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TEMPORAL VARIATION IN OHIO RIVER MACROINVERTEBRATES: A HISTORICAL ROCK BASKET COMPARISON (1965-1971 AND 2002)
Citation:
WOOTEN, M. S., B. R. JOHNSON, AND E. B. EMERY. TEMPORAL VARIATION IN OHIO RIVER MACROINVERTEBRATES: A HISTORICAL ROCK BASKET COMPARISON (1965-1971 AND 2002). JOURNAL OF FRESHWATER ECOLOGY. Oikos Publishers Incorporated, La Crosse, WI, 21(4):561-574, (2006).
Impact/Purpose:
The goal of this research is to develop methods and indicators that are useful for evaluating the condition of aquatic communities, for assessing the restoration of aquatic communities in response to mitigation and best management practices, and for determining the exposure of aquatic communities to different classes of stressors (i.e., pesticides, sedimentation, habitat alteration).
Description:
The U.S. Environmental Protection Agency (USEPA) used rock basket artificial substrates to sample benthic macroinvertebrates of the Ohio River from 1965-1971. The objective of this study was to repeat the rock basket surveys in 2002 to evaluate changes in the benthic assemblage and to assess health of the community since passage of the 1972 Clean Water Act (CWA). Rock baskets of the same configuration were placed in the vicinity of the historic locations and were allowed to colonize for the same six week period in summer 2002. Macroinvertebrates collected from 2002 baskets were compared to those of historic samples by use of non-metric multidimensional scaling (NMDS), proportional indices of community similarity, and by comparison of commonly used macroinvertebrate metrics. Analyses were generally performed at the genus (insects) or order (non-insect) level to minimize taxonomic discrepancies between time periods. A total of 62 taxa groups were identified across all years, with midges and oligochaetes generally dominating. Only 10-16 taxa groups accounted for >93% of all individuals in each year, but taxa contributions varied greatly among years. The 2002 benthic assemblage was distinct from past years with increases in taxa richness and EPT taxa, and a decline in the number of oligochaetes. Differences in 2002 data are partially attributed to a replacement of the amphipod Crangonyx sp. by Gammarus sp. and the invasion of zebra mussels (Dreissena polymorpha) during the late 1980s. Our findings indicate the Ohio River benthic community today is markedly different from that of the 1960s and has shown general improvement since passage of the 1972 CWA.