FIGURE O.7 (left panel) Variation in pH of global mean surface waters with CO2. (right panel) Global coral reef distribution and their net community calcification; the biological production of calcium carbonate skeleton or shell material, relative to their pre-industrial rate (280 ppm), in percent, taking into account both ocean acidification and thermal bleaching; the loss of algal symbionts in response to warming and other stressors, for each reef location at CO2 stabilization levels of 380, 450, and 560 ppm. Source: Silverman et al. (2009). {4.9; 5.8}

FIGURE O.7 (left panel) Variation in pH of global mean surface waters with CO2. (right panel) Global coral reef distribution and their net community calcification; the biological production of calcium carbonate skeleton or shell material, relative to their pre-industrial rate (280 ppm), in percent, taking into account both ocean acidification and thermal bleaching; the loss of algal symbionts in response to warming and other stressors, for each reef location at CO2 stabilization levels of 380, 450, and 560 ppm. Source: Silverman et al. (2009). {4.9; 5.8}

Impacts of CO2, pH, and Climate Change on Ocean Biology

The patterns and rates of ocean primary production will change due to higher sea surface temperatures and increased vertical stratification, altering the base of the marine food-web. Observations indicate a strong negative relationship between marine primary productivity and warming in the tropics and subtropics, most likely due to reduced nutrient supply, and low-latitude primary production is projected to decline on basin-scales under future climate warming. Primary production in some temperate and polar regions is projected to increase due to warming, reduced vertical mixing, and reduced sea ice cover. Subsurface oxygen levels are projected to decline due to warmer waters and altered ocean circulation, leading to an enlargement of oxygen minimum zones. {5.8}

The geographic range of many marine species is shifting poleward and to deeper waters due to ocean warming. Individual marine species will change differentially, for example with the ranges of pelagic fish likely changed more than those of demersal fish. Few studies have looked com-



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