Mercury accumulation, biomagnification, and relationships to δC, δN and δS of fishes and marine mammals in a coastal Arctic marine food web.

Combining mercury and stable isotope data sets of consumers facilitates the quantification of whether contaminant variation in predators is due to diet, habitat use and/or environmental factors. We investigated inter-species variation in total Hg (THg) concentrations, trophic magnification slope between δN and THg, and relationships of THg with δC and δS in 15 fish and four marine mammal species (249 individuals in total) in coastal Arctic waters. Median THg concentration in muscle varied between species ranging from 0.08 ± 0.04 μg g dw in capelin to 3.10 ± 0.80 μg g dw in beluga whales. Both δN (r = 0.26) and δS (r = 0.19) best explained variation in log-THg across consumers. Higher THg concentrations occurred in higher trophic level species that consumed more pelagic-associated prey than consumers that rely on the benthic microbial-based food web. Our study illustrates the importance of using a multi-isotopic approach that includes δS when investigating trophic Hg dynamics in coastal marine systems.