Metabolic disruptions in marine environments: synthetic eternal chemicals PFBS impact widespread microbial eukaryotes

Pollution caused by per- and polyfluoroalkyl substances (PFAS) is an urgent environmental issue, as these substances are widespread, highly persistent and toxic to many organisms. Nevertheless, the effects of PFAS on microbial eukaryotes have hardly been analysed yet. In this study, we investigated the influence of perfluorobutane sulfonic acid (PFBS) in different concentrations (0, 0.1, 1, 10, and 100 µg/L) on the metabolism of five benthic foraminifera taxa: Bulimina marginata , Cassidulina laevigata , Eubuliminella sp. , Globobulimina turgida and Nonionella sp. T1. In laboratory experiments, foraminifera were incubated with the pollutant for three days while maintaining natural physical parameters from the sampling site in the Gullmar Fjord, Sweden. Our results show that even at low PFBS concentrations, a disruption in the metabolic activity, detected through feeding with isotopically ( ¹³ C and ¹⁵ N) labelled algae, was observed. Even the lowest concentrations of PFBS (0.1 µg/L) completely inhibited metabolic cycles in these protists. With the exception of one species ( C. laevigata ), which exhibited generally very low metabolic activity during incubation, all species demonstrated significant decreases in food uptake, suggesting species-specific impact of PFBS. Since a reduction in metabolic activity was evident in all studied taxa, we conclude that PFBS is highly toxic to microbial eukaryotes.