"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. We saw huge differences in contaminant levels, which we attribute, at least in part, to the differences in foraging patterns between the two species," Finkelstein said.
The high contaminant load in black-footed albatrosses foraging in the California Current probably reflects the long history of industrial and agricultural discharges along the West Coast, Finkelstein said. But she added that the distribution and transport of contaminants in the North Pacific involves processes that are still not fully understood.
Concentrations of DDE (the main breakdown product of DDT) and PCBs in both black-footed and Laysan albatrosses were 130 to 360 percent higher in the samples Finkelstein collected in 2000 and 2001 than in samples collected by previous researchers in 1991 and 1992. The increases were much greater in black-footed albatrosses than in Laysan albatrosses, Finkelstein noted. DDE concentrations, for example, increased 360 percent in black-footed and 170 percent in Laysan albatrosses.
Many countries do not regulate the manufacture and use of PCBs and DDT as strictly as the United States does now, and these compounds continue to be released into the marine environment.
"The increases we saw compared with ten years ago probably reflect the ongoing use of these chemicals in countries that border the Pacific," Finkelstein said.
The biggest current threat to albatross populations in the North Pacific is the longline fishing industry, which kills significant numbers of both black-footed and Laysan albatrosses. But the contaminants measured in this study may also take a toll. Comparable levels of these contaminants in other species, such as herring gulls and Caspian terns in t
Source:University of California - Santa Cruz