Primary production
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Primary production is the production of biological organic compounds from inorganic materials through photosynthesis or chemosynthesis. Organisms that can create biomass in this manner (notably plants) are known as primary producers, and form the basis of the food chain.
Primary production in oceanography and limnology refers to the production of biomass by phytoplankton in aquatic environments utilizing energy from sunlight. The small algal cells are then consumed by — and provide organic building blocks and energyfor — small animals such as ciliates, copepods, and krill. Primary production is the basis for all life in the open oceans.
Primary production is a flux that can be measured during a unit of time by 3 techniques : variations of oxygen concentrations in a bottle (technique used from 1927), incorporation of 14 Carbon (the 14C atom replace the natural 12C in a molecule of sodium bicarbonate; Steeman-Nielsen technique of 1952) and modulated in vivo fluorescence (a more recent technique that is always under developpment at present time). However, the most common technique is the 14C technique using different incubator (under natural or artificial light) and different unit of time (from hours to day). According to the incubation time, net or growth primary production can be estimated. Net primary production will be estimated under short incubation time (1h), because loss (by respiration and organic material excretion) of 14C incorporated during incubation will be very limited. However, loss processes will be greater using long incubation time. Loss processes can range between 10 and 60% of incorporated 14C according to environmental conditions and species. So primary production is a complex process and rate estimations in a natural marine system of carbon flux must be considered cautiously.