Development and application of a general freshwater mussel habitat model

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Brook D. Herman, Environmental Laboratory, U.S. Army Corps of Engineers, Vicksburg, MS, Todd M. Swannack, Environmental Laboratory, U.S. Army Engineer Research and Development Center, USACE, Vicksburg, MS, Todd Slack, USACE-Engineer Research and Development Center, Vicksburg, MS and Carra Carrillo, Environmental Laboratory, US Army Corps of Engineers, Vicksburg, MS

Background/Question/Methods
Over 300 species of freshwater mussels in North America are becoming endangered faster than any other group of species. They provide important ecosystem goods and services and contribute to freshwater diversity. Planning freshwater mussel habitat restoration projects is complicated because life history requirements are complex. Ecological models help to determine important ecosystem components that are relevant to restore and maintain a species or community of interest. They can also elucidate differences between proposed restoration alternatives and prioritize restoration sites. This poster will describe the development and application of a general freshwater mussel habitat model. The objectives of the model are to be applicable throughout the range of the North American freshwater species, be sensitive to differences in proposed restoration actions or sites and contain parameters that reflect system-level functions, structures and processes that provide suitable habitat for freshwater mussels.
The first step in model development was to review critical life history traits and environmental drivers of mussel species. Based off of the review we came to consensus on important model parameters that met model objectives using the group mediated model development approach. Next model development steps included comparing model to a previously developed mussel habitat model and applying model to a real-world planning study.
Results/Conclusions
Important model parameters were determined to be connectivity of waterway for host fish species, diversity of host fish species, percent aquatic cover, quality of substrate, summer maximum water temperature for adults and juveniles and flow regime. Results of model output comparison indicted model agreement when applying both models to the same river reach. Model was applied to the Schuylkill River Aquatic Ecosystem Restoration Feasibility Study (Schuylkill), located in Philadelphia, Pennsylvania. Application of the model revealed that the trade-offs made during development between being general enough to be applied to all freshwater mussel species throughout range and being sensitive to proposed habitat restoration actions resulted in the model being too general, such that the original model was not sensitive enough to site specifics in the Schuylkill River. Model was then modified through the group mediated model development approach, which resulted in an appropriate level of sensitivity to proposed restoration actions for the project site. In conclusion, model generality can be a beneficial for wide variety of applications, but it can be a determent to answering site or project specific questions. However, there is time and effort saved by modifying an existing model vs. developing a new model.