Mercury levels in mountain lions living in the fog zone of the Santa Cruz mountains were 3x higher than in mountain lions living outside the fog zone. Toxicologist Peter Weiss-Penzias says that levels are higher in lichens and deer here too, but mercury levels become more concentrated as you move up the food chain. Mercury is approaching toxic levels in these mountain lions. Although not [yet] at fatal levels, mercury can reduce reproductive success, leading to conservation concerns.
Mercury is naturally occurring, but also enters the atmosphere via mining and coal emissions. In oceans, it is converted by deep-water bacteria into methylmercury. Upwelling brings this most toxic form of mercury back to the surface, where it reenters the atmosphere and is carried inland by fog. When fog condenses in the environment, water enters plant systems where it bioaccumulates and gets into the food chain.
Apparently, Weiss-Penzias became interested in mercury in fog while riding his bike int he Santa Cruz mountains. Fog condensed on his glasses, and he was curious about its contents, so he sent some samples to a lab. The lab told him they’d have to re-run the tests because they couldn’t believe how high the mercury levels were.