Award: OCE-1129339

Mercury and selenium are two elements found in trace concentrations in ocean water and biota. One, selenium, is an essential nutrient while the other is a potent toxin that can build up to alarmingly levels in fish. Previous research has suggested that the behavior in the environment of these two very different elements are in some ways entwined. For example, across a wide range of fish, when selenium concentrations in their tissues are high, the mercury concentrations are low, and vice versa. The cause of this behavior is unknown, but if explored could potentially offer a way to deal with the ever increasing concentrations of mercury in seafood. During this project, lead by researchers at the University of Connecticut, the Woods Hole Oceanographic Institution had a few research questions to address. These included 1) whether or not seleno-cysteine, a selenium containing amino acid, could increase the rate at which mercury is transformed into the highly bioaccumulative form monomethylmercury by enhancing the rate at which mercury enters bacteria who can perform the methylation; 2) whether another form of selenium, dimethylselenide, can directly methylate without bacteria and 3) whether there are detectable amounts of seleno-cysteine in seawater. Through our research, we found that none of these appear true. This interesting result suggests that the mercury-selenium interaction described above likely is the result of processes that occur within foodwebs, and allows further research to focus on those lines of investigation. Last Modified: 12/15/2014 Submitted by: Carl H Lamborg