Temperature modulates PFAS accumulation and energy allocation in sheepshead minnows

Climate warming and chemical pollution shape aquatic ecosystems, yet the mechanisms underlying their combined effects remain poorly understood. We investigated how climate-relevant surface water warming alters per- and polyfluoroalkyl substances (PFAS) toxicokinetics and their effects on sheepshead minnows ( Cyprinodon variegatus ) physiological performance. Adult fish were chronically exposed to an environmentally relevant PFAS mixture (perfluorooctane sulfonate (PFOS) + perfluorooctanoate (PFOA)) under three warming scenarios. Tissue PFAS concentrations, whole-organism metabolic rates, swimming performance, reproductive parameters and somatic indices were assessed. Temperature modified PFAS tissue concentrations in a compound- and tissue-specific manner, notably promoting PFOA redistribution to eggs. Metabolic responses were temperature-dependent: at 26 °C, higher tissue PFAS concentrations were associated with elevated standard and maximum metabolic rates (SMR and MMR), maintaining aerobic scope (AS). At 28.5 °C, SMR remained stable while MMR and AS declined with rising PFAS, indicating reduced oxygen available for energetically demanding activities. Despite unchanged swimming and reproductive outputs, an increased hepatosomatic index with increasing tissue PFAS concentrations and altered PFAS distribution suggest detoxification costs. These findings indicate that warming is likely to exacerbate contaminant stress, with consequences for coastal fish population resilience and offspring development. PFAS risk assessment should account for multiple stressors under ongoing climate change.