Environmental influences on fish assemblages in Lake Huron tributaries

Streams fish assemblages are affected by multiple environmental, chemical, physical and biotic factors.  We sampled stream fish assemblages in nine tributaries of Lake Huron to determine assemblage composition, diversity, abiotic, and biotic factors that highly influence the assemblage.  Sampling occurred in spring and late summer by electrofishing four to seven sites per stream.  Spring sampling included large numbers of gravid individuals including northern pike, white suckers, and yellow perch.  Canonical correspondence analysis results suggest that distance from Lake Huron, presence of spawners, conductivity, dissolved oxygen, temperature, and specific conductance significantly explain variation in the species distributions.  Spring species richness increased with distance from stream origin, percent gravel/cobble in the substrate, and conductivity; density increased with presence of spawners and decreased with turbidity.  Summer species richness increased with distance from stream origin and the amount of gravel/cobble; density increased with distance from stream origin, dredging history, habitat diversity, percent gravel/cobble in the substrate and conductivity but decreased with bank slope, specific conductance and temperature.  These small Great Lakes tributaries host a diverse and dynamic fish assemblage and are important spring spawning grounds, supplemental aquatic habitat for lentic species, and nursery areas for larval and young-of-year individuals.