Date on Master's Thesis/Doctoral Dissertation

8-2025

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Biology

Degree Program

Biology, PhD

Committee Chair

Kolmann, Matthew

Committee Member

Mehring, Andrew

Committee Member

McGregor, Monte

Committee Member

Yanoviak, Steve

Committee Member

Pigg, Rachel

Author's Keywords

Unionidae; Host-parasite; bioassessment; Ohio River basin; phylogenetic comparative methods; growth modeling

Abstract

Freshwater mussels are long-lived benthic invertebrates that play key roles in nutrient cycling, water filtration, and habitat stability in rivers and streams. Despite their ecological importance, they are among the most imperiled faunal groups in North America, with their persistence increasingly threatened by environmental degradation and disruptions to host–parasite dynamics. This dissertation integrates host ecology, community structure, and demographic modeling to assess population viability and guide conservation priorities for mussel species in Kentucky river systems. The first chapter introduces the ecological context and conservation urgency surrounding freshwater mussels. In particular, emphasizing the need for multi-scale approaches to understand how parasitic mussels interact with their hosts and how these interactions, in turn, may relate to correlations between mussel and fish community diversity. The second chapter investigates host specificity in two common species, Actinonaias ligamentina and Eurynia dilatata, using in vivo infestation trials and phylogenetic comparative analyses. Results demonstrate that host use by the two mussels only partially overlaps and host susceptibility is phylogenetically structured, offering predictive insight into host compatibility and informing propagation strategies for data-deficient or rare taxa. The third chapter examines mussel and fish community composition across nine sites in five river systems using standardized field surveys and multivariate analyses. Weak spatial congruence between mussel and fish assemblages underscores the importance of abiotic and historical drivers in shaping community patterns, and a composite site-scoring framework is introduced to support targeted conservation and restoration planning. The fourth chapter models demographic structure in Actinonaias ligamentina, Eurynia dilatata, and the federally endangered Cyprogenia stegaria using Gaussian mixture models and von Bertalanffy growth functions. These analyses reveal multiple distinct size cohorts, evidence of sustained recruitment, and temporal shifts in community composition, particularly at long-term monitoring sites influenced by environmental change. Collectively, these studies advance a flexible, data-driven framework for mussel conservation that integrates experimental host validation, community ecology, and demographic modeling. By identifying viable populations, predicting host compatibility, and prioritizing habitats for protection, this work contributes theoretical insights and practical tools for informing mussel conservation policy and guiding restoration efforts. Together, these tools enhance the long-term viability of freshwater biodiversity in ecosystems facing mounting anthropogenic pressures.

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