Sentinel Sharks: tracking anthropogenic contamination in the marine ecosystem

Over the last century anthropogenic activities have rapidly increased the influx of metals entering the marine environment, which can bioaccumulate and biomagnify in marine top consumers. This may elicit sublethal effects, having broad implications for human seafood consumers. Shark vertebrae can provide a lifelong record of the water in which they dwell, implying that sharks may act as sentinels of anthropogenic influences over a long time. Using fishing discards from across the UK we will sample metal exposure in a top marine predator, the small-spotted catshark Scyliorhinus canicula. We will compare current and historic metal exposure by sampling soft tissues and shark vertebrae at locations across the UK that differ in water quality. In analysing vertebrae, we will assess the impact of the 'anthropause' (the mass reduction in anthropogenic activities due to SARS CoV-2) on contaminants in marine top predators. In addition, we will test the hypothesis that parasites accumulate metal at a different rate than the host, potentially providing a fitness benefit to the shark. We will use laser ablation plasma source mass spectrometry (LA-ICP-MS) to determine the trace element composition of shark vertebrae, tissue and parasites and compare this to ecological markers. In doing so, we will be able to identify which elements can be used to trace anthropogenic water pollution, their sensitivity to changes in anthropogenic pollution and the role of parasitism in bioaccumulation. Work will be supervised by an interdisciplinary team from Cardiff and Exeter University consisting of ecologists, fishery experts and geochemists joined by a stakeholder management group; Cefas.