Incorporating habitat characteristics and fish hosts to predict freshwater mussel (Bivalvia: Unionidae) distributions in the Lake Erie drainage, southeastern Michigan

Museum records and survey data were used at 52 sites across the Lake Erie drainage in southeastern Michigan to test the hypothesis that the presence of a mussel species is independent of the presence of its fish host. Two host specific mussels, Epioblasma triquetra and Lampsilis fasciola, were dependent of the distributions of their fish hosts, Percina caprodes and Micropterus dolomieu, respectively. Host generalists showed significant associations mainly with only one fish species.;Mussel species richness was positively correlated when mussel subfamilies and fish families were considered. Mussel species richness within the subfamily Ambleminae and tribe Pleurobemini were correlated with the fish species richness in the family Ictaluridae. The tribe Lampsilini was positively correlated with the fish species richness in the Percidae and Centrarchidae families.;To test the hypothesis that mussel densities do not increase with an increase in fish host densities, mussel and fish were quantified in 100 m sections at 24 sites in the Lake Erie drainage. Habitat characteristics were also recorded to test the hypothesis that mussels are independent of variations in habitat. Mussels increased with the increase in density and relative abundance of fish hosts, but results varied with mussel species. Epioblasma triquetra was positively correlated with P. caprodes . Three other host generalists, Lampsilis cardium, L. siliquoidea , and V. iris, were correlated with one or more of their fish hosts. Mussels were positively correlated with few habitat values.;From the above results, predictive multilinear regression models were developed for nine mussel species (Elliptio dilatata, E. triquetra, Fusconaia flava, L. cardium, L. siliquoidea, L. fasciola, Ptychobranchus fasciolaris, Strophitus undulatus and Villosa iris) using both fish and habitat variables to predict mussel distributions. These models can be tested in other areas of the Lake Erie drainage (Ohio, Canada) or other drainages in Michigan. Because of the complex interactions between habitat, mussels, and host fish, future models should consider path analyses.