Dam building binge in Amazon will shred ecosystems, scientists warn

Source: Science Magazine

LIMA—Once upon a time, thousands of dorados, a giant among catfish, would swim more than 3000 kilometers from the mouth of the Amazon River to spawn during the austral autumn in Bolivia's Mamoré River, in the foothills of the Andes. But the dorado, which can grow to more than 2 meters in length, is disappearing from those waters, and scientists blame two hydropower dams that Brazil erected a decade ago on the Madeira River.

"The dams are blocking the fish," says Michael Goulding, a Wildlife Conservation Society aquatic ecologist in Gainesville, Florida, who has been studying the dorado since the 1970s. They are "probably on their way to extinction" in Peru and Bolivia.

Most Amazon dams are in Brazil, where scientists have raised concerns about the displacement of local communities and emissions of greenhouse gases such as carbon dioxide and methane from large reservoirs. But as countries seek new energy sources to drive economic growth, a surge in dam construction on the eastern flank of the Andes could further threaten fish migration and sediment flows, Elizabeth Anderson, a conservation ecologist at Florida International University in Miami, and colleagues warn today in Science Advances.