Coccolithophores
Introduction
Coccolithophores are a type of marine phytoplankton that are distinguished by their calcium carbonate (CaCO3) plates, known as coccoliths. These unicellular, photosynthetic organisms play a crucial role in the carbon cycle, as well as in the production of oxygen and the food chain in the ocean.
Biology and Structure
Coccolithophores belong to the division Haptophyta, and they are typically 5-10 micrometers in diameter. The coccoliths that form their exoskeleton are made up of individual plates of calcium carbonate, which are produced inside the cell and then extruded to the surface. The structure and arrangement of these coccoliths can be used to identify different species of coccolithophores.
Ecological Role
Coccolithophores are a major component of the phytoplankton community and play a significant role in the marine ecosystem. They contribute to primary production by photosynthesizing, and they are a food source for various marine organisms. Additionally, their production of calcium carbonate plays a role in the carbon cycle and affects the chemistry of the ocean.
Coccolithophores and the Carbon Cycle
Coccolithophores play a critical role in the carbon cycle due to their production and deposition of calcium carbonate. This process, known as calcification, involves the uptake of dissolved inorganic carbon from the surrounding water, which is then used to produce calcium carbonate. The coccoliths are eventually shed and sink to the seafloor, where they contribute to the formation of sedimentary rock and the sequestration of carbon.
Impact of Climate Change
The response of coccolithophores to climate change is a topic of ongoing research. Changes in ocean temperature, acidity, and nutrient availability can all impact coccolithophore populations and their role in the carbon cycle. Some studies suggest that increased levels of carbon dioxide could enhance coccolithophore growth and calcification, while others indicate potential negative impacts.