Status and Trends in Benthic Macroinvertebrate Communities as an Indicator ofWater Quality at Maryland's Core Monitoring Stations, 1976-1992

摘要

Benthic macroinvertebrate communities have been sampled at 27 of Maryland's COREmonitoring stations since 1976. On average, the benthic samples have been collected annually during the spring to summer months using either a Surber sampler or Fullner modified Hester Dendy multiplate sampler, Using this database of 17 years of benthic information, water quality trends were determined by examining the macroinvertebrate community over time, from 1976 to 1992. Four measures were selected to evaluate the macroinvertebrate community: taxa number; Shannon-Weiner diversity index; modified Hilsenhoff biotic index; and percentage of Ephemeroptera, Plecoptera, Trichoptera (%EPT). These community measures were analyzed for significant correlations with time using non-parametric statistical tests.