"Here in California, insanely high levels of mercury have been found in cougars and mountain lions in the mountains between Santa Cruz and the Bay Area"

That area is on top of a mercury mine - there's a reason it's called "Almaden Quicksilver County Park", because the primary economic activity before it became a preserve was mercury mining. The southern Santa Cruz mountains sits on top of a massive mercury deposit.

I'd really like to see the evidence that it's because of the fog. When you have pervasive elevated mercury levels throughout the food chain in an area that's a natural mercury deposit, the obvious explanation is that animals, plants, and fungi are picking it up from the soil, rather than it's being wafted in through the fog. (Mercury is quite heavy and isn't soluble in water, so the idea that the fog somehow wafts it in strikes me as bullshit.)