Policy ForumDevelopment and Environment

Balancing hydropower and biodiversity in the Amazon, Congo, and Mekong

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Science  08 Jan 2016:
Vol. 351, Issue 6269, pp. 128-129
DOI: 10.1126/science.aac7082

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  • RE: Amazonian manatee threatened with extinction by massive dam-building plan in the Amazon
    • Eduardo Arraut, Researcher, Wildlife Conservation Research Unit, Oxford University, and Remote Sensing Division, National Institute for Space Research
    • Other Contributors:
      • Miriam Marmontel, Researcher, Mamirauá Sustainable Development Institute

    In their Policy Forum “Balancing hydropower and biodiversity in the Amazon, Congo, and Mekong“ (8 January p. 128-129), K.O. Winemiller et al. call for more ‘sophisticated and holistic hydropower planning” in the Amazon, Congo and Mekong basins (1). This is indeed incredibly important, because as it is now these very complex ecosystems are being managed in a highly reductionist manner – a socio-environmental disaster is the natural future scenario of current actions. In Tropical dams: To build or not to build?” (29 January p. 456), P. Fearnside goes deeper in the matter by arguing that ‘it is essential to face whether such a massive dam-building plan should exist’, given its large and fundamentally irreversible environmental and social impacts and small regional benefits (2). With regards to the Amazon basin, the plan includes dams or dam cascades in virtually all large and most medium-size rivers (1–3). We think P. Fearnside poses a very important point that must not be overlooked, and here we present an additional reason for reconsidering this massive dam-building plan in the Amazon: the threat of putting Amazonian manatees (Trichechus inunguis) on a direct path to extinction in the wild.
    Amazonian manatees are aquatic and range throughout lowland Amazon basin (4). In typical droughts, the lowland basin transforms into disconnected and shallow water bodies, so manatees take refuge in rias (naturally blocked river stretches) or large perennial lakes (5–7). While migr...

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    Competing Interests: None declared.
  • RE: How many new Peruvian dams?

    In their article “Balancing hydropower and biodiversity in the Amazon, Congo, and Mekong” (Science 351, 128-129; 2014), Winemiller et al. reported a total of 37 proposals of hydropower projects to be build in Peru. However, at least 18 (18037 MW) are projects: without feasibility studies (n=8), flooded by others hydropower dams (n=4), are the same project (n=4) and, unfeasible projects because are located in natural protected areas where there is not allowed to modify the landscape (n=2) (1-3). Nevertheless, this total could be higher considering projects with definitive concession or expected to be build in some years according to National Grid Operator (COES), but dismissed due to technical or socio-environmental infeasibility (2, 4-7). It is important to difference between political statements or investment promotion of hydropower projects from feasible projects. I suggest a careful analysis comparing data bases from non-governmental organisms with other sources (government, grid operator, etc.)
    Peruvian electricity was mainly generated by hydropower in 2000 (81 %). Nowadays, is generated mainly by natural gas (50 % in 2014) (8). The decrease in new hydropower projects is due to the promotion of natural gas use (9) and a moratorium of new hydropower projects (10) by national government, mandatory deadlines to owners of new projects under penalty or denied of electrical concession and the necessity to adequate projects to comply with regulation to conserve enviro...

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    Competing Interests: None declared.
  • RE: Hydropower and flood pulse: biodiversity loss in the long term
    • Bruno Sampaio Sant'Anna, Researcher / Professor, Federal University of Amazonas
    • Other Contributors:
      • Gustavo Yomar Hattori, Researcher / Professor, Federal University of Amazonas

    Biodiversity loss can occur directly or indirectly in the medium and long term due to hydropower installation and operation. As Winemiller et al. (2016) highlight, large dams delay and attenuate seasonal flood pulses. The alterations in the flood pulse modify the range of water to regions that seasonally flood, in time and space. Many species have been adapting for thousands of years living in this periodic cycle of flooding and dry season, and species occupy niches from different flood plain regions. Mollusks have adapted to live in terrestrial and aquatic ecosystems by drastically decreasing their metabolism, with aestivation in response to dry periods. Birds annually feed and breed in areas periodically flooded, and seedlings are adapted to be submerged for several months in the wet season, among countless others examples. Each flood plain system has specific features influenced by the flood pulse of rivers and lakes, which promotes environmental heterogeneity and has been associated to higher or lower diversity. Aquatic diversity can influence community resilience, which is important information for determining how the impacts of the flood pulse change, but long-term ecological research is necessary to obtain this data. Furthermore, some flood plain regions have scarce data from local diversity. According Dittrich et al. (2016), local diversity is the main information for management and conservation of the floodplain community. So changes in the flood pulse automatical...

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    Competing Interests: None declared.

    In their important paper published in Science, vol. 351, issue 6269 pp. 128-129, Winemiller K.O. et al gave a very good summary of the impact of dam construction in the three basins on fish biodiversity However, the construction of dams in the Amazon, Congo and Mekong basins affects not only fish biodiversity but also the hydrosocial cycle, that is the hydrological dynamics, the human activities in connection with the biodiversity of terrestrial and aquatic ecosystems. This was demonstrated by the Amazon Basin (1) but is most probable valid for the Mekong and Congo basins.
    Deforestation that occurs with reservoir construction also affects fish biodiversity and the ecological dynamics of the aquatic ecosystems such as creeks, lakes and wetlands. (2)
    The present plans to develop the Amazon, Congo and Mekong Rivers with the construction of several reservoirs, as shown by the authors will introduce a large scale change in the hydrological cycle in the hydrosocial cycle and ecosystem services that are key to the maintenance of evolutive and biodiversity processes (3).
    Besides the overall impact in the aquatic and terrestrial ecosystems construction of Amazonian reservoirs results in the emissions of greenhouse gases affecting aquatic biodiversity and fish biodiversity downstream the reservoirs.(4,5) Greenhouse gases may also be produced in the Congo and Mekong basin reservoirs.
    For the Amazonian reservoirs there are another threats not described by the a...

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    Competing Interests: None declared.

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