used to have a number of bleach plants that heavily polluted the area, but those levels have since died down. Overall, the mercury levels in the Savannah River system isn’t that much of a concern these days, Haskins said. “As our brown snakes got bigger, they had higher amounts of mercury,” Haskins said. ![]() In addition, snakes seemed to accumulate mercury from prey they eat - or “bio-magnify” - compared to the fish tested previously in the region. They also found that the snakes’ mercury levels correlated well with other species used as indicators. “It was basically a validation of what had been done previously.” “They were extremely correlated,” Haskins said. The tail clipping is much easier and quicker than blood extraction, and the researchers wanted to validate that such a method worked just as well. Once they captured the snakes, they took blood samples and cut the 1-centimeter tips off the end of their tails. They captured snakes in four main regions of the river with varying levels of mercury known from studies on other species. Researchers jumped off boats, into the Savannah River to catch watersnakes. “Brown watersnakes are easier to catch if you don’t mind getting bit.” Other studies sometimes used alligators ( Alligator mississippiensis), but those can be “more temperamental and dangerous,” Haskins said. They set out by boat, capturing more than 120 snakes and snagging the reptiles as they basked on rocks in the river. You get to get out on the water and see all kinds of stuff - eagles, sturgeon, bobcat,” he said. To test this theory, he and his team caught watersnakes on the Savannah River system in the summers of 20. Since mercury bio-accumulates in the snakes’ bodies over time, Haskins thought these reptiles may be better indicators of the mercury contamination in a given waterway. ![]() The reptiles also often stay put in smaller areas than many fish, which makes them better heralds of potential contamination at a specific site. Watersnakes, on the other hand, eat contaminated fish, consuming the mercury inside of them in the process. While scientists usually use fish as a model species to test for mercury levels in a given area, fish usually swim around a wider area, making it harder to pinpoint the mercury quantity in specific areas. “It gives you a nice little snapshot of what’s going on in that area.”īrown watersnakes ( Nerodia taxispilota) are found throughout the eastern United States. “One of the advantage of brown watersnakes is they have a really high site fidelity,” said David Haskins, a PhD candidate at the University of Georgia and the lead author of a study published recently in Science of the Total Environment. The tips of watersnakes’ tails retain levels of mercury that could indicate how contaminated rivers and streams are with toxins.
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