Zooplankton of South Carolina

by David M. Knott; extracted from:

South Carolina Department of Natural Resources and National Oceanic and Atmospheric Administration, Coastal Services Center. 2000. Characterization of the Ashepoo-Combahee-Edisto (ACE) Basin, South Carolina. CD-ROM. SC Marine Resources Center Special Scientific Report Number 17. NOAA/CSC/20010-CD. Charleston, SC: NOAA Coastal Services Center.

Definition

Organisms that live in aquatic

environments face certain challenges that

their terrestrial counterparts do not. One

of the obvious differences is the motion

of the fluid medium, which presents

opportunities and drawbacks that are

unique to animals and plants that live

suspended in the water column. Among

the benefits this lifestyle offers are

enhanced dispersal of the population,

which may be achieved at a relatively low

energy cost, the resultant high gene flow

among dispersed populations, and the

ability to readily expand into new

habitats.

Aquatic organisms with limited

swimming ability relative to the strength

of ambient currents are said to be

planktonic. The term plankton is derived

from the Greek word planktos, which

means wandering or drifting. Organisms

such as these, whose distributions are

closely tied to the movement of the water

mass in which they reside, are at risk of

being transported away from conditions

that are necessary for their survival.

Classification

Biologists typically classify plankton into three general categories based on their phylogeny:

phytoplankton are microscopic algae and other photosynthetic organisms; zooplankton are

animals, mainly invertebrates; and ichthyoplankton comprise the larval fish component of the

plankton.

Zooplankters are classified based not only on their taxonomy, but frequently they are grouped

according to their size (Table 1). Larger planktonic organisms (mesoplankton and above) are

usually collected by towing finely woven conical plankton nets behind a vessel or streaming

nets out from a fixed object in a swift current. The size of the openings in the netting material

(mesh size) depends on the size-class of plankton being targeted. The smaller classes of

plankton (microplankton and below) are generally collected by trapping water in bottles

because nets fine enough to retain them clog rapidly when they are towed.

Table 1. Zooplankton size classification.

Grouping of plankton based upon size classifications adopted by Omori and Ikeda

(1984).

Group 1

Size Limits Major Organisms

1. Ultrananoplankton <2 µm Free Bacteria

2. Nanoplankton 2-20 µm Fungi, Small Flagellates, Small Diatoms

3. Microplankton 20-200 µm Most Phytoplankton Species, Foraminiferans, Ciliates,

Rotifers, Copepod and Other Crustacean Nauplii

4. Mesoplankton 200 µm - 2

mm

Cladocerans, Copepods, Larvaceans, Larval

Crustaceans

5. Macroplankton 2-20 mm Pteropods, Copepods, Euphausids, Chaetognaths,

Larval and Post Larval Crustaceans

6. Micronekton 20-200

mm Cephalopods, Euphausids, Sergestids, Myctophids

7. Megaloplankton >20 mm Scyphozoans, Thalacians (Gelatinous plankton) 1 Groups 1 to 3 are collected with water bottles, while Groups 4 to 6 are most frequently

collected by net; Group 7 includes gelatinous salps and medusae, which are difficult to

capture using nets without damaging the specimens.

A third way of classifying zooplankters is based on the relative length of their planktonic life.

Organisms that remain planktonic throughout the entire duration of their life cycle are

referred to as holoplankters, and these are the permanent zooplanktonic residents of the water

column. Other organisms, which spend only a portion of their lives as plankters, usually

during the larval stages, are called meroplankters. Most of the common benthic invertebrates

of coastal and estuarine waters have meroplanktonic larvae.

Trophic Importance

The estuarine zooplankton are of considerable trophic importance. Many copepods and other

zooplankters, especially estuarine species, are omnivores that derive the majority of their

nutrition by feeding on heterotrophic protists such as ciliates and dinoflagellates, although

under some circumstances they may rely more heavily on microphytoplankton (Kleppel et al.

1998). In localities where macrophytes are abundant, such as salt marshes or seagrass beds,

zooplankton standing stocks may obtain much of their nutrition by feeding on detritus

(Roman et al. 1983). In estuaries, heterotrophic protists are an important component of the

microzooplankton, since they provide a link between bacterial production and higher trophic

levels (Heip et al. 1995). Their importance in the diets of many marine and freshwater

zooplankton species was emphasized by Sanders and Wickham (1993), who noted that

protists serve as a necessary link in the transfer of bacterial biomass to larger organisms.

