How new beaver dams might damage the environment
Learn about a toxic downside to restoration of beaver habitat: a temporary spike in methylmercury levels downstream from new beaver dams.
© American Chemical Society (A Britannica Publishing Partner)
-
Encyclopædia Britannica, Inc.NASA's new telescope can capture images 100 times larger than Hubble.Media Editor: Elijah Tan
-
Encyclopædia Britannica, Inc.Volcanologist Janine Krippner dives into the details.
-
Contunico © ZDF Studios GmbH, MainzLearn about lightning and thunder.
-
Contunico © ZDF Studios GmbH, Mainz; Thumbnail © Banol2007/Dreamstime.comLearn about the effects of overfishing and climate change on the world's fish supply.
-
© MinuteEarth (A Britannica Publishing Partner)Animals face a variety of threats when they migrate across the infrastructure built by humans. The video highlights some ways special kinds of bridges can assist animals in their journeys across roads, clear-cuts, and other barriers.
-
Science in Seconds (www.scienceinseconds.com) (A Britannica Publishing Partner)Camouflaged camera traps are useful for understanding how an animal behaves in the wild.
-
© Behind the News (A Britannica Publishing Partner)In 2017, India's Ganges River and its main tributary, the Yamuna River, were granted human rights.
Transcript
Beavers are fun to watch, a national symbol of at least one country, and a conservation success story. But the conservation may be coming at a dangerous cost. And researchers say it's another good reason not to destroy beaver habitats. After being hunted nearly to extinction, beavers are making a big comeback, delighting conservationists and helping restore wetland ecosystems.
But a new study in Environmental Science and Technology, a journal of the American Chemical Society, shows that restoration is having an unintended side effect. Levels of methylmercury are 3 and 1/2 times higher downstream from newly constructed dams compared to older or recolonized dams. Animals readily absorb this form of the heavy metal, which damages the brain and other organs. It can build up in the food chain and is particularly dangerous to children and infants. Researchers at the Swedish University of Agricultural Sciences think the higher levels are a result of beavers digging up river banks and felling trees, activities that can alter the water chemistry.
Fortunately, it seems to be a temporary spike. Elevated methylmercury was not found downstream from recolonized dams or dams older than about five or six years. The researchers say it's important to limit beaver hunting and destruction of beaver dams so that the ecosystems have a chance to mature and these guys get a permanent home.
But a new study in Environmental Science and Technology, a journal of the American Chemical Society, shows that restoration is having an unintended side effect. Levels of methylmercury are 3 and 1/2 times higher downstream from newly constructed dams compared to older or recolonized dams. Animals readily absorb this form of the heavy metal, which damages the brain and other organs. It can build up in the food chain and is particularly dangerous to children and infants. Researchers at the Swedish University of Agricultural Sciences think the higher levels are a result of beavers digging up river banks and felling trees, activities that can alter the water chemistry.
Fortunately, it seems to be a temporary spike. Elevated methylmercury was not found downstream from recolonized dams or dams older than about five or six years. The researchers say it's important to limit beaver hunting and destruction of beaver dams so that the ecosystems have a chance to mature and these guys get a permanent home.