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Coral Fossils Document Past Sea Life

February 16, 2010

Scientists may use fossilized coral reefs in the Great Barrier Reefs to understand how sea levels have changed over the past 20,000 years.

An international team of researchers plan to spend 45 days at sea, gathering core samples from about 40 sites.

Coral, which is described as the “tree of the sea”, have growth rings that show seasonal variations.

Researchers say that samples taken of the coral will also help show past sea temperatures, as well as other changes to the reef.

Alan Stevenson, team leader of marine geology at the British Geological Survey (BGS), said the fossilized corals’ annual growth rings provided an insight to conditions under waves.

“We can then analyze those rings to build up a very detailed picture of what the ocean was like when they were forming, including temperature and salinity, ” he said.

Stevenson told BBC News that the Great Barrier Reef is about half a million years old.

“Over this time, parts have died out… as sea levels change. Basically, corals drown when it becomes too deep for them.”

The team plans to collect samples of fossilized corals that were developed between 20,000 to 10,000 years ago.

“We will core into a ‘time capsule’ of sediments that holds information on the environmental evolution of the reef since the last glaciation some 20,000 years ago,” said Dan Evans, a marine geologist at BGS and science manager for the ECORD Science Operator.

Researchers currently believe that there were three periods in which the sea level rise was accelerated:  19,000, 13,800 and 11,300 years ago.

“By understanding more about the past, we can understand a little bit more about the future,” said Stevenson.

The team will gather core samples, some of which are 490 ft below the seabed.

Stevenson said that the expedition would not disturb the live coral in the World Heritage site.

“Obviously, it is a national park and we are in there with the permission of the Great Barrier Reef Marine Park authority. If they were not happy, then we would not be there.”

The European Consortium for Ocean Research Drilling (ECORD) and the forms part of the Integrated Ocean Drilling Program (IODP) all are funding the expedition.

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