Physical and ecological characterization of the Charleston Harbor estuarine system final report submitted to the South Carolina Coastal Council, Charleston, South Carolina

[From the U.S. Government Printing Office, www.gpo.gov]

APhysical and Ecological

....512 : Characterization
SP-Z5 of the
Charleston Harbor
Estuarine System

Executive
-~0 _ ~Summary

541.5
. E8
1990
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EXECUTIVE SUMMARY

Submitted to
the

South Carolina Coastal Council
Charleston, South Carolina

A PHYSICAL AND ECOLOGICAL CHARACTERIZATION OF THE
CHARLESTON HARBOR ESTUARINE SYSTEM

Edited by

Robert F. Van Dolah
Priscilla H. Wendt
Elizabeth L. Wenner
and P. (I. B
Paul A. Sandifer 217 ME 0 ROA

Submitted by
the

Marine Resources Division
South Carolina Wildlife and Marine Resources Department

in cooperation with PftPerty of csc Library
the

South Carolina Sea Grant Consortium
South Carolina Department of Health and Environmental Control
University of South Carolina
and
The Citadel

May, 1990

This study was funded under Grant #NA87AA-D-CZ068
through the South Carolina Coastal Council
US Department of Commerce
NOAA Coastal Services Center Library
2234 South Hobson Avenue
Charleston, SC 29405-2413

INTRODUCTION reduce the associated sediment load
coming into the estuary.
In 1985, the U.S. Army Corps of
Engineers completed the "Cooper River Several hydrologic changes were
Rediversion Project" which significantly anticipated as a result of the Rediversion
altered hydrologic conditions in the lower Project, including an extension of the
portions of the Santee-Cooper drainage estuarine boundaries and redistribution of
basin. The Charleston Harbor estuary salinity regimes within the estuary,
comprises a major portion of this drainage changes in the vertical mixing and current
basin in the coastal zone of South patterns, a reduction in water levels in the
Carolina (Figure 1) and represents the upper Cooper River, and a decrease in
State's third largest estuary encompassing the dilution and flushing rates of
more than 26,000 hectares of valuable pollutants. These physical changes were
marshlands and open water habitat. also expected to alter the distribution and
abundance of floral and faunal
The harbor system also supports communities in this estuary, including
the state's largest port facilities. These recreationally and commercially valuable
facilities currently make Charleston species of fishes and crustaceans.
Harbor the third largest home port
nationwide for the U.S. Navy and the Concern over the anticipated
second largest commercial port along the changes prompted several studies,
Atlantic seaboard in terms of container including an assessment of selected
cargo handled. Prior to rediversion, the biological communities which was begun
cost of maintaining adequate shipping in 1984 by the Marine Resources Division
channels for the port had increased to of the South Carolina Wildlife and Marine
more than five million dollars/year. Resources Department. This study was
Much of the sedimentation problem was expanded considerably in 1987 in order to
attributed to an earlier water diversion provide a more comprehensive assessment
project completed in 1942 by the South of the Charleston Harbor eatuary. The
Carolina Public Service Authority. This expanded study involved researchers from
project involved construction of two dams several agencies and institutions and
to form lakes Marion and Moultrie and included several major objectives. These
construction of a diversion canal to were to:
connect these lakes (Figure 1).
Approximately 88% of the Santee River 1) Describe the hydrographic
flow was then diverted into the Cooper conditions in the Harbor basin and
River, changing the average freshwater Cooper, Wando, and Ashley River
flow into this river from approximately 2 systems following rediversion, and
to 442 cubic meters/second. identify seasonal changes in basic
water quality parameters
The Cooper River Rediversion throughout these estuaries.
Project, completed in 1985, rediverted
approximately 70% of this water flow back 2) Characterize the nutrient and
into the Santee River system through organic carbon levels and the
another canal at St. Stephens (Figure 1). physical dynamics of the Charleston
This reduced the freshwater flow into the Harbor estuary following
Cooper River to approximately 122 cubic rediversion.
meters/second which, in turn, should

LAKE MARLON a

I~~~~~~~(
Wilson Dam

Diversion Canled .

