Drake’s estimate, massive
amounts of oyster reefs have disappeared since the turn of the century. However, we believe that
Drake’s estimate was unrealistically high. The effects of commercial harvesting and storm or
erosional activities could account for some oyster bed losses, however the disappearance of over
4 ha of oyster beds from within the Duplin River seems excessively high considering the characteristics of the area. Furthermore, other oyster survey reports state that little change in overall
oyster bed distribution had occurred by 1926 or 1967. It appears the overall area of oyster beds
within the Duplin has remained fairly constant, but that the coverage by live oysters has decreased significantly due primarily to past commercial fishing activities. The results of this
survey will provide future researchers with the exact locations and dimensions of currently
existing oyster beds so that they can document future changes to the oyster population within the
Duplin River of the Sapelo Island National Estuarine Research Reserve.
List of Figures
Figure 1.
The location of oyster beds within the Duplin River of the Sapelo Island National
Estuarine Research Reserve. Each dot represents a GIS data point recorded on a
CD-ROM along with the particular attributes of individual beds: length, width and
percent live coverage.
Figure 2.
The location of oyster beds within the lower third of the Duplin River of the
Sapelo Island National Estuarine Research Reserve. Each dot represents a GIS
data point recorded on a CD-ROM along with the particular attributes of individual beds: length, width and percent live coverage.
Figure 3.
The location of oyster beds within the middle third of the Duplin River of the
Sapelo Island National Estuarine Research Reserve. Each dot represents a GIS
data point recorded on a CD-ROM along with the particular attributes of individual beds: length, width and percent live coverage.
Figure 4.
The location of oyster beds within the upper third of the Duplin River of the
Sapelo Island National Estuarine Research Reserve. Each dot represents a GIS
data point recorded on a CD-ROM along with the particular attributes of individual beds: length, width and percent live coverage.
Figure 5.
The location of live patches of oysters within much larger areas of dead shell in
the Duplin River of the Sapelo Island National Estuarine Research Reserve.
Each dot represents a GIS data point recorded on a CD-ROM along with the
particular attributes of individual beds: length, width and percent live coverage.
List of Tables
Appendix I.
Location, size of bed, and percent live coverage for individual oyster beds within
the Duplin River, Sapelo Island, GA.
Table of Contents
Acknowledgments................................................................................................................3
Abstract.................................................................................................................................4
List of Figures.......................................................................................................................5
List of Tables........................................................................................................................6
Table of Contents..................................................................................................................7
Introduction...........................................................................................................................8
Objective...............................................................................................................................8
Site Description.....................................................................................................................9
Methodology.........................................................................................................................9
Results.................................................................................................................................10
Figures.................................................................................................................................11
Discussion...........................................................................................................................16
References...........................................................................................................................19
Appendix.............................................................................................................................21
Introduction
The eastern oyster, Crassostrea virginica (Gmelin, 1791), is a plentiful bivalve that
ranges from the Gulf of St. Lawrence, Canada to the Gulf of Mexico and to the West Indies
(Abbott 1974). It is abundant throughout its natural range and supports major fisheries in most
areas. Oysters occur in a wide range of estuarine environments inhabiting areas with salinity as
low as 5 ppt to areas at the mouths of estuaries with 40 ppt seawater (Galtsoff 1964). Changes in
oyster abundance and distribution can be used as indicators of environmental change, whether
the alteration is due to fluctuations in natural environmental parameters, overfishing or from
anthropogenically induced changes.
Previous studies by the Marine Extension Service’s Shellfish Aquaculture Laboratory of
oyster population dynamics within the Duplin River, near Sapelo Island, Georgia have shown
that oyster recruitment rates can vary greatly from year to year. The Duplin River and its associated marshes and uplands make up the Sapelo Island National Estuarine Research Reserve
(SINERR). In 1992, oyster recruitment rates as high as 32,000 spat per m2 per month at the
Marsh Landing site were recorded with decreasing rates at two sites farther up the river. However, recruitment rates were an order of magnitude lower the following year, with no recruitment
occurring at the upper river site. In addition, oyster recruitment occurred earlier in the year
during 1993 than in 1992. The same reduction in recruitment and timing of oyster settlement in
1993 was observed in oyster beds 90 km farther north along the Georgia coast in the Wassaw
Sound area. Thus, the difference in oyster recruitment patterns between years was attributed to
natural cyclic events rather than anthropogenically induced causes (O’Beirn et al. 1996).
