Contaminants in Tracked Seabirds Showing Regional
Patterns of Marine Pollution
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Abstract
Ocean-scale
monitoring of pollution is challenging. Seabirds are useful indicators
because they travel over a broad foraging range. Nevertheless, this
coarse spatial resolution is not fine enough to discriminate pollution
in a finer scale. Previous studies have demonstrated that pollution
levels are higher in the Sea of Japan and South and East China Seas
than the Northen Pacific Ocean. To test these findings in a wide-ranging
animal, we tracked streaked shearwaters
(<i>Calonectris leucomelas</i>) from four islands in Japan
using global positioning system (GPS) and measured persistent organic pollutants (POPs) in the oil of their
preen glands. The POPs did not change during 6 to 21 days when birds
from Awashima were foraging only in the Sea of Japan, while it increased
when they crossed to the Pacific through the Tsugaru Strait and foraged
along the eastern coast of Hokkaido where industrial cities occur.
These results indicate that POPs in the oil reflect relatively short-term
exposure. Concentrations of POPs displayed greater variation among
regions. Total polychlorinated biphenyls were highest in birds foraging
in a small area of the semiclosed Seto Inland Sea surrounded by urbanized
coast, <i>p,p</i>′-dichlorodiphenyltrichloroethane
(DDT) was highest in birds foraging in the East China Sea, and total
hexachlorocyclohexanes were highest in birds foraging in the Sea of
Japan. All were lowest in birds foraging in the Pacific. This distribution
of POPs concentration partly agrees with previous findings based on
mussels, fish, and seawater and possibly reflects the mobility and
emission sources of each type of POP. These results highlight the
importance of information on the foraging area of highly mobile top
predators to make them more effective monitors of regional marine
pollution