[Relationship between photosynthetic activity and assimilation of organic matter in marine plankton mixotrophic algae--the possibility of different metabolic strategies].

The relationship between photosynthetic and heterotrophic activities of plankton mixotrophic algae is characterized by the type of metabolic strategy. Algae with a primary photoautotrophic strategy grow at the expense of photosynthesis without uptake of organic substrates when inorganic and organic nutrients are available. They assimilate only organic substrates when inorganic nutrients are in shortage, while heterotrophic activity supports photosynthesis under conditions of inorganic nutrients deficiency. Algae with a primary heterotrophic strategy grow heterotrophicaly under repletion of inorganic and organic nutrients. Photosynthesis occurs only when organic substrates are depleted. The most mixotrophic algae combine the features of a primary photoautotrophic and a primary heterotrophic strategies. The varieties of metabolic types of mixotrophic algae form a continuum with a primary photoautotrophic strategy on the one end and a primary heterotrophic strategy on the other. The natural conditions allowing mixotrophic algae to use one or other metabolic strategy are determined by the dynamic of inorganic and organic nutrients.