This project inventoried and mapped the existing oyster beds within the SINERR. Long
term environmental alterations in the Duplin River oyster population can be monitored by measuring changes in the size and shape of individual oyster beds over time. Comparing currently
existing oyster beds with maps of beds from historic records shows the distribution of live
oysters within the Duplin River has declined appreciably (Harris 1980). Some of this change was
caused by overharvesting and mismanagement of oyster beds by the State (Harris 1980). Today,
this area is closed to commercial harvesting.
Objective
The objective of this study was to document the current distribution of oyster beds located within the Duplin River. Distribution of oyster beds was determined from a field survey.
Data was recorded in the GIS database system which the SINERR has been developing to store
information about the environment of Sapelo Island. It is envisioned that this survey will be used
as a benchmark with which to judge any future environmental changes to the oyster beds within
SINERR.
Site Description
SINERR is typical of the coastal Georgia marsh system. It covers an area in excess of
1,255 hectares. The reserve is located to the west of Sapelo Island and incorporates a portion of
high ground to the south and west of the island. The Duplin River is approximately 9.5 km in
length and runs from north to south into Doboy Sound. It has no significant freshwater source
and therefore has been referred to as an elongated tidal bay (Ragotzkie and Bryson 1955). The
reserve also includes the small island called Little Sapelo as well as Mary, Jack, Fishing, Moses
and Pumpkin Hammocks. Also included is the marsh between the Duplin River and Teakettle
Creek up to approximately the area referred to as High Point on the northwestern end of Sapelo
Island, as well as the marsh and creek systems from the mouth of the Duplin River to Dean
Creek on the southwestern end of Sapelo Island. Creeks within SINERR are Barn, Dean, Factory,
Lighthouse, Oakdale, Mary, and Post Office Creeks.
Methodology
All eastern oyster beds were sampled from the mouth of the Duplin River to its upper
extent except for those occurring in waters less than 0.3 m at low tide or less than 3 meters in
overall length and width. Sampling for oyster beds within the Duplin River watershed was
conducted with a 21-ft Carolina Skiff. Data were collected from August 1999 to August 2000.
Two individuals measured the length, defined as the distance parallel to the adjacent river or
creek and the width which was measured at the widest point of each oyster bed. The area of the
bed was calculated based on an oval shape using the following formula:
Area = [(length/2)(width/2)]π
A Bushnell Yardage Pro 500 laser range finder was used to measure length and width of the
oyster beds. The manufacturer claims an accuracy of one meter, which agrees with our field
trials. The Yardage Pro does not function at distances less than 18 meters. For small-sized oyster
beds, a fiberglass measuring tape was used to determine bed dimensions. Using the measured
dimensions of the bed, the exact center was located and marked. Once an overall area for the
entire oyster bed was determined, the percentage of live oysters was estimated visually. A
Trimble Geoexplorer II GPS was used to record the position of the bed. A researcher stood on the
center of the bed and logged 150 positions. The length and width measurements for the beds and
percent live approximation were input as attributes to the GPS file while logging the 150 positions.
In some cases, the dimensions of the oyster bed was difficult to determine due to scattering of shells or burial of shell or oysters by mud. In those cases, the end of the bed was determined to be the point where oyster shells were not contiguous but were scattered in the mud. In
the case of mud burial, the endpoint was determined to be the point at which shells could no
longer be seen. No effort was made to excavate shells that may or may not have been buried. In
some cases, a creek mouth would intersect an oyster bed, making the end point determination
difficult. Where this occurred, the creek was said to bisect the oyster bed with the resulting
abutted oyster beds having a common end at the mouth of the bisecting creek.