Zooplankton density and volume specific biomass are usually greater in estuaries than in

other aquatic habitats, reflecting the generally higher productivity of an estuarine

environment. The species of fish and shellfish responsible for over 85 percent (by weight) of

the commercial fisheries landings of the southeastern Atlantic states are estuarine or

estuarine-dependent at some life stage (Burrell 1975a). For many of these species that depend

on estuaries as spawning or nursery grounds (e.g., Atlantic croaker, Atlantic menhaden,

seatrout, drum, blue crab, and white shrimp), an abundant zooplanktonic population is

necessary. Recently, Allen et al. (1995) described how competition for zooplankton as food in

a high salinity South Carolina estuary may be minimized by vertical and lateral partitioning

and temporal shifts in dietary selectivity. Similar partitioning of zooplankton food sources,

based upon prey size, has been documented for freshwater fish species such as the threadfin

shad and blueback herring introduced to the Jocassee Reservoir in the 1970s (Davis and Foltz

1991).

Certain mesoplankters, particularly copepods and cladocerans, are essential as food for early

fish larvae and for larger predacious zooplankters, which in turn are fed upon by late larval

and postlarval fish and other organisms. In estuaries, macroplankters such as mysid shrimp

and gammarid amphipods may be the most important food chain link in habitats bounded by

extensive salt and brackish marshes, which themselves often are important fish nursery

grounds (Ragotzkie 1959; Van Engel and Joseph 1968; University of Georgia Marine

Institute 1971). In fresh water, most larval fish are zooplanktivores, frequently selecting

small-bodied organisms like rotifers and copepods. Cladocerans, which are generally larger,

are preferentially selected by older fish.

Zooplankton Behavior

Although the diverse assemblages of zooplankton in marine, estuarine and freshwater habitats

are all subjected to the vagaries of the water in which they reside, they do not all respond

similarly to the forces that cause the water to move. By using selective behavior in response

to various physical cues, even planktonic organisms can exert some influence on the ultimate

outcome of their transport (Epifanio 1988). Thus, by responding to salinity cues, some

planktonic species may be distributed only within restricted zones in coastal waters, such as

the low-salinity regions of estuaries, while others with may reside only in coastal waters and

the high-salinity reaches near the estuary mouth.

Another important aspect of zooplankton behavior is the periodic vertical migration exhibited

by many copepods (Steele and Henderson 1998). The diel (or daily) vertical migration

(DVM) of many planktonic organisms may be influenced by the abundance of both food

items and predators, as well as other environmental cues such as light, salinity, and

temperature. In addition to locating food and avoiding predators, zooplankton may benefit

from the changes in their bioenergetics that result from metabolic rates that differ on either

side of the thermocline (McLaren 1963) in stratified waters. Avent et al. (1998) recently

provided evidence that a common species of the estuarine copepod genus Acartia exhibits an

endogenous vertical migration with a period that coincides with the semi-diurnal tide in San

Francisco Bay (Figure 1).

Figure 1. Migration behavior of the calanoid copepod Acartia tonsa.

Freshwater Zooplankton

Studies of the zooplankton of freshwater habitats in coastal regions of the southeastern states

are limited, and virtually nothing has been published on the freshwater plankton of the ACE

Basin. Sandifer et al. (1980) reviewed the literature describing the general characteristics of

freshwater zooplankton in riverine, palustrine and lacustrine habitats of the coastal sea islands

of the southeast United States. Among the early studies were those of Turner (1910), who

described the copepod and cladoceran fauna of wetland habitats near Augusta, Georgia. The

zooplankton of the temporary and permanent ponds and ditches sampled by Turner (1910)

included 4 species of calanoid copepods, 10 cyclopoids, 1 harpacticoid, and 24 species of

cladocerans. The copepod Cyclops serulatus and the cladoceran Simocephalus serrulatus

were the most widely distributed taxa.

More recent research has described the species richness and population dynamics of

zooplankton in another type of palustrine habitat, the Carolina bays of the Savannah River

site of the U.S. Department of Energy. These geological features are shallow, poorly drained

elliptical or oval depressions that number in the hundreds of thousands throughout the

Atlantic coastal plain from New Jersey to Florida. Their distribution and ecological status in

South Carolina was addressed by Bennett and Nelson (1991), who noted that 20 of these

features are located in Colleton County; however their precise locations, and consequently

their inclusion within the ACE Basin characterization area, was not described. Sharitz and

Gibbons (1982) discussed the ecology of southeastern Carolina bays, but made no mention of

their zooplankton.

Mahoney et al. (1990) reported that Carolina bays on the upper South Carolina coastal plain

support exceptionally rich zooplankton communities, compared with temporary ponds

elsewhere. These communities are generally dominated early in the wet season by crustacean

taxa with long generation times, such as anostracans, conchostracans and calanoid copepods.

In the 23 bays studied, seven species of the calanoid genus Diaptomus were common; none of

which are typically found in nearby permanent waters. Another group of crustaceans, the

cladocerans, were represented by 26 genera and at least 44 species, many of which showed

considerable overlap between the fauna of the temporary bay ponds and permanent reservoir

waters. Other major invertebrate taxa collected in the Carolina bays were cyclopoid and

harpacticoid copepods; the crustacean orders Amphipoda, Isopoda, and Ostracoda; the insect

orders Ephemeroptera, Odonata, Coleoptera, Trichoptera; the Dipteran families

Ceratopogonidae, Chaoboridae, Chironomidae, and Culicidae; and oligochaetes, nematodes

and aquatic mites.

