Hydroelectric dams were recently recognized to threaten a number of species on reservoir islands. Popular around the world, hydroelectric dams were discovered to have a reduction in animal and plant life after flooding.
The dams have been said to protect species from hunting and deforestation, but research has shown a disturbing trend. After careful inspection it was realized that every year different species are reduced after dam construction.
One of the researchers, Isabel Jones, stated, “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.”
200 islands with large dams were evaluated for changes in species richness, including birds, mammals, amphibians, reptiles, invertebrates, and plants. The research tracked changes over a time period of less than a year as well as over 90 years at the start of the reservoir fillings. The evidence for declining species does not surface in assessment procedures for upcoming dams.
What can be done to balance the negative effects of hydroelectric dams? It may come to deciding between species losses and the amount of hydropower output by conducting an official assessment.
Professor Carlos Peres, a co-author of the research, stated, “Current practices to minimize 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.”
In the meantime, the research found that on average islands had 35 percent fewer species than nearby mainland sites. In some cases, such as with a Southern American bird community, the reduction was as high as 87 percent. Hopefully the negative effects of the dams can be balanced with careful planning and assessment.