Simulating Human Impact on Reef Environments, CSM, 12/14/06
By Moises Velasquez-Manoff
Source: Christian Science Monitor
Les Kaufman, a professor of biology at Boston University, heads the Marine Management Area Science Program. His group is developing a computer model that simulates the interaction between humans and reef ecosystems. Photo Credit: Moises Velasquez-Manoff
Ten years ago, biologist Les Kaufman had an epiphany while bedding down in a tent in western Uganda. "I was going to have to learn a lot more about people in order to save fishes," he says.
In his lifetime, he'd seen the greater part of the Caribbean reefs bleach and disintegrate into piles of rubble. He'd seen the fantastic diversity of fish species in Africa's Lake Victoria, the source of the Nile, collapse from the double whammy of intentionally introduced Nile perch and runoff from denuded hillsides. In both cases, economic factors drove ecological disasters. If conservation efforts were to succeed, Dr. Kaufman realized, people's financial and political situations would have to be factored into the equation.
Now at Boston University, Kaufman heads the Marine Management Area Science program (MMAS). Working with Conservation International, he aims to combine understanding from both the social and "hard" sciences and turn it into effective ecosystem management. A global network of monitoring sites informs MMAS, and a computer model of human and reef ecosystem interaction is central to the project. Still in the early stages of development, the Marine Integrated Decision Analysis System (MIDAS) will allow anyone with a decent computer to simulate human activity's impact on the reef environment.
With some predicting the collapse of world fisheries by midcentury and warning that human activity is leading to earth's sixth mass extinction, never has effective ecosystem management been more important, say scientists.
"They're the future," says Andrew Rosenberg, professor of natural resources at the University of New Hampshire in Durham and an adviser on the project, referring to Kaufman's group. "If we don't figure out how to manage the complex system, it'll either collapse or be dramatically simplified."
Not only is the continued existence of our natural heritage at stake, say scientists, but also humankind's well-being. The human sphere remains inextricably linked to the natural.
For the same reasons diversification is important in financial planning, nature's diversity is an asset in its own right. The more diverse an ecosystem is, the more likely it is to survive disturbance - and the more likely the survival of those species that depend on it.
Home to 4,000 fish species - one-sixth of the estimated 25,000 types of fish in the world - coral reefs are one of the most diverse ecosystems on the planet.
But with an estimated 10 percent of world reefs already gone, some say that another 70 percent are at risk of disappearing within the next 40 years. Some problems, such as rising ocean temperatures and acidification due to elevated carbon-dioxide levels, are global in scope. Other factors, like agricultural pollution and fishing with dynamite, are local. From a strict ecological standpoint, however, the imperative is simple: Preserve enough of a functioning ecosystem through this critical time to allow natural evolution to continue.
But the goal of MMAS is to move beyond a completely nature-centered approach. "People are only going to support conservation for biodiversity for so long - until their own needs come into play," says Leah Bunce, MMAS senior program director at Conservation International in Washington, D.C. In other words, an ecosystem is only worth what the people inhabiting it think it's worth.
That's where MIDAS comes in. By distilling known relationships between the natural and human spheres into mathematical equations, the model will allow people to see both the short- and long-term consequences of their decisions. "We're not managing resources; we're managing people," says Kaufman.
Let's say, for example, that laws limiting the harvest of big fish are either absent or not enforced. The removal of top predators like sharks leads to an explosion of midsize predators, which were the big species' prey. The midsize fish gorge on small grazers, which leads to a growth of the algae the grazers would previously have kept in check. The faster-growing algae then dominates and eventually displaces the coral reef, which needs clear water to grow. A seaweed forest replaces the reef system.
And what about a boom of hotels? Their effect depends on how many. A few hotels, for example, may initially benefit reefs on the coast of Belize, where pressure to develop is intense. (It's also where the first version of MIDAS is centered. Future versions of MIDAS will include five other observation sites: the Galapagos and the Pacific coast of Panama, Brazil's northeastern coast, Fiji, western New Guinea, and northern Madagascar.) People flock to areas of natural beauty, which leads to redoubled conservation efforts. Locals have jobs and income. Everyone's content.
But more people means more sewage, which, if discharged untreated, causes algal blooms that smother reefs. And while a short-term influx of cash from business is good, its long-term effects depend on how profits are distributed throughout the society. Income disparity is a well-known predictor of environmental degradation. It leads not only to social unrest, which destabilizes social institutions, but also to a skewed economy.
If basic necessities become unaffordable to a large portion of the population, then people are more likely to chop down a forest or clean out a fishery in order to survive than to think about preserving long-term productivity.
Each of these scenarios has a tipping point when accumulated stresses lead to sudden reorganization of the system, an alternate stable state. The same patch of ocean can be dominated by jellyfish or fin fish, seaweed or coral. "It's very unlikely that we like all of them the same," says Kaufman.