Damned without those beavers

Beavers aid the removal of harmful pollutants from streams and creeks, a recent study from the University of Rhode Island has concluded, while a trial in Devon has showed the animals can help make water up to three times cleaner.

Beaver dams help remove up to 45 percent of harmful nitrogen from waterways. Less nitrogen leads to healthier streams, creeks, and rivers, improving habitat for fish and other wildlife.

Beaver dams trap water to form ponds where aquatic plants can grow. Dead leaves and plant matter will sink to the bottom and decompose, producing food for bacteria.

When oxygen in the water is low, bacteria will break down nitrates to obtain the oxygen in them and release the nitrogen out of the water as gas.

Nitrogen is one of the most problematic pollutants found in rivers. Nitrates, nitrogen-based chemicals found in fertilisers and other common chemicals, drain from agricultural and urban areas after rain as polluted runoff.

This then causes eutrophication- algae blooms result in underwater dead zones where fish and other aquatic life struggle to survive due to a lack of oxygen.

Professor Brazier from the University of Exeter said, “Farmers should be happy that beavers are solving some of the problems that intensive farming creates. If we bring beavers back itís just one tool we need to solve Britain’s crisis of soil loss and diffuse agricultural pollution of waterways, but it’s a useful tool.”

As well as reducing pollutants, beavers help reduce soil erosion and reduce the risk of flooding. The benefits of beavers are being more widely reported worldwide.

Their numbers are rebounding in the US after becoming close to extinction.  Despite controversy, calls for their re-introduction into Scotland are increasing, as trials are being carried out.

Professor Brazier added, “The public is currently paying people to build leaky dams to keep storm waters in the uplands. The beavers can do it free of charge and even build their own homes.”


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March 2021
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