Geographic variation of persistent organic pollutants in Hawaiian monk seals Monachus schauinslandi in the main Hawaiian Islands

Geographic variation in the levels of persistent organic pollutants (POPs) was assessed in the serum of Hawaiian monk seals Monachus schauinslandiwere outfitted with tracking devices to map their home ranges, which were then compared with the POP levels in their serum. Seals with similar ranges were shown to have similar POP levels, and seals with home ranges around the island of O'ahu had significantly higher summed polychlorinated biphenyls and polybrominated diphenyl ethers than seals around the islands of Kaua'i and Moloka'i. This difference was not seen for summed diphenyl-dichlorotriphenylethanes or chlordanes. Non-metric multi-dimensional scaling (NMS) was used to determine if this geographic variation in serum POP levels was associated with specific POPs, watersheds, or state land use districts. The NMS ordination revealed patterns at the island scale, rather than the finer watershed scale. Additionally, there were differences in the land use characteristics adjacent to seals' home ranges between 2 islands: seals with home ranges around O'ahu had a high percentage of area adjacent to urban land use districts, and seals with home ranges around Moloka'i had a high percentage of area adjacent to rural and agricultural land use districts. Integration of serum POP levels and seal home ranges revealed geographic patterns that will help assess the risk of POPs to individual seals. The integrated approach highlighted in this study is applicable to other marine wildlife exposed to local and non-point pollutants.