Proposed dams on the Amazon, Mekong, and Congo rivers are threatening one-third of the planet's freshwater fish.
Very few dams have been built on the world's three largest tropical rivers, but that might change.
Increasing demand for clean energy in these areas coupled with better accessibility to remote areas has led developers to reconsider the possibility of damming these three major rivers. There are currently over 450 proposed damming projects in these massive watersheds.
A team of 39 American, Brazilian, and European scientists stated that "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."
Those speaking in favor of the damming projects point out that new and improved fish ladders will help freshwater fish move upstream unhindered by the dams, but the scientists warn that fish ladders "have proved unsuccessful and even harmful. Large dams delay and attenuate seasonal food pulses, reducing fish access to floodplain habitats that are an essential nursery area and feeding grounds."
Researchers worry that the 334 dams proposed along the Amazon river basin would not only threaten freshwater fish, but have other negative affects, including expanding deforestation and the forced relocation of human populations.
The 99 proposed dams along the Mekong river in China and its tributaries in Thailand, Cambodia, and Laos will likely affect food supplies across the region.
The Congo river has the fewest proposed projects, but a proposed dam across Ingra Falls, which drops 96 meters in just 14 kilometers, could harness over 83% of the river's volume and substantially reduce its flow downstream.
While it is understandable that these nations and organizations are trying to harness the power of the world's largest tropical rivers, the longterm affects may not be worth the rewards. Aside from the damage done to freshwater fish, transforming a wild river into an electricity turbine will change the landscape, culture, and people that make it so unique.
Humans should think long and hard before taking steps to alter what Mother Nature has taken thousands of years to create. It's too late to turn back the clock on some of our own environmental discretions, but hopefully we have learned enough to advise developing nations not to make the same mistakes.