Calcium carbonate
As the pH of marine systems decreases, it causes calcium carbonate (CaCO3) to dissociate to keep in chemical equilibrium. Calcium carbonate is vital to calcifying organisms such as shellfish, corals, and coccolithophores (a type of phytoplankton). Acidification also harms micro-organisms in the environment. These organisms either directly provide humans with a food source or supports an ecosystem important to humans.