Southern Corals Unlock Climate Clues

[mrmoshe]

Southern corals unlock climate clues

While great attention is being given to the threat of global warming to corals of the Great Barrier Reef, the corals off southern Australia are giving scientists information about climate change.

As divers and fishermen in southern waters know well, corals are not restricted to tropical waters.

The most obvious of the southern versions occur in large boulder-like formations known in South Australia as bommies.

They are now throwing new light on the history of Australia's southern oceans, revealing details of past climates and the human impact on the sea.

Sam Burgess of the Australian National University and the ARC Centre of Excellence for Coral Reef Studies, is completing a PhD on these little-known South Australian corals, proving their importance to issues of climate change and ocean health.

"Most people are surprised to learn that there are large corals in these colder waters," Ms Burgess said.

"They think corals only occur in the warmer waters of the tropics."

Ms Burgess has treated areas off the coast of Adelaide and the Spencer Gulf as her workplace for the past four years.

"There is a lot more diversity in temperate reefs and cold-water corals than people expect," she said.

"This coral species occurs sporadically as an encrusting growth form on the Great Barrier Reef, but in the temperate waters [of southern Australia] they are the dominant coral species."

By drilling out small samples of coral bommies and studying their chemical content, Ms Burgess has found ways to read the temperature and pollution of the waters back hundreds of years.

So far the corals have confirmed a 1.5 degree rise in water temperatures over the last 130 years, as has been shown in other coral reef studies of the tropics.

"[The study] helps add to the knowledge gained from research conducted in the tropics by filling in the holes in our understanding of the ocean's chemistry in the past," Ms Burgess said.

The corals show signs of contamination from human activities, with traces of some chemicals and heavy metals increasing since industrial development in the area.