Impacts of toxicants in the marine ecosystem on the health of Australian fur seals (Arctocephalus pusillus doriferus): spatial variation in heavy metals and investigations of endocrine disruption

A collaborative project undertaken at the Faculty of Veterinary Science, The University of Sydney 2014 - 2016. Supervised by Dr Rachael Gray

Co-investigators:

Dr Michael Lynch,  Veterinary Services Melbourne Zoo; Dr Roger Kirkwood, Ecosystems Department Institute for Marine Ecosystems Studies (IMARES-Wageningen University Research); Dr Julie Mondon, School of Life and Environmental Sciences, Deakin University

Summary

The Australian fur seal colony at Lady Julia Percy (LJP) Island, Victoria is being impacted by an emerging, recently identified alopecia (hair loss) syndrome. The syndrome has distinct gender and age biases, affecting up to 50% of juvenile females, reducing body condition thereby increasing juvenile mortality risk. Given the high prevalence, it has the potentional to contribute to population decline.

Detectable, and in some cases, high levels of persistent organic pollutants (POPs), including dl-PCBs/PCBs, PCDD/Fs and PBDEs were detected in pup samples collected from Seal Rocks and in juvenile fur samples collected from Lady Julia Percy Island. Alopecia affected seals demonstrated significantly higher levels of dl-PCBs/PCBs compared to non-alopecia affected seals suggesting a potential toxicity-mediated alopecia syndrome in the Australian fur seal, due to the impact of these anthropogenic toxicants on the endocrine system. The development of a methodology for the extraction of POPs from pinniped fur was a significant outcome of this study, enabling ongoing monitoring of these toxicants in pinniped species. Significant differences were also seen in the geospatial distribution of toxicants including arsenic, cadmium, mercury, nickel and lead in Australian fur seal pups, likely due to differing maternal foraging habits and/or varying prey availability. The concentrations of these heavy metals were comparatively low, and not considered to be contributing to disease.

As upper trophic species, marine mammals are sentinels for monitoring the health of the marine ecosystem. An important health issue affecting a significant proportion of the population is recognised in the Australian fur seal, a dominant marine predator in southern Australian waters. Thus, an ecosystem contamination issue may be being expressed in the health of a top marine predator. Demonstration of anthropogenic impacts associated with environmental contaminants will inform mitigation strategies, aiding species and ecosystem conservation.

 

 

Figure 1. Bilaterally symmetrical alopecia in a female Australian fur seal, Arctocephalus pusillus doriferus, at Lady Julia Percy Island, Victoria. Image: Dr Michael Lynch