[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
c.2








                      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







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         I~~~~~~~(
                                   Wilson Dam

                       Diversion Canled                                          .

             ,                   tU~~r~~lEM                A dzOULTRI


                                   Plnopols am






    O      ~~~10      20 Mlle l    /B                      X    \
    0   10    20    30 KNomeier.



     South Carolina \
                >    %             \    D        A ~~~~~~~~CHARLESTONX
                                                     HARBOR




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

                                            2







      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

                                           3








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

                                           4








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

                                          5








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

                                          6








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

                                          7








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

                                           8








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

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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.

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                                              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

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      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.

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