Monthly mean primary productivity (1997–2016)

The average concentration of chlorophyll-a (chl-a) in phytoplankton over the period 1997 to February 2016.
Concentrations of chl-a in phytoplankton are used to assess primary productivity in our oceans. Phytoplankton are primary producers of biomass (mass of living organisms) and form the main basis of marine food chains. They use the chl-a pigment to capture the sun’s energy through the process of photosynthesis. Phytoplankton growth is affected by the availability of nutrients and light, which in turn are affected by the structure of the surface water column. The surface water column structure is affected by oceanographic and climate processes; large-scale changes to climate and oceanographic conditions can lead to changes in phytoplankton growth and chl-a concentrations.