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A
study shows that 86 per cent of the world's rivers have been damaged by human
. The study was conducted by researchers from a university in Toulouse, France. They examined
on over 2,500 rivers around the world. They did not look at rivers in the
regions of the Arctic and Antarctica or in
. The scientists looked into changes to
over the past 200 years. They discovered that biodiversity in over
of rivers has been
damaged by humans. The researchers said there were many reasons for
damage. A big reason is the
of new species of fish into rivers. Other reasons include pollution, dams, overfishing, farming and climate change.