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0 10 20 30 KNomeier.

South Carolina \
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Figure 1. Map of the lower Santee-Cooper drainage system showing aspects of the diversion and
rediversion system. The Charleston Harbor estuary is shown within the circle.

3) Describe seasonal and yearly with particular emphasis on (a)
changes in the bottom dwelling defining the distribution of
invertebrate communities in the recreationally and commercially
harbor basin and associated river important species of finfish, shrimp
systems, and evaluate the and crabs, and (b) identifying
distribution of these communities patterns of recruitment for some of
in relation to various natural and these species in different portions
anthropogenic environmental of the estuary.
parameters. These studies also
provided information on the 5) Describe changes in the
distribution of surficial sediments macrophyte (plant) communities in
within the estuary. the upper Cooper River where
changes in water levels were
4) Describe seasonal and yearly expected.
changes in the fish and crustacean
communities present in the harbor 6) Document organic and inorganic
basin and associated river systems, contaminant concentrations

throughout the Charleston Harbor nitrite, total ammonia and ortho-
estuary, with particular emphasis phosphate measurements taken at selected
on determining the pollutant levels stations.
in sediments and in the tissues of
important fish, crustacean, and Results indicate that the salinity
molluscan species. levels in the Cooper River and harbor
basin have been much higher since
7) Evaluate the significance of rediversion. On average, the mean
changes resulting from rediversion freshwater line (<0.5 ppt) on the surface
by comparing the post-rediversion was approximately 6 km (3.2 mi.) further
information with data obtained upriver in the Cooper River after
prior to rediversion, where rediversion, and approximately 2.5 km (1.3
available. mi.) further upriver on the bottom. After
rediversion, it appeared that salinity in the
8) Convene a series of research/ harbor basin and Cooper River were
technical workshops to identify and primarily controlled by tidal stage rather
evaluate extant information/data than by freshwater flow. Turbidity levels
sources, with particular emphases at the mouth of the harbor were
on (a) identifying major data needs significantly lower during post-rediversion
and strategies for acquiring needed sampling (approximately 3x lower),
research data, and (b) determining although no significant differences were
the requirements and mechanics observed in the rest of the estuary. No
for establishing a comprehensive significant differences were observed for
information/data base for the nutrient levels in the estuary between pre-
estuary. and post-rediversion sampling.

This document provides a brief Salinities throughout the estuary
overview of the findings from these major exhibited no distinct seasonal trends after
study components. rediversion. Salinities in the Ashley and
Wando Rivers were less stratified than
those in the Cooper River and harbor
HYDROGRAPHY basin. Percent saturation of dissolved
oxygen exhibited distinct seasonal trends
Hydrographic data were collected throughout the system, with highest levels
by the South Carolina Marine Resources occurring in the winter. Lower levels of
Division from surface and bottom depths dissolved oxygen occurred in spring and
as part of the regular trawl and bottom fall, and the lowest levels were recorded
grab sampling conducted from November in late summer. Dissolved oxygen in the
1984 through 1988. A more intensive Cooper River generally decreased upriver
sampling program was completed in 1988 to the middle portion of the river, and
that included monthly surface and bottom then began to increase further upriver. In
measurements from 36 sites throughout addition, the upper Ashley River stations
the estuary during high and low slack exhibited significantly lower dissolved
tides. Hydrographic parameters recorded oxygen saturation levels than those found
included: temperature, specific in the harbor basin. Turbidity levels were
conductance, salinity and dissolved oxygen highest in the upper Ashley River,
at all stations, as well as turbidity, nitrate, somewhat lower in the harbor basin, and

