Distribution and bioaccumulation of per- and polyfluoroalkyl substances (PFAS) in marine intertidal invertebrates - A multi-bioindicator study from Cape Town, South Africa.

Per- and polyfluoroalkyl substances (PFAS) are toxic, bioaccumulative, and highly persistent, raising global concerns over their environmental and health impacts. Effective biomonitoring is essential, particularly in regions that remain understudied. This study investigated PFAS bioaccumulation in five intertidal invertebrate species (mussels, limpets, periwinkles, sea urchins, and anemones) from False Bay, South Africa, a biodiverse coastal embayment of high ecological and socio-economic value but with a history of pollution from urbanisation and wastewater outfall. We investigated spatial variability in PFAS contamination to identify potential hotspots and examined species-specific accumulation profiles to assess the suitability of different taxa as bioindicators. Fourteen of the 15 targeted PFAS were detected, with legacy compounds (68 %) occurring more frequently than emerging (40 %) ones. Total PFAS concentrations ranged from 1.55 ng g-1 to 421 ng g-1 dw. Five legacy compounds (i.e. PFOA, PFOS, PFDoA, PFDA, and PFNA) along with the emerging compound ADONA, were detected in the vast majority of samples. Spatial trends indicated a contamination hotspot along the northwestern coastline of the bay, associated with urban and tourism activities, whereas wastewater treatment plant outfall was not strongly associated with PFAS contamination. Species differed markedly in accumulation profiles, with benthic feeders containing higher concentrations of long-chain PFAS and filter feeders preferentially accumulating short-chain compounds. Sea urchins and periwinkles showed the highest multi-compound accumulation, supporting their use as effective bioindicators in coastal zones. Overall, ∑PFAS concentrations exceeded those reported for most other regions of the world, raising concerns about potential risks to both environmental and human health.