The Australian sea lion, Neophoca cinerea, occupies an upper trophic level within the marine ecosystem and as such, are a useful indicator species of trace element and heavy metal (toxicant) concentrations. Anthropogenic sources of toxicants when at high concentrations can be associated with increased susceptibility to disease and mortality and reduced reproductive success. Several toxicants, including Hg, Se, As, and Pb, are known to transfer from mother to foetus through placental transfer, and via lactation. As such, toxicant concentrations in pups can be used as a proxy for maternal levels. N. cinerea is listed as endangered (IUCN Red List, 2008) and a specific objective of the Recovery Plan for the species is to investigate and mitigate potential threats, including pollutant exposure. As such, monitoring of toxicant concentrations in pups is important for the conservation and management of N. cinerea.
Inductively coupled plasma mass spectroscopy was used to determine the concentration of 13 elements, Hg, Pb, As, Se, Cd, Mg, Al, Co, Ni, Cu, Zn, Cr, and Fe, in liver and hair samples collected from N. cinerea pups sampled at Seal Bay and Dangerous Reef, South Australia from 2006 to 2013. Whilst the mean concentration of the majority of elements analysed were within expected reference values for pinnipeds, the concentration of mercury (Hg) in both liver (mean = 28.9 μg/g drywt; n=39) and hair (mean =5.4 μg/g drywt; n = 199) are amongst some of the highest reported in pinnipeds.
In addition to presenting reference intervals for 13 elements in pup tissues, we report the effect of colony site, live versus dead pup status, year of sampling, and pup sex on these concentrations. The suitability of hair as a non-invasive sample for monitoring trace elements and heavy metals in the endangered Australian sea lion will also be discussed.