lowest in the Cooper and Wando Rivers. could be explained by variability in river
No seasonal trends in turbidity were flow.
observed at any stations in the estuary.
Surface water turbidity typically
Nutrient levels were generally displayed two peaks related to location in
higher during summer months than during the estuary. A peak in the upper reaches
winter months, although each basin (30-35 km upstream) suggested increased
exhibited unique seasonal changes. Levels flocculation of particulate matter at the
of nutrients were similar in the Cooper upper zone of fresh/salt water mixing. A
and Wando Rivers and harbor basin. second peak in the harbor suggested
Nutrient levels in the Ashley River, considerable influence of turbulence,
however, were significantly higher than resuspension, and influx of particulates
nutrient levels recorded from the rest of from the coastal ocean and from the
the estuary. The upper Ashley River Ashley River. Surface turbidity was
stations exhibited extremely high significantly correlated with concentrations
concentrations of nitrate and ortho- of particulate organic carbon (POC) and
phosphate (often 5-10x higher than the phytoplankton (algae) biomass.
rest of estuary), which decreased in the
seaward direction. Total organic matter in the
estuarine waters was dominated by
dissolved organic carbon (DOC) which
NUTRIENTS AND ORGANIC varied largely between 1 and 10 mg/i with
CARBON a mean of 4.7 mg/l. There were
significant spatial differences in DOC
An intensive study of nutrients, concentrations with higher concentrations
organic carbon, and general water quality in the surface water and in mid-estuarine
was also conducted along the Charleston reaches. Mixing diagrams indicated a net
Harbor/Cooper River estuarine gradient source of DOC within the mid-estuarine
by researchers at the University of South area, especially in the bottom waters,
Carolina. This study involved sampling perhaps related to effluent from the
along a 45-km (24 mi.) transect from the Westvaco paper mill.
mouth of Charleston Harbor up the
Cooper River through industrialized urban Particulate organic carbon (POC)
areas to relatively undeveloped tidal generally constituted approximately 25%
freshwater reaches. During this study of the total organic carbon and varied
period (Feb. 1988-Feb. 1989), freshwater between 0.1 and 4.7 mg/l, with an overall
inflow was highly variable on a daily basis mean of 1.3 mg/l. POC was composed
(0-330 cubic meters/second), although largely of detrital material, except during
seasonal fluctuations were not as great. phytoplankton peaks when algal carbon
accounted for >50% of the total POC.
With reduced flows in the Cooper Seasonal variability in POC was
River (following rediversion), salinities dominated by peaks during the winter and
were less variable and less predictable. summer corresponding to peaks in
However, salinity was still significantly phytoplankton biomass. Phytoplankton
correlated with weekly mean flows. Up to biomass was typically higher in freshwater
55% of the variability in salinity in the areas and declined significantly through
upper and middle reaches of the estuary the estuary, but showed some recovery in

the harbor area. This pattern suggests a were no significant differences between
net loss of freshwater phytoplankton high and low tide levels. Highest NN
through the estuarine areas and a partial concentrations occurred during late
succession to marine and estuarine species summer (August and September).
in the harbor.

