ABSTRACT
Lakes have long been considered as prototypes of ecosystems, i.e., more or less closed units, well defined physically, and characterized by a certain functional autonomy. 12 As for any ecosystem, overall function is based on the dependence and interdependence of the various communities of living organisms and their interactions with the abiotic environment. The overall functional metabolism can be divided into two main parts:
Photosynthetic production of organic material by autotrophic organisms
Consumption and degradation (respiration) of this organic material by heterotrophs (animals, microbes) with the concomitant recycling (mineralization) of nutrients
