Abstract
Persistent organic pollutants (POPs) have been associated with lowered reproductive potential,3 impaired immune function,2,4 decreased endocrine function,1 and cancer6 in marine mammals. Despite this potential threat, little is known about the levels or effects of POPs in Hawaiian monk seals (HMS), especially those from the subpopulation in the main Hawaiian Islands (MHI). Only two studies have been performed to date investigating POPs in the HMS, but only on populations within the remote Northwestern Hawaiian Islands (NWHI).5,7 This study examined concentrations of a large suite of POPs in the blubber and serum of juvenile and adult HMS from the MHI. Additionally, geographic variation in the level of POPs within MHI seals was assessed in serum to investigate variability based on the space use of individuals. Adult females were found to have the lowest blubber levels of most POPs, whereas adult males have highest levels. POPs in serum were significantly different in adult males compared with adult females for chlordanes and summed dichlorodiphenyltrichloroethanes (DDTs). Lipid-normalized concentrations of chlordanes, DDTs, polychlorinated biphenyls (PCBs), and mirex in paired blubber and serum samples were significantly correlated. Contaminant levels from the MHI were at similar or lower levels than those from remote NWHI populations. Twenty seals were also outfitted with satellite or cellular tracking devices to map their home ranges, which were then compared with the POP levels in their blood serum. Results based on Mantel's tests show that seals with similar geographic ranges have similar POP levels, suggesting significant spatial covariation of their distributions and pollutant signatures. Additional investigation using Analysis of Variance revealed that seals with home ranges around the island of Oahu had significantly higher summed PCBs and polybrominated diphenyl ethers by both wet weight and lipid weight, than seals around the islands of Kauai and Molokai. This difference was not seen for summed DDTs or chlordanes. The integration of data for serum POP levels and home ranges revealed geographic variation patterns that will inform HMS management within the MHI by helping to assess risk to individual seals and to identify suitable locations for translocation of individuals. Determining levels of POPs is an important step towards assessing one of the many potential health threats to this critically endangered pinniped species.
Acknowledgements
The authors wish to thank the NOAA Pacific Islands Fisheries Science Center (PIFSC) Hawaiian monk seal research program staff for providing samples, life history information, tracking data, and field assistance; Bernadita Anulacion, Daryle Boyd, Jennie Bolton, Catherine Sloan, Karen Tilbury, and their colleagues at the Northwest Fisheries Science Center Environmental Assessment program for sample analysis and guidance. Funding was provided by NOAA's PIFSC, NOAA's Nancy Foster Scholarship program, and NOAA Fisheries' Marine Mammal Health and Stranding Response Program. All sample collection and research was conducted under the Marine Mammal Protection Act Scientific Research Permit Numbers 848-1335, 848-1695 and 10137 and safe handling and capture protocols of NOAA Fisheries.
* Presenting author
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