Establishing concentrations of anthropogenic toxicants in Australian pinnipeds and the role they play in health

Abstract

Long-lived species and upper trophic level predators, such as pinnipeds, are highly vulnerable to the bioaccumulation of toxicants which makes them an important sentinel species for evaluating marine ecosystem health. This thesis directly addresses this knowledge gap by aiming to investigate the concentrations of persistent organic pollutants (POPs), per and polyfluoroalkyl substances (PFAS) and non-essential heavy metals in the Australian sea lion (N. cinerea), Australian fur seal (Arctocephalus pusillus doriferus), and the long-nosed fur seal (Arctocephalus forsteri), and the impact they have on health. PFAS concentrations were significantly greater (p < 0.05) in Australian fur seals compared to Australian sea lion pups, except for perfluorooctanoic Acid (PFOA), which exhibited greater concentrations in Australian sea lions. These findings highlight species-specific differences in PFAS profiles and magnitude of concentrations across colony locations. Significant differences (p < 0.05) in liver concentrations of POPs were observed between Australian sea lions and Australian fur seals. Associations were also found between greater POPs concentrations and mortality groups (infectious disease/trauma and starvation) in Australian sea lion pups. Lastly, temporal differences in mercury (Hg) and arsenic (As) concentrations were identified in Australian sea lion pups across breeding seasons, exceeding toxic thresholds for humans and marine mammals. Lower selenium (Se) levels and Se:Hg ratios in N. cinerea compared to sympatric species indicate a concerning vulnerability to mercury toxicity in Australian sea lion pups. The high concentrations of toxicants identified in Australian pinnipeds and the identification of association with health, highlights the imperative to have ongoing monitoring in Australian sentinel marine mammals.