Mercury and stable carbon and nitrogen isotopes in the natal Fur of two Antarctic pinniped species. (February 2022) - Kehrig, Helena A.
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 13 C and δ 15 N) 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 15 N values and TPs are similar among both species, indicating that gestating SES and AFS mothers feed at the same trophic level. Significantly different δ 13 C 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 13 C observed for both species reflect not only contrasting feeding habits and anthropogenic Hg inputs, but also maternal foraging strategies. Graphical abstract: Image 1 Highlights: Southern elephant (SES) and Antarctic fur (AFS) seal lanugo was analyzed. Hg, δ 13 C, δ 15 N and trophic position (TP) were determined. Over 50% SES pups presented neurologically damaging Hg concentrations. δ 15 N and TP indicate similar gestating SES and AFS trophic levels. Prey and Hg bioavailability influence SES and AFS bioaccumulation.