Primary Productivity

Primary Productivity

Primary Productivity

Oxygenic photographs existed freely in water use water as an electron donor to reduce carbon dioxide are called primary producers.

They include algae and cyanobacteria. They are also called phytoplankton. Plankton means floating.

They obtain energy from light and reduce carbon dioxide to organic matter. The activity of guilds of heterotrophic microorganisms in aquatic ecosystems depends to a major extent on the rate of primary production.

Oxygenic phototrophs produce new organic matter as well as oxygen. If photosynthetic activity is very high, the excessive organic matter can lead to oxygen depletion and anoxic condition. This in turn triggers anaerobic metabolisms such as anaerobic respiration and fermentations.

Like phytoplankton, anoxygenic photosynthetic prokaryotes can also fix carbon dioxide into organic matter. But these organisms use reduced substances such as hydrogen sulfide or hydrogen as photosynthetic electron donors.

Nevertheless, organic matter produced by anoxygenic phototrophs can be diffuse into oxic waters and increase respiration accelerating the spread of anoxic conditions.

Much of the primary productivity is due to photosynthesis by prochlorophytes which  are tiny prokaryotic phototrophs containing chlorophylls a and chlorophyll b.

Prochlorococcus is an important primary producer and dominant oxygen phototroph. Cells of Prochlorococcus account for 50% of net primary production.

Primary Productivity

Written By

Sadia Akhtar
Student of Department of Microbiology
Jagannath University.
Email- sadiabd810@yahoo.com