Species-specific patterns of metal accumulation in deep-sea sharks

Deep sea sharks combine ecological importance with exceptional sensitivity to chemical contamination, making them strategic sentinels for offshore pollution. We quantified eight metals (Al, B, Cd, Cu, Fe, Ni, Pb, Zn) in the dorsal muscle of 51 specimens representing seven deep sea shark species occurring at the depth from 400 to 1100 m from the Canary Islands, using inductively coupled plasma optical emission spectrometry. Comparative multivariate evaluation revealed pronounced interspecific contrasts: Deania quadrispinosa and D. profundorum accumulated the highest loads (Al ≤ 32 mg/kg w.w., Zn ≤ 35 mg/kg w.w., Cd ≤ 0.29 mg/kg w.w.), whereas Apristurus laurussonii consistently exhibited the lowest concentrations. Elemental fingerprints clustered by habitat depth and phylogenetic lineage, underscoring the role of evolutionary history in exposure risk, while feeding mode showed no consistent influence. Several individuals exceeded FAO/WHO seafood safety limits for cadmium (0.05 mg/kg w.w.) and lead (0.30 mg/kg w.w.), signalling potential dietary hazards where shark meat is consumed or traded. These findings document marked metal enrichment along volcanic island slopes, position Canary Island deep sea sharks as high resolution bioindicators of multielement pollution and highlight the need to integrate ecotoxicological thresholds into regional conservation measures and seafood monitoring frameworks.