Water Quality Assessment of Irondequoit Creek using Benthic Macroinvertebrates

Abstract

The Rochester Embayment of Lake Ontario is one the 43 Great Lakes' Areas of Concern designated by the Environmental Protection Agency (Monroe County 1993). As part of a Remedial Action Plan (RAP), degradation ofbenthos was one of the 14 use impairments identified for the Rochester Embayment (Monroe County 1993). Stage II of the RAP identified stream health monitoring as a method of identifying existing and future conditions of the Embayment and its tributaries, including Irondequoit Creek. There is much debate in the "world" of stream health biomonitoring using aquatic macro invertebrates regarding methods of collection, sample size and taxonomic resolution required to obtain accurate stream health assessments. My study compared stream health at three locations in Irondequoit Creek (upstream, midstream and downstream) and in three habitats (gravel, mud and vegetation) and evaluated methods of sampling macro invertebrates and analyzing stream health used by the Stream Biomonitoring Unit ofthe New York State Department ofEnvironmental Conservation (Bode et al. 1996). There were few differences between upstream (primarily agricultural or rural land use) and midstream (primarily agricultural and suburban l~d use) communities, but stream health decreased from upstream to downstream (primarily .urban/suburban land use). As expected, community differences were found across habitats (gravel, vegetation, mud) at the same sampling locations. Fixed 100 count · methods were compared with entire macro invertebrate samples in the gravel habitat at the midstream location (Powder Mill Park, Rochester, NY). Although metric values for random and haphazard samples of 100 organisms differed from values for whole samples, stream health assessments did not differ.