Oral Presentation Society for Freshwater Science 2026 Annual Meeting

Identifying ecologically relevant host fishes across the Atlantic Slope  (135724)

Stefanie J Farrington 1 2 , Allison H Roy 3 , David Perkins 2 , Graziella V DiRenzo 3 , John G Gibbons 4 , Christina A Murphy 5 , Timothy Warren 2
  1. Organismic and Evolutionary Biology Program, Massachusetts Cooperative Fish and Wildlife Research Unit, University of Massachusetts, University of Massachusetts Amherst, Amherst, MA, USA
  2. Richard Cronin Aquatic Resource Center, U.S. Fish & Wildlife Service, Sunderland, MA, USA
  3. Department of Environmental Conservation, University of Massachusetts, U.S. Geological Survey, Massachusetts Cooperative Fish and Wildlife Research Unit , Amherst, MA, USA
  4. Department of Food Science, University of Massachusetts Amherst, Amherst, MA, USA
  5. Department of Wildlife, Fisheries, and Conservation Biology, University of Maine, U.S. Geological Survey, Maine Cooperative Fish and Wildlife Research Unit, Orono, Maine, USA

Freshwater mussels (Unionids) rely on access to suitable host fishes to reproduce, making understanding of this obligate-affiliate relationship vital to developing effective conservation and restoration plans for mussels. Nearly all host fish assessments have occurred in a single location with a single population of mussels and fishes, although it is unlikely that host fishes are equally suitable and available across a mussel’s distribution. Furthermore, knowledge of host fishes for freshwater mussel species is largely based on laboratory studies, despite an inherent disconnect between physiological host observations and in situ host interactions. The goal of this study was to assess host fish use by Unionids in six watersheds across the Atlantic Slope. Working in collaboration with state, federal, and academic organizations conducting fish collections in our target areas, we collected twelve species of fishes in the Percidae, Centrarchidae, and Moronidae families, and we examined their gills for attached glochidia. Of the 518 individuals collected, 45 fishes had at least one glochidium present (232 total glochidia). We ran a Principal Component Analysis (PCA) to compare our samples to a reference database for morphometric measurements of glochidia (shell height, length, hinge length, and overall shape), compiled using existing literature. We mapped where in multivariate space our unknown glochidia samples fell within the 95% confidence ellipses for each species in the PCA: 42 glochidia samples fell within an ellipse and could be identified to species or genus. We identified five novel mussel-host relationships with no previous evidence of transformation or infection in the literature, highlighting the utility of natural infection as a means of host fish identification. Future work for this project will expand the reference data used to identify candidate species and will incorporate DNA sequencing of the glochidia samples to validate the morphometric assessments.