Fishes of Indiana streams: current and historic assemblage structure |
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Authors: | Stephen J Jacquemin Mark Pyron |
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Institution: | (1) Department of Biology, Aquatic Biology and Fisheries Center, Ball State University, Muncie, IN 47306, USA; |
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Abstract: | We examined Indiana fish assemblages using taxonomy and ecological categories to assess temporal shifts in community structure
and recent environmental relationships. Historic (1945) and recent (1996–2007) presence/absence data were compiled by subbasin
and analyzed with Nonmetric Multidimensional Scaling (NMS) ordination and by species richness. Canonical Correspondence Analysis
(CCA) was used to test taxonomic identity and ecological category abundance data for explanation with recent (1996–2007) environmental
variables. We found a decrease in assemblage heterogeneity for recent assemblages and an increase in the number of tolerant
species per subbasin. Recent Indiana streams are dominated by tolerant fishes with generalist life history strategies and
low functional variation. The use of ecological categories resulted in weaker relationships with environmental variables than
analyses with taxonomic identities. Analyses using taxonomy resulted in strong assemblage explanation from stream size and
flow variation, while analyses using ecological categories resulted in strong assemblage explanation from habitat variation
in silt substrates and flow. Analyses of recent assemblage structure using ecological categories resulted in decreased assemblage
variation among subbasins than in analyses using taxonomic identities. We found that fish assemblages of Indiana streams are
structured primarily by habitat complexity and have been altered during the past 50 years through multiple disturbances including
fragmentation, siltation, and species introductions. |
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