WASHINGTON - From the lowland gorillas of Africa to corals of the Galapagos Islands, more than 16,300 species are threatened with extinction, the World Conservation Union said on Wednesday in its annual Red List.

In what is billed as the world's most authoritative assessment of Earth's plants and animals, the global group considered 41,415 species and found that of those, 16,306 were under threat, said Craig Hilton-Tailor, the list's manager.

That is nearly 200 more species of wildlife than last year, Hilton-Tailor said in a telephone interview. Even so, there are probably many more than that, he said.

"The estimate is low; we know it's low," Hilton-Tailor said. "We've only really looked at the tip of the iceberg in terms of species that are out there that are known to science."

The World Conservation Union -- a global group whose members includes nations, government agencies, non-governmental organizations and thousands of scientists -- aims to "influence, encourage and assist societies" to conserve nature and natural resources.

While it does not play a major role in U.S. decisions on wildlife conservation because the United States does this through its own Endangered Species Act, the conservation union is highly influential in other regions, particularly in developing countries which cannot afford to make their own assessments of which species are in trouble.

Three of the new species added to this year's list are corals in the Galapagos, which are critically endangered by the warm-water Pacific Ocean pattern El Nino and by climate change, the group said in a statement.

CLIMATE CHANGE IS ONE CAUSE

Hilton-Tailor said global warming is a factor in these and other species' endangerment, but not the only factor.

"It's really hard to identify whether it's climate change or not that's driving some of these species to extinction," he said. "Climate change doesn't operate by itself, it's operating in tandem with other threats and it's usually the combination of climate change and possibly the threat of a new disease ... it's different combinations that can push species over the brink."

The Red List is aimed at policy makers and ordinary people, Hilton-Tailor said.

"If everybody on the planet cooperated and adopted a sustainable way of living, a lot of these problems would go away," he said. He acknowledged that such cooperation has not occurred in the course of human history.

Asked to name a particularly troubling example, Hilton-Tailor mentioned the western lowland gorilla, which moves from endangered to critically endangered on the latest list. Its decline is due to the Ebola virus and commercial hunting of so-called bush meat.

This case points up the need for better viral controls, and for an alternative source of food for people in the gorilla's range, from Angola to Congo to Gabon.

Development is the culprit in the decline of the Yangtze River dolphin, also known as the baiji, Hilton-Tailor said. It is critically endangered and possibly extinct, with perhaps one or two individual creatures remaining.

Changes in river flows due to dams, pollution, over-fishing and the use of electric shocks to fish in the Yangtze system are all factors in the cetacean's disappearance. Heavy river traffic in fast-developing China is another cause.

"Any poor dolphin would really have to do amazing acrobatics to avoid being hit by one of those ships," Hilton-Tailor said.