Diversity and distribution of fish habitat throughout the U.S. Great Lakes Basin: Can we conserve communities?

Conservation of living aquatic resources requires management of diverse, interconnected systems, largely due to the strong dependence of species occurrence and abundance on habitat conditions (at a variety of spatial scales). New habitat classification and predictive tools now allow conservationists and managers to assess potential fish community diversity and composition throughout lotic habitats of the US Great Lakes Basin at scales from the stream segment to the entire basin. We developed a multi-scale habitat classification system that can characterize the fish fauna (model predicted) of any habitat unit or drainage. We identified a total of 2,160 distinct lotic fish assemblages. These were distributed across 136,107 stream segments. More than half of these assemblages occurred on 10 or few stream segments and a few (1%) were widespread, occurring on >1,000 stream segments each. These tools help address questions such as, what is the rarest (or most common) lotic fish habitat? Where is it found? What fish species are expected to be found there? And what are the abiotic characteristics? It is clear that not all drainage units have the same potential for species diversity or composition. This classification system may be useful to prioritize protection and restoration efforts throughout the region.