How are the Ca cycle and the C cycle linked in marine environments? How will increased carbon ...

 Several eukaryotic phototrophic microorganisms form calcareous (calcium-containing) exoskeletons. These planktonic phototrophs are also very important primary producers and fix large amounts of carbon dioxide into organic carbon in the ocean. In addition, the exoskeletons are composed of CaCO3 (calcium carbonate). Carbon dioxide gas is very soluble in the ocean. As the atmospheric concentration of carbon dioxide increases, more carbon dioxide dissolves in the ocean in the form of carbon acid, lowering the pH and dissolving calcium carbonate. The acidification of the oceans is predicted to reduce the rate of formation of calcareous shells, which may reduce primary production and have effects on multiple nutrient cycles (C, Ca, N).