Dams and Extinction: Going, Going, Gone

In a reversal of the animated movie Madagascar, all of the world's Kihansi spray toads suddenly found themselves living in the Bronx Zoo, far from their home at the base of a waterfall in Tanzania. The tiny toads were no match for a dam that destroyed not only their life in the wild, but a beautiful waterfall too. "Maybe the story will have a happy ending," The New York Times wistfully mused.

The UN has declared 2010 the Year of Biodiversity as a wake up call on the state of the planet's endangered plants and animals. "The latest data from scientists indicates to us that the loss of species is occurring at anywhere between 100-1000 times faster than has traditionally been the case," says Achim Steiner, head of UNEP.

The number-one cause of species extinction is habitat loss. The number one habitat type with the highest loss of biodiversity is thought to be freshwater ecosystems.

The dam-building industry is probably not planning a big celebration for Biodiversity Year. In fact, if it was up to them, they might rename it "the Year of see-no-evil." Or maybe simply "Don't Ask, Don't Tell Year."  Although dams are one of the leading causes of aquatic species extinction, we don't even know exactly what has been lost. Most of the time, there is no marking of the passage of loss, no requirement on dam owners to account for species at risk after the dam is built.

In the past sixty years or so, we've dammed most of the world's major rivers, resulting in huge hydrological changes, and major disruptions to the web of life once supported by free-flowing waters. Gone are the famed river dolphins of the Yangtze, thanks to Three Gorges Dam - the first human-caused extinction of a dolphin species.  Most of the damned species are less charismatic than the Baiji dolphin, but no less important in the big web of life.

Tragically, many governments are planning big, destructive dams in biodiversity hotspots.  Brazil's President Lula wants to build the world's third biggest dam in the Amazon. He says the Belo Monte Dam won't proceed without an $800 million "mitigation fund" to compensate indigenous people living in the dam's way, and to address the project's environmental impacts. But species on the edge can't use money, they need habitat. The Kihansi Spray Toad can tell you all about that; the millions spent have not brought back its watery world.

Southeast Asia's Mekong is another species-rich ecosystem that is threatened by a wave of big dams (the species at risk include another dolphin, and many, many fish that provide the bulk of protein for the region's people).  The most remarkable animal that could fall to the walls of concrete now being built or planned by China, Laos, Burma and Vietnam is the giant Mekong Catfish, a grizzly-bear-sized creature that breaks all records for freshwater fish. More than a thousand fish species live in the Mekong River system, a biodiversity second only to the Amazon. The river's fisheries support some 40 million people, and bring in $2 billion a year.

We can't do anything once a species is lost. But we – the species with almost total power over this planet – can most definitely do better at preserving our fellow species, and stop pushing others over the brink. For freshwater species, that means letting rivers flow; restoring and preserving wetlands; ending the pollution of waterways, and preventing diversions that dry up lakes and rivers.

Everyone on our planet needs healthy rivers. It's time to get serious about protecting these lifelines, and just say no to destructive dams.

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This blog originally appeared on Huffington Post.