Despite being hailed as conservation sanctuaries that protect species from hunting and deforestation, reservoir islands created by large dams across the world undergo sustained loss of species every year, new research has found.
"We found a devastating reduction in species over time in the majority of reservoir islands we studied. On average, islands have 35 percent fewer species than nearby mainland sites. One South American bird community suffered as much as 87 percent loss of species on reservoir islands," said lead study author Isabel Jones from University of Stirling in Scotland.
"No matter where the dam is located, the island size, or which species are present, there is sustained loss of species, with many in existing dams still potentially facing extinction," Jones noted.
The research was published in the journal Biological Conservation.
The conservation experts examined research covering changes in species richness of birds, mammals, amphibians, reptiles, invertebrates and plants on more than 200 islands created by large dams, including Brazil's Balbina reservoir and China's Thousand Island Lake.
Loss of species was investigated over a period of less than one year to over 90 years from when islands were created by reservoir filling.
With more than 50,000 large dams operating globally, including in highly biodiverse regions such as the Amazon Basin, and many future dams planned to help meet rising energy demands, the researchers believe more needs to be done to account for the long-term loss of species on reservoir islands.
"Current practices to minimise the detrimental impacts of major hydroelectric dams include tropical forest set-asides, but this is a mirage if the remaining terrestrial biota becomes stranded in small islands -- this needs to be taken into account in new infrastructure developments," co-author of the research Carlos Peres, professor at University of East Anglia in Norwich, England, added.
"Strong environmental licensing should be put in place to assess species losses versus the amount of hydropower output to even-up the biodiversity balance sheet," Peres said.
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