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Description of Aquatic Macrofauna in Plum Island Sound

Aquatic macrofauna are abundant and diverse throughout the Plum Island Sound estuary. Twenty eight species of fish have been recorded in the brackish to marine areas and another 10 from the freshwater portions (Jerome et al. 1968, Deegan, unpublished data). The zooplankton and benthic fauna are typical of shallow estuaries in the Gulf of Maine (Jerome et al. 1968). The upper estuary shows the mixing of fish species from freshwater, diadromous and nursery life-histories that is typical of oligohaline zones. Estuarine species such as mummichogs (Fundulus heteroclitus), Atlantic silversides (Menidia menidia), winter flounder (Pleuronectes americanus) and bluefish (Pomatomus saltatrix) co-exist with typical freshwater species such as bluegill (Lepomis macrochirus) and white perch (Morone americana) in the upper estuary. Many of these species are present as larval and juvenile forms and achieve phenomenal growth during the summer months in this productive region. As is typical in the oligohaline reach of many estuaries (Day et al. 1989) the benthic community is reduced in species richness and, in particular, the bivalve community is noticeably absent. The dominant crustacean macrofauna are mysids, sand shrimp (Crangon septemspinosa) and the whitefingered mud crab (Rhithropanopeus harrisii). In mid-estuary, the fish community is dominated by typical species such as Atlantic silversides, mummichogs, winter flounder, three-spined sticklebacks (Gasterosteus aculatus), blackspotted stickleback (Gasterosteus wheatlandi) and bluefish. The large macrofaunal crustacean community is dominated by sand shrimp and green crabs (Carcinus maenus). The conspicuous pelagic filter feeding bivalve species are ribbed mussels (Modiolus demissus) along the marsh banks, soft shell clams (Mya arenaria) in the tidal flats and oysters (Crassotrea virginica) in the river channel. In the lower estuary the nearshore fish community is again dominated by typical estuarine species such as Atlantic silversides and mummichogs, but also included sizable populations of menhaden (Brevoortia tyrannus), smelt (Osmerus mordax), winter flounder and blackspotted sticklebacks. Sand shrimp and green crabs are again the dominant macrocrustaceans. Bivalve communities of blue mussels (Mytilus edulis) and soft shell clams are prevalent with mussel beds fringing the shoreline which drops off quickly to a deep (8 m) tidal channel.

This material is based upon work supported by the National Science Foundation under Cooperative Agreement #OCE-9726921, #OCE-0423565, #OCE-1058747. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.