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1. Methylmercury uptake by diverse marine phytoplankton

   https://doi.org/10.1002/lno.10318  

   Lee, Cheng-Shiuan ; Fisher, Nicholas S. ( September 2016 , Limnology and Oceanography)
2. Bioaccumulation of methylmercury in a marine diatom and the influence of dissolved organic matter

   https://doi.org/10.1016/j.marchem.2017.09.005  

   Lee, Cheng-Shiuan ; Fisher, Nicholas S. ( December 2017 , Marine Chemistry)
3. A Global Model for Methylmercury Formation and Uptake at the Base of Marine Food Webs

   https://doi.org/10.1029/2019GB006348  

   Zhang, Yanxu ; Soerensen, Anne L. ; Schartup, Amina T. ; Sunderland, Elsie M. ( February 2020 , Global Biogeochemical Cycles)

   Monomethylmercury (CH₃Hg) is the only form of mercury (Hg) known to biomagnify in food webs. Here we investigate factors driving methylated mercury [MeHg = CH₃Hg + (CH₃)₂Hg)] production and degradation across the global ocean and uptake and trophic transfer at the base of marine food webs. We develop a new global 3‐D simulation of MeHg in seawater and phyto/zooplankton within the Massachusetts Institute of Technology general circulation model. We find that high modeled MeHg concentrations in polar regions are driven by reduced demethylation due to lower solar radiation and colder temperatures. In the eastern tropical subsurface waters of the Atlantic and Pacific Oceans, the model results suggest that high MeHg concentrations are associated with enhanced microbial activity and atmospheric inputs of inorganic Hg. Global budget analysis indicates that upward advection/diffusion from subsurface ocean provides 17% of MeHg in the surface ocean. Modeled open ocean phytoplankton concentrations are relatively uniform because lowest modeled seawater MeHg concentrations occur in oligotrophic regions with the smallest size classes of phytoplankton, with relatively high uptake of MeHg and vice versa. Diatoms and synechococcus are the two most important phytoplankton categories for transferring MeHg from seawater to herbivorous zooplankton, contributing 35% and 25%, respectively. Modeled ratios of MeHg concentrations between herbivorous zooplankton and phytoplankton are 0.74–0.78 for picoplankton (i.e., no biomagnification) and 2.6–4.5 for eukaryotic phytoplankton. The spatial distribution of the trophic magnification factor is largely determined by the zooplankton concentrations. Changing ocean biogeochemistry resulting from climate change is expected to have a significant impact on marine MeHg formation and bioaccumulation.

    

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

   https://doi.org/10.1038/s41598-019-54056-7  

   Weiss-Penzias, Peter S. ; Bank, Michael S. ; Clifford, Deana L. ; Torregrosa, Alicia ; Zheng, Belle ; Lin, Wendy ; Wilmers, Christopher C. ( November 2019 , Scientific Reports)

   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.

    

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5. Freshwater discharges drive high levels of methylmercury in Arctic marine biota

   https://doi.org/10.1073/pnas.1505541112  

   Schartup, Amina T. ; Balcom, Prentiss H. ; Soerensen, Anne L. ; Gosnell, Kathleen J. ; Calder, Ryan S. ; Mason, Robert P. ; Sunderland, Elsie M. ( September 2015 , Proceedings of the National Academy of Sciences)