Mountain lions dwelling in the Santa Cruz Mountains along the California coastline have three times as much mercury in their system as those in other parts of the state, a University of California, Santa Cruz study shows.
Blame marine fog banks that often cloud the mountains, says the study, published Tuesday in Scientific Reports.
The fog introduces mercury, a toxic chemical, to the ecosystem, which makes its way up the food chain into mountain lions, according to researchers.
Researchers also found elevated mercury in lichen eaten by deer, which are hunted by the mountain lions, who are apex predators in the region, the study reports.
"Lichen don't have any roots so the presence of elevated methylmercury in lichen must come from the atmosphere," said Peter Weiss-Penzias, an environmental toxicologist who led the study, according to a UC Santa Cruz release.
"Mercury becomes increasingly concentrated in organisms higher up the food chain," Weiss-Penzias said, the release reports.
The study says mercury concentration increases 1,000 times for each step on the food chain, meaning mountain lions are at more risk than humans exposed to toxins in the fog.
The elevated mercury levels documented by the study are nearing toxic thresholds which could interfere with reproduction and "even survival," researchers say.
Scientists tested the fur and whiskers of 94 coastal mountain lions and 18 noncoastal lions for mercury in the study.
Mercury, which is a naturally occurring element, enters the environment "through a variety of natural processes and human activities," including mining and coal-fired power plants, the UC Santa Cruz release says.
"Mercury is a global pollutant," said Weiss-Penzias. "What's emitted in China can affect the United States just as much as what's emitted in the United States."
Algae in the ocean convert mercury to methylmercury, its most toxic form, which can be reabsorbed into the atmosphere and come ashore as marine fog, the release says.
Weiss-Penzias got the idea for the research while riding his bicycle to work about 10 years ago, according to the release.
"I was riding through this absolute fog-storm, with water dripping off my glasses, and I just wondered, 'What's in this stuff?'" he recalled, the release says.
