Human footprint harms ecosystems

Dal-led study involved researchers around the world

- April 7, 2011

(Thomas Vignaud Photo)
(Thomas Vignaud Photo)

You might think a highly diverse ecosystem like a coral reef would be better prepared to combat stressors—things like overfishing, coastal development, pollution and climate change. After all, if a few select species are removed from such a rich ecosystem teeming with marine life forms small and large, they might not be missed as others sweep in to replace them.

Not so, according to a new global scientific field study. 

“We thought these very diverse ecosystems would be very very resilient,” says Camilo Mora, the Dalhousie researcher who led the study. “But it turns out they are very sensitive to the loss of species.”

Pulling out pieces

To illustrate his point, he compares the coral reef to the computerized device that you’re now looking at to view this story. “Imagine if someone started pulling out pieces from the back, not very many pieces, just one or two. Still, it’s very likely the computer is not going to work anymore,” says Dr. Mora, on the phone from Colombia.

Coral reefs, which develop in shallow, warm water, usually near land, are so specialized and so refined, he continues, “that if you take out one or two species, it will impair the whole ecosystem.”

Researchers reporting in the journal PlosBiology say the situation is alarming. Many people around the world depend on coral reefs for their livelihood, for fishing and tourism, and yet the density of human populations in close proximity to coral reefs is adding to their decline.

Sixty-six researchers from 49 countries around the world collaborated on the study. Although challenging to work with so many people, Dr. Mora says it was necessary to document the scale of the problem.

Quite a debate erupted, Dr. Mora reports, on recommending a course of action to take. He said some researchers wanted to see more Marine Protected Areas established, even though “they’re not working.”

That approach also bypasses the real problem: human overpopulation. More than 75 per cent of the world’s reefs are located near human settlements. What’s more, many of the developing countries in proximity to reefs have booming populations—populations that could double within the next 50 years.

Too many people

“Human overpopulation is a very sensitive topic,” says Dr. Mora. “Unfortunately, we find again and again that our global population cannot be sustainably supported without the deterioration of the world’s natural resources and the resulting backlash on human welfare.

“We expect to take a lot of heat for the study, but we have to start talking about overpopulation and start doing something about it.”

SEE STUDY: Global Human Footprint on the Linkage between Biodiversity and Ecosystem Functioning in Reef Fishes


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