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Ecosystems Research Yields Surprising Results

2003-08-12

When researchers probing two well-known health problems in different parts of the developing world unearthed surprising results, a new approach to problem-solving — the ecosystems approach — led them far beyond usual solutions, an international conference sponsored by Canada’s International Development Research Centre (IDRC) heard May 20.

In the Brazilian Amazon, it had long been known that the Tapajós River was being contaminated by gold operations, and that the river’s mercury concentration had climbed fivefold in 40 years. Consequently, the health of villagers who relied on fish from the river as a major part of their diet was being affected.

“We all thought the same thing: the mercury was coming from the gold miners,” said Marc Lucotte, a Université du Québec à Montréal (UQÀM) researcher who worked with communities along the Tapajós River in the Brazilian Amazon with support from IDRC.

But then Lucotte’s joint team from UQÀM’s Institute of Environmental Studies and Brazil’s Federal University of Para looked more closely, and found that the mercury permeating the huge river was more than could be released into the system “by even half a million miners.” [See related article: Fishing for Less Mercury in the Amazon]

Uncovering the reason for contamination

More testing uncovered the source: the nearby soil. It was washing into the water system as an influx of settlers to the remote area slashed and burned the jungle to clear the land of vegetation. The mercury “has been accumulating for thousands and millions of years,” Lucotte told participants at the International Forum on Ecosystem Approaches to Human Health, held at UQÀM, May 18^th to the 23^rd, 2003.

Armed with that knowledge, the research team — which included experts in neurotoxicology, ethnobotany, sociology, and forestry — responded in two ways. It continued searching for ways to help the local people reduce their exposure to mercury — for example, by determining which fish species of do not contain high mercury levels — but it also introduced settlers to eco-forestry, a new form of land clearing that reduces soil erosion.

A member of a Canadian research network on mercury praised the team’s breakthrough work. “Through science we now know that deforestation is one of the main determinants in methylmercury uptake, a revelation we didn’t know five years ago,” said Luke Trip, of the Collaborative Mercury Research Network, also based at UQÀM.

A new look at malaria

In Kenya, the proposed solutions to deal with malaria in a rice farming area were equally multifaceted once researchers confirmed that prevalence of the disease was “exactly the opposite of what we expected to find,” according to Clifford Mutero of the South Africa-based Systemwide Initiative on Malaria and Agriculture (SIMA).

After studying the Mwea Rice Irrigation Scheme and gathering information from local farmers through extensive consultations, his inter-disciplinary team expected to find greater malaria prevalence in two irrigated sections of the government-controlled land, relative to two non-irrigated areas. Not so. What they discovered instead was that mosquitoes in the irrigated section preferred the blood of cattle to that of humans. [See related article: Cause and Solution: A New Perspective on Malaria and Agriculture]

“The fact that you have found mosquitoes feeding on cattle does not signal the end of the research, if you are using the ecosystems approach,” said entomologist Mutero in an interview. Researchers go on to consider the question: “How do you exploit this (knowledge) for the community’s benefit?” he says.

UQÀM’s Lucotte used the term “pretext” to describe the same process — to make local people “aware that there is a relationship between the environment, their health status, and the economy.”

Environmental ecosystems conditions

The ecosystems approach, where problems are considered as intertwined in a particular context and not as isolated phenomena in research laboratories, is often not taken into account by health systems, said conference co-chair Donna Mergler.

She used malaria as an example. “Malaria is acute when a person comes in to see the physician, but it’s not only an acute health problem. It’s a major community health problem that is very strongly linked to environmental ecosystem conditions,” she said.

Mutero’s Kenya team included a sociologist, anthropologist, and statistician, as well as a medical entomologist, medical parasitologist, crop/livestock expert, and veterinarian. Among the ecosystem conditions the team identified was a law discouraging villagers who live in irrigated areas from owning cattle. The law was in place because droppings from grazing animals could pollute the fields.

Researchers suggested an alternative: “zero grazing.” In this scenario, animals don’t graze, but rather are fed on waste farm products, in this case the rice husks that villagers typically burn.

Among the other avenues researchers considered was the issue of cattle ownership, said Mutero. “You can’t tell everyone, ‘you need to have a cow’, because not all villagers can afford one, but you can try to keep the cow ownership level the same or slightly higher.”

Marty Logan is a freelance writer based in Montréal.

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