A new study has found that reservoir islands created by large dams across the world suffer loss of species every year. Reservoir islands, however are termed conservation sanctuaries to protect species from hunting and deforestation.

These islands were found to have 35 per cent lesser species than nearby mainland ecologies. In the case of a South American bird community, as much as 87 per cent loss of species on reservoir islands was recorded. This seems to be observed universally.

“We found a devastating reduction in species over time in the majority of reservoir islands we studied. On average, islands have 35 per cent fewer species than nearby mainland sites. One South American bird community suffered as much as 87 per cent loss of species on reservoir islands,” said chief 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


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The findings of the research were published in the journal Biological Conservation.

The conservation experts studied changes in species, richness of birds, mammals, amphibians, reptiles, invertebrates and plants on over 200 islands created by large dams, including Brazil’s Balbina reservoir and China’s Thousand Island Lake.

The study was done on the loss of species over a period of less than one year to over 90 years from when islands came into existence by reservoir filling.

There are over 50,000 large dams operating globally, including in highly biodiverse regions such as the Amazon basin. Many dams are being planned for the future to help meet rising energy demands. In this scenario, these researchers believe more needs to be done to conserve species and prevent 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, said.

“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 added.
The study becomes important for India which is poised to increased its reservoirs and dam projects in the coming years.

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About Ramya Naresh

Ramya is a homemaker who likes to live in harmony with Nature, believing that each form of life is a wonder in itself. She values living in the present and looks forward to each day in all its freshness. She is a Senior Writer with India's Endangered.

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