Global Biodiversity Threatened by Piecemeal Dam Development


​Conservation International statement in regard to policy paper “Balancing hydropower and biodiversity in the Amazon, Congo, and Mekong​” published in Science


​Arlington, Va. USA (January 8, 2015) – In a policy paper published by the journal Science today, over 40 scientists from academic and civil society institutions around the world argued that the expansion of hydropower dams in the Amazon, Congo and Mekong river basins poses a catastrophic threat to global freshwater biodiversity. The lead author of the study is Kirk Winemiller of Texas A&M University, a member a Belmont Forum/National Science Foundation​ team led by Conservation International that studies the impacts of global change on biodiversity and people.  

Conservation International understands the demand for energy development in these regions, however, with the unprecedented amount of hydropower development proposed or underway in these iconic river basins, there is an urgent need to better understand the cumulative environmental impact of these projects before they are built in order to strike the proper balance between producing hydropower and sustaining the irreplaceable biodiversity of these rivers. The consequences of ignoring these cumulative impacts has born out in the tragic histories of many of world’s other iconic rivers including the Colorado, Rio Grande, Indus and Yellow rivers. These often run dry, because hydropower and irrigation developments took place without a more integrative and strategic planning at the basin scale.

“These are the three rivers with the highest remaining biodiversity of freshwater fish species on the planet and the scale of hydropower expansion poses a serious threat to that biodiversity,” said Leo Saenz, director of eco-hydrology for Conservation International and co-author on the paper. Saenz and colleagues from Kings College London have mapped over 40,000 existing and proposed hydropower dams, which is the largest geo-referenced inventory of dams available. 

“The food supply and health of literally millions of people hangs in the balance and we have to do a better job,” said Lee Hannah, senior fellow for climate change biology at Conservation International and lead scientist of the Belmont Forum research. “These rivers are the canaries in the coal mine for thousands of other tropical fisheries. We need to understand these complex systems, but we also need conservation action even as research results are unfolding.” 

Saenz elaborated: “When impact assessments are conducted now, they are done on a specific site with no analysis into the cumulative impacts that multiple dams can have at the basin scale and from ridge to reef into the future. There is simply no understanding of how the construction of a dam today, and another five years from now, and another in ten years – all in the same river basin – will impact the biodiversity found in these rivers and push it past a point of no return, where large scale species extinctions are imminent. The history of heavily dammed rivers also tells us that the livelihoods of many human communities, often the poor, can result permanently affected when rivers run dry. Not to mention, this can also negatively impact the opportunities for tourism and freshwater recreation that can also help to support local economies.”

“We want to see multilateral and development banks, which often provide loans that finance dam developments, move to require thorough cumulative impact assessments at the basin scale, that benefit from the most robust science available today, especially for those rivers that include multiple planned construction sites over time,” Saenz said. “Only through this kind of analysis together with thorough basin scale integrated and strategic planning can we ensure that the threshold of biodiversity resilience, beyond which species extinctions are imminent, is not surpassed by hydropower and development.”

The Amazon, Congo and Mekong rivers hold roughly one-third of the world’s freshwater fish species, most of which are not found outside these remarkable basins. The Amazon is home to over 2,300 fish species with new species descried each year. The Congo holds over 1,000 different fish species and the Mekong is home to 850 species and has already been felt the impacts of hydropower development.

In these three rivers there are plans for 450 dams, some of which have already begun construction. Loss of biodiversity in these rivers has rippling impacts on millions of people that depend on the Amazon, Congo and Mekong rivers for clean and drinkable water, food and jobs. The Lower Mekong delta directly supports 60 million people with an inland fishery valued at US$17 billion.

On the Amazon: “The Amazon has outstanding freshwater biodiversity that provides food security for millions of people, but that is threatened by the way hydropower expansion is taking place. We need to be smart about how we develop hydropower so we can meet energy needs while also securing the ecosystems and biodiversity that people depend on for their prosperity and well-being."

On the Congo: "The vast forest of the Congo Basin is the second largest tropical rainforest on Earth and about 40 million Africans rely on its incredibly rich and diverse ecosystem for food, fresh water, shelter and medicine. It is home to many critically endangered species including forest elephants, gorillas, okapis, and bonobos – human beings’ closest living relative. Of the hundreds of mammal species that have been discovered there, 39 are found nowhere else on Earth, and of its estimated 10,000 plant species, 3,300 are unique to the region. Any energy development, including hydropower, in this unique biodiversity, must ensure that it works in consonance with the ecosystem and not against it".
– Michael O’Brien-Onyeka, senior vice president for Conservation International Africa & Madagascar Field Division

On the Mekong: “Hundreds of dams are planned for the Mekong. It is not only the main stem of the Mekong that is important for sustaining biodiversity, but also smaller rivers and streams, where we are still discovering freshwater dependent species, vital for sustaining the wealth of biodiversity that exists. Information about species impacts related to development projects is often limited, and yet decisions impacting them go forward anyway. We have seen that spatial planning, and the inclusion of data about biodiversity, into criteria for development projects is increasing in the Mekong. Even if it is only used to raise awareness, that is an important start to increase transparency around impacts, trade-offs and pave the way for better informed decision making.”


Photographs available for media (***Please Provide Image Credits***): 

For more information, contact:
Kevin Connor, Senior Media Relations Manager, Conservation International 
Office +1 703 341 2405/ mobile +1 410 868 1369/ email 

About the Belmont Forum
The Belmont Forum is a collaboration of research agencies from 14 countries, all pooling resources to create multinational science teams to help solve global environmental problems.  The National Science Foundation is the participating research agency from the United States.  Global change and tropical fisheries is one theme being addressed by Belmont Forum scientists. Learn more at

About Conservation International
Since 1987, Conservation International has been working to improve human well-being through the care of nature. With the guiding principle that nature doesn't need people, but people need nature for food, water, health and livelihoods—CI works with more than 1,000 partners around the world to ensure a healthy, more prosperous planet that supports the well-being of people. Learn more about CI and the "Nature Is Speaking" campaign, and follow CI's work on Facebook, Twitter, Instagram and YouTube.

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