Behind Threats to World's Largest Freshwater Wetland

By Anna Brendle
for National Geographic News
January 10, 2003

Covering 50,000 square miles, (140,000 square kilometers) the Pantanal is the world's largest freshwater wetland. Its central tributary is the Paraguay River, which flows through central-western Brazil, eastern Bolivia, and eastern Paraguay, covering an area larger than the size of Greece or the U.S. state of Louisiana.

Capuchin and Howler monkeys, capybaras, toucans, anacondas, caimans, tapirs, endangered jaguars, rare Hyacinthine macaws, and giant river otters in addition to thousands of varieties of butterflies and brightly colored flowers create an inland ecological paradise. But without increased attention and scientific research, all this could be threatened.

National Geographic EXPLORER recently traveled to Brazil to produce a new television documentary, Brazil's Vanishing Cowboys, which examines cattle herders' lives in the Pantanal, particularly as they drive their animals to high ground during each rainy season. Along the way they encounter the hazards of floods, alligators, and jaguars.

To find out more about the Pantanal, the threats to this unique region, and efforts to save it, National Geographic News spoke with Frederick Swarts, director of the Waterland Research Institute and Secretary-General of the World Conference on Preservation and Sustainable Development in the Pantanal. The nonprofit organization is based in Washington. D.C. and Brazil.

I understand that the Pantanal is the world's largest freshwater wetland. What is the importance of this wetland to its surrounding region?

For one, the Pantanal basin provides flood abatement because it acts as sponge. The Pantanal has a regulatory effect on the Paraguay River, extensively reducing and delaying the height of the flood peak and thus reducing the flood risk downstream. Without it, there is the potential for extensive flooding of the Paraguay River and the Parana into which it flows, affecting Brazil, Paraguay and Argentinian communities.

There's also considerable biodiversity, with a great number of bird species, and the Pantanal basin provides biodiversity protection.

Issues of water purification are also important because the river removes heavy metals from mining industries in region.

What are the greatest threats to the Pantanal?

Various hydrological projects pose some of the greatest threats. One proposed project is called Hydrovia. This project, which would require considerable dredging and removal of rock outcroppings, has not been approved. Nonetheless, there is a danger that it is being implemented on a piecemeal basis. River dredging has happened on a smaller scale in the Pantanal, for example. If there's considerable dredging, water flows at deeper depths and more quickly. This could drain the Pantanal, and alter its diverse ecosystems.

Roughly 80 percent of the Pantanal is located in Brazil, and of that, 98 percent is privately owned. Therefore, the Brazilian government is limited in its power to control what happens to that area. In Bolivia and Paraguay, the Pantanal is more protected. But only 10 to 15 percent of the total area lies in Bolivia and 5 to 10 percent in Paraguay.

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