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Study: Islets in large water tanks protect biodiversity

The current view of the ecological value of large water tanks will need to be reconsidered. "Eco" hydroelectric power projects were due to its impact on the surrounding biodiversity still quite pitiful balance, which can improve nezatopených leaving several islets, as local centers of diversity. But as mentioned extensive study of English, University of Stirling, these pieces of land for the conservation of species diversity to nothing.

Isabel Jones, together with colleagues embarked on a detailed evaluation of the species diversity of life on different islands, field ridges and artificially preserved shallows surrounded by water level in reservoirs around the world. They have been given as an example of "the conservation potential" implemented projects of large hydropower plants. But after searched out more than 200 such sites worldwide, including hydraulic structures grandiose type of Brazilian rainforest container Balbina or Chinese system of lakes Thousand Islands came to exactly the opposite conclusion.

It does not matter whether it will be monitored on islands biodiversity measured by the number of species of birds, mammals, amphibians, reptiles, invertebrates and plants, virtually every time on them will be smaller than the diversity of life before creating his own waterworks. And what is worse, on the mainland in the immediate vicinity of the dam lives more and more species of animals than on these islands, which in turn were previously considered "center" local diversity. "Across the surveyed sites have seen a devastating reduction in the number of species," says Jones . "on average, they lived on the islands about 35% fewer species than the nearest land, but perhaps in the case of a group of South American bird that was a reduction of up to 87%."

Jones and his team solved water works relatively new, less than a year old, as well as the islands situated in the middle of the water of 90 years. As a result, she also managed to detect a trend in the gradual decline in the number of species. Staff freshly flooded islands will 'nezakonzervuje in time ", but the loss of species on them with every passing year continues. And regardless of the location of the tank, the size and number of islands, or the number of species. "We knew that the flooding of the valley by building a water tank is through the liquidation of habitats immediate impact on the local flora and fauna," says Jones. "But part of this process apparently also a sort of decay debt that animals on islands continue paying off. "

The world currently operates more than 50 000 large water reservoirs, often in areas with a high degree of diversity, such as Amazon. Thousands of others in these places they plan and prepare. "The idea that isolated islands in these reservoirs of hydroelectric power plants somehow contribute to the preservation of the original diversity, smacks of wishful thinking, but not the reality," says Professor Carlos Peres, co-author of the study. "The current practice simply does not work and plans to build infrastructure must be included in the new procedures. "Peres also advocates an approach in which there should be a clear comparison irretrievable loss of biodiversity in the construction site, and own performance hydroelectric power plants in order to evaluate the real contribution of some hydroelectric plants.

Author: Radomír Dohnal

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