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Australia, Japan Top Global Ocean Diversity List

A survey of global marine species has identified Australian and Japanese waters as the most diverse on Earth. The authors of the study warn, however, that pollution and climate change pose serious threats to the health of our oceans.

A 10-year effort to count the world's marine life shows that each of the world's oceans contains about thousands of known forms of life, ranging from single-celled creatures to whales and sea birds.

This natural wealth is described in a series of papers published this week by the online Public Library of Science, known as PLoS One.

The Census of Marine Life shows that the seas around Australia, which stretch from icy Antarctica to the warm tropics, are home to the world's richest array of marine animals, with about 33,000 species. That is followed by the ocean around Japan and China.

There is a warning, though, that the effects of climate change, pollution and overfishing are destabilizing marine environments.

Mark Costello, a marine scientist from the Leigh Marine Laboratory at New Zealand's University of Auckland, says sea life faces a variety of threats.

"Overfishing topped the list, so everywhere in the world fish stocks are under pressure," he said. "And then, secondly habitat loss, especially in coastal areas and pollution in coastal areas primarily as well. So, there are fairly significant threats and, you know, you look back and you find lots of case studies on different species and different places which show there is some local context that is pretty much the case everywhere in the world now."

Other threats include rising water temperatures, oxygen depletion and the increasing acidity of the water.

The marine census involved hundreds of scientists from around the world who surveyed 25 important marine areas. They found that the seas still harbor great secrets. It is estimated that 30 percent of fish species in the oceans have yet to be formally named, along with 80 percent of small invertebrates and other small animals.

The survey aims to provide the most accurate assessment of life in the oceans. The final report is to be released in October.