Ancient plankton study points to climate change threats: New Zealand study

New Zealand scientists said Friday they had discovered how and when more than 2,000 species of ancient marine plankton died out, possibly indicating which existing species are threatened by climate change.

According to the findings, the extinction rate of the ancient marine plankton was largely influenced by global changes in climate, and the ocean's dramatic changes in temperature and circulation patterns.

The study used computer-optimized analysis to examine the exact time of origination and extinction of graptolites, an extinct group of ancient marine animal that lived more than 400 million years ago.

"We found that extinction happens in short bursts or episodes, separated by longer settled spells, rather than gradually and continuously," said Professor James Crampton, of Victoria University.

"When the world had a warm 'greenhouse' climate, there were low rates of extinction among the plankton. Then there was a sharp change to a cooler, fluctuating 'icehouse' climate like today, and several sharp peaks in the extinction rate, including one very severe peak where graptolites were almost wiped out."

The researchers examined each of the 2,041 species of the plankton through their 70-million-year history.

"Our analysis also shows that minor changes in the climate affected the newly evolved species of plankton - these new species were unable to compete and became extinct," said Crampton.

"In contrast, the most abrupt, severe episodes of environmental change affected the old species more profoundly - in this situation, the old guard was disadvantaged," he said.

"So it is the severity of the change in the environment that determines if old or new species are prone to extinction. Overall the extinction changes were very rapid and the ecosystem was relatively unstable."

The researchers believed the findings demonstrated the effect the current global climate might have on ocean habitats.

"Our research suggests that the modern rate of environmental change could alter the balance of extinction risk, so that the old species will be at greatest risk," said Crampton. Enditem