New research has shown resevoir islands do not sustain pre-flood animal and plant life levels.
Resevoir islands created when a dam is completed experience year-on-year species loss, according to research from the University of Stirling.
“We found a devastating reduction in species over time in the majority of reservoir islands we studied. On average, islands have 35% fewer species than nearby mainland sites, however one South American bird community suffered as much as 87% loss of species on reservoir islands,” said researcher and lead author for the study Isabel Jones.
Species loss did not depend on dam location, island size or which species were present. The research warns that existing dams could also face extinction on their islands.
Researchers examined 200 large dam-created islands, including China’s Thousand Island Lake and Brazil’s Balbina.
The International Commission on Large Dams records 58,402 dams in the world. China leads with 23,842, followed by the United States with 9,264.
“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,” said research co-author Carlos Peres of the University of East Anglia.
“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.”