Methylmercury in Plankton on the Continental Margin of the Northwest Atlantic Ocean

Abstract

<p>Accumulation by plankton is a key process influencing the trophic transfer of monomethylmercury (MMHg) in aquatic food webs and its levels in fish. Although humans are exposed to toxic MMHg principally by the consumption of seafood, there is a near absence of information on MMHg distributions in marine phytoplankton and zooplankton. As part of a comprehensive study of mercury and MMHg cycling on the continental margin of the northwest Atlantic Ocean, we are investigating the spatial and temporal variability of MMHg in planktonic communities, bioconcentration factors of MMHg between water and phytoplankton, trophic transfer between phyto-and zooplankton, and differences in MMHg bioaccumulation among size fractions of zooplankton communities. Phytoplankton and zooplankton were sampled with trace-metal clean techniques from 31 locations ranging from near-shore waters (e.g., Cape Cod Bay) to remote stations near the offshore extent of the continental margin during three oceanographic cruises in 2008-2010. Preliminary results suggest that MMHg in primary producers (i.e., phytoplankton) is related to the amounts in filtered water, which is indicative of a relatively constant bioconcentration factor. Additionally, MMHg increases in concentration within the planktonic community from primary producers to grazers and differs among size fractions of the zooplankton community. Results of this study will improve our knowledge of environmental and biological factors influencing MMHg incorporation into marine food webs and help constrain oceanic budgets and cycling models of this contaminant.</p><p>This presentation occurred at the Wright State University Campus-Wide Celebration of Research, Scholarship and Creative Activities on April 8, 2011</p>