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To: Bread Upon The Water who wrote (118848)	8/19/2009 4:58:02 PM
From: Paul Kern	Read Replies (1) \| Respond to of 541902

I've missed the boat here on this one. There's a relationship between the planet getting warmer and the ocean's ability to retain (absorb?) CO2 which, I think, helps form calcium carbonate It forms carbonic acid.

To: Bread Upon The Water who wrote (118848)	8/19/2009 7:08:11 PM
From: Sam	Read Replies (1) \| Respond to of 541902

I think what happens is that as CO2 goes into the ocean, it combines with the water to create carbonic acid. But as it does does so, it leaches out some of the calcium carbonate that is there. Calcium carbonate is used by many shell fish, plankton and coral to make their shells. When there is less that is available--or when it is changed from calcium carbonate to calcium bicarbonate--then shell formation is inhibited. This makes them even more susceptible to the slightly higher acidity of the ocean, and makes it more difficult for them to grow and reproduce. At least, that is an outline of the story as I understand it. I'll see if I can find someone who knows more than I do to confirm it.

To: Bread Upon The Water who wrote (118848)	8/19/2009 7:23:59 PM
From: Wharf Rat	Read Replies (1) \| Respond to of 541902

Shellfish face an uncertain future in a high CO2 world May 27th, 2009 Overfishing and disease have decimated shellfish populations in many of the world's temperate estuarine and coastal ecosystems. Smithsonian scientists, led by Whitman Miller, ecologist at the Smithsonian Environmental Research Center in Edgewater, Md., have discovered another serious threat to these valuable filter feeders—rising levels of atmospheric carbon dioxide that contribute to the acidification of open ocean, coastal and estuarine waters. Their findings are being published in the open-access, peer-reviewed journal PLoS ONE, May 27. For shellfish and other organisms that have calcium carbonate shells and structures, the problem begins when atmospheric CO2 dissolves in seawater and creates carbonic acid that is then rapidly transformed into carbonate and bicarbonate ions in the water. Increased acidity tips the balance toward bicarbonate formation and away from carbonate. Less carbonate in the water means that shellfish have fewer building blocks to generate their shells. If the water is acidic enough, shells can even begin to dissolve. "Estuarine and coastal ecosystems may be especially vulnerable to changes in water chemistry caused by elevated CO2 because their relative shallowness, reduced salinity and lower alkalinity makes them inherently less buffered to changes in pH than in the open ocean," said Miller. For many calcifying organisms, CO2-induced acidification poses a serious challenge because these organisms may experience reduced rates of growth and calcification that "when combined with other environmental stresses, could spell disaster." Larval oysters are thought to be particularly susceptible to acidification since larvae produce shells made of aragonite, a crystalline form of calcium carbonate that is prone to erosion at low pH. Adult oysters continue to build shell but generate calcite, a more durable form of calcium carbonate. In Miller's study, the larvae of Eastern oysters (Crassostrea virginica) and Suminoe oysters (Crassostrea ariakensis) were cultured in estuarine water that was held at four separate CO2 concentrations, reflecting atmospheric conditions from the pre-industrial era, the present, and those predicted in the coming 50 and 100 years. To test the effects of acidification, Miller monitored their growth and measured the amounts of calcium carbonate deposited in larval shells over the course of one month. Miller and his team found that Eastern oysters experienced a 16 percent decrease in shell area and a 42 percent reduction in calcium content when specimens in the pre-industrial CO2 treatment were compared with those exposed to the levels predicted for the year 2100. Surprisingly, the closely related Suminoe oysters from Asia showed no change to either growth or calcification. physorg.com