The section of the Duplin River near Doboy Sound tended to be dominated by large
berms of dead oyster shell, containing patchy areas of live oysters. These berms were surveyed
and recorded in the same fashion as other oyster beds. Live patches of oysters were often part of
the larger oyster beds, but were separately surveyed and recorded by GPS. To differentiate, these
files and GPS positions were referred to as “Live Portion” while all other beds were referred to
as “Entire Bed.” Elsewhere in the Duplin River, live oysters tended to be dispersed equally about
the oyster bed, so it was unnecessary to record a “Live Portion.” The positions of the entire beds
are colored differently than the live portions in the GIS overlay, so they can be easily distinguished. Each position, indicated by a colored point, is linked to attributes of that position so
that the user can click on a point and see the length, width, and percent live coverage of a given
oyster bed.
The raw GPS positions were transferred from the Trimble GPS unit to a Dell Dimension
XPS T600 computer using Trimble Pathfinder Office 2.10 software. For each oyster bed surveyed, 150 positions were averaged and differentially corrected to achieve a single position with
final accuracy of approximately 1 - 3 meters. The differentially corrected GPS positions were
exported into Arcview GIS 3.1 software where the GPS positions were overlaid on a digital
orthophoto map of the Duplin River. The projection of the map is UTM and the datum is North
American Datum 1983.
Results
The location of the various oyster beds within the Duplin River are shown in Figure 1 and
listed in Appendix I. Beds occur from the mouth to the headwaters of the Duplin River but, in
general, decrease in both number and size as one reaches the headwaters. Many bed locations are
so close together that they appear to merge (Figure 1). Figures 2 through 4 show the distribution
of beds within the lower, middle and upper segments of the Duplin River, respectively.
A total of 209 oyster beds (Appendix 1) was located within the Duplin River covering a
total area of 43,567 m2 or 4.4 ha. Beds ranged in size from 3,555 m2 to 3.2 m2, with a mean size
of 208.5 ± 33.7 (SE) m2. Of the total bed area, live oysters covered 13,124 m2 or 1.3 ha. Of the
209 beds, 12 beds had no live oysters (ranging in size from 10 to 2,268 m2, with a mean of 249
± 177 m2), while the remaining beds had from 1% to 100% coverage by live oysters. Overall
coverage by live oysters within Duplin River beds was 30.1%. The mean coverage by live
oysters was 62.8 ± 6.9 m2 with areas of live oysters ranging in size from 0.56 to 677.7 m2.
Near the mouth of the Duplin River, oyster beds are massive, but composed of mostly
dead shell with sparse patches of live oysters mixed amongst the shell wash. Figure 5 shows the
locations of these live oyster patches, which range in size from 10.2 to 496 m2, amongst the
larger dead shell areas.
FIGURE 1 The location of oyster beds within the Duplin River of the Sapelo Island National Estuarine
Research Reserve. Each dot represents a GIS data point recorded on a CD-ROM along with the
particular attributes of individual beds: length, width and percent live coverage.
FIGURE 2 The location of oyster beds within the lower third of the Duplin River of the Sapelo Island
National Estuarine Research Reserve. Each dot represents a GIS data point recorded on a CD-ROM
along with the particular attributes of individual beds: length, width and percent live coverage.
FIGURE 3 The location of oyster beds within the middle third of the Duplin River of the Sapelo Island
National Estuarine Research Reserve. Each dot represents a GIS data point recorded on a CD-ROM
along with the particular attributes of individual beds: length, width and percent live coverage.
FIGURE 4 The location of oyster beds within the upper third of the Duplin River of the Sapelo Island National
Estuarine Research Reserve. Each dot represents a GIS data point recorded on a CD-ROM along with the particular
attributes of individual beds: length, width and percent live coverage.
