Scope 6-David Weisrock-104B Water Resources Research Institute Annual Base Program 2021-2026

Streams, lakes, and rivers are a resource to Kentucky both environmentally and economically, yet the health of these freshwaters is at risk of contamination. Native freshwater mussels are essential for the health and ecosystem function of Kentucky streams. They are the primary means of silt filtration in our lakes and streams. Loss of native mussels can lead to nutrient overload, resulting in algal blooms and low oxygen dead zones, decreasing the health and species diversity in our water systems. Over half of native Kentucky mussel species are currently at risk of extinction. Anthropogenic changes to our streams are the main cause of mussel population decline, but the recent invasion of the Asian clam (Corbicula fluminea) into Kentucky waters also jeopardizes native mussel survival. Here we use 16S rRNA gene sequencing and microbiome analysis to identify the planktonic species particular bivalves consume as well as the relative proportion of their diet made up of cyanobacteria—a taxon with species members known to cause toxic algal blooms. These results will help us understand the effect that mussel species loss will have on Kentucky stream health and help to inform decisions regarding mussel conservation and reintroduction into Kentucky streams. We will also investigate the impact of species and location on diet and gut microbial composition in the community structure of native species. Comparisons across taxa will give us insight into the roles that life history and evolutionary history play in gut microbiome and diet composition in these important stream species.