Mercury and stable carbon and nitrogen isotopes in the natal Fur of two Antarctic pinniped species.

Abstract Southern elephant seal (SES) and Antarctic fur seal (AFS) are short Southern Ocean food web top predators and are spatial and temporal trend bioindicators of Antarctic Hg bioavailability. Hg, stable isotope composition (δ 13C and δ 15N) and trophic position (TP) regarding sex were determined using lanugo samples from Antarctic pinnipeds pups (SES n = 35 and AFS n = 11). Hg concentrations in over 50% of the SES pups (mean 5.9 ± 3.1 mg kg−1 dry wt.) are compatible with those found to cause neurologic damage to polar bears in the Arctic. No significant differences regarding sexes for SES or AFS are found based on mean Hg concentrations normalized by body weight. δ 15N values and TPs are similar among both species, indicating that gestating SES and AFS mothers feed at the same trophic level. Significantly different δ 13C values were found, indicating distinct feeding grounds for mothers belonging to both species when pup lanugo is formed in utero; while SES females like to feed in Antarctic waters, AFS females remain in sub-Antarctic waters. The differences in Hg and δ 13C observed for both species reflect not only contrasting feeding habits and anthropogenic Hg inputs, but also maternal foraging strategies.