To adequately define primary production we must first have a basic understanding of the food chain. All organisms feed off from the organisms below them on the food chain. The base, the very first level of organism has to feed on something too. These organisms create their food through the process of photosynthesis or chemosynthesis. This is what a primary producer does, makes its food from inorganic materials.
In the ocean, this is done in one of two ways in one of two places. Photosynthesis is performed by phytoplankton on or near the surface of the sea. This process takes carbon dioxide and water and combines them with the help of the energy contained in sunlight creates a monosaccharide and oxygen. We often hear about photosynthesis as a way to produce oxygen but very rarely do we talk about this equally essential product, the building block of the food chain.
CO2 + H2O + light CH2O + O2
The other process, chemosynthesis, doesn’t get as much press as photosynthesis because it only happens deep in the ocean around thermal vents. Here there is no sunlight, so organisms adapted to into lithotropes able to transform carbon dioxide, oxygen and hydrogen sulfide and creates a monosaccharide, sulfur and water.
CO2 + O2 + 4 H2S CH2O + 4 S + 3 H2O
Both processes create the basic organic unit of energy, monosaccharide (CH2O). This energy is then either used by the creating organism or consumed by a larger organism, further up on the food chain. Now that we’ve answered the question What is primary productivity? Who are the producers?