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by Mika Pringle Tolson |
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| Doris Vidal, a doctoral student in Integrative Biology at UC Berkeley, has received a TSR&TP fellowship to study the adaptation and response of an aquatic invertebrate, the Lumbricid worm Sparganophylus peasrsei, to environmental mercury exposure. She explains, "I'm trying to see what allows these organisms to survive after they are exposed to mercury and how the mercury is affecting them." She wants to be able to link how the worms adapt and how their adaptations will affect the ecosystem where they live.
Vidal chose five reservoirs around the San Francisco Bay Area to conduct her study. Two are contaminated by nearby mercury mines, and three are clean water sources. |
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 TSR&TP Fellowship Recipient Doris Vidal. Courtesy photo. |
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| Her preliminary findings have surprised her. "Even the organisms from two of the expected uncontaminated areas have really high levels of tolerance to mercury," says Vidal. Though the water from the clean reservoirs did not contain significant amounts of inorganic mercury, the sediments did. The Lumbricid worm is a benthic species, and Vidal has discovered that they may have several strategies to deal with stressful situations. They normally burrow in the sediment, but when exposed to mercury, the worms "wave their tails in the water to obtain more oxygen." Lumbricid worms from all the reservoirs sampled exhibited this behavior. However, Vidal found that organisms from one reservoir with high known concentrations of mercury "seemed to be much more adapted or acclimated to deal with the mercury." These worms were able to live in waters with mercury levels many times higher than worms from other reservoirs. |
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 The Lumbricid worm, Sparganophylus pearsei, was not previously known to be present in western North America. Courtesy photo. |
The family (Sparganophilidae) of Vidal's experimental species is primarily tropical. She chose the worm Sparganophylus pearsei because of its relatively large size - up to 18 cm in length - and species distribution. In researching its life history, Vidal found that the species was not known to be present in western North America. She and other scientists worked on the taxonomy and description, and an article about this new species was published in the summer 1999 issue of the journal Megadrilica. Vidal says the discovery of this worm is "very significant because we have an organism that can be developed as a potential biomarker that can live in ranges from very hot water to very cold water. I think this is significant, especially for me coming from Mexico, because most biomarkers and bioassays have been created for developed countries, which are not often in tropical areas." In addition to developing an inexpensive biomarker, Vidal hopes her research will lead to helping clean up contaminated sites. Ultimately she'd like to "see what we can learn from the way these organisms have developed adaptations or acclimations to contaminated places, and how we can apply this knowledge for bioremediation." |
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Doris Vidal can be reached via email at pingui@socrates.berkeley.edu |
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