The population dynamics of zooplankton in Rainbow Bay, one of the 23 Carolina bays

mentioned above, were studied by Taylor and Mahoney (1990). They observed a temporal

pattern in that Carolina bay pond that was typical of many others. The community was

initially dominated by the copepods Diaptomus stagnalis and either Acanthocyclops vernalis

or Diacyclops haueri, but later in the hydroperiod by cyclopoid copepods and cladocerans,

including Daphnia laevis and Simocephalus spp. Experiments conducted on sediments from

the dry pond bed suggested that the time of emergence from resting stages was a determinant

of the initial succession of species in this temporary aquatic habitat. Predation by amphibian

larvae (primarily salamanders) was not sufficient in this pond to limit the abundance of the

predominant zooplankters; thus, population growth was limited for extended periods by

insufficient food.

The zooplankton of lakes and rivers is generally dominated by the free-living non-

photosynthetic protists, rotifers and microcrustaceans; however, the species composition of

these groups may be quite different in lacustrine habitats than in riverine ones (Sandifer et al.

1980). Hudson (1975) described the zooplankton of Keowee Reservoir, a man-made lake in

the South Carolina piedmont region. Of the 53 species of copepods and cladocerans identified

from the reservoir, only about 15 were common in the plankton, while the remainder were

littoral or benthic species. Diaptomus mississippiensis, Mesocyclops edax, and Tropocyclops

prasinus were the most abundant copepods, while Diaphanosoma branchyurum, Holopedium

amazonicum, Daphnia ambigua, and two species of Bosmina were the most abundant

planktonic cladocerans. More recent research on the zooplankton of reservoirs in South

Carolina focused on the spatial heterogeneity of the plankton communities (Betsill and Van

den Avyle 1994) and the effects of thermal stresses caused by nuclear reactor cooling

effluents (Taylor et al. 1993).

Riverine zooplankton of coastal South Carolina has not been intensively studied. Herlong and

Mallin (1985) noted that the zooplankton below an impoundment on Black Creek, South

Carolina, was augmented by the impoundment outfall, making it much denser than that

upstream from the impoundment. Dames and Moore Associates (1975) sampled freshwater

creeks and portions of the Cooper River, collecting 12 taxa of rotifers, 4 taxa of copepods,

and 2 taxa of cladocerans. Rotifers and copepods together comprised nearly 90 percent or

more of the total number of zooplankters at all six sample sites. The most abundant rotifers

were Polyarthra sp. and Keratella cochlearis, while the only genus of copepod identified was

Diaptomus. The cladocerans Bosmia longirostris and Alonella sp. were dominant within that

taxon.

Estuarine Zooplankton

Estuarine Mesozooplankton The abundance of mesozooplankton

in the North Edisto River at Bluff

Point (Figure 2), near the boundary

of the ACE Basin Characterization

Area, was described by Knott

(1980). Surface samples collected

weekly from May 1975 to May

1976 in the river and two adjacent

upland saltwater impoundments

yielded more than 146 unique taxa

(Table 2).

Figure 2. Site sampled for estuarine mesozooplankton by

Knott (1980).

Table 2. Zooplankton taxa collected by Knott (1980).

Zooplankton taxa collected in weekly samples from the North

Edisto River at Bluff Point and in two nearby saltwater

impoundments from May 1975 to May 1976

Phylum, Class or

Subclass Order

Lowest Practical Identification

Level and Life History Descriptor

Sarcomastigophora Foraminiferida Undetermined Foraminferan

Ciliophora Oligotrichida Undetermined Tintinnidan

Hydrozoa

Blackfordia virginica

Eutima mira

Tubularia crocea (actinula larvae)

Undetermined hydromedusae (12

taxa)

Ctenophora Mnemiopsis leidyi

Beroë ovata

Rotifera Undetermined Rotifera

Kinorhyncha Pycnophyes beaufortensis

Nematoda Undetermined Nematoda

Polychaeta

Spionida Undetermined Spionidae

Phyllodocida Undetermined Syllidae

Undetermined larvae (9 taxa)

Mollusca

Gastropoda veligers

Bivalvia veligers

Hiatella arctica

Arachnida Acariformes Undetermined Acarina

Branchiopoda Cladocera Penilia avirostris

Podon polyphemoides

Ostracoda Undetermined Ostracoda

Copepoda Calanoida

Acartia tonsa

Centropages furcatus

Centropages hamatus

Eurytemora affinis

Labidocera aestiva

Paracalanus sp.

