Foraging depth depicts resource partitioning and contamination level in a pelagic shark assemblage: Insights from mercury stable isotopes

The decline of shark populations in the world ocean is affecting ecosystem structure and function an unpredictable way new ecological information today needed to better understand role sharks their habitats. In particular, characterization foraging patterns crucial foresee evolution dynamics between prey. Many species use mesopelagic area as a major ground but degree which different pelagic rely on this habitat remains overlooked. order depict vertical dimension trophic ecology, we used mercury stable isotopes muscle three (the blue Prionace glauca, shortfin mako Isurus oxyrinchus smooth hammerhead Sphyrna zygaena) from northeastern Pacific region. Δ199Hg values, ranging 1.40 2.13‰ sharks, suggested diet mostly based prey oceanic We additionally carbon nitrogen (δ13C, δ15N) alone or combination with assess resource partitioning species. Adding resulted decrease overlap estimates compared those δ13C/δ15N alone, demonstrating that multi-isotope modeling for accurate description Mainly, it reveals they forage at average depths expressed through within assemblages. Concomitantly, total concentration (THg) differed increased feeding depth. Overall, study highlights key zone among important depth gradients reports competition using isotopes. It also suggests may play pivotal differences THg co-occurring high level