Mixotrophic nutrition of summer phytoplankton species in the Římov reservoir
Planktonic cyanobacteria and algae belong among the autotrophic organisms, which are an important component of freshwater food web. Cyanobacterial and algal taxa have been described in both laboratory and field experiment as potential consumers of dissolved organic compounds. The uptake of organic carbon appears to be enhanced in low light environment with high organic carbon concentration, however, an efficient uptake of glucose and amino acids was recorded also at natural concentration. A capacity to use organic substrate in addition to the inorganic carbon uptake may be an important factor in the manifestation of cyanobacterial blooms in fresh waters. The aim of the project is to investigate mixotrophic nutrition particularly among the cyanobacterial bloom forming taxa by means of in situ experiments in the Římov Reservoir. Microautoradiography and scintillation method will be employed in evaluation of two organic substrates uptake in two different depths. In laboratory experiments, quantification of organic carbon uptake will be made using previously and freshly isolated cyanobacterial strains. After organic carbon addition, cyanobacterial biomass increases and growth stimulation will be investigated.