Ocean Acidification and Related Indicators

Abstract

Ocean acidification is one of the main consequences of global climate change. It is caused by the increasing input of atmospheric CO 2 in the world ocean, which in turn is affecting the marine carbonate system and resulting by now in a measurable decline in seawater pH. Thus, several key water quality parameters (alkalinity, partial pressure of CO 2 , concentration of dissolved inorganic carbon -DIC, and the seawater pH) serve as environmental indicators for ocean acidification. In addition, many pelagic and benthic marine organisms, particularly those that are calcifying, negatively or positively respond to acidification so that their physiological parameters (calcification, photosynthesis, growth) may also act as indicators of this phenomenon. On the ecosystem level, potential environmental indicators for acidification can be found in the sedimentary record (mineralogy, crystallography), in the benthic community (relative abundance of calcifying versus non-calcifying organisms, rugosity), or in the overall production, cementation, and erosion of inorganic carbon.