Marine fog inputs appear to increase methylmercury bioaccumulation in a coastal terrestrial food web

Abstract

Coastal marine atmospheric fog has recently been implicated as a potential source of ocean-derived monomethylmercury (MMHg) to coastal terrestrial ecosystems through the process of sea-to-land advection of foggy air masses followed by wet deposition. This study examined whether pumas (Puma concolor) in coastal central California, USA, and their associated food web, have elevated concentrations of MMHg, which could be indicative of their habitat being in a region that is regularly inundated with marine fog. We found that adult puma fur and fur-normalized whiskers in our marine fog-influenced study region had a mean (±SE) total Hg (THg) (a convenient surrogate for MMHg) concentration of 1544 ± 151 ng g−1 (N = 94), which was three times higher (P < 0.01) than mean THg in comparable samples from inland areas of California (492 ± 119 ng g−1, N = 18). Pumas in California eat primarily black-tailed and/or mule deer (Odocoileus hemionus), and THg in deer fur from the two regions was also significantly different (coastal 28.1 ± 2.9, N = 55, vs. inland 15.5 ± 1.5 ng g−1, N = 40). We suggest that atmospheric deposition of MMHg through fog may be contributing to this pattern, as we also observed significantly higher MMHg concentrations in lace lichen (Ramalina menziesii), a deer food and a bioindicator of atmospheric deposition, at sites with the highest fog frequencies. At these ocean-facing sites, deer samples had significantly higher THg concentrations compared to those from more inland bay-facing sites. Our results suggest that fog-borne MMHg, while likely a small fraction of Hg in all atmospheric deposition, may contribute, disproportionately, to the bioaccumulation of Hg to levels that approach toxicological thresholds in at least one apex predator. As global mercury levels increase, coastal food webs may be at risk to the toxicological effects of increased methylmercury burdens.

Mercury content in the Siberian tiger (Panthera tigris altaica Temminck, 1844) from the coastal and inland areas of the Russia

“…1 A). The absolute values of THg in Usnea lichens from the coast in the south of the Russian Far East turned out to be higher than in the Ramalina menziesii lichens (from the same order Lecanorales and the same ecological form as Usnea ) from the coast in California 3 (0.138 ± 0.012 mg kg −1 ). It is possible that such differences are related to species-specific features of their thalli.…”

“…Weiss-Penzias et al 3 do not give the average THg for inland lichens, but they show that the high MMHg content in lichens on the coast is obtained through coastal marine atmospheric fog. We compared our data with those for THg on Bathurst Island 22 , where the spatial pattern in THg enrichment was very similar to that of MMHg, with enrichment highest at coastal sites and decreasing within 10 km, suggesting similar origins of atmospheric THg and MMHg to lichens.…”

“…Potential sources of inorganic Hg and MMHg to lichens are diverse (e.g. 3 , 22 ). MMHg from THg can range from 4.4 to 23% 3 , therefore special future studies are needed to understand the dynamics of Hg species in lichen.…”

“…Key studies of Weiss-Penzias et al 1 – 3 have shown that terrestrial ecosystems are likely to receive ocean-derived monomethylmercury (MMHg) through the coastal marine atmospheric fog. This seems incredible and yet very important, as the problem of mercury pollution of inanimate and living matter on the planet has been a hot spot in science and politics for more than half a century.…”

Unacknowledged Potential Factors in Catastrophic Bat Die-off Arising from Coal Fly Ash Geoengineering

“…Other elemental contaminants of California pacific coastal fog were found to be consistent with CFA contamination [52]. Recent investigations of a limited number of species demonstrated that pacific coastal biota had significantly greater mercury content than comparable species from inland areas not exposed to the coastal fog [93]. Although bats were not included in that study, they should be for future investigations.…”