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IMPACTS OF DREISSENID SHELLS ON BENTHIC HABITAT AND MACROINVERTEBRATES IN STREAMS

The physical effects of dreissenid invasions are well documented in lakes, but few studies have assessed their impacts in streams. Dreissenid mussels can alter benthic habitats by aggregating on substrates, dying off, and leaving mass quantities of shells behind. We quantified dreissenid shell densities in the Rouge and Huron rivers downstream of dammed lakes, and evaluated their impact on the macroinvertebrate communities. Shell densities were highest immediately downstream of dams, sometimes covering 100% of the substrate. We found no correlation between shell densities and macroinvertebrate total abundance (p>0.05) in either river, however, community composition varied with shell density. Lower macroinvertebrate diversity was associated with high shell densities in the Rouge and Huron Rivers (p<0.05), compared to areas with low shell densities; likewise, lower relative abundances of sensitive taxa (p<0.05) were noted as shell densities increased in the Huron River. Rivers impacted by Dreissenid invasions can experience losses in habitation heterogeneity, and significant changes in macroinvertebrate community composition. Changes in the native fauna resulting from physical alterations in the benthic structure by an invasive species can have ecosystem wide implications.

Darrin Hunt (Primary Presenter/Author), Wayne State University, eb5832@wayne.edu;


Donna Kashian ( Co-Presenter/Co-Author), Wayne State University, dkashian@wayne.edu;