The differences in contaminant levels between black-footed and Laysan albatrosses indicate regional differences in the contamination of North Pacific waters, said Myra Finkelstein, a postdoctoral researcher at the University of California, Santa Cruz, who led the study.
"The black-footed albatrosses forage mostly in the California Current, whereas the Laysan albatrosses forage at higher latitudes near Alaska. So it appears that the California Current system has significantly higher concentrations of these contaminants," Finkelstein said.
The researchers published their findings in the April issue of the journal Ecological Applications.
Mercury and organochlorine compounds such as PCBs (polychlorinated biphenyls), DDT, and related compounds persist in the environment for a long time and build up in the tissues of animals high on the food chain. Analysis of blood samples showed that concentrations of these compounds in black-footed albatrosses were 370 to 460 percent higher than in Laysan albatrosses.
The two species breed at the same sites in the Hawaiian Islands. But when they leave their breeding colonies on foraging trips, the black-footed albatrosses head northeast toward the West Coast of North America, while Laysan albatrosses head northwest toward the northern and western regions of the North Pacific.
Black-footed and Laysan albatrosses both consume a mixed diet of squid, fish, and fish eggs. Finkelstein analyzed nitrogen isotope ratios in the two species--an indicator of an animal's "trophic lev
Source:University of Pittsburgh Medical Center