Mercury is a potent neurotoxin of significant ecological and public health concern. As wildlife and humanexposure occurs largely through fish, 44 states have issued fish consumption advisories regarding Hgcontamination including 21 statewide advisories for freshwater and 12 for coastal waters. More than 90% offish and shellfish consumed by humans come from marine systems but research on Hg fate in marineecosystems remains limited. Humans and wildlife also have elevated exposures to Hg via fish fromreservoirs that are considered 'Hg hotspots'. Project 7 studies mechanisms driving site-to site variation inbioavailability, bioaccumulation, and trophic transfer of Hg in aquatic food webs across a gradient fromforested to industrialized watersheds. In both field and experimental studies we will investigate parallelprocesses influencing inorganic and MeHg fate in reservoirs and estuaries with a focus on lower trophiclevels where Hg enters the food web. We predict that site-to-site variation in Hg bioavailability andbioaccumulation will be based on environmental properties such as physical (surface area, watershed area),chemical (pH, nutrients, organic carbon), ecological (benthic and pelagic feeding), and land use factors(agricultural, forested, industrial). We will use field survey and experimental approaches to identify themechanisms controlling Hg bioavailability to pelagic and benthic food webs and evaluate their relativeimportance as conduits of Hg trophic transfer. This proposal has three specific aims.
Aim 1 characterizesHg bioavailability, bioaccumulation, and trophic transfer in the field and tests whether the bioaccumulationand transfer of Hg is enhanced in contaminated sites while at the same time diminished by increasingorganic matter in the environment.
Aim 2 investigates the strength and consistency of benthic vs. pelagicfood webs as conduits of Hg to fish and the degree to which the quantity and quality of organic matter insediments and water diminish Hg uptake and transfer.
Aim 3 investigates the role of specific mechanismssuch as somatic growth dilution in controlling bioaccumulation of Hg by individual organisms. Results fromall three aims will be synthesized into a mathematical contaminant fate model that will assess the net effectof the multiple ecological and biogeochemical factors influencing Hg bioavailability, bioaccumulation, andtrophic transfer.
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