April 11, 2006 — Black-footed albatrosses, which forage in California waters, have several times as many contaminants in their bodies as Laysan albatrosses, which forage further north, while contaminant levels have increased in both species over the last 10 years, says a new study published in the April issue of the journal Ecological Applications.

"The black-footed albatrosses forage mostly in the California Current, whereas the Laysan albatrosses forage at higher latitudes near Alaska," said Myra Finkelstein, leader of the study and a postdoctoral researcher at the University of California, Santa Cruz, in a press release. "So it appears that the California Current system has significantly higher concentrations of these contaminants."

Albatross blood samples taken in 2000 and 2001 were found to have 130- to 360-percent higher contaminant concentrations than those taken in 1991 and 1992, said the release, with black-footed albatrosses experiencing the greatest increase.

The two species breed on the same Hawaiian islands, but black-footed albatrosses head northeast toward the west coast of North America to forage while Laysan albatrosses head northwest toward the northern and western regions of the North Pacific.

Both species feed on the same types of animals — squid, fish and fish eggs — and both occupy the same trophic level, or position in the food chain.

Because albatrosses are at the top of the marine food chain, their bodies tend to accumulate toxic contaminants, such as mercury, PCBs (polychlorinated biphenyls) and DDT (dichloro-diphenyl-trichloroethane).

"Biomagnification means that you get higher concentrations of these compounds as you go up the food chain, but these species appear to be feeding at the same trophic level," said Finkelstein in the release.

"We saw huge differences in contaminant levels, which we attribute, at least in part, to the differences in foraging patterns between the two species," said Finkelstein.

Finkelstein suspects that a long history of industrial and agricultural discharges along the western coast of the United States partly explains why contaminant concentrations are higher in black-footed albatrosses than Laysan albatrosses, said the release.

Though no longer produced in the United States, PCBs (oily liquids used in coolants and lubricants) and DDT (an organic pesticide) are highly persistent in the environment and continue to be produced by other countries.

"The increases we saw compared with 10 years ago probably reflect the ongoing use of these chemicals in countries that border the Pacific," said Finkelstein in the release.

"It is very difficult to show a cause-and-effect link in a wild population, but there is evidence of health impacts in other species at these contaminant levels," said Finkelstein. "We are only beginning to understand many of the subtle effects they can have, such as endocrine disruption and effects on the immune system.

"A lot of people think this issue has been taken care of, but it is still very much a problem."