College of Arts & Sciences


Biology 3.0

Ecosystems and Us

A New Conservation Science Ties It All Together

By Chris Berdik

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Professor Les Kaufman and a team of researchers have gathered in Cambodia to examine and model the food webs at Tonle Sap Lake, the country’s primary source for fish, rice, and protein. Video by Alan Wong

Every spring, the monsoon rains begin to swell the Mekong River, and millions of Cambodians welcome the floods. The reason is simple: floods bring fish.

Fishing villages ring a Cambodian lake, a tributary of the lower Mekong called Tonle Sap, which can grow to five times its normal size during these floods. The lake inundates vast stretches of scrub brush and forest, soaking up nutrients from the soil, and supporting an incredible array of animals and plants, including crocodiles, snakes, water birds—some of them endangered species. Most important, the swollen lake is a nursery for hundreds of migratory fish species that swim there to spawn.

The people of the Tonle Sap live in floating houses that move with the season, and they travel by boat. When the water recedes, it flows back through narrow channels into the Mekong, where villagers string up nets for a massive catch—about 350 metric tons of fish. The fishery employs about two million people and feeds millions more. It supplies around 75 percent of the animal protein eaten by Cambodians, not to mention a worldwide market of fish paste, fish sauce, and fish oil dietary supplements.

Above: A woman holds a Wallago attu, a large catfish and one of Tonle Sap’s “River Giants” that is a prized food fish. Below: biologist and ecosystems researcher Les Kaufman at Tonle Sap. Photos by Jonny Armstrong and courtesy of Les Kaufman

But, the Tonle Sap is in grave danger. Upstream on the Mekong, in China, Lao People’s Democratic Republic, and Thailand, government engineers are planning more and bigger hydropower dams that could stem the annual flooding—the so-called “pulse system”—that makes the lake teem with fish. Simultaneously, the watershed’s forests are being cleared, either for fuel wood or to make room for agriculture, increasing soil erosion and degrading the habitat. Finally, a changing global climate threatens to bring longer, hotter dry seasons that could lower the water levels and raise water temperature in the shallow Tonle Sap, further disrupting the ecosystem.

Something will have to give. The region needs more power to fuel its emerging economies and alleviate widespread poverty in a booming population. But, it also needs the fish, clean water, and the biodiversity of the Tonle Sap. Finding a way to manage these competing needs is the core of a new initiative led by Arts & Sciences Biology Professor Les Kaufman.

Traditional environmental protection aims to safeguard wilderness areas and specific endangered species and places blanket restrictions on natural resource development. According to Kaufman, walling off nature is no longer a viable solution. It leads to simplistic conservation measures that may even cause more problems. Ecosystems are dynamic networks of relationships between living things and the habitat they share. That includes humans who are part of the ecosystem and profit from its continued health in innumerable ways—from food to energy to recreation and cultural legacy. Kaufman spotlights these “ecosystem services” in massive computer models of natural systems that also factor in the complex relationships between species, climate, topography, geochemistry, economics, and even human psychology.

His modeling work, called MIMES (Multi-scale Integrated Models of Ecosystem Services), forecasts the likely impacts of conservation and development choices, along with the effects of climate change, on ecosystems and the people who depend on them. Kaufman began this work about five years ago by modeling coastal ecosystems of Massachusetts. Now, backed by a three-year, $500,000 grant from the MacArthur Foundation, Kaufman and collaborators at several other universities and Conservation International are focused on the Tonle Sap. In the long term, they hope this system-focused approach to conservation will revolutionize the way the world’s natural resources are managed.

“Our goal is to turn ecosystem management from a turf war, where everyone is just trying to protect their own narrow interest for another year, into a possible future in which everybody wins,” Kaufman says. With the world’s population set to hit 9 billion by midcentury and evidence of a changing climate all around us, the pressure to chart a sustainable future mounts daily.

“There’s a strong consensus among scientists that we’re in real danger if we don’t radically change our systems of production, consumption, and values,” says Kaufman. “We want to create the science that can be a guidance system for sustainability.”


Kaufman spends endless hours peering at tiny pieces of preserved fish and poring over photos and videos of fish in the wild. The specimens are from hundreds of species living in the Tonle Sap. Kaufman studies their DNA, life cycles, physiology, diet, and how they move.

“Basically, I memorize fishes,” says Kaufman. Despite MIMES’s holistic focus, a systems model is only as good as its data. For instance, the fish Kaufman memorizes include scores of small, silver species that all look very much alike and are all harvested and eaten, but actually play very different roles in the ecosystem and in meeting the population’s dietary needs.

