Use of a Bioaccumulation Model to Simulate Methylmercury Biomagnification by Fish in the South River, Virginia, USA

The Bioaccumulation and Aquatic System Simulator (BASS) model was utilized to demonstrate understanding of bioaccumulation and biomagnification of methylmercury (MeHg) in the South River (Virginia) and to develop a numerical representation of the food web for potential remedial options’ analysis. The BASS model (v2.4) was used to accurately simulate the MeHg bioaccumulation dynamics of smallmouth bass (Micropterus dolomieu), redbreast sunfish (Lepomis auritus), and common shiners (Notropis cornutus) among a concentration gradient of MeHg in the South River. The BASS model confirms the importance of dietary pathway uptake of MeHg and shows that the MeHg concentration in food items varies spatially in the South River and controls the MeHg concentrations in fish tissue. The resulting calibrated model may be used to simulate food web responses to changes in MeHg concentrations in South River media or to the structure of the food web for future system states, such as due to climate change or remediation. Additionally, the BASS model has been used to assess the feasibility of fisheries management options designed to reduce MeHg concentrations in sportfish such as brown trout (Salmo trutta), rainbow trout (Oncorhynchus mykiss), channel catfish (Ictalurus punctatus), and smallmouth bass (Micropterus dolomieu) in the South River.