Using Juvenile Freshwater Mussels as Bioindicators to Identify Causes and Sources of Stream Degradation Associated with Mussel Declines

In 2015, we began development of a direct method to address the causes of freshwater mussel declines. Our method involves placing captively propagated juvenile mussels in streams and monitoring their survival and growth. We found that mussels did not grow in streams that have previously lost their mussel faunas. In 2016, we propose to focus on two streams, Nolin River and Horse Lick Creek, which have lost their mussel faunas in recent decades, and which did not support normal mussel growth in 2015. We will place juvenile mussels in silos throughout these watersheds at an array of sites located upstream and downstream of each major tributary. By assessing growth and survival of mussels at each site, we hope to identify sources of water quality degradation that negatively affect mussels. We will also measure mussel food resources (bacteria and diatoms), water quality, and fish and insect assemblages at each site (fish and insect sampling will be conducted in Horse Lick Creek only). Bacteria, diatom, and water quality data will allow assessment of specific factors that may be associated with reduced mussel survival or growth. Information on fish and insect assemblages will assess the availability of mussel host fishes and the effects of water quality degradation on other components of the ecosystem. Identification of the causes of mussel declines and the sources of water quality degradation is essential for recovering affected streams and for preventing similar declines in other streams in the future.