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An Assessment of Stressor Extent and Biological Condition in the North American Mid-continent Great Rivers (USA)
Citation:
ANGRADI, T. R., D. W. BOLGRIEN, T. M. JICHA, M. S. PEARSON, D. L. TAYLOR, M. F. MOFFETT, K. A. BLOCKSOM, D. M. WALTERS, C. M. ELONEN, L. E. ANDERSON, J. M. LAZORCHAK, E. D. REAVIES, A. R. KIRETA, AND B. H. HILL. An Assessment of Stressor Extent and Biological Condition in the North American Mid-continent Great Rivers (USA). River Systems. E. Schweizerbart'sche Verlagsbuchhandlung, Stuttgart, Germany, 19(2):143-163, (2011).
Impact/Purpose:
To document research results
Description:
We assessed the North American mid-continent great rivers (Upper Mississippi, Missouri, and Ohio). We estimated the extent of each river in most- (MDC) or least-disturbed condition (LDC) based on multiple biological response indicators: fi sh and macroinvertebrate, trophic state based on chlorophyll a, macrophyte cover, and exposure of fi sh-eating wildlife to toxic contaminants in fi sh tissue (Hg, total chlordane, total DDT, PCBs). We estimated the extent of stressors on each river including nutrients, suspended solids, sediment toxicity, invasive species, and land use (agriculture and impervious surface). All three rivers had a greater percent of their river length in MDC than in LDC based on fi sh assemblages. The Upper Mississippi River had the greatest percent of river length with eutrophic status. The Ohio River had the greatest percent of river length with fi sh with tissue contaminant levels toxic to wildlife. Overall, condition indices based on fi sh assemblages were more sensitive to stress than macroinvertebrate indices. Compared to the streams in its basin, more of the Upper Mississippi and Missouri Rivers were in MDC for nutrients than the Ohio River. Invasive species (Asian carp and Dreissenid mussels) were less widespread and less abundant on the Missouri River than on the other great rivers. The Ohio River had the most urbanized fl oodplains (greatest percent impervious surface). The Missouri River had the most fl oodplain agriculture. The effect of large urban areas on river condition was apparent for several indicators. Ecosystem condition based in fi sh assemblages, trophic state, and fi sh tissue contamination was related to land use on the fl oodplain and at the subcatchment scale. This is the fi rst unbiased bioassessment of the mid-continent great rivers in the United States. The indicators, condition thresholds, results, and recommendations from this program are a starting point for improved future great river assessments.