Parvocalanus crassirostris

Pseudodiaptomus coronatus

Temora turbinata

Tortanus setacaudatus

Cyclopoida

Corycaeus sp. 1

Corycaeus sp. 2

Ergasilus versicolor

Halicyclops sp. 1

Halicyclops sp. 2

Hemicyclops adhaerens

Microcyclops varicans

Oithona colcarva

Oithona simplex

Saphirella tropica

Saphirella sp.

Cyclopoida undetermined (3 taxa)

Harpacticoida

Alteutha oblonga

Ameira (parvula?)

Amphiascus parvus

Cletocamptus sp.

Dactylopodia tisboides

Diarthrodes (dissimilis?)

Enhydrosoma longifurcatum

Euterpina acutifrons

Halectinosoma winonae

Harpacticus (gracilis?)

Heterolaophonte quinquespinosa

Laophonte elongatatriarticulata

Laophonte (cornuta?)

Leptocaris brevicornis

Longipedia helgolandica

Metis sp.

Microarthridion littorale

Nannopus palustris

Nitocra lacustris

Parategastes (sphaericus?)

Paronychocamptus curticaudatus

Paronychocamptus wilsoni

Paronychocamptus sp.

Pseudobradya sp.

Robertsonia knoxi

Robertsonia propinqua

Robertsonia sp.

Thompsonula hyaenae

Tisbe furcata

Harpacticoida undetermined (10

taxa)

Cirripedia Nauplii

Cypris larvae

Malacostraca

Mysidacea Undetermined Mysid

Cumacea Undetermined Cumacean

Isopoda

Aegathoa oculata

Edotea montosa

Isopoda ndetermined (3 taxa)

Amphipoda

Caprella equilibra

Corophium acherusicum

Caprellidae undetermined

Corophiidae undetermined

Gammaridae undetermined

Decapoda

Undetermined zoeae

Acetes americanus

Alpheus sp. zoea

Palaemonetes pugio

Palaemonetes vulgaris

Palaemonetes sp. zoeae

Undetermined brachyuran zoeae

Undetermined brachyuran

megalopae

Dissodactylus sp. zoeae

Eurypanopeus depressus zoeae

Hexapanopeus angustifrons zoeae

Neopanope sayi zoeae

Pagurus longicarpus glaucothoë

Panopeus herbstii zoea

Pinnixa chaetopterana zoeae

Pinnotheres ostreum zoeae

Rhithropanopeus harrisii zoeae

Sesarma sp. zoeae

Uca sp. zoeae

Upogebia sp. zoeae

Insecta

Odonata Enallagma sp. nymph

Hemiptera Notonecta sp.

Diptera Culicidae larvae

Chironomidae larvae

Bryozoa Cyphonautes larvae

Echinodermata Ophiuroidea ophiopluteus larvae

Chaetognatha Undetermined Chaetognatha

Ascideacea Tadpole larvae

Larvacea Oikopleura sp.

Osteichthyes Fish eggs

Fish larvae

Source: Knott, 1980

Considerable seasonal variation in total

zooplankton abundance was noted in the river, as

well as in the impoundments (Figure 3). In the

river, monthly mean densities greater than 10,000

indiv./m3 occurred from April through June, with

a peak during April of 1976 (23,325 indiv./m3).

Although zooplankton abundances in the river

remained above 6000 indiv./m3 year round, this

was not the case in the impoundments, where late

fall/winter minimums of only a few hundred

indiv/m3 were observed. The significant winter

decline in zooplankton abundance in the

impoundments was attributed to decreased algal

productivity during the colder months, coupled

with the absence of a detrital food supply like that

found throughout the year in the river (Knott 1980). Figure 3.

The calanoid copepod Acartia tonsa was

by far the most abundant

mesozooplankter in the Edisto River at

Bluff Point. Its numerical

dominance was even more

pronounced in the nearby saltwater

impoundments, where it was 1 to 2

orders of magnitude greater in

abundance than any other species

(Figure 4). In contrast to A. tonsa, the

second most abundant species in the

river, the harpacticoid copepod

Euterpina acutifrons, did not

successfully colonize the ponds.

Rotifers and barnacle larvae

(cirripedes) were among the

remaining dominant species in

samples from the river, along with the

calanoids Parvocalanus

crassirostris, Pseudodiaptomus

coronatus, and copepod nauplii.

Figure 4.

The total zooplankton abundance reported by Knott (1980) in the North Edisto River was

similar to that described at North Inlet, South Carolina, by Lonsdale and Coull (1977), who

used comparable methods and equipment to investigate composition and seasonality of

mesozooplankton in that high salinity estuary. The overall mean abundance in the North

Edisto (10,148 indiv./m3) was only slightly greater than at North Inlet (9,257 indiv./m

3).

Similarity between the species composition of these two locations was also high, with a 67

percent coincidence among the 12 dominant mesoplanktonic taxa collected at each site.

