Abstract

Unionid mussel populations in a section of the Clinch River in Virginia, USA, has declined substantially, but the causes of the decline remain unknown. To investigate this zone of decline (ZOD), we deployed juvenile freshwater mussels (Villosa iris in 2012 and Lampsilis fasciola in 2013) in both cages and silos at sites within the Clinch River System. We analyzed mussel tissues for trace element and organic contaminant concentrations, shells for trace elements, and environmental media (total water, dissolved water, particulate sediment, and bedload sediment) for both inorganic and organic contaminants. We found a few differences between mussels deployed in cages and those deployed in silos: survival was slightly lower in cages due to periodic sedimentation. Our results identified the ZOD based on the accumulation of trace elements (notably As, Cu, Fe, Mn, Ni, and Sr), polycyclic aromatic hydrocarbons (PAHs), and δ15N enrichment, with especially high concentrations found in the human-impacted tributaries, Dumps Creek and Guest River. Some correlations were found between environmental media and both mussel tissues and shells. In particular, PAHs and Mn had several significant relationships between bioaccumulated concentrations and environmental concentrations. Finally, Co, Cu, Fe, and V in soft tissues negatively correlated with mussel growth, whereas bioaccumulated PAH concentrations correlated negatively with resident mussel densities.

Document Type

Article

Publication Date

2025

Notes/Citation Information

© 2025 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/ licenses/by/4.0/).

Digital Object Identifier (DOI)

https://doi.org/10.3390/d17080503

Funding Information

This research was funded by the U.S. Geological Survey (USGS) through the U.S. Fish and Wildlife Service (USFWS) Science Support Partnership (SPP) Program via Research Work Order No. 197, administered through the USGS North Carolina and Virginia Cooperative Fish and Wildlife Research Units. The participation of Jason Unrine in this study was made possible by a U.S. Department of Agriculture, National Institute of Food and Agriculture Project (KY006133A) and a National Institute of Environmental Health Sciences Grant (P30ES026529). The participation of W. Gregory Cope in this study was made possible by the Research Capacity Fund (Hatch) project award no. 7007359 from the U.S. Department of Agriculture’s National Institute of Food and Agriculture.

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