As the human population increases so too does the need for water and energy. Currently, 58,402 dams (over 15-m in height) operate globally, primarily serving irrigation and energy generation needs. The U.S. Energy Information Administration predicts that world energy consumption will increase 56 percent by 2040.
While hydropower is often viewed as a green energy source, a recent study from University of Stirling, University of East Anglia, and Smithsonian Tropical Research Institute researchers concluded that hydropower dams have a detrimental effect on species populating the areas where they’re created.
“The construction of dams,” the researchers wrote in a study published in Biological Conservation, “directly impacts both terrestrial and freshwater ecosystems through inundation of habitat, compositional changes in biological communicates, and the loss of structural and functional connectivity between upper and lower reaches of watersheds.”
In the study, the researchers compiled species richness data from nearly 250 reservoir land-bridge islands. Notable areas included the Balbina reservoir in Brazil, and China’s Thousand Island Lake. Loss of species was studied between less than one year and more than 90 years, depending on the dam and reservoir investigated.
”Changes in island communities may not occur immediately after inundation; instead, species may be subject to an ‘extinction debt’ whereby a portion of species are initially lost, followed, potentially multiple generations later, by further species extinctions,” the researchers wrote.
According to the researchers, on average the reservoir islands have 35 percent less species than nearby mainland areas. “However one South American bird community suffered as much as 87 percent loss of species on reservoirs islands,” noted lead author University of Stirling researcher Isabel Jones in a statement.
In order to combat this loss, the researchers recommended mitigation measures be put in place. They could include “conducting wildlife inventories and environmental impact assessments before reservoir filling, creating new habitats such as wetland zones within the reservoir system, and conservation offsets such as strictly protecting land both within and surrounding reservoirs,” the researchers wrote.
They called for further studies on the direct and indirect ecological impacts of such reservoirs.