Furthermore, similarity between the mesozooplankton of these two sites with that described

qualitatively by Burrell (1975b) from the Wando River, South Carolina, suggests that

estuarine waters of the ACE Basin are likely to support a comparable community. Although

the literature contains scant reference to studies of estuarine zooplankton of the ACE Basin

itself, one might expect it to resemble that which typically inhabits many southeastern and

Gulf coast estuaries, based on the similarities between estuarine zooplankton in the North

Edisto River and elsewhere in South Carolina and that described from North Carolina (Mallin

1991), Georgia (Stickney and Knowles 1975), the Florida Gulf coast and Keys (Grice 1960),

and the Gulf of Mexico (Buskey 1993).

The relative contribution of meroplanktonic organisms to total zooplankton abundance was

uniformly low (3 to 21 percent) in the North Edisto River. The predominant meroplanktonic

taxa were gastropod veligers (which peaked in spring), barnacle larvae (which peaked in

winter/early spring), and decapod crustacean larvae (which peaked in spring and summer).

Although a variety of decapod crustacean larvae were collected (at least 20 species ), they

contributed relatively few numbers to the total mesoplankton community (Table 2). Many of

the planktonic larvae of decapods are macroplanktonic, and they may not have been

efficiently captured by the 30 centimeter (12 inch) diameter net with 147 mm mesh deployed

by Knott (1980). Samples collected in North Inlet, South Carolina, by Lonsdale and Coull

(1977), using a nearly identical plankton net, also contained relatively few meroplanktonic

larvae (25 percent by number), suggesting a sampling bias against some of the larger

crustacean larvae that might be able to avoid capture by these small fine-meshed nets.

Copepods were predominant among the mesozooplankton of the North Edisto River, both in

terms of species richness (63 different species) and abundance (78 percent in the river; 95 to

98 percent in the ponds)(Knott 1980). The copepods comprised 24 truly planktonic species in

the orders Calanoida and Cyclopoida and a rich representation of the Harpacticoida (39

species), all but three of which were typically benthic organisms that were suspended at the

shallow river station by tidal turbulence.

Estuarine Macrozooplankton Early studies of macrozooplankton in South Carolina targeted the larval stages of

commercially important crustaceans. Fisheries researchers conducted periodic plankton

sampling in the Wando, Cooper and Ashley Rivers near Charleston, South Carolina, and in

the Santee River to the north, using nets designed to capture macroplankton (Bears Bluff

Laboratories, Inc. 1964). In addition to larval crustaceans, two taxa were among the

numerically dominant organisms at most stations: copepods (which were not quantitatively

represented because of the coarse mesh nets) and the medusa stage (jellyfish) of

undifferentiated species of coelenterates. Burrell (1975b) also found coelenterate medusae to

be seasonally abundant in the Wando River, including Blackfordia virginica and Nemopsis

bachei, along with the comb jelly Mnemiopsis. Hester (1976) and Calder and Hester (1978)

described a rich planktonic coelenterate fauna in South Carolina estuaries.

SCDNR Ingress Studies

Blue crab and white shrimp are two decapod crustaceans with significant commercial value in

South Carolina. Both of these species have a life history that includes offshore larval

development and an estuarine nursery habitat (Figures 5 and 6).

Figure 5. Figure 6.

Much is known about the use of South Carolina salt marsh nursery habitats by these two

species (Boylan and Wenner 1993; Mense and Wenner 1989; Wenner and Beatty 1993), but

less is understood of the links between their offshore and estuarine life history stages.

Consequently, studies conducted in 1993-1994 in the ACE Basin Characterization Area by

SCDNR focused on the way in

which coastal oceanographic and

meteorological processes influence

the movement of planktonic

postlarvae of these two species

from the inner continental shelf

through the North Edisto Inlet, to

their estuarine nursery grounds.

Postlarvae of both species are

macrozooplankton that are

potentially influenced by strong

tidal forces, wind stress, bottom

friction, and buoyancy fluxes. The

ingress studies in the North Edisto

Inlet were designed to explain

some of the ways in which

postlarval decapod distributions

(both spatial and temporal) are

related to the physical processes of Figure 7. Location of sampling for ingress studies.

transport. These specifically address ways in which periodic phenomena such as tides and

daily or lunar cycles, and less predictable ones such as wind-generated currents, interact to

influence the transport of planktonic larvae of these two species through the inlet and into the

estuary.

Blue crabs spawn in the lower estuary, and

their planktonic larvae are exported to the

coastal ocean where they develop to the

postlarval stage known as the megalopa

(Figure 5). Subsequent ingress of

megalopae through coastal inlets precedes

their settlement and recruitment to the salt

marsh nursery habitat. In South Carolina,

ingress and settlement peak between

August and November.

Megalopal ingress was investigated during

the spring and fall of 1993 and 1994 by

Knott and others (unpublished data), who

examined plankton collections from the

North Edisto River Inlet. Plankton samples

were classified based on wind stress

conditions at the time of their collection.

