Nearshore Habitat and Fish Assemblages along a Gradient of Shoreline Development
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Littoral habitat is a critical component of lake ecosystems. Expansion of residential development along lakeshores has led to habitat modification, which may alter lentic fish communities. Previous studies have linked lakeshore development to reductions in abundance of aquatic vegetation and coarse woody structure (CWS), and many have quantified the influence of the density of docks on aquatic habitat structure and individual fish species. However, few studies have quantified fish assemblages relative to the effect of density or pattern of development. Using docks as a proxy for development, we calculated dock density, cumulative dock area, and estimates of the proportion of shoreline that was developed, affected by development, or left in large undeveloped segments for 28 Minnesota lakes. We assessed nearshore structural habitat (aquatic vegetation, CWS, and riparian features), a lake-wide fish index of biotic integrity (IBI), and nearshore components of the fish IBI relative to the development measures derived from docks. The nearshore IBI metrics were community composition metrics based on the proportion of intolerant, small benthic-dwelling, and vegetation-dwelling species caught in nearshore sampling, which we also evaluated individually and summed as a nearshore IBI. All measures of development were correlated and performed similarly in our models. Emergent vegetation and CWS declined with increasing development. Nearshore fish IBI declined with increasing development, but the lake-wide IBI did not change significantly with development. The decline of the nearshore fish IBI appeared to have been driven by a decline in vegetation-dwelling species.
Received June 9, 2016; accepted January 6, 2017 Published online March 15, 2017