FIGURE 5 The location of live patches of oysters within much larger areas of dead shell in the Duplin River
of the Sapelo Island National Estuarine Research Reserve. Each dot represents a GIS data point recorded
on a CD-ROM along with the particular attributes of individual beds: length, width and percent live coverage.
Discussion
Little change in the distribution of oysters in Georgia was noted from 1891 to 1967
(Linton 1969); however, apparently observable declines in the population have been reported
since 1967 by Harris (1980). The first oyster distribution study was performed by Drake in 1891.
He observed a decline in live oyster beds in Georgia, especially in areas near the oyster houses.
The Georgia oyster industry peaked in 1908 when 8 million pounds of meat were landed mostly
for the canning industry (Harris 1980). By 1910, landings had dropped to 3 million pounds, and
since then they have continued to decline. Only 6,956 pounds of oyster meat was landed in
Georgia in 1998 (Georgia Department of Natural Resources). Galtsoff and Luce (1930) noted in
their 1925 study of Georgia oysters that little had changed in terms of oyster distribution between
1891 and 1925. Galtsoff and Luce (1930) did not provide any data to substantiate their claims,
and were simply reporting general observations. Linton (1969) in his study of oysters also reported few changes in oyster distribution within coastal Georgia; however, he reported a total of
4,130 hectares of oysters as compared to only 700 hectares reported by Drake (1891). As pointed
out by Harris (1980), it is unlikely that the oyster population had grown between 1891 and 1969.
In fact it is reasonable to assume that: the oyster population declined considerably (Sullivan
1997) due to heavy fishing pressure. Bahr and Lanier (1981) in their oyster reef ecological study
state “In summary, reef distribution along the Georgia coast surprisingly has changed little over
the last 90 years. Oyster reefs occur (in general) today in approximately the same locations
where they occurred in 1889........ The living oyster reef area, however, significantly has declined
in the same period.”
Our survey of the oyster distribution within the Duplin River yielded 43,567 m2 (4.4 ha)
of oyster beds with 13,124 m2 (1.3 ha) of that total being comprised of live oysters. Our numbers
differ from previous studies. Harris (1980) reported 9,632 m2 or 1.0 ha of live oysters in the
Duplin River; whereas Drake (1891) reported 8.9 ha of oysters presumably both live and dead
shell areas. Bahr (1974) estimated 6,040 m2 of live oysters within the river which accounted for
0.06% of the Duplin River marsh and river area of 11,420,000 m2. Bahr’s (1974) estimate was
based upon a two day boat survey with apparently no actual direct measurements of beds.
Linton’s (1969) oyster distribution gave no estimates of oyster bed coverage per body of water,
but estimated that 4,130 ha of live oysters occurred in Georgia. According to the oyster distribution maps generated from Linton’s survey (found in Johnson et al. 1974; appendix vi, figure 35a
to 35 h), no oysters occurred farther up the Duplin River than Pumpkin Hammock; whereas
Harris (1980) shows several sizeable beds in the upper reaches of the river. Our survey found
many small beds in the upper reaches of the River in areas that both Harris (1980) and Linton
(1969) reported finding no oysters.
The Sapelo Island residents talk of days past when the headwaters of the Duplin River
were fed by freshwater aquifers which flowed into the Duplin River. They also claimed that
freshwater fish could be caught in the headwaters of the Duplin River. However, these aquifers
have dried up and island residents claim that the construction and operation of pulp mills were
responsible for the end of the surface-discharging aquifers (Evans, 1985). The loss of freshwater
input into the headwaters of the Duplin River could account for the gradual movement of oyster
beds into this area over time, however, there are no long-term salinity records for the Duplin
River to support this possibility.