The distribution pattern of total PHYSICAL DYNAMICS
POC was dominated by a higher
concentration in the upper portions of the Hydrographic sampling was also
estuary and in the bottom waters. Mixing conducted in the harbor basin and Cooper
diagrams suggested a net loss of POC River to further characterize the physical
from the surface waters to bottom waters dynamics of the estuary. Measurements
in the harbor region. The sinking and included current velocity records and
decomposition of POC from the surface vertical profiles of conductivity,
waters also probably accounts for some of temperature, density, and transmissivity
the observed DOC source in the bottom collected along a longitudinal transect of
waters. the Cooper River and a cross-sectional
transect of the Harbor entrance. A two-
Dissolved phosphorus (P04) varied dimensional numerical circulation/
between <0.01 and 6.0 tug at./I. There dispersion model of the Charleston
were significant spatial trends in P04 estuary was developed and extended to
distribution. Higher concentrations include tidal portions of the Ashley,
observed in the harbor at high tide Cooper, and Wando Rivers. The
suggested a potential oceanic source. numerical model, together with the
Concentrations varied linearly with hydrographic field data and additional
salinity, suggesting a net balance in data obtained from United States
sources and sinks of PO4 through the Geological Survey and National Ocean
estuary. Higher concentrations occurred Survey/National Oceanic and
in bottom waters, with peak levels Atmospheric Administration, are being
occurring in March and July. used to assess salinity responses of the
Charleston Harbor/Cooper River
Dissolved inorganic nitrogen was estuarine system.
composed of slightly higher ammonia
(NH4) concentrations than nitrate/nitrite
concentrations (NN). Ammonia ranged SEDIMENTS
from < 0.01 Ag at./I to 126.5 gtg at./I, with
a mean of 3.78 btg at./I. Higher Sediment samples were collected
concentrations were detected during low throughout the harbor system as part of
tide and in surface waters at mid-estuary the sampling effort to assess benthic
stations. Mixing diagrams suggest a major macrofaunal communities. These samples
source in mid-estuarine areas. Peak NN provided information on the spatial and
concentrations were typically located one seasonal distribution of sediments in the
station below peak NH4 concentrations at harbor system both before and after
low tide and one station above at high rediversion.
tide, suggesting rapid oxidation of the
ammonia entering the estuary in the mid- The four-year seasonal study
estuarine reaches. Unlike NH4, there revealed several non-seasonal fluctuations

in the distribution of surficial sediments in seasonal abundance of benthic organisms
the estuary. Changes in bed material at in the Ashley River and to more
harbor basin stations were attributed to thoroughly evaluate the distribution of
spatial variability rather than temporal benthic communities throughout the lower
(seasonal) fluctuations. All three portion of the estuary in relation to
tributaries reflected a trend towards natural and anthropogenic factors.
sandier sediments proceeding upriver.
This corresponded to a decrease in the Results from the four-year study
percentage of silt and clay with increasing indicate that the spatial distribution of
distance from the river mouth. Possible benthic macrofauna is similar in many
effects of rediversion were noted at the respects to that of other gradient estuaries
lowest station in the Cooper River, where along the mid-Atlantic, southeast, and
the occurrence of fine-grained sediments Gulf coasts of the United States. Cluster
increased during the three-year period and nodal analyses showed clear
following rediversion. distinctions among tidal freshwater, low
salinity (oligo-mesohaline) and high
Results from intensive sampling at salinity (meso-polyhaline) brackish water
178 stations in the harbor basin and lower faunal groups. Within each salinity zone,
portions of each river system were benthic assemblages were further
compared with historical data. The distinguished by their affinities for
northern half of the harbor basin and different sediment types. Temporal
portions of the mouths of the three patterns of distribution and abundance
tributaries were considerably sandier than were not as readily apparent as spatial
before rediversion. Sand was less trends. Although total numbers of
dominant upriver, possibly due to the individuals and species varied greatly
decreased tidal sorting of the sediments throughout the four-year study, no
which allowed more fine-grained materials consistent seasonal or annual periodicity
to settle out. Organic matter was closely in these fluctuations was evident. These
associated with the occurrence of silt- and findings are consistent with observations
clay-size material (fines) both before and made by other researchers that estuaries
after rediversion, but those materials are typically inconstant environments, with
became more widely distributed in all benthic fauna dominated by opportunistic
reaches of the estuary after rediversion, species which characteristically have
based on comparisons with data obtained widely fluctuating abundances. Although
from an earlier study. effects of rediversion on the benthos are
difficult to infer from this study in the
absence of a long-term pre-rediversion
BENTHIC MACROFAUNAL database, comparison of pre- and post-
COMMUNITIES rediversion data collected in this study
and other studies suggests that the
Benthic macrofaunal communities qualitative composition of the
were sampled at several locations within macrobenthos has not changed markedly
the harbor basin, Cooper River, and since rediversion. Despite the lack of
Wando River from 1984 through 1988 to evidence for drastic alterations of the
evaluate seasonal and yearly changes in benthos, a few of the dominant species
these assemblages. Additional sampling appeared to exhibit a trend toward
was also conducted in 1988 to assess the

