Summary: Methylmercury (MeHg) toxicity is well documented and widely known (National Research Council, 2000).  Marine food webs tend to bioconcentrate MeHg, therefore toxicity becomes magnified with increased trophic position.   There is significant research quantifying inorganic mercury (HgI) and MeHg concentrations in fish and higher predators, however, very little is known and understood about the onset of mercury transfer from the initial dissolved source in the water column into primary producers.  It is important to understand the mechanisms of transfer of inorganic mercury (HgI) and MeHg through initial trophic levels, because this is where the highest biomagnifications occurs.  Thus, I will be investigating the transfer of mercury and methyl mercury from primary producers to primary consumers.  Two hypotheses are driving my proposed research.  First, I propose that HgI and MeHg bioaccumulation factors are greater than previously determined, and are functions of exposure concentration.  Second, water column chemistry, especially the concentration and nature of dissolved organic matter, is a major determinant on bioaccumulation by phytoplankton, though it has little impact on trophic transfer.  To test this I will culture native phytoplankton, enrich them with isotopically distinct mercury and methylmercury, and then feed them to cultured native zooplankton in order to assess the assimilation efficiency, as well as transfer concentration.  Collected samples will be analyzed in the analytical lab at the University of Connecticut using our high sensitivity Element2 ICP-MS in low resolution mode (Mason and Sullivan, 1999; Mason et al., 2001; Kim et al., 2004).  Through carefully controlled laboratory experiment the effects of different water Hg concentrations and the presence of different amounts and forms of organic matter will be quantified for various phytoplankton and zooplankton species.

Summary: While the phenomenon of mercury neurotoxicity through fish consumption is now well known, Mercury biogeochemistry in coastal and open ocean waters has been understudied to the advantage of freshwater and atmospheric systems; even though over 60% of fish products consumed come from marine systems (EPA, 2002). I intend to address this issue by studying 2 stations in Long Island Sound. Station 1 is located in Western Sound and Station 2 in Eastern Sound (Hammerschmidt et al., 2004). Mercury sediment content decreases west to east and appears to be related to sediment organic matter. While there have been measurements of MonoMethyl Mercury (MMHg) and methylation rates in sediments (Mason and Lawrence, 1999), there have been no studies directly examining the link between the sediment and/or water column production and bioaccumulation, and the role of water column speciation in MMHg formation and accumulation. There is the potential for production of MMHg in the low oxygen waters (Monperrus et al., 2007) that persist during summer in Western Long Island Sound (WLIS). I want to follow more closely the dynamics of MMHg formation and cycling in the water column at these two stations and combine geochemical measurements (studies of how dissolved organic matter, sulfide and other parameters affect Hg methylation and MMHg accumulation and demethylation) and water column methylation/demethylation assays with collection of particulate, zooplankton and planktivorous fish (larval fish or silversides) to assess transfer of MMHg to the food chain.

Summary: Endocrine disrupting chemicals (EDCs) are exogenous compounds that can provoke biological effects by disturbing the normal hormonal homeostatic control mechanisms in the body. Of particular concern are EDCs that interfere with the functions of the steroid sex hormones, including estrogen and testosterone, causing irreversible damage to the developing fetus. The synthetic estrogen diethylstilboestrol [DES] given to pregnant women to prevent miscarriage resulted in children that were significantly affected by the in utero exposure, with consequences ranging from malformations, sterility after puberty, and cancer.  We are exposed to a great number of EDCs as they are found in many products and applications, including pharmaceuticals, agricultural chemicals, plastics and personal care products. I am interested in looking for EDCs in our local coastal marine environment and exploring questions regarding the fate, persistence and transport of some known EDCs.  In particular, I am interested in whether trace levels of these pollutants could be biologically active due to possibility of synergism between different EDCs.