Marine phytoplankton constitutes about half of the world’s biomass production. Similar to trees it needs CO2, water, and light as major energy source for a process called photosynthesis, and nutrients for the general cell functioning. However, while trees grow at fixed locations and can become hundreds of years old, these unicellular algae are freely floating in the water and have high turnover rates. Changes in the environmental conditions are therefore quickly mirrored in the phytoplankton’s abundances, locations, and species compositions. The most important factors determining the growth of phytoplankton - the environmental drivers - are water temperature, light intensity, and the availability of nutrients and inorganic carbon.
Climate change is massively altering each of these drivers, pushing them outside their natural fluctuation ranges. Phytoplankton therefore has to face completely new conditions in its habitats. As it plays a significant role in the fixation of atmospheric CO2, the transport of carbon to the deep ocean, and in the oceanic food web, it is of urgent need to make robust projections on its future.
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