Trophogenic zone
In oceanography and limnology , the trophogenic zone (from the Greek trophe nutrition; gennan to produce), which is also known as the nutrient layer or superstructure layer , is the surface area of a body of water that is flooded with light . Since photosynthesis can take place here , depending on the nutrient content, a more or less extensive plant growth can be found in this area, especially in the form of phytoplankton ( algae ) and other underwater plants , and thus primary production is possible. The trophogenic zone is influenced by external temperatures and other climatic conditions and influences them in turn.
The trophogenic zone is often equated with the epilimnion of a body of water. However, this is only partially correct:
Photosynthesis takes place in the trophogenic zone with light and provides oxygen and the build-up of biomass. At the same time, the organisms living there breathe constantly. The balance is trophogenic only to the extent and as long as the light-controlled photosynthesis is greater than breathing . This depends on the amount of light available, which fluctuates with the weather and time of day, and the depth of light penetration into the water. At night, however, the water layer flooded with light during the day is also tropholytic, i.e. H. Biomass is degraded net. From these relationships it follows that the trophogenic zone must be defined in relation to time: currently, on a daily average, over the stagnation period or even on an annual average. This depends on the question at hand.