Coccolithophores–a type of phytoplankton–are single-celled marine plants that primarily live in the subpolar regions of the world. Unlike other types of phytoplankton, coccolithophores are covered in round plates (called "coccoliths") made of calcite (a form of calcium carbonate, CaCO3). When the coccolithophores die, age, or reproduce, they shed the coccoliths; in areas with high concentrations of coccolithophores, these shedded coccoliths can turn the water a milky blue color–a phenomenon that can be seen from space. It is estimated that coccolithophores produce more than 1.5 million tons of calcite each year, making them the ocean's leading producer of calcite and a potentially large influence on the global carbon cycle. Unfortunately, the calcite coccoliths also make the coccolithophores susceptible to ocean acidification, as changing pH might dissolve the coccoliths or make it more difficult for the coccolithophores to build these calcite plates.
An international team of scientists is studying a feature known as the Great Southern Coccolithophore Belt (the "Great Belt")--an area with a high concentration of coccolithophores that stretches around the entire Southern Hemisphere in the Southern Ocean. The Marine Biogeochemistry Lab at BIOS is a partner in the Great Belt Research Cruise, providing personnel and laboratory facilities to measure the total alkalinity and dissolved inorganic carbon (DIC) both in the water column and other experiments conducted on the cruise. By analyzing samples collected at 120 sites across the Southern Ocean, researchers will be able to discover which species are present, what influences their distribution, how they affect the global carbon system, and how they might be impacted by ocean acidification.