Metal accumulation and growth rates of freshwater mussels, <i>Lampsilis cardium</i>, in a contaminated watershed

Anthropogenic pollution from hydrocarbon extraction poses significant ecological challenges for survival and natural propagation of freshwater mussels. This article examines the impact of two pollution sources, oil and gas produced water (OGPW) and coal mine discharges (CMDs), within the Dunkard Creek watershed and attempts to reveal the source of water pollution affecting the growth of juvenile freshwater mussels. Over a decade following an accidental release of mine water that led to an extinction event and despite apparent improved water quality, there is no documented native recruitment of juvenile mussels. Here, we deployed silo cages containing juvenile and adult Lampsilis cardium mussels for a 6-month survey at various locations along the main stem to access current survivability and aquatic health. Relatively low mortality rates were observed among placed mussels; however, significantly reduced growth was observed at three downstream locations when compared with the upstream sample location. The results indicate increased stress responses that may be impeding natural juvenile reproduction within the watershed. Water chemistry analyses reveal distinct patterns downstream of the Miracle Run tributary with increased sulfate and conductivity levels and slightly elevated calcium, magnesium, strontium, and barium during low flow conditions. Metal to calcium ratios in mussel tissue, along with elevated sediment radium activities and decreased radium isotopic ratios (228Ra/226Ra), indicate some local influence of OGPW with mixed OGPW and CMD contributions to water quality throughout the watershed. This study highlights the complex interplay between anthropogenic activities, water chemistry, and the effects of low or unknown constituent concentrations on freshwater mussel growth.