Natural labs help scientists study ocean acidification

Scientists are using “natural laboratories” — seafloor vents that release millions of streams of small bubbles of carbon dioxide – to study how ocean acidification may affect the future of coral reefs and other marine ecosystems as global carbon dioxide emissions rise.
These techniques and others were discussed Tuesday during the second press briefing at the Third International Symposium on The Ocean in a High-CO2 World in Monterey, Calif.

When Dr. Katharina Fabricius of the Australian Institute of Marine Science in Australia discovered the carbon dioxide vents in Papua New Guinea “ocean acidification wasn’t an issue.” Her recent work at the sites would show that “seagrasses do amazingly well, but coral reefs cannot survive when conditions get too corrosive.”

“There is an absolute threshold for coral reefs of pH 7.8,” she added.

Ocean acidification refers to the change in the pH level, which measures the acidity of a liquid. The pH of the ocean is changing as the ocean absorbs more carbon dioxide from the atmosphere. Indeed, the oceans are now 30% more acidic than at the start of the industrial revolution 250 years ago.

Dr. David Kline of the Scripps Institution of Oceanography in California, adapted a deep water experiment to create an underwater “time machine” so levels of carbon dioxide could be controlled to projected levels.

“Our work suggests coral reefs may be in more danger than we thought,” he said.

But it is not just coral reefs affected. All organisms with hard shells or exoskeletons will be forced to adapt to rapidly changing ocean chemistry.

Some organisms are responding in unexpected ways, said Dr. David Hutchins of the University of Southern California. Phytoplankton, tiny organisms at the base of the food chain are showing surprising responses. “Without them we wouldn’t have fish and whales,” he said.

“One type that provides nitrogen to the food chain actually produces more nitrogen in high carbon dioxide situations,” Dr. Hutchins said. “It seems a switch was triggered to produce more nitrogen. The surprise was that when we changed conditions back again the trigger appeared to be stuck in the ‘on’ position. We’re trying to figure out why they should do that.”

The three scientists were joined on the panel by Dr. Steve Widdicombe of the Plymouth Marine Laboratory in the United Kingdom, who said that a suite of techniques is necessary to better understand how ecosystems respond to ocean acidification.

“Ecosystems are in a world that changes rapidly and frequently,” he said. “We need to understand how they can live with the systems they have and what they need to adapt.”

Editor’s Note: The views expressed in this press release are those of individual scientists and may not represent the views of conference sponsors.

International Geosphere-Biosphere Programme
, 26 September 2012. Article.

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