The most complete oyster survey of the Duplin River prior to this report was conducted
by Harris (1980). Harris reports 9,632 m2 of live oyster beds in the Duplin River (Table 1), but
shows 11,324 m2 on the map of Sapelo Island. As noted on the map of the Duplin River in
Harris’ (1980) report, many of the areas in the upper Duplin River were marked as having sparse
or very sparse densities of live oysters. Perhaps the total area of oyster beds listed on the map
was adjusted downwards to correct for the observed sparsity of live oysters in some beds. This
correction may account for the discrepancy in the stated value in Table 1 of Harris’ report and
that listed on the map. Our estimate was 13,124 m2. Harris determined the area of oyster beds by
a rectangular formula, length by width; whereas we used an oval formula. Correcting for the
difference in formulas used to determine area (0.7854), we arrived at an adjusted mean for total
live coverage of 16,556 m2. Our adjusted estimate is substantially greater than Harris’ (1980)
estimate. It is our belief that our higher estimate is due to a more accurate survey than that
performed by Harris (1980) rather than to the formation of new beds. Harris (1980) relied on
aerial photos to mark beds and to determine their size; we made on-site measurements of each
bed.
Drake (1891) reported 8.9 ha of oysters within the Duplin River; whereas, we reported
only 4.4 ha. Assuming that Drake’s estimate was accurate, in just over a century, half of the
oyster beds within the Duplin River have vanished. Overfishing certainly has taken its toll on the
oyster population in Georgia and commercial harvesting of oysters within the Duplin River had
occurred (Sullivan 1997). An oyster shucking house opened by Howard Coffin in 1922 on
Sapelo Island remained in operation until 1934 (Sullivan 1997). Declines in live oysters near
oyster houses have been noted as far back as 1891 by Drake, however, this does not explain the
vast difference in oyster bed area between 1891 (8.9 ha) and 2000 (4.4 ha). Bahr (1974) plotted
the distribution of oysters within the Duplin River compared to beds mapped by Drake (1891).
Many beds located by Drake (1891) contained no live oysters by 1974. This observation led Bahr
and Lanier (1981) to conclude the overall area of oyster beds within the Duplin River had not
changed that much, but a decrease in the live oysters within the beds had indeed occurred over
time. Harris (1980) also reported massive oyster beds in areas where today, few beds exist. Along
the east bank of Little Sapelo Island in the Duplin River, Harris (1980) reported a massive 2,652
m2 bed. Today most of this area houses scattered oyster beds, and obvious signs of river bank
erosion are present. Oyster beds may well have been lost over time to storm events and natural
erosional processes as well as commercial activities. It is hard to believe that harvesting and
erosion could account for the loss of 4 ha of oyster beds within the Duplin River in a century. As
a result, we believe that Drake’s (1891) estimate of 8.9 ha of oyster beds within the Duplin River
was unrealistically high.
Since this project was designed to examine long-term changes in the Duplin River oyster
population, we made no estimates of individual oyster bed density. Oyster density on any par-
ticular bed will change radically with each season. During spawning season, oyster densities will
increase rapidly due to recruitment. Recruitment rates as high as 32,000 spat per m2 per month
have been recorded in the Duplin River (O’Beirn et al. 1996, 1997). Oyster densities decrease
rapidly in the fall as mortalities from the oyster disease Perkinsus marinus increase. Numbers
will stabilize over winter and increase again during the next spawning season which lasts from
May to October (Heffernan et al. 1989; O’Beirn et al. 1994, 1996, 1997).
This report and its corresponding GIS database will provide a benchmark for future
oyster bed surveys. In all previous oyster surveys of the Duplin River, the exact location of beds
was not reported. Most oyster bed positions were marked according to their relationship to
natural structures, such as creek branches and hammock locations. All beds in this study were
plotted by longitude and latitude according to the determination of the exact center of the bed. In
the future, researchers can relocate the exact spot from which we determined the bed size and remeasure the bed to determine its increase or decrease in overall coverage. This GIS database for
oyster beds will provide baseline information crucial for determining the future impacts of
environmental changes on the Sapelo Island National Esturaine Research Reserve.
