Mercury-Laden Sea Lion Carcasses Threaten California’s Coastal Condors

From Trendradars.com, March 12, 2021

By Joshua Rapp Learn smithsonianmag.com
August 8, 2016

From the viewpoint of a high-soaring California condor, it’s easy to overlook small dietary problems. But researchers on the ground have found that the accumulation of chemicals in the marine mammals the scavengers feed on in central California could be having devastating effects on their eggs.

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“It turns out that marine mammals are filled with all kinds of contaminants that are passed onto the bird,” says Carolyn Kurle, assistant professor of biology at the University of California at San Diego and the lead author of a recent study published in Environmental Science and Technology. She says that these high levels of contaminants could be complicating the recovery of one of the rarest birds in the world.

Two toxic chemicals—the banned pesticide DDT and carcinogenic toxins called polychlorinated biphenyls (PCBs)—were dumped into the Los Angeles sewer system as recently as the 1970s by chemical and electronics companies, respectively. Much of this ended up in the ocean and sank to the seabed near the Channel Islands where California sea lions spend several months of every year breeding.

“After their breeding season they spread all up and down the coast all the way up to Vancouver and beyond,” Kurle says. When these marine mammals die, they form a major part of the diet of the central California condor population.

…… Peter Cook, an assistant professor at New College of Florida who was not involved in the study, says any research that helps biologists working to connect the dots on how humans are impacting wildlife is worthwhile. “It’s always a complicated web of interactions,” he says.

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