AUTHORS: Andrew McElwain, Department of Biological Sciences, SUNY Oswego; Andrew Gascho Landis, Department of Fisheries, Wildlife, and Environmental Science, SUNY Cobleskill; Peter D. Hazelton, MassWildlife
ABSTRACT. North America contains approximately 298 species of freshwater mussels (Margaritiferidae: 5, Unionidae: 293). Freshwater mussels are intriguing because they are parasites of fishes during their larval period and because they use their gills for brooding glochidia, respiration, and filter feeding. Freshwater mussels are valued for the ecosystem service of removing particles from the water; however, this form of feeding leaves them vulnerable to contaminants in the water. Unfortunately, we are losing many species as a result of contaminants, habitat degradation, non-native species introductions, and diseases. Herein we report preliminary results from an investigation into a shell deformity among Elliptio complanata, Lampsilis radiata, Strophitus undulatus (Unionidae), and Margaritifera margaritifera (Margaritiferidae) from the Nashua River, Massachusetts that were collected during the summer of 2017. Affected mussels display a truncated posterior shell margin and the severity of this deformity ranges from slight to severe. Prevalence values and sample sizes (data sourced from whole mussels and empty shells) are as follows: E. complanata, 49%, n = 71; L. radiata, 33%, n = 3; S. undulatus, 100%, n = 1; M. margaritifera, 57%, n = 7. It has been proposed that these deformities are caused by agricultural or household chemicals, or possibly parasitic infection (Strayer 2008). We are interested in exploring the mechanisms that are responsible for this shell deformity to hopefully shed light on the responsible factors. We are examining potential microscopic changes to the shell using light and scanning electron microscopy, histopathological changes to the mantle, and shell thin-sections to look for changes in growth and longevity. We are presently uncertain whether this deformity results from shell damage or cellular changes to the mantle that would alter shell growth. Although the primary literature contains little information about shell deformities among freshwater mussels, we suspect this problem may occur elsewhere in the Northeastern U.S.
