The effects of a controlled fluctuating nutrient environment on continuous cultures of phytoplankton monitored by computers

A completely automatic continuous phytoplankton culturing device is described. This computer-controlled system monitors simultaneously and automatically the basic culture parameters of several chemostats, i.e., limiting nutrient concentrations, cell size spectra, cell densities and temperatures. Culture pH can also be regulated. The dilution rate and the limiting nutrient concentration in the enrichment medium may be programmed to follow different dynamic patterns with time. An example is given with a sinusoidal variation of the dilution rate. Applications are discussed, which concern the advantages to modelling gained by acquiring information from continuously fluctuating systems rather than from nutrient-pulsed systems.