Certain ocean organisms, particularly shellfish and corals, are losing their ability to form skeletons as a result of increasing "ocean acidification," a marine environmental problem triggered by accumulating concentrations of dissolved carbon dioxide in the ocean, a new report said.

In turn, some marine species that are dependent or feed on shell-building organisms, including the clown fish, may find it harder to avoid their predators and to make their way home.

These findings were released by the United Nations Environment Program (UNEP) on Thursday at the United Nations Climate Change Conference in Cancun, Mexico.

Carol Turley, a senior scientist at the UK's Plymouth Marine Laboratory, which collaborated with UNEP in the research, told the media that such phenomena were posing a threat to billions of people who depend directly or indirectly on shellfish for protein and livelihoods.

The researchers said they observed an acidification process currently at a speed not seen in 65 million years - since the extinction of dinosaurs. And the mean pH value of the ocean has decreased by 30 percent.

"This is a global issue," Turley said. "All oceans are affected, though some of them are affected earlier."

She pointed out that in those highly industrialized areas where sulfur is added to the ocean, the impact is even bigger.

According to Tim Kasten with UNEP, the quickest way to stop this aggravation is "rapid and substantial" carbon emission cuts.

"The other thing is to determine the vulnerability (of different species) to ocean acidification," he added.