Environmental exposure of freshwater mussels to contaminants of emerging concern: Implications for species conservation

Contaminants of emerging concern (CECs) are prevalent in aquatic landscapes and may be a factor in population declines of aquatic and terrestrial fauna. Yet, there are limited data to assess the impacts of CECs to species. Understanding CEC impacts is particularly important for imperiled freshwater mussels which provide valuable ecosystem services. CEC exposure of freshwater mussels was characterized by evaluating sites with and without the federally endangered mussel (Villosa fabalis) in three subwatersheds of the Maumee River, Ohio, USA, a tributary of the Great Lakes Basin. Analyses of water, sediment, and tissue concentrations of two common mussels (Eurynia dilatata and Lampsilis cardium) indicated different CEC exposures across all 6 sites. Distinct CEC signatures were found across the three media types suggesting as mussels interact with water and sediment they may be experiencing different exposure concentrations and mixtures of CECs at different life stages. Of the 83 CECs which were detected, agricultural CECs dominated sediments, pharmaceuticals were common in tissues and water, and 16 of the 83 CECs were found co-occurring in mussel tissue, water, and sediment. There were no species differences in the CEC signatures indicating all mussels, including species of concern, may be experiencing similar exposure. Comparisons to known CEC standards indicate some exceedances in the Maumee watershed including locations of federally listed mussel species. This study provides evidence of the complexity of CEC mixes in a Great Lakes watershed and the need to understand how CECs impact declining aquatic fauna.