California Sea Grant College Program

The common scientific wisdom is that dissolved organic debris (from rotting dead plant material, for example) reduces the biological activity, and hence toxicity, of heavy metals such as mercury. Prior to the start of this project, however, a study showed that organic debris could also sometimes enhance build up of the toxic form of mercury in phytoplankton. This toxic form is called methylmercury (MeHg). It is produced in the aquatic environment by sulfur-reducing bacteria and biomagnifies through aquatic food chains.