Relevance of lake physical habitat indices to fish and riparian birds

Despite the historical focus on water quality, it is becoming increasingly evident that physical habitat conditions also significantly affect lake biota. We examined associations between fish and bird assemblages and lake physical habitat based on relatively rapid assessments of Northeast US lakes. Richness of intolerant fish species declined, and that of tolerant fish species increased across regional gradients of increasing shoreline human development and decreasing abundance and structural complexity of riparian vegetation and littoral cover. Breeding bird assemblages observed in the nearshore littoral and riparian area of these lakes were similarly affected by disturbance and habitat simplification. The percentage of native neotropical migrant birds declined, and the percent of tolerant bird species increased across the same gradients. We conclude that our relatively rapid physical habitat assessments produce biologically relevant metrics useful for evaluating lake physical habitat condition and potential impacts on lake biota in regional and national lake assessments.