Landscape associations with native and invasive freshwater mussels

Landscape impacts on aquatic organisms can play important roles in community structure and distributions, and landscape alteration can present unique challenges for organisms like freshwater mussels (Bivalvia: Unionidae) that can be compounded by the presence of invasive species. This study examined the impacts of landscape variables on native freshwater mussel and invasive Corbicula spp. distributions and densities in the Kalamazoo River watershed, MI, USA. Landscape impacts were analyzed at three spatial scales using GIS and regression tree analyses to determine factors influencing unionid and corbiculid densities. Results indicated that land use, geology, and longitudinal position in the watershed influence densities of unionids and corbiculids. In addition, corbiculid density was found to be important in determining unionid density and distribution at the reach scale. Results showed that landscape variables can influence invasive and native mussel species and emphasize the need to incorporate spatial information into our understanding of the relationships among organisms and their environments. The knowledge gained here contributes to evidence of the impacts that landscape can have on the abundance and distribution of both native and invasive organisms and provides insight into the associations of invasive Corbicula spp. with landscape variables and native unionids at multiple spatial scales.