Comparison of Benthic Communities in Dredged and Undredged Areas of the St. Lawrence River, Cape Vincent, N.y

Macroinvertebrate communities were compared in dredged and undredged areas of the St. Lawrence near Cape Vincent, N.Y., by sampling with a Ponar dredge in 3 seasons. No significant differences existed in numbers of Gammarus spp. and species of Oligochaeta between dredged and undredged areas. The chironomids Pseudochironomus and Stictochironomus spp. were significantly less abundant and Clinotanypus was significantly more abundant at previously dredged sites. Among mollusks, Bithynia tentaculata and Sphaerium corneum were found in significantly greater densities at undredged stations. Total macroinvertebrate abundance was greater in undredged areas. The differences in total abundance of invertebrates and abundance of individual species in dredged and undredged areas appear to be related to the presence of gyttjatype sediments caused by breakwater construction and dredging operations at least 40 years ago. O H I O J . SCI. 82(4): 165, 1982