Climate change: acid oceans altering marine life

Some of the first species impacted by increasingly acidic oceans have been identified just as scientists meet in Copenhagen this week to present new data showing that climate change is far more urgent and serious than current economic problems.

One affected species, foraminifera, a sand grain-sized plankton, is responsible for the sequestration of 25 to 50 percent of the carbon the oceans absorb and thus plays a major role in keeping atmospheric carbon dioxide (CO2) concentrations at much lower levels than they would be otherwise. Now scientists have learned that foraminifera (forams) shells are much thinner in oceans made more acidic by the enormous volumes of CO2 released in the burning of fossil fuels.

It was only a few years ago that researchers realised that human emissions of CO2 were making the surface waters of oceans more acidic. That prompted a rush of new research to determine what the impacts might be. It turns out that forams, other shell forming species like mussels, as well as corals and fish are casualties in humanity’s giant, uncontrolled experiment that involves injecting huge quantities of CO2 into the atmosphere.

“We think we are the first to document effects in the field as opposed to in a laboratory experiment,” said William Howard of the Antarctic Climate and Ecosystems Cooperative Research Centre, Hobart, Tasmania, Australia.

The shells of one species of foraminifera (Globigerina bulloides) in the Southern Ocean are 30 to 35 percent thinner than shells than those shells formed prior to the industrial period, Howard and colleagues wrote in a paper published in Nature Geoscience Mar. 8.

Howard told IPS that forams live in the surface waters and when they die they fall to the ocean bottom. As they fell through the water column researchers collected them and compared their shell weights with forams in the sediments. Forams are widespread, numerous and have a 200-million-year-old ancestry. Their hard calcite shells are well preserved, providing a detailed fossil record of their time on Earth.

Stephen Leahy, IPS NEWS, 10 March 2009. Full article.

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