With the exception of the spring 1993

cruise, when very few megalopae were

collected, ingress was significantly greater when the wind blew up the coast and slightly

onshore. A quantitative vector-scalar correlation (the correlation is between wind stress

vectors and the corresponding scalar values of megalopal density, thereby accounting for the

magnitude as well as the precise direction of wind stress) also showed a significant

association between ingress and upcoast winds with an onshore component during the fall

1993 cruise. Although a dissimilar result was obtained for the fall 1994 cruise, when

downcoast winds were significantly correlated with ingress, these apparently contrasting

results were both consistent with 3-D model simulations of the study area, which predict

significant ingress of passive particles released at the surface during both upwelling and

downwelling conditions (Blanton et al. 1998).

The transport of blue crab megalopae may differ from that described for postlarval white

shrimp largely due to differences in the behavior and vertical distribution of the two species

in near shore coastal waters. Penaeus setiferus broadcasts its eggs on the seafloor of the

shallow continental shelf over several months in the spring and early summer. After the

hatchlings pass through several larval stages, they reach the postlarval stage, which ingresses

through inlets to the salt marsh nursery grounds (Figure 7). In South Carolina, the period of

peak ingress usually occurs in June (DeLancey and others 1994).

Wenner et al. (1998) described the importance of wind stress on the transport of white shrimp

postlarvae through the North Edisto River inlet

during 1993 and 1994. Their study demonstrated

that ingress of white shrimp is enhanced by easterly

to northeasterly winds, which push surface waters

toward the coast. This forcing may move many

shrimp postlarvae into the shallow area near the

inlet mouth, where they can be easily transported

through the inlet into the estuary. The authors noted

that variability in winds and other physical

processes may explain much of the inter-annual

variability in transport of larvae to their nursery

grounds. white shrimp postlarva

Studies by other researchers working in the North Inlet estuary of South Carolina provide

additional insight into the composition and dynamics of a macroplanktonic community that is

likely to closely resemble that in the ACE Basin. Tidal, day-night, and day-to-day patterns of

macrozooplanktonic abundance were described by Houser and Allen (1996), who observed

large pulses of crab and shrimp larvae originating from nocturnal hatching events in the upper

reaches of a tidal creek. The most abundant organisms in their 6-month series of daily

samples were fish larvae (primarily the goby Gobiosoma), larval and postlarval decapod

crustaceans (including the snapping shrimps Alpheus spp., the fiddler crabs Uca spp., the

grass shrimps Palaemonetes spp., and the commercially valuable shrimps Penaeus spp.),

juvenile bivalves, the holoplanktonic chaetognaths (arrow worms), gammarid amphipods and

hydromedusae. Further seaward in Town Creek, near the inlet of the same estuary, Moore and

Reis (1983) observed a similar macrozooplanktonic community dominated by the mysid

crustacean Neomysis americanus. At that locality they also noted greater numbers of the

holoplanktonic decapod crustaceans Acetes americanus and Lucifer faxoni, which are more

typical residents of shallow coastal oceanic environments and high salinity inlets. Further

documentation of such tidal incursions of coastal macrozooplankton into this estuary was

provided by Costello and Stancyk (1983), who described the mechanism by which the

macroplanktonic appendicularian Oikopleura dioica enters the North Inlet from the ocean.

References

Allen, D. M., W. S. Johnson, and V. Ogburn-Matthews. 1995. Trophic relationships and seasonal utilization of

salt-marsh creeks by zooplanktivorous fishes. Environmental Biology of Fishes 42(1):37-50.

Avent, S. R., S. M. Bollens, and S. P. Troia. 1998. Diel vertical migration in zooplankton: experimental

investigations using video-microscopy and plankton mini-towers. In American Geophysical Union (ed).

1998 Ocean Sciences Meeting, 9-13 February 1998, San Diego, CA. American Geophysical Union,

Washington, DC.

Bears Bluff Laboratories, Inc. 1964. Biological studies of Charleston Harbor, S.C. and the Santee River.

Submitted to the USFWS, contract no. 14-16-0004-1024.

Bennett, S. H. and J. B. Nelson. 1991. Distribution and status of Carolina bays in South Carolina. Nongame and

Heritage Trust Section, South Carolina Wildlife and Marine Resources Department.

Betsill, R. K. and M. J. Van den Avyle. 1994. Spatial heterogeneity of reservoir zooplankton: a matter of

timing? Hydrobiologia 277(1):63-70.

Blanton, J. O., F. E. Werner, A. Kapolnai, B. O. Blanton, D. Knott, and E. L. Wenner. 1998. Wind-generated

transport of ficticious passive larvae into shallow tidal estuaries. Fisheries Oceanography 8 (suppl. 2):210-

223.

Bowman, T. E. 1971. The distribution of calanoid copepods off the southeastern United States between Cape

Hatteras and southern Florida. Smithsonian Contributions to Zoology 96.

