The influence of temperature and conductivity on metabolism and Per- and Polyfluoroalkyl Substance (PFAS) bioconcentration in Bluegill (Lepomis macrochirus)

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Abstract
Aquatic organisms may be exposed to multiple concurrent stressors, including anthropogenic contaminants and alterations to abiotic parameters such as temperature and conductivity. Amid global climate change, elucidating the interactions between chemical and environmental factors is a priority. In recent years, per- and polyfluoroalkyl substances (PFAS) have emerged as contaminants of global concern owing to their persistence, bioaccumulation potential, and toxicity. While limited studies have documented the influence of temperature and conductivity on PFAS bioaccumulation in fish, the underlying physiological drivers associated with changes to uptake and elimination remain poorly understood. Therefore, the present study aimed to determine the influence of temperature and conductivity on metabolic parameters and bioconcentration of an environmentally relevant PFAS mixture in bluegill, Lepomis macrochirus . Fish were exposed to a mixture of perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), perfluorooctanoic acid (PFOA), and perfluorohexanoic acid (PFHxA) at 20 and 25 °C and conductivity levels of 300, 600, and 1200 µS/cm for a 32-day uptake and 32-day depuration period. Additionally, we measured individual resting metabolic rate (RMR), maximum metabolic rate (MMR), and aerobic scope under the same temperature and conductivity conditions. Overall, PFOS and PFHxS accumulation in the liver were consistently higher in fish at 20 °C compared to 25 °C, which was linked to more rapid contaminant elimination at higher temperatures. Resting and maximum metabolic rates increased with temperature, independent of conductivity. These results will facilitate the development of robust bioaccumulation models to enhance predictive modeling of PFAS accumulation and aid in understanding the physiological drivers of fish contaminant accumulation.
Funding Information
  • Strategic Environmental Research and Development Program (ER19-1193)

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