decreasing abundance in certain reaches with relatively low estimates of diversity
of the estuary. (H'<2.0). While this may reflect some
effects from the higher concentration of
Results from the more intensive industrial and port facilities in this river
short-term assessment of the bottom compared to the other two river systems,
organisms at 178 stations in the harbor comparison of the other community
basin and lower reaches of the three river parameters among the sites sampled in all
systems showed species distribution three rivers did not show major
patterns which were generally similar to differences that could be clearly related
those noted in the four-year study. to anthropogenic activities. This may be
Environmental factors which showed some due, in part, to the large variability
correlation to the benthic community observed in both the benthic and
variables measured included location in environmental variables, which tends to
the estuary, salinity, and sediment obscure evidence of biological stress.
characteristics (percent sand, percent
calcium carbonate, percent organic
content, and sand grain size). None of FINFISH AND INVERTEBRATE
these parameters was strongly correlated COMMUNITIES
with the community variables measured
due, in part, to the high degree of Fish and invertebrate populations
variance in the data obtained, combined were sampled by trawl at nine locations in
with a lack of well-defined gradients in the Cooper River, Wando River and
the salinity and sediment regimes within harbor basin over the four-year study
the sampled portion of the estuary. Many period. Three stations were also sampled
of the numerically dominant taxa seasonally in the Ashley River during
collected, such as mollusks, polychaetes, 1988.
oligochates, nematodes, and amphipods,
were abundant throughout the study area, Comparison of catches obtained
although their distribution was often very after rediversion with those collected prior
patchy. to rediversion in this study and other
studies indicated that there has been a
The short-term study did not reveal significant increase in the number of taxa
any clear relationships between the and number of individuals since
abundance and distribution of benthic rediversion occurred, although the
organisms and various anthropogenic dominant species were essentially the
activities in the estuary. Within the same. A significant decrease in the
harbor basin, a few sites showed evidence biomass of fishes was also noted following
of reduced benthic diversity, low faunal rediversion. Invertebrate biomass, on the
abundance, or small scale differences in other hand, increased after rediversion.
community composition that may have
reflected perturbations from dredging Analyses of specific changes in the
operations and the sewage outfall at Plum abundance of twenty-three species, which
Island. Among the three river systems, were evaluated because of their numerical
average diversity estimates were lower in dominance or economic importance in the
the Cooper River than in the Ashley and estuary, revealed several different
Wando Rivers. The Cooper River also patterns. No significant differences were
had the highest percentage of stations found in the abundance or biomass of five