Boylan, J. M. and E. L. Wenner. 1993. Settlement of brachyuran megalopae in a South Carolina estuary. Marine

Ecology Progress Series 97:237-246.

Brownlee, D. C. and F. Jacobs. 1987. Mesozooplankton and microzooplankton in the Chesapeake Bay. In S.K.

Majumdar, L.W. Hall Jr., and H.M. Austin (eds). Contaminant Problems and Management of Living

Chesapeake Bay Resources. Pennsylvania Academy of Science, Easton, PA.

Burrell, V. G., Jr. 1975a. The relationship of proposed offshore nuclear power plants to marine fisheries of the

South Atlantic region of the United States. In Institute of Electrical and Electronic Engineers (eds).

Proceedings of the Ocean '75 Conference, San Diego, CA. Institute of Electrical and Electronic Engineers,

New York, NY.

Burrell, V. G., Jr. 1975b. A preliminary list of the most common species of zooplankton found in the Wando

River, August 1972-August 1974. Unpublished data from the South Carolina Department of Natural

Resources, Charleston, SC. Summarized in Sandifer et al. 1980.

Buskey, E. J. 1993. Annual pattern of micro- and mesozooplankton abundance and biomass in a subtropical

estuary. Journal of Plankton Research 15(8):907-924.

Calder, D. R. and B. S. Hester. 1978. Phylum Cnidaria In An annotated checklist of the biota of the coastal zone

of South Carolina, Zingmark,R. G. (ed.) University of South Carolina Press, Columbia, SC.

Costello, J. and S. E. Stancyk. 1983. Tidal influence upon appendicularian abundance in North Inlet estuary,

South Carolina. Journal of Plankton Research 5(2):263-277.

Daborn, G. R. and M. Brylinsky. 1981. Zooplankton diversity and species associations in the inner Bay of

Fundy. Estuaries 4(3):253.

Dames and Moore Associates. 1975. Environmental assessment report on a proposed chemical plant, Berkeley

County, South Carolina. Prepared for Amoco Chemicals Corporation. Park Ridge, IL.

Davis, B. M. and J. W. Foltz. 1991. Food of blueback herring and threadfin shad in Jocassee Reservoir, South

Carolina. Transactions of the American Fisheries Society 120(5):605-613.

DeLancey, L. B., J. E. Jenkins, and J. D. Whitaker. 1994. Results of long-term, seasonal sampling for Penaeus

postlarvae at Breach Inlet, South Carolina. Fishery Bulletin 92:633-640.

Durbin, A. G. and E. G. Durbin. 1981. Standing stock and estimated production rates of phytoplankton and

zooplankton in Narragansett Bay, Rhode Island. Estuaries 4(1):24-41.

Epifanio, C. E. 1988. Transport of invertebrate larvae between estuaries and the continental shelf. American

Fisheries Society Symposium 3:104-114.

Fulton, R. S. III. 1983. Interactive effects of temperature and predation on an estuarine zooplankton community.

Journal of Experimental Marine Biology and Ecology 72:67-81.

Fulton, R. S. III. 1984. Predation, production and the organization of an estuarine copepod community. Journal

of Plankton Research 6(3):399-415.

Grice, G. D. 1960. Calanoid and cyclopoid copepods collected from the Florida Gulf coast and Florida Keys in

1954 and 1955. Bulletin of Marine Science 10:217-226.

Grice, G. D. and N. H. Marcus. 1981. Dormant eggs of marine copepods. Oceanography and Marine Biology:

An Annual Review 19:125-140.

Heip, C. H. R., N. K. Goosen, P. M. J. Herman, J. Kromkamp, J. J. Middelburg, and K. Soetaert. 1995.

Production and consumption of biological particles in temperate tidal estuaries. Oceanography and Marine

Biology: An Annual Review 33:1-149.

Herlong, D. D. and M. A. Mallin. 1985. The benthos-plankton relationship upstream and downstream of a

blackwater impoundment. Journal of Freshwater Ecology 3(1):47-59.

Hester, B. S. 1976. Distribution and seasonality of hydromedusae in South Carolina estuaries. Masters of

Science Thesis, College of Charleston, Charleston, SC.

Hopkins, T. L. 1977. Zooplankton distribution in surface waters of Tampa Bay, Florida. Bulletin of Marine

Science 27(3):467-478.

Houser, D. S. and D. M. Allen. 1996. Zooplankton dynamics in an intertidal salt-marsh basin. Estuaries

19(3):659-673.

Hudson, P. L. 1975. 1975 annual report: southeastern reservoir investigation. United States Fish and Wildlife

Service. Clemson, SC.

Kleppel, G. S., C. A. Burkart, L. Houchin, and C. Tomas. 1998. Egg production in the copepod Acartia tonsa in

Florida Bay during summer. The roles of food environment and diet. Estuaries 21(2):328-339.

Knott, D. M. 1980. The zooplankton of the North Edisto River and two artificial saltwater impoundments.