Copies of the GIS database for oyster distribution within the Duplin River of the Sapelo
Island National Estuarine Research reserve can be obtained by contacting the offices of either:
Sapleo Island National Estuarine Research Reserve
P.O. Box 15
Sapelo Island, GA 31327
(912) 485-2251
or
Marine Extension Service
School of Marine Programs
University of Georgia
220 Marine Science Building
Athens, GA 30602-3636
(706) 542-8849
References
Abbott, R.T. 1974. American Seashells, second edition. Van Nostrand Reinhold Company, New
York.
Bahr, L.M., Jr. 1974. Aspects of the structure and function of the intertidal oyster ref community
in Georgia. Dissertation, University of Georgia, Athens, 149 pp.
Bahr, L.N. and W.P. Lanier. 1981. The ecology of intertidal oyster reefs of the south Atlantic
Coast: A community profile. U.S. Fish and Wildlife Service, Office of Biological Services,
Washington D.C. FWS/OBS-81/15. 105 pp.
Drake J.C. 1891. On the sounds and estuaries of Georgia with reference to oyster culture. U.S.
Coast and Geodetic Survey Bull. 19, 1891. Pp. 179-209. Washington D.C.
Evans, J. 1985. Changes in wading bird habitat on Georgia islands. Pages 1077-1092, in:
Magoon, O.T. (Ed.), Coastal Zone ‘85: Proceedings of the Fourth Symposium on Coastal
and Ocean Management, Omni International Hotel, Baltimore, Maryland, July 30-August
2, 1985. American Society of Civil Engineers, New York.
Galtsoff, P.S. 1964. The American Oyster Crassostrea virginica Gmelin. Fish. Bull. 64:1-480.
Galtsoff, P.S. and R.H. Luce. 1930. Oyster investigations in Georgia. Report of the United States
Commissioner of Fisheries for 1930, Fisheries Document 1077, 61-100 pp.
Harris, D.C. 1980. Survey of the intertidal and subtidal oyster resources of the Georgia coast.
Georgia Department of Natural Resources, Coastal Resources Division, (Project Number
2-234-R). Brunswick, GA 44 pp.
Heffernan, P.B., R.L. Walker and J.L. Carr. 1989. Gametogenic cycles of three marine bivalves in
Wassaw Sound, Georgia: II. Crassostrea virginica (Gmelin, 1791). Journal of Shellfish
Research 8: 61-70.
Linton, T.L. 1969. Inventory of the intertidal oyster resources of Georgia. Pages 2-6, In: Linton,
T.F. (Ed) Feasibility Study of Methods for Improving Oyster Production in Georgia. Final
Report, Marine Fisheries Division, Georgia Game and Fish Commission and the University of Georgia.
O’Beirn, F.X., R.L. Walker and M.L. Jansen. 1997. Reproductive biology and parasite (Perkinsus
marinus) prevalence in the eastern oyster, Crassostrea virginica, within a Georgia tidal
river. Journal of the Elisha Mitchell Scientific Society 113: 22-36.
O’Beirn, F.X., R.L. Walker, M,L. Jansen and C.R. Spruck. 1996. Recruitment, gametogenesis
and parasite (Perkinsus marinus) prevalence in the eastern oyster, Crassostrea virginica,
within the Sapelo Island National Estuarine Research Reserve. School of Marine Programs, Marine Technical report 96-1. Athens, GA
O’Beirn, F.X., P.B. Heffernan and R.L. Walker. 1994. Recruitment of Crassostrea virginica: A
tool for monitoring the aquatic health of the Sapelo Island National Estuarine Research
Reserve. School of Marine Programs, Marine Technical report 94-2. Athens, GA
Ragotzkie, R.A. and R.A. Bryson. 1955. Hydrography of the Duplin River, Sapelo Island, Georgia. Bull. Mar. Sci. Gulf and Carib. 5:297-314.
Sullivan, B. 1997. Early Days on the Georgia Tidewater. The Story of McIntosh County &
Sapelo. Published by the McIntosh County Board of Commissioners, 5th Edition, Darien
Printing and Graphics, Darien, GA.