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The Dammed Mekong

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Vince Resh's work in West Africa was an ideal training ground for his next major project: monitoring the health of Asia's Mekong River.

From its headwaters in Tibet, the Mekong tumbles south through the peaks of the Himalaya, through China and Laos, and slows into wide, muddy meanders as it snakes past Thailand, Cambodia, and finally empties into the South China Sea at the southern tip of Vietnam. Its floodwaters inundate more than 54,000 square miles of rice paddies and farm fields. Its reaches include the world's most important freshwater fishery, Cambodia's Tonlé Sap Lake. Fish caught here during the Mekong’s annual floods are dried or smoked, then shipped throughout Southeast Asia. Altogether, some 90 million people rely on the river for food, water and transportation — more than any other river on the planet.

This ancient cycle of flooding and planting, fishing and farming is now on the verge of major change. As China continues its headlong rush into the global economy, its thirst for electricity has grown apace. To power its factories and light its brimming cities, China is building a series of eight dams on the main stem of the Mekong.

China’s neighbors fear the dams could cause a catastrophe downstream. If operated to produce a consistent level of power, the dams will even out the river's seasonal surges. Stemming wet season floods and increasing dry season releases will disrupt conditions for reproduction of river fauna and flora, not to mention regional farming capacity.

Four downstream states — Cambodia, Laos, Thailand, and Vietnam — want to be able to detect any changes to the river's biology after the dams are built. Through an intergovernmental alliance known as the Mekong Commission, they asked Resh in 2001 to build a monitoring system on the Mekong.

One month a year for the following seven years, Resh traveled throughout the Mekong with national experts to identify sampling sites, set up a survey program, and trained national collaborators. The sites ranged from virtually wild reaches of river, to sections downstream from farms, below tributary dams, and next to cities. By comparing tributaries that have been dammed against reaches that have not been affected, Resh says, "we can see what's affected and make predictions about what we should be looking for," Resh says.

On the Mekong, Resh found many parallels with his work in Africa. "In both cases, we were working on huge systems that we knew nothing about. In Africa we knew nothing about the fish and the other animals. Virtually the same thing was true in Southeast Asia."

The team had to develop its own identification guides to river species such as crabs and diatoms, insects and algae, all of which have different responses to water conditions and pollution. "You have some that are absolutely clean water species, and you've got others that are found only in the worst conditions." The types of species found and their fluctuations in certain water conditions produce a reliable measure of river health.

Strangely enough, science hasn't been Resh's sole focus in the Mekong. "A lot of what we were doing was trying to bring these national experts together, getting them to talk to each other civilly, and, for example, not have the Cambodians nicking at the Vietnamese because they invaded their country." To encourage crosscultural exchange, the data analysis is divided along national lines: the Thais are performing the diatom identifications, while the Laos have taken invertebrates, and the Vietnamese zooplankton. The distribution forces each country to cooperate to produce a meaningful picture of the health of the waterway.

Baseline data from the program will be compared against future conditions to detect any shifts in the river's ecology. Evidence of any problems can then be presented to China to lobby for changes. Already the program has produced a "report card" showing the health of the river in different areas, starting literally a mile below the China border. "Compared to other international rivers, the Mekong is in great shape. Even the sewage doesn't go into the river, because they back it up into marshlands, so that they can use it for fertilizer and agriculture."

In 2008 Resh and his Australian colleague will turn the program over to the Mekong countries to run on their own. "It's going to become a completely Asian program. It's like with your kids: you want to help them become their own person; you want them to become independent."

-Kathleen M. Wong

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