species: the brief squid (Lolligunucula and southern flounder. The increased use
brevis), brown shrimp (Penaeus aztecus), of the Charleston Harbor estuarine system
blue catfish (Ictalurus furcatus), summer by a greater number of smaller individuals
flounder (Paralichthys dentatus), and may have resulted from increased
blackcheek tonguefish (Symphurus utilization of the estuary as a nursery
plagiusa). Yearly fluctuations independent area. Finally, nine taxa exhibited an
of rediversion were noted for eleven taxa: upriver shift in their peak abundances of
the pink shrimp (Penaeus duorarum), 11-22 km (6-12 mi). This corresponded to
roughneck shrimp (Trachypenaeus the upriver shift in salinity resulting from
constrictus), lesser blue crab (Callinectes rediversion. These species were pink
similis), Atlantic menhaden (Brevoortia shrimp, white shrimp, blue crab, bay
tyrannus), white catfish (Ictalurus catus), anchovy, white catfish, blue catfish, spot,
sea catfish (Ariopsis felis), spotted hake Atlantic croaker, and hogchoker.
(Urophycis regia), silver perch (Bairdiella
chrysoura), weakfish (Cynoscion regalis), The increased utilization of the
star drum (Stellifer lanceolatus), and estuary by more taxa, more individuals,
hogchoker (Trinectes maculatus). and younger individuals has not been
Significant increases were observed in the reported for other estuaries which have
abundance and biomass of four species undergone similar reductions in freshwater
after rediversion: white shrimp (Penaeus flow. However, more time may be
setiferus), grass shrimp (Palaemonetes required before the full effects of
vulgaris), bay anchovy (Anchoa mitchilli), rediversion are apparent. Alternatively,
and southern flounder (Paralichthys long-term negative impacts on these
lethostigma). The increases in white faunal elements may be minimal.
shrimp may have resulted from a
combination of recovery from poor
recruitment caused by a cold winter in the RECRUITMENT STUDIES
first year of this study and increased
exploitation of a more stable environment Artificial settlement substrates were
after rediversion. One species, blue crab sampled over a 15-month period to collect
(Callinectes sapidus), exhibited a decrease crab postlarvae at a single site in the
in abundance and biomass. The harbor basin to examine the relationships
hydrographic changes resulting from among light phase, lunar phase, vertical
rediversion should not have produced the distribution, and settlement. Among the
observed decreases since blue crabs are 19 brachyuran crab taxa collected, the
tolerant of salinity changes much greater most prevalent species in both number
than those resulting from rediversion. and frequency of occurrence was the blue
Two species, spot (Leiostomus xanthurus) crab (Callinectes sapidus). Other
and Atlantic croaker (Micropogonias numerically important species included the
undulatus), showed significant increases in common mud crab (Panopeus herbstii),
abundance, decreases in biomass, and and the fiddler crabs (Uca spp).
increases in the frequency of smaller Settlement patterns were highly episodic,
individuals. Eight taxa also showed an with approximately 42% of the total
increase in the frequency of smaller number of megalopae (postlarvae)
individuals. These were the white shrimp, collected on a single sampling date. Diel
bay anchovy, white catfish, blue catfish, differences in abundance were apparent,
weakfish, star drum, summer flounder, with a significantly greater number of

megalopae collected at night. Although Ingress of penaeid shrimp and blue
light phase was found to have a significant crab to study sites was seasonal, occurring
effect on overall abundance, it had little in March-April for brown shrimp (P.
influence on the vertical distribution of aztecus), June for pink shrimp (P.
brachyuran megalopae. Temperature was duorarum) and white shrimp (P. setiferus),
the only physical factor that was and August-October for blue crab (C.
significantly correlated with megalopal sapidus). Density of penaeid shrimp and
abundance. In Charleston Harbor, the blue crab megalopae appeared to be
period of major ingress of blue crab related to lunar day but trends were not
postlarvae occurred from August through consistent among species. Distribution of
October in both 1987 and 1988. Blue the other numerically dominant decapod
crab megalopae exhibited a semilunar species, Palaemonetes pugio and P.
pattern of settlement. Peak settlement vulgaris, revealed a general pattern of
occurred around the quarter moons, with winter recruitment with juveniles present
greatest settlement on waning lunar in spring and summer. Peak recruitment
phases. of the numerically dominant finfish (spot,
L. xanthurus; Atlantic menhaden, B.
Juvenile blue crabs constituted less tyrannus; Atlantic croaker, M. undulatus;
than 0.3% of the total catch of early stage and summer flounder, P. lethostigma)
crabs and megalopae of Callinectes occurred in the creeks during winter and
sapidus, which suggests that ingress into early spring, while bay anchovy, A.
estuarine habitats occurs at the megalopal mitchilli, was present throughout the year.
stage. However, this study revealed that
the juvenile is the primary stage of From October, 1987 through April
recruitment of other portunid crabs. 1989, the adult stocks of blue crab were
sampled using crab pots set biweekly at
The recruitment of decapod creeks sampled by sled and trawl. The
crustaceans and fishes into tidal marsh crab pots were fished for six hours during
creeks was also assessed through biweekly each of 1162 sets, resulting in the capture
sampling with a bottom plankton sled and of 3,916 male and 1,013 female crabs.
juvenile trawl from October 1987 through Catch rates responded to temperature
April 1989. All sampling was conducted variation, with greatest catches recorded
at two creeks (Orange Grove and Bull) in during warm weather and fewest crabs
the Ashley River and Schooner Creek captured during coldest weather. Mean
near the entrance of Charleston Harbor. total carapace width (TCW) also varied
Trawl sampling revealed that the greatest seasonally. The smallest crabs were
number of decapod crustacean and fish captured during late winter and early
species occurred at Schooner Creek. spring. Mean TCW increased each
Species composition differed among the summer to a peak in late fall. On
three creeks and seasonally. The most average, larger crabs were captured at
striking differences in species composition Schooner Creek, the most seaward site,
were between Schooner Creek, which was while the most crabs were captured at
characterized by stenohaline marine Bull Creek, the uppermost site in the
species in summer and fall, and Bull Ashley River. Molt activity was also
Creek, which was characterized by greatest at Bull Creek, where many
estuarine transient and resident species. pubertal pre-molt females were captured.
Mark-recapture studies and tag/releases

