PFAS (Per- and polyfluoroalkyl substances), known as “forever chemicals” due to their extreme persistence, are a common and widespread pollutant accumulating in marine and estuarine environments and organisms. PFOS (Perfluorooctane sulfonate), a specific and highly studied type of PFAS, is readily detected in coastal ecosystems, however less is known about its impacts to estuarine fish health and survival.
In addition to chemical stressors, estuarine habitats are also experiencing increasing trends in surface water temperature. In an effort to better understand how thermal stress will impact estuarine organisms’ response to existing pollutants, NCCOS scientists and partners examined the effects of PFOS on two species of fish found in southeastern U.S. estuaries, juvenile red drum and adult sheepshead minnow, under two different temperatures (20°C and 30°C). 20°C represents a standard toxicity test temperature, while 30°C is within the higher range of current temperatures found in southeastern U.S. estuarine habitats.
The combined stress of PFOS exposure at the higher temperature resulted in 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 the sheepshead minnow.
These results indicate that PFOS and temperature have the potential to act together to exacerbate toxicity in estuarine fish species. While these species experience rapid temperature, salinity, and other environmental shifts in their estuarine habitat, adding a chemical stressor may cause individuals to be more susceptible to thermal stress. Alternatively, thermal stress may make fish more sensitive to PFOS. The study higlights the importance of testing chemicals under variable natural conditions to further understanding of environmental risk, and expanding species used in ecological risk assessments.
This work is authorized under the National Coastal Monitoring Act- Title V MPRSA.