Development, Calibration, and Validation of a Fish Assemblage Reservoir Index of Sustainability for the Midwestern United States


School of Public and Environmental Affairs, Indiana University, 1315 E. Tenth Street, Bloomington, IN 47405. Division of Fishes, Aquatic Research Center, Indiana Biological Survey, 6400 S. Fairfax Road, Bloomington, IN 47401.

Assessment of reservoir lakes has been limited because they are non-natural, anthropogenically created habitats that function intermediately between lakes and rivers. A reservoir index of biological sustainability (IBS) was developed for reservoir lakes in the Midwestern United States. A stratified random probability sampling design was used, based on lake surface area, to calibrate the perceived potential reference condition (N = 107 lakes). Fifty candidate attributes of reservoir fish assemblage structure and function were evaluated based on a range test, skewness, redundancy, failure of the initial hypothesis, and insufficient numbers of taxa to optimize data spread between degraded and “least-impacted” reaches. Ten metrics were chosen to assess biological stability of fish assemblages. Metrics that showed a statistically significant relationship with anthropogenic disturbance included, number of species; number of benthic species; number of centrarchid species, including black basses; percent individuals as lake obligate species; percent individuals as omnivores, insectivores, and carnivores; percent individuals as tolerant species; and relative abundance. The percent individuals with deformities, eroded fins, lesions, and tumors (DELT) anomalies are included in the model as a preventative measure of contaminant stress. The index was validated using an independent dataset (N=129) from the Interior River Lowland that compared land use types, including “minimally impaired condition” reference, acid mine drainage, residential, urban, forested, thermal, drinking water, and resort/camp lakes. Reference reservoirs significantly differed from anthropogenically impaired acid mine drainage and drinking water reservoirs, but were not statistically different from forested reservoirs.   

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