were carried out with internal-anchor CONTAMINANTS
"spaghetti" tags. Tagging mortality was
high, with summer taggings resulting in Trace metals and organic
the lowest tag return rate. Apparently, contaminants were studied in sediment
tagging mortality varied directly with and animal tissue samples collected from
temperature. The few recaptures the estuary over a two-year period.
obtained indicated that blue crab Chromium and copper were widespread
movements were not far from the location constituents in the sediments. Copper was
of release. also common in tissue but chromium was
not detected in any tissue samples.
Concentrations for both metals were
MACROPHYTE VEGETATION typical of other industrialized southeastern
locations, with higher levels generally
The characteristics of macrophyte associated with fine-grained sediments and
vegetation in a tidal freshwater marsh on areas of industrialization. Chromium
the Cooper River were studied in 1988 for concentrations in the sediments were as
comparison with pre-rediversion data high as 81.18 ppm at a lower Cooper
collected at the same site in 1982. River station. The maximum
Comparisons included species concentration for copper (208.2 ppm) was
composition, net above ground primary detected in oysters from the lower Ashley
productivity, patterns of seasonal River, whereas copper in sediments did
succession, trends in species standing crop, not exceed 39.95 ppm. Cadmium was not
and changes in species cover. The detected in any sediments, but it was
number of species present increased found in oysters at concentrations up to
slightly from 44 in 1982 to 47 in 1988. 3.11 ppm as well as in one blue crab
Net primary production decreased from sample (1.79 ppm) and one shrimp sample
1571 grains dry weight/meter squared in (1.35 ppm). Probably because of a lack of
1982 to 1432 grains dry weight/meter analytical sensitivity, lead was not detected
squared in 1988. Several dominant in any tissue samples, and it was detected
species; e.g., Zizaniopsis, Peltrandra and in sediment samples at only five stations.
Lycopus, showed decreased mean standing Lead concentrations were moderately
crops in 1988. On the other hand, high, however, with the maximum being
approximately one third of the species 88.1 ppm. Mercury was present in 41% of
common to both years had increased the tissue samples and 44% of the
frequencies in 1988 with only one species, sediment samples with maxima of 21.0
Lycopus, showing a decreased frequency. ppb and 25.7 ppb respectively.
Species abundance also increased in 1988.
Seasonal succession occurred in both Synthetic organic chemicals were
years, although no two corresponding generally not detected in the sediment
months had the same dominant species. samples analyzed except at one station in
Two periods of maximum biomass the lower Ashley River. This station had
occurred in 1982 but there was only one a relatively high concentration of
peak period in 1988. All events noted polynuclear aromatic hydrocarbons
were successional in nature and appeared (PAH's) compared to other estuarine
to be related to lowered water levels. areas within the state. The PAH's ranged
up to 4.4 ppm fluoranthane, 4.1 ppm
pyrene, and 1.18 ppm chrysene.

