Benthic Invertebrates of the Lower West River

The purpose of this study was to document existing benthic organisms of the lower West River in New Haven and West Haven, Connecticut, in order to enable monitoring of salt marsh restoration. Seventeen sites were sampled between the Chapel Street Bridge and the mouth of the West River during the month of July 1995. All sites contained polychaete worms and other organisms typical of estuarine systems. The northernmost sites also contained some freshwater organisms, the most abundant of which were chironomids and freshwater snails. The presence of estuarine fauna within tide-restricted portions of the West River is attributed primarily to the malfunctioning of tide gates during the sampling season in combination with a regional drought. These conditions provided a favorable environment for estuarine organisms to colonize and provided an opportunity to determine that restoration of the estuarine benthos would occur if estuarine water flow was returned to the river as a part of salt marsh restoration. Periodic sampling of the benthic community would be an effective component of restoration monitoring. Benthic invertebrate communities are integral components of both freshwater and estuarine systems. The benthos – those organisms that live on or within sediments – influence sediment and bottom-water chemistry (Rhoads et al. 1977, Aller 1980, 1982), alter sediment organic content (Pearson and Rosenberg 1978) and structure (Rhoads and Young 1970, 1971, Bokuniewicz et al. 1975, Rhoads et al. 1978, Rhoads and Boyer 1982), and serve as major prey species for crustaceans and fish (Virnstein 1977). Although freshwater and estuarine benthos perform similar ecological functions, organismal composition is quite different. Common members of freshwater benthic communities include oligochaete worms, chironomids (dipteran larvae), numerous other insect larvae, insect adults, leeches, freshwater gastropods (snails), and freshwater bivalves (e.g., clams). Estuarine benthos typically include nematode worms, polychaete worms, amphipods, crustaceans, marine gastropods, and marine mollusks. Rhoads and Germano (1982) documented a series of predictable, successional stages for estuarine benthic communities. These successional sequences (Stages I, II and III) are characterized by particular, functional types of benthic organisms. One functional type succeeds another over time if all else remains stable. Organisms comprising Stage I estuarine assemblages colonize newly available seafloor, such as that which becomes available when a freshwater habitat is inundated by saline water. A change in benthic community composition