Award: OCE-1634048

The project was a collaboration between researchers at three institutions (University of Connecticut (UConn), Sony Brook University and Rutgers University). The research at the UConn (Department of Marine Sciences) was focused on examining the transformations of mercury (Hg) between its inorganic (elemental Hg and ionic Hg) and organic forms (methylmercury (MeHg)) by marine phytoplankton using laboratory and field experiments, and how these changes compare to those due to chemical reactions happening in the absence of microbes. Methylmercury is the form of Hg that bioaccumulates into fish and seafood and is the form that is of concern for human health if it builds up to high enough concentrations in the seafood consumed. The biggest increase in concentration of MeHg in the marine food chain is between the water and phytoplankton and so this is the primary reason for the focus of this study. The studies at UConn concentrated on abiotic transformations and factors influencing MeHg concentrations in the field, with studies also examining net methylation (net conversion of ionic Hg to MeHg), and reactions between ionic and elemental Hg in coastal waters, and how these affect the amount of MeHg that is taken up into plankton. The UConn research team also performed laboratory studies to examine the factors that influence the uptake of MeHg into different types of organisms, including dinoflagellates which are an important class of plankton in coastal waters, and which are heterotrophic. Field research involved collaborations with the University of Rhode Island, where a graduate student collected samples for MeHg. She also participated in a NOAA cruise in east coast coastal waters. Additionally, experiments looked at how the formation of volatile Hg correlates with phytoplankton distributions. These studies were completed during ocean research expeditions as well as in coastal waters in the northeastern USA. Models were developed to help understand the relationships between variables and highlight the controlling factors and how they influence the level of MeHg in the food chain, and as a result, human exposure. Over the course of the project, six different graduate students were involved in some aspect of the research. Two students have since graduated from the program. Three papers have so far been published and students have presented the results at numerous international meetings. A graduate student, who has worked on the project, and whose long-term interest is scientific writing, wrote an article for the general public on how mercury gets into the marine food chain that was recently published (https://oceanbites.org/patricia_myer/). The results of this study will help global policy makers and managers develop better strategies to reduce human exposure to MeHg from seafood consumption. Last Modified: 10/01/2020 Submitted by: Robert P Mason