Elemental concentrations and persistent organic pollutants in the endangered Hawaiian monk seal and select prey species from the Northwest Hawaiian Islands

The endangered Hawaiian monk seal (HMS), endemic to the Northwest Hawaiian Islands (NWHI), is slowly becoming established within the Main Hawaiian Islands (MHI) (state of Hawai’i), which may place the seals in areas of higher anthropogenic (urban industrialization, agricultural practices, and military activity) and natural (volcanic activity) sources of trace elemental contaminants (heavy metals) and persistent organic pollutants (POP) compared to the NWHI. HMS bone, which represents up to 10 years of a seal’s life, was opportunistically collected from skeletons of naturally deceased seals from the NWHI as were whole dominant fish prey species from the southern NWHI. Preliminary data from 6 NWHI females from early 2000s show Zn (108 – 203 µg/g) yielded the highest concentrations followed by Cu (0.73 – 3.3 µg/g), Cr (0.97 – 6.3 µg/g), and Pb (0.75 – 4.8 µg/g), and no detectable Ni. Preliminary data from 8 fish species show Cr (67.8 – 462 µg/g) and Zn (150 – 501 µg/g) yielded the highest concentrations followed by Cu (23.1 – 144 µg/g) and Ni (13.6 – 28.8 µg/g), and no detectable Pb. Lead (Pb) is the only nonessential element tested in the preliminary study and the only element to show an order of magnitude higher concentration than potential prey. Five samples each of bone and homogenized prey were analyzed for polychlorinated biphenyls (PCB); it yielded total PCB concentration 4280 ng/g – 10400 ng/g in seal bone, similar to or slightly less than an order higher than previously reported values in HMS blubber and serum. Whole prey contained total PCBs of 5830 – 16500 ng/g. Further analyses of more trace elements as well as specific herbicides/insecticides (PCB), flame retardants (PBDE), and petroleum products (PAH) are ensuing. By studying the spatial distribution of the seals relative to crustal weathering and anthropogenic inputs, we may use the seals as biomonitors of these environmental contaminants.