Coccolithophores

Subject: Environment

Context:

National Centre for Polar and Ocean Research (NCPOR) has conducted research on Coccolithophores and has found that there is a decrease in the concentration of oceanic calcium carbonate (CaCO3) in the southern Indian ocean.

Concept:

• Coccolithophores (ancient marine algae) have been playing a key role in marine ecosystems and the global carbon cycle for millions of years.

• Coccolithophores calcify marine phytoplankton. Coccolithophores build exoskeletons from individual CaCO3plates consisting of chalk and seashells building the tiny plates on their exterior.
• Though carbon dioxide is produced during the formation of these plates, coccolithophores help in removing it from the atmosphere and ocean by consuming it during photosynthesis.
• At equilibrium, coccolithophores absorb more carbon dioxide than they produce, which is beneficial for the ocean ecosystem.
• Its abundance and diversity enrichment of coccolithophores highly depend on factors such as silicate concentrations, calcium carbonate concentration, diatom abundance, light intensity and availability of macro and possibly micronutrient concentrations.
• Recent decrease in CaCO3 is attributed to the increase in the concentration of another single-celled algae known as diatoms. This, in turn, will affect the growth and skeleton structure of coccolithophores, with potential significance for the world ocean ecosystem.
• The research team’s analysis revealed that the reduction of coccolithophore diversity in the early summer and late summer periods is due to an increase in the presence of diatom algae, which occurs after sea ice breakdown with climate change and ocean acidification, and increases the silicate concentration in the waters of the Southern Ocean.
• The results of the study point to climate change as a major reason for the altered coccolithophore calcification rate.
• These investigations are important for future intervention to bring positive changes in the marine ecosystem and global carbon cycle.