Freshwater Mussel Assessment in the Upper Nottoway River and its Tributaries on Fort Pickett, Virginia

The upper reaches of the Nottoway River and its tributaries on Fort Pickett, Virginia are located within one of the most diverse river basins of the Atlantic Slope region. Freshwater mussels are vital components of these aquatic ecosystems and are often referred to as ecosystem engineers. Mussel surveys on Fort Pickett have historically concentrated on the central reaches of the Nottoway below the reservoir. Thus, assessments in tributaries and sites above the reservoir were needed. We evaluated a total of 68 sites across Fort Pickett and implemented a two-phase sampling design using time-constrained and quadrat-based surveys at a sub-set of these sites. We documented a total of 9 mussel species, including the state threatened Atlantic pigtoe and state species of concern eastern lampmussel. We found that mussels were patchily distributed and densities and species richness varied greatly between sites. Generally, species richness was lower and densities were higher in the tributaries compared to the main-stem of the Nottoway. Our findings of local mussel populations in the tributaries suggest that these areas may serve as spatial refugia for populations of several species. We found little evidence of recent recruitment across species, even at sites with high densities, indicating the need for water-quality testing and host fish surveys to identify management actions needed to support long-term population viability across species. Riparian and habitat protection should extend to the tributaries as well as to the main-stem of the Nottoway. Furthermore, we recommend additional surveys above the reservoir and in the Controlled Access Area, routine monitoring for Atlantic pigtoe and eastern lampmussel, as well as water quality assessments.