Biodiversity Study Sounds an Extinction Alert (for Things with Spines)

Article excerpt

Biodiversity researchers warn that 20 percent of vertebrate species are threatened with extinction, largely because of human damage to habitats. But conservation efforts, they say, are effective.

If a creature has a spine and walks, flies, swims, or crawls, it may be in serious trouble.

Some 20 percent of all vertebrate species on Earth are threatened by extinction, according to a newly published survey - a study the research team involved says is the most exhaustive to date on biodiversity among vertebrates.

The losses are due largely to human encroachment on habitat, over- fishing and over-hunting, as well as the arrival of invasive species in habitats whose natural inhabitants have no defenses against the invaders, the study says.

But within an admittedly bleak global picture, the researchers add, conservation efforts have halted the decline in some species and brought others a significant step closer to recovery.

"The bad news can be extremely disheartening," says Ana Rodrigues, a scientist with the Center for Functional and Evolutionary Ecology in Paris and one of a team of 174 scientists from 38 countries who co-authored the study.

"But our results show that conservation efforts are not wasted," she adds.

Biodiversity refers to the variety of plant and animal species in an ecosystem. Generally the greater the diversity, the more resilient the ecosystem is to disturbances, either natural or man- made.

Using an internationally recognized "red list" index that tries to capture changes in a species' population size, structure, and geographic range, among other factors, the team found that without conservation programs, biodiversity among birds and mammals would have declined an additional 18 percent over the past 30 years. The programs range from efforts to establish safe havens such as marine protected areas or wildlife reserves to campaigns to battle invasive species.

The report draws on research conducted by some 3,000 scientists worldwide. It was published Tuesday on the journal Science's website as delegates from 194 countries were meeting in Nagoya, Japan, to try to set conservation targets for the next decade under the UN's Convention on Biological Diversity, which is scheduled to end Oct. 29.

Eight years ago, parties to the convention agreed to significantly reduce the rate of biodiversity loss by 2010. But in April, a study published online in Science showed that the rate of decline in biodiversity across a broad range of plants and animals was not slowing. Countries had failed to meet the 2010 goal.

Losses in tropics

For this latest project, the team focused on vertebrates - a group that includes animals that are most important to humans either for food or for their cultural or social significance. The group looked at 25,780 vertebrate species. …