|
The study found lower levels of mercury in the captive animals,particularly compared to wild dolphins tested off the Atlantic andGulf coasts of Florida, a state that is in the path ofmercury-laden fumes from power plants. The aquarium dolphins arefed smaller fish from North Atlantic waters, where mercurypollution is less prevalent. The findings were published in a recent issue of Science of theTotal Environment. Although these results represent a significantcase study, the research focused on a small number of animals, andEdward Bouwer, chair of the Department of Geography andEnvironmental Engineering at Johns Hopkins and supervisor/co-authorof the study, cautioned against drawing wide-ranging conclusionsfrom the research. "This is just one snapshot, one puzzle piece," saidBouwer. "What we'd like to do now is repeat this project withaquariums in other parts of the world. The goal is to get a clearercomparison of mercury-related health risks facing dolphins both incaptivity and in the wild. This type of research can give us hintsabout how the type of diet and where it originated can affectmercury-related health problems in captive dolphins, compared totheir cousins in the wild." Public health officials are concerned about human consumption ofmercury, particularly in a form called methylmercury, because itcan damage the brain and other parts of the nervous system,especially in young children. Dolphins that ingest too muchmethylmercury can suffer similar harm. Mercury is emitted as a gas from coal- and oil-fired power plants.Some makes its way into the ocean, where bacteria turn it intomethylmercury, which moves up the food chain. Eventually, it turnsup in the large fish that serve as dinner for wild dolphins. Onceingested, the heavy metal makes its way into the animals'bloodstream, where it can begin to damage the nervous system. With this in mind, the Johns Hopkins and National Aquariumresearchers wanted to investigate mercury exposure differencesbetween captive and wild dolphins whose diets came from differentregions. The team collected blood samples from seven aquariumdolphins, ages 2 to 38, and tested them for mercury, methylmercuryand a third chemical, selenium, which appears to help ward off thetoxic effects. The researchers compared their results against those derived fromwild dolphin blood samples collected in earlier capture-and-releasestudies conducted in the waters off Charleston, S.C.; Indian RiverLagoon on Florida's Atlantic coast; and Sarasota, on Florida's GulfCoast. "While mercury levels in the wild dolphins off South Carolinawere slightly higher than those in the National Aquarium dolphins,readings from the dolphins off the Florida coasts weresignificantly higher," said Yongseok Hong, postdoctoral fellowin the Department of Geography and Environmental Engineering inJohns Hopkins' Whiting School of Engineering and lead author of thestudy. "The difference in mercury exposure was attributed todifferences in the dolphins' diets," he said. "Theaquarium dolphins were fed a consistent level of small fish-capelinand herring-that were caught in North Atlantic waters offNewfoundland and New England. Lower levels of mercury are expectedin these waters, compared to the waters off Florida." Leigh Clayton, the National Aquarium's director of animal health,said the team members who care for the aquarium's dolphins wereenthusiastic about contributing to this study because it gave thema chance to more fully evaluate the food that the team feeds to itsmarine mammals. "It is important that we gain a better understanding of themercury levels in the North Atlantic food chain in order to ensurewe're providing the best diet possible to our dolphins,"Clayton said. "The research we have done with Johns Hopkinshas provided helpful information for our marine mammals team andallows us, at this time, to have confidence that our current fishfood sources do not have excessively elevated mercury levels." Last December, after the study was conducted, the U.S.Environmental Protection Agency adopted strict standards aimed atreducing the release of toxic air pollution from coal- andoil-fired power plants, a key source of mercury contamination insea water. Co-authors of the study were Clayton; Sue Hunter, the NationalAquarium's director of animal programs and marine mammals; and ErikRifkin, of the National Aquarium Conservation Center. Three highschool students -- Amelia Jones, Sara Hamilton and Debbie Brill --helped with sample analysis. Funding for the research was provided by the National Aquarium andby the Center for Contaminant Transport Fate and Remediation at TheJohns Hopkins University. Color digital images available; contactPhil Sneiderman or Kate Hendrickson. I am an expert from ipl-lasermachines.com, while we provides the quality product, such as Microdermabrasion Machines , IPL Beauty Machine Manufacturer, Anti Aging Machine,and more.
Related Articles -
Microdermabrasion Machines, IPL Beauty Machine Manufacturer,
|