Masters of Science Thesis, College of Charleston, Charleston, SC.

Knott, D., J. Amft, C. Barans, J. Blanton, B. Stender, P. Verity, E. Wenner, and F. Werner. (in preparation,

1998). The influence of wind forcing on the ingress of blue crab megalopae into a South Carolina coastal

inlet.

Lonsdale, D. J. and B. C. Coull. 1977. Composition and seasonality of zooplankton of North Inlet, South

Carolina. Chesapeake Science 18(3):272-283.

Mahoney, D. L., M. A. Mort, and B. E. Taylor. 1990. Species richness of calanoid copepods, cladocerans and

other branchiopods in Carolina Bay temporary ponds. American Midlands Naturalist 123(2):244-258.

Mallin, M. A. 1991. Zooplankton abundance and community structure in a mesohaline North Carolina estuary.

Estuaries 14(4):481-488.

McLaren, I. A. 1963. Effects of temperature on growth of zooplankton and the adaptive value of vertical

migration. Journal of the Fisheries Research Board of Canada 26:199-220.

Mense, D. J. and E. L. Wenner. 1989. Distribution and abundance of early life history stages of the blue crab,

Callinectes sapidus, in tidal marsh creeks near Charleston, SC. Estuaries 12(3):157-168.

Moore, R. H. and R. R. Reis. 1983. Analysis of spatial and temporal variations in biomass and community

structure of motile organisms in Town Creek, a South Carolina tidal pass. Contributions in Marine Science

26:111-125.

Omori, M. and T. Ikeda. 1984. Methods in Marine Zooplankton Ecology. John Wiley & Sons. New York,NY.

Ragotzkie, R. A. 1959. Plankton productivity in estuarine waters of Georgia. Publications of the Institute of

Marine Science, University of Texas 6:146-158.

Roman, M. R., M. R. Reeve, and J. L. Froggatt. 1983. Carbon production and export from Biscayne Bay,

Florida. Vol. I: Temporal patterns in primary production, seston and zooplankton. Estuarine, Coastal and

Shelf Science 17:45-59.

Sanders, R. W. and S. A. Wickham. 1993. Planktonic protozoa and metazoa: predation, food quality and

population control. Marine Microbial Food Webs 7(2):197-223.

Sandifer, P. A., J. V. Miglarese, D. R. Calder, J. J. Manzi, and L. A. Barclay. 1980. Ecological characterization

of the Sea Island coastal region of South Carolina and Georgia. Vol. III: Biological features of the

characterization area. U.S. Fish and Wildlife Service, Office of Biological Services, Washington, D.C.

FWS/OBS-79/42.

Sharitz, R. R. and J. W. Gibbons. 1982. The ecology of southeastern shrub bogs (Pocosins) and Carolina bays: a

community profile. United States Fish and Wildlife Service, Division of Biological Services, Washington,

DC. FWS/OBS-82/04.

Steele, J. H. and E. W. Henderson. 1998. Vertical migration of copepods. Journal of Plankton Research

20(4):787-799.

Stickney, R. R. and S. C. Knowles. 1975. Summer zooplankton distribution in a Georgia estuary. Marine

Biology 33:147-154.

Taylor, B. E. and D. L. Mahoney. 1990. Zooplankton in Rainbow Bay, a Carolina bay pond: population

dynamics in a temporary habitat. Freshwater Biology 24:597-612.

Taylor, B. E., A. E. DeBiase, and D. L. Mahoney. 1993. Development of the zooplankton assemblage in a new

cooling reservoir. Archiv fur Hydrobiologie 128(2):129-148.

Turner, C. H. 1910. Ecological notes on the cladocera and copepoda of Augusta, Georgia, with description of

new or little known species. Transactions of the Academy of Sciences of St. Louis 19(10):151-176.

University of Georgia Marine Institute. 1971. Notes on the natural history and invertebrate fauna of the upper

north Newport River In An ecological survey of the north and south Newport Rivers and adjacent waters

with respect to possible effects of treated kraft mill effluent. Final Report to the Georgia Water Quality

Control Board. UGA #D2422-122.

Van Engel, W. A. and E. B. Joseph. 1968. The characterization of coastal and estuarine fish nursery grounds as

natural communities. U. S. Department of the Interior, Fish and Wildlife Service, Bureau of Commercial

Fisheries.

Wenner, E. L. and H. R. Beatty. 1993. Utilization of shallow estuarine habitats in South Carolina, U.S.A., by

postlarval and juvenile stages of Penaeus spp. (Decapoda: Penaeidae). Journal of Crustacean Biology

13(2):280-295.

Wenner, E., D. Knott, J. Blanton, C. Barans, and J. Amft. 1998. Roles of tidal and wind- generated currents in

transporting white shrimp (Penaeus setiferus) postlarvae through a South Carolina (USA) inlet. Journal of

Plankton Research 20(12):2333-2356.