Dams increase risk of alien aquatic invaders

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In the unfolding global biodiversity crisis, freshwater ecosystems are losing even more species than terrestrial or marine environments are. Evidence points to dam construction and biological invasions as major culprits in these losses. In the U.S. alone, more than 80,000 major dams and 2.5 million smaller impoundments (such as reservoirs) have altered natural hydrology, and nearly 1000 introduced species now disrupt native aquatic systems. A new study published in the September issue of Frontiers in Ecology and the Environment (2008, 6, 357–363) concludes that dam construction and biological invasions are closely linked.