A study of microscopic ancient marine algae (Coccolithophores) has found that there is a decrease in the concentration of oceanic calcium carbonate (CaCO3) in the Southern Indian Ocean.

Try this question:

Q.The Coccolithophores sometimes seen in news are-

(a) Diatoms

(b) Algae

(c) Coral Polyps

(d) Sea grass

Coccolithophores

• Coccolithophores are single-celled algae living in the upper layers of the world’s oceans.
• They have been playing a key role in marine ecosystems and the global carbon cycle for millions of years.
• They calcify marine phytoplankton that produces up to 40% of open ocean calcium carbonate and responsible for 20% of the global net marine primary productivity.
• They build exoskeletons from individual CaCO3 plates consisting of chalk and seashells building the tiny plates on their exterior.

Role as a carbon sink

• 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, they absorb more carbon dioxide than they produce, which is beneficial for the ocean ecosystem.
• These investigations are important for future intervention to bring positive changes in the marine ecosystem and the global carbon cycle.

Threats

• The reduction of coccolithophores 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.
• Their existence is highly dependent on time and influenced by various environmental factors such as silicate concentrations, calcium carbonate concentration, diatom abundance, light intensity and availability of macro and possibly micronutrient concentrations.

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