Around the world - Hydro dam boom threatens a third of the world's freshwater fish

Plans to build huge dams in the Amazon, Mekong and Congo could devastate freshwater biodiversity in these tropical river basins, say ecologists.

One third of the world’s freshwater fish are at risk if dozens of large hydroelectric dams are built in the Amazon, Congo and Mekong basins, aquatic ecologists have warned.
Very few dams have so far been built in the basins of the world’s three great tropical rivers because of their remoteness and vast catchment areas. But rising demand for clean electricity in burgeoning tropical cities, and new roads to areas once considered impossible to access, has led to plans for over 450 dams for the three mega-diverse river basins.

If the dams are built, tropical freshwater biodiversity, which is at its most diverse in the three river basins, could be devastated, say the authors.

The Chinese spent $26bn to moderate the ecological impacts of the Three Gorges dam.

  Source: Reuters, In The Guardian

  “Large dams invariably reduce fish diversity and block movements that enable migratory species to complete their life cycles. This may be particularly devastating to tropical river fisheries where many species migrate hundreds of kilometres,” said the team of 39 American, Brazilian and European authors in the journal Science.
They dismiss many of the arguments put forward by dam builders that better designed fish passages incorporated into major dams allow species to move freely up rivers.

The Guardian