Along with researchers at the University of Washington, Kaufman will plot the Tonle Sap food web, which will become the basis for algorithms of what eats what in the ecosystem model. Meanwhile, collaborators at other universities, supported by their own MacArthur grants, are modeling river flow scenarios based on various dam proposals, the dispersal of carbon and nitrogen in the ecosystem, and the probable effects of climate change.

This information will feed the MIMES model of the Tonle Sap. So will data on the economics of the fishery and the potential effects on water flow and fish migration resulting from more than a hundred hydropower dams that are operating, under construction, or planned upstream. Hydropower is most attractive for a region desperate for energy and facing international pressure to avoid high-polluting fossil fuels. Plus, dam building creates lots of jobs. Kaufman’s model will reflect these benefits, but also the costs of dams, which disrupt the normal water and nutrient flow and could devastate populations of migratory fish that are the backbone of Tonle Sap’s economy and Cambodia’s food supply.

Despite the many threats to the Tonle Sap, Kaufman and his fellow researchers see a unique moment of opportunity for their systems-focused approach. The project’s partners include Cambodian scientists, the Cambodian government’s fisheries management service, and resident wildlife rangers. In 2012, the Cambodian government cancelled the private allotments that had governed all fishing on the Tonle Sap for years and substituted about 20 community-based fishery management zones. It also proposed several conservation areas where fishing would be restricted. Exactly how these community fisheries will operate, where the conservation areas will be positioned, and how any regulations may be enforced are all still to be decided.

“There’s a window here of maybe a few years when the communities are trying to figure out how they’ll manage the resources,” says Lee Hannah, Conservation International’s senior fellow in climate change biology. “It’s an opportunity to get some good science in place.”

Importantly, the goal of that science is not just to highlight the dangers of development but to find ways that it can occur while minimizing damage to the ecosystem. For instance, where you place a hydropower dam, how you build it, and how and when you operate it all make a difference to its environmental impact.

“It’s not realistic to say, no dams and no electricity,” says Tracy Farrell, Conservation International’s senior technical director of special projects, who is stationed in Cambodia. “What hasn’t been done, and what governments are desperate for,” she says, “is an analysis of where the dams could be operated, so we can have a more informed dialogue about the trade-offs.”


The MIMES project’s three-year goal is to create a model of the Tonle Sap ecosystem, including its people and economy, which can project trade-offs between power for new industries and food the fishery supplies, and between jobs created by dam construction and the number of fish species that may become extinct as a result.

But even the most intricate ecosystem model is useless if only scientists can understand it. Kaufman and his team want everyone to use this model, from local fishermen to business and government leaders to representatives of the Mekong River Commission. Thus, Kaufman has paired his MIMES models with a specialized software that translates their super technical readouts into simple, interactive, graphic simulations for nonscientist decision makers. The software project, called MIDAS (Marine Integrated Decision Analysis System), is led by CAS Professor of Earth & Environment Suchi Gopal. While MIMES is extremely complicated and algorithm-heavy, MIDAS operates more like a game, albeit one with very serious stakes.

MIDAS lets you plug a specific fishing restriction or an offshore drilling operation into an existing ecosystem, stir in a changing climate, and then watch simple, graphic reports on the fates of various species and economic segments after one year, five years, or any given time frame. “It’s a dynamic, nonlinear model, so it can forecast the surprises,” says Kaufman.

Modeling something as complex as ecosystems is a perpetual work in progress, with a need for continuous refinements from new data and regular tests of the model’s predictions. Along these lines, modeling the Tonle Sap presents some unique challenges and opportunities.

For instance, compared to the well-studied waters of coastal Massachusetts, Gopal says there’s a “data gap” in the understanding of the Tonle Sap and Mekong River system. Plus, she says, “there’s a lot of useful information that exists only in people’s heads, their memories,” which is why she’s trying to give MIDAS a measure of interactive, social-networking functionality, so users can contribute their own knowledge to the model.

Kaufman and Gopal also hope to increase the model’s reflection of human behavior by adding in game theory, behavioral economics, and the local cultural traditions and know-how, which they hope to learn from extensive interviews and surveys with the Tonle Sap locals. After all, Kaufman points out, these are people who have lived sustainably within this ecosystem for centuries.

“It’s a little arrogant to think we’re going to swoop in there and solve the problem,” Kaufman says. “It was already solved, but now the whole world is about to change.”

Chris Berdik is a freelance science journalist and author of Mind Over Mind: The Surprising Power of Expectations (Current, 2012).