Seminar: Ocean acidification, piscine acid-base balance, and CaCO3 production

Martin Grosell, Ph.D.
University of Miami, RSMAS
Monterey Bay Aquarium Research Institute
Wednesday — April 6, 2011
Pacific Forum — 3:00 p.m.

Marine fish contribute significant quantities of CaCO3 to the oceanic inorganic carbon cycle as part of their hypo-osmoregulatory strategy. Piscine CaCO3 production relies on plasma HCO3– and partial pressure of CO2 (PCO2) and can thus be expected to be sensitive to alterations of acid-base balance. Fish effectively defend blood pH even in the presence of CO2 levels as high as 5-10% and are therefore not expected to be among organisms most sensitive to ocean acidification. However, the robust compensatory response to elevated ambient PCO2 includes finely tuned elevation of plasma HCO3– to maintain pH despite elevated blood PCO2. Indeed, gulf toadfish exposed to 750, 1000 and 1900 ppm CO2 display initial acidosis but rapid compensation by significantly elevated plasma HCO3-. The elevated plasma PCO2 and HCO3– during exposure to elevated ambient CO2 results in increased intestinal base secretion and rectal base excretion which includes CaCO3. Based on these observations, predicted elevations of PCO2 will result in greater piscine CaCO3 production.

Monterey Bay Aquarium Research Institute seminars, web site.

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