Factors affecting spatial and temporal patterns in perfluoroalkyl acid (PFAA) concentrations in migratory aquatic species: a case study of an exploited crustacean.

Per- and poly-fluorinated alkyl substances (PFASs, including perfluoroakyl acids [PFAAs]) have been used in a range of applications, and are widely distributed throughout the environment including environmental media in aquatic systems. Recent literature provides multiple reports of these compounds in a range of aquatic species, but temporal and spatial variability in tissue concentrations is rarely assessed in a rigorous way. Using an important fishery species of representative biology as a case study (Eastern School Prawn, Metapenaeus macleayi), temporal (month-to-month, and year-to-year) and spatial (intra-estuarine and oceanic) variability in PFAAs concentrations was assessed alongside potential contributing factors. Perfluorooctane sulfonate (PFOS) was the dominant PFAA detected, and there was significant spatial variation in concentration driven primarily by distance to major point sources. There was also substantial variation in PFOS among months, likely driven by behavioural physiological or ecological factors. Importantly, muscle tissue concentrations were unrelated to surface water inputs of PFAAs into the estuary. A numerical model linking prawn migration data with concentrations in the estuarine nursery accurately predicted PFOS concentrations in adjacent oceanic trawling grounds. The results demonstrate the magnitude of temporal and spatial variation in PFAA concentrations, which has implications for assessing PFAA exposure risk through seafood consumption for free-ranging aquatic animals.