Assessment of Freshwater Mussel Communities of Small Stream Mouths Along Lake Erie

Invasion of lakes and rivers by dreissenid mussels pushed out native species, particularly freshwater mussels in the Unionidae, across the northern hemisphere, and perhaps most infamously, within the Laurentian Great Lakes. However, several coastal areas along the shallowest of these lakes, Lake Erie, may be refugia for native species, but the conditions under which native species persist are unknown. I surveyed river mouths of small streams along the Lake Erie coastline and compared species abundance to land use assessed by remote sensing techniques and to standard measures of water chemistry. Sampling focused on stream zones influenced by lake-water levels for three streams each in the western and central basins of Lake Erie and in Sandusky Bay. Eight of the nine streams possessed mussels: Pyganodon grandis (7 streams), Toxolasma parvum (5 streams), Quadrula quadrula (5 streams), Lasmigona complanata (5 streams), Leptodea fragilis (4 streams), and Utterbackia imbecillus (2 streams), while Amblema plicata, Obliquaria reflexa and Uniomerus tetralasmus were found each in only one stream. Distinct bathymetric features did not affect diversity levels, although water chemistry may have reduced abundance in some streams and unionid abundance was positively correlated with turbidity. Regional land use altered species dominance, as streams within physiographic regions containing higher amounts of silt were dominated by Q. quadrula, while more mixed habitat was dominated by P. grandis. Because, river mouths are refugia for unionid mussels, these areas must return to or come under regulatory control to monitor habitat alteration, a process stopped in this region following the belief that dreissenid mussels had eradicated all species of interes