Multistressor Interaction of Perfluorooctane Sulfonate ( <scp>PFOS</scp> ) and Temperature in Two Estuarine Fish Species, Red Drum ( <scp> <i>Sciaenops ocellatus</i> </scp> ) and Sheepshead Minnow ( <scp> <i>Cyprinodon variegatus</i> </scp> )

Perfluorooctane sulfonate (PFOS), a perfluoroalkyl substance (PFAS), is characterized by a long, fluorinated carbon chain which makes it ideal for oil- and water-repellent products but detrimental for the environment, where it persists and accumulates in organisms. PFOS has been detected in coastal ecosystems, but information on impacts to estuarine fish health and survival is lacking. In addition, potential rising temperatures due to climate change may alter organism physiology and bioavailability of chemical contaminants. This study examines the effects of PFOS on two species of fish found in Southeastern United States estuaries, the recreationally important red drum (Sciaenops ocellatus) and the standard toxicity test species sheepshead minnow (Cyprinodon variegatus), under two different temperatures (20°C and 30°C). The combined stress of PFOS exposure at the higher temperature yielded significantly greater chemical uptake and mortality in both species compared to PFOS at 20°C. The enhanced effect of temperature on PFOS mortality was greatest for C. variegatus. The combined stress of PFOS exposure and elevated temperature caused the greatest change in gene expression in C. variegatus relative to the individual stressors. Similarly, routine metabolic rates for S. ocellatus were significantly higher when exposed to the combined stress of PFOS exposure and elevated temperature. The results indicate that elevated temperature and PFOS act together to exacerbate toxicity in these estuarine fish. Sublethal responses to PFOS and temperature observed in this study could have long-term repercussions for fisheries. This study demonstrates the importance of expanding species used in ecological risk assessments and creating applicable results for wild species.