sources and sinks of phytoplankton
Tissue samples examined in this production; evaluating the roles of
study contained several different synthetic phytoplankton production, organic carbon
chemicals. Polychlorinated biphenyls flux, submerged macrophytes and benthic
(PCB's) were the most common organic macro- and microalgae; and establishing
form detected in the tissue samples, the adequacy of existing criteria used in
although no levels exceeded 538 ppb. management and planning decisions. The
Other organics in tissue included magnitude of this research program will
chloroform, benzoic acid, require considerable augmentation of
hexachlorobutadiene, isophorone, 1,2,4 - existing institutional capabilities.
trichlorobenzene, some PAH's, and some
organochlorine pesticides. Though these All workshops concluded that a
compounds were generally less than 500 comprehensive management plan for
ppb, some did exceed 1000 ppb, e.g., 1430 Charleston Harbor was desirable. The
ppb benzoic acid in oysters in the lower most frequently identified concern related
Wando River. to such a plan was political support for its
success. Factors key to achieving such
Anthropogenic sources probably support are: (1) widespread involvement
accounted for the majority of the organic of all those potentially affected by the
compounds and metals found. Even management plan, and (2) public
though the chemicals detected did not commitment for protection of resources in
exceed any published Environmental the future. Workshop participants also
Protection Agency and US Food and Drug agreed that improved capabilities to
Administration limits, they may pose some archive and retrieve relevant data are
threat with respect to sublethal effects on important, but that a single integrated
estuarine organisms. database is probably impractical. The
technical workshops initiated a process of
defining specific objectives, data needs,
TECHNICAL WORKSHOPS and existing sources of these data through
which a workable data management
Four workshops were conducted on system for the Charleston Harbor estuary
major areas of concern to the research can be developed. Further steps toward
and technical communities involved with developing such a system include: (1)
the Charleston Harbor estuary: (1) design of an information translation
hydrography, circulation and modelling; process that will produce the particular
(2) water quality, nutrient fluxes, and syntheses needed by decision-makers, (2)
contaminants; (3) phytoplankton and specification of archiving procedures for
macrophyte productivity; and (4) estuarine new data sets collected as part of research
fauna. Major objectives identified for undertaken in support of estuarine
research to support management needs of management, and (3) identification of
the estuary included developing hydrologic information contained in existing data sets
models; identifying the effects of whose relevance warrants re-formatting to
anthropogenic sources on selected achieve consistency with other data sets.
organisms; defining the oxygen
requirements of selected organisms;
modelling dissolved oxygen and sediment
dynamics within the estuary; identifying

OVERALL CONCLUSION
(4) Another notable finding of the
The Charleston Harbor estuary study is that, while a variety of
appears to be in relatively good shape contaminants were detected in
from a biological/ecological perspective, sediments and in animal tissues
and has not been drastically altered as a from the harbor system, none were
result of the Cooper River Rediversion especially high. Nevertheless,
Project during the period covered by this because of the reduced river flow
study. Some changes have occurred, into Charleston Harbor now, the
however. Among the most obvious are residence time for pollutants is
the following: probably greater, increasing
opportunities for food-chain
(1) Waters in the harbor basin and the bioaccumulation and impacts on
three associated river systems are the aquatic fauna.
more saline than before and the
salinity regimes throughout the I l e challenge now is for those
estuary are more stable. Other involved and interested in Charleston
water quality factors, such as Harbor to come together and develop
dissolved oxygen and nutrient harbor-wide monitoring, management, and
levels, have not changed much as a research programs to insure that this
result of rediversion. national ecological resource is not further
degraded by man's activities.
(2) There may be less sedimentation of
fine materials (muds) than before
in the lower harbor, and there
appears to be some reduction in
turbidity, at least at the mouth of
the harbor.

(3) Some changes in the floral and
faunal assemblages have occurred,
but no major differences in the
overall community structure or
declines in species diversity were
detected that could be clearly
related to rediversion effects.
Some negative trends may be
associated with areas of heavy
impact by man. On the other
hand, the harbor may well be a
more productive nursery area than
before for a variety of marine fish
and motile invertebrates (including
shrimp). Additional time will be
required before the fall effects of
rediversion on the biota in the
estuary are known.