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by Mika Pringle Tolson |
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| Many researchers have studied the effects of mercury on ecosystems, but very little is known about how ecosystems affect mercury transfer. Sudeep Chandra, a UC Davis graduate student in Environmental Science and Policy and Ecotoxicology Lead Campus Program trainee, is helping to demystify the processes that regulate heavy metal cycling with his ecological studies of contaminated lakes. Specifically, Chandra is investigating how nutrition factors into the uptake of mercury in the food web. | ||||||||||||
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| He explains, "The nutrition is being transferred to energy. I started thinking about what goes along with the transfer in the food web, what contaminants also move up the food chain, and what the properties are within a contaminant like mercury that might be important in its transfer up the food web." Chandra and his colleagues have been examining the food web composition of different lakes and studying the mercury, algae, plankton, and fish over time to look for correlations. Preliminary findings from studies of two northern California lakes contaminated by nearby mercury mines, Clear Lake and Davis Creek Reservoir, have indicated a relationship between the ecological composition of the lower food chain and mercury levels in fish. Diatoms have greater levels of essential fatty acids than blue green algae, and Chandra has found that the lake with more diatoms has a higher concentration of mercury in plankton and fish. Says Chandra, "Different algae have different nutrients. In systems where there's a mixed diet, the fish become more robust, grow larger, and their reproductive rates are higher. We have started linking this to essential fat concentrations in their diet." When the fish have a better diet, they eat more and subsequently bioaccumulate more mercury. However, Chandra cautions that there are other possible variables in these lakes that may change the findings once more data points are added to the study. Chandra and similar ecologists' research are helping to change the way we think about mercury contamination. "I think the field is moving away from a consulting point of view where we just measure the amount of mercury in different ecosystems and try to quantify which systems we should fish in and which we shouldn't. Now we're in the process-oriented phase where we're looking at the transformation and processes of biomagnification so we can go to other sites and apply the same principles. This is what we need to target when we try to clean it up." Sudeep Chandra can be reached via email at schandra@ucdavis.edu |
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