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Isabelle Levesque-Du Bose

Size Variation and Morphometric Analysis of Freshwater Mussels (Elliptio complanata) in the Susquehanna River

Isabelle Levesque-Du Bose ’23
Peter Foradora, Joanna Raup-Collado
Faculty Mentor(s):
Tristan Stayton, Department of Biology
Sean Reese, Center for Sustainability and the Environment
Elizabeth Capaldi, Department of Biology, Animal Behavior
Funding Source:
Department of Biology

Freshwater mussels are a vastly understudied group of animals, and as a result, basic life history characteristics are unknown for many species. In some species, gravid females display a deceptive lure made from part of their mantle, but unless the female is displaying the lure, it is difficult to quickly and accurately determine the sex of mussels based on their external morphology. As a result, local mussel populations have hidden sex ratios, making estimates of population growth difficult. Using live Eastern elliptio mussels (Elliptio complanata) from the Susquehanna River and the Buffalo Creek, we sought to determine if there is a predictive relationship between sex and shape. Samples of gonadal fluid were extracted from the visceral mass to determine the sex of each individual. These data were then connected to three measurements of the corresponding shell: length, width, and depth (girth). No sexual dimorphism was present using these simple measurements. However, in a subset of the population sampled, further morphometric analyses of shape from digitized photographs of the animals revealed differences between the sexes, displaying a level of dimorphism previously unknown in this species. Determining the sex of live individuals has important implications for future studies of mussel biology, including answering questions related to mussel reproduction, demography, and population distribution.

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