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A recent research shows that 86% of the world’s rivers have been damaged by human activities. The research 【小题1】 (conduct) by experts from a university in Toulouse, France, 【小题2】 examined data on over 2,500 rivers around the world. 【小题3】 (look) into changes in biodiversity (多样性) over the past 200 years, the scientists discovered that biodiversity in over half of the rivers has been seriously damaged by humans. The researchers said there were many reasons 【小题4】 this damage. A big reason is the 【小题5】 (introduce) of new species of fish into rivers. Other reasons include pollution, dams, overfishing, farming 【小题6】 climate change.

Unsurprisingly, the worst-hit rivers are in western Europe and North America. This is because these regions have large and rich 【小题7】 (city) crowded with people. The lead researcher Brosse said: “Rivers which have the most economic development around them, like the Mississippi River, are the most 【小题8】 (strong) affected.” The River Thames in London was one of the worst-affected rivers in the study. The least-affected rivers are in Africa and Australia. This is probably due to a 【小题9】 (slow) rate of industrialization in Africa and smaller population around rivers in Australia. Brosse added that rivers in many rich nations are unrecognizable compared with how they 【小题10】 (be) 200 years ago.