Broadly, I am interested in aquatic pollution issues, and how human activities affect aquatic ecosystems. Prior to entering graduate school, I worked briefly for a water treatment plant in Lyon, France, and it was there that I decided that I wanted to do research. I worked with a team of engineers and water treatment specialists to try to devise a treatment strategy to eliminate toxins produced by a recurrent bloom of algae in a way that was both economically feasible and environmentally sound. While this was challenging, I found myself asking more profound ecological questions that couldn’t be answered under the scope of the project. I decided to apply to graduate school.
While in graduate school, my interests became more focused on contaminant cycling and food web issues. I enrolled in such courses as Marine Pollution, New Production and Biogeochemical Cycling, and Ecology. With the guidance of my thesis advisor, I became interested in the biogeochemical cycling of metals, and in trying to predict how metals might behave in the environment and in organisms based on their chemical characteristics.
The overall focus of my doctoral research is to investigate patterns in metal trophic transfer in marine piscivorous food webs in order to predict which metals are likely to display biomagnification. Although mercury (and possibly cesium) are the only metals that have been recognized to biomagnify in aquatic food webs, there is evidence that biomagnification does occur for a number of potentially toxic elements, including cadmium, zinc, polonium, and the metalloid selenium. In an attempt to elucidate potential patterns in metal biomagnification, I conducted trophic transfer experiments using radioisotopes of class A, class B, and transition metals in contrasting marine food webs.
I spent the spring and summer semesters of 2005 doing an internship at the International Atomic Energy Agency Marine Environmental Laboratory (IAEA-MEL) in Monaco, where I completed laboratory work towards my doctoral dissertation that would not be possible at my home institution.
While uptake and depuration kinetics have been well described for phytoplankton and zooplankton, quantitative estimates for these parameters for trace metals in fish, especially piscivorous fish are rare. For this reason, four species of top fish predators were chosen to represent different phylogenies and habitats. Preliminary work suggests that cartilaginous fish (the dogfish Scyliorhinus canicula) concentrated certain metals from the dissolved phase to a much greater extent than the bony benthic flatfish (Psetta maxima). We included these two species in our trophic transfer study, as well as two pelagic species, the sea bass and sea bream. All of these species are endemic to the Mediterranean, and all are harvested for human consumption, and so are of interest with respect to their ability to concentrate potentially toxic metals. The planktivorous fish prey used were larval sea bream. The larval sea bream were fed starved crustacean nauplii (Artemia salinas) which had been fed radiolabelled phytoplankton (Isochrysis galbana).
The results from this study will allow us to make predictions as to which types of metals are likely to biomagnify in different marine food chains. These predictions will be tested in a future field study in the Mediterranean, and further laboratory work will include experiments to understand the mechanistic basis for metal biomagnification in fish.
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