Invasive Burmese pythons (Python bivittatus) as sentinels for PFAS biomonitoring in the Greater Everglades Ecosystem.

The invasive Burmese python (Python bivittatus) is an optimal sentinel to monitor the presence and impact of chemicals of emerging concern in the Florida Everglades, a designated World Heritage Site. As a relatively long-lived apex predator, that is both a generalist and a holophagous consumer of prey, python tissue burdens can highlight the bioaccumulative potential of pollutants, reflecting what is present in the ecosystem. Further, as these invasive snakes are targeted for removal by the state, opportunistic sampling of this semi-aquatic apex predator reduces the need for handling of vulnerable native species. In this study, livers from 67 pythons, collected within or near the Greater Everglades Ecosystem, were monitored for 30 per- and polyfluoroalkyl substances (PFAS) using high-performance liquid chromatography-tandem mass spectrometry. Across all python livers, linear perfluorooctanesulfonic acid was the most prominent PFAS by both frequency (93%) and concentration (median 89 ng/g dw). While no statistical difference was determined in PFAS concentrations in livers collected from pythons sampled from eastern and western sampling locations (surrounding the Everglades), a sex-based difference was observed. Overall, males had a statistically higher ∑PFAS concentration (p < 0.0001) when compared to females. Further, females tended to have lower ∑PFAS concentrations as they become longer and heavier, suggesting potential maternal transfer. The median ∑PFAS concentration was 111 ng/g dw, which exceeded that observed in livers collected from native apex predators, American alligators (Alligator mississippiensis). As demonstrated herein, pythons represent an optimal sentinel for assessing the overall PFAS burden within the greater Everglades ecosystem.