Catherine M Gatenby | Search USGS

USGS2026

Characterization of the native freshwater mussel assemblage across a reach of the Rappahannock River, Virginia

Native freshwater mussels occur in rivers of all sizes, yet much of the literature focuses on small- to medium-sized rivers, likely because of logistic challenges of sampling deep, fast, and turbid large rivers. As large-river surveys become more common, the information resulting from a systematic sampling design can provide baseline data on population sizes to inform decision making by resource managers. We collected baseline data on mussel resources in the Rappahannock River, Virginia, in August 2024. This Atlantic coast river, which drains into the Chesapeake Bay, is ∼320 km long, up to 1.6 km wide, and up to 35 m deep. We conducted a systematic quantitative survey across the 75-km reach of the river from Fredericksburg to Leedstown, Virginia. Divers obtained 187 whole substrate samples to estimate the species richness, density, population size, size distribution, community composition, and longitudinal spatial distribution of the native mussel assemblage. Six species were found, and the community was dominated by Eastern Elliptio ( Elliptio complanata ). Mean reach density (± 1 standard error) and population size was 1.25 (0.21) mussels m 22 and 19.3 (3.3) million mussels, respectively. The presence of few fresh dead mussels indicated low to moderate natural mortality. Shell length ranged from 32 to 122 mm, and multiple size classes were observed in E. complanata . Species richness and density had similar longitudinal patterns, with the highest values in the middle of the sampled reach (river kilometers 60–95). These data provide resource managers with baseline information on the spatial distribution, density, length demography, diversity, and evenness of native freshwater mussels across this reach of the Rappahannock River. Identification of mussel occurrence, density, and evidence of reproduction can be used by managers to aid conservation and management decisions such as prioritizing areas for reintroductions and habitat restoration.

Virginia↗

USGS2017

Developing a landscape‐scale, multi‐species, and cost‐efficient conservation strategy for imperilled aquatic species in the Upper Tennessee River Basin, USA

Strategic conservation of imperilled species faces several major challenges including uncertainty in species response to management actions, budgetary constraints that limit options, and the need to scale expected conservation benefits from local to landscape levels and from single to multiple species. A structured decision‐making process was applied to address these challenges and identify a cost‐effective conservation strategy for the Federally listed endangered and threatened aquatic species in the Upper Tennessee River Basin (UTRB). The UTRB, which encompasses a landscape of ~58 000 km 2 , primarily in western North Carolina, eastern Tennessee, and south‐western Virginia, harbours one of the most globally diverse assemblages of freshwater fishes and mussels at temperate latitudes. To develop a strategy for conservation of 12 fish species and 24 mussel species over a 20‐year period, a management strategy that would best recover these species was identified given costs and uncertainty in management effectiveness. The main insights came from a trade‐off analysis that compared alternative allocations of effort among management actions. A strategy emphasizing population management, which included propagation and translocation, performed best across a wide range of objective weightings and was robust to uncertainty in management effectiveness. Species prioritization was based on the expected conservation benefit from the best performing strategy, degree of imperilment, and species‐specific management costs. Sub‐basin prioritization was based on expected conservation benefit from the best performing strategy and feasibility of habitat management and threat abatement. Although the strategy was developed for imperilled aquatic species in the UTRB, the structured process is applicable for developing cost‐efficient strategies to conserve multiple species across a landscape under uncertain management effectiveness. The process can assist a manager with limited resources to understand which species to work on, where to conduct that work, and what work would be most beneficial for those species in those catchments.

Alabama, Georgia, Kentucky, North Carolina, Tennes↗