An apparatus for automatic counting and controlling density of pelagic food particles in cultures of marine organisms

A particle control system is described for automatic collection of samples, and determination and control of the density of particles in marine suspensions. Densities are determined electronically, allowing colourless microorganisms to be detected. Computer operated magnetic valves allow multiple cultures to be sampled, measured and fed, using compressed air and a vacuum pump. Conditions and variables, determined in the software, enable flexible adjustment to specific culture conditions. The system was applied in the cultivation of the copepod Acartia clausi Giesbrecht, using a 95 m orifice with a particle size range of 8 to 32 m. Some results are given of monitoring and controlling the density of heterotrophic flagellates as food in the copepod cultures at different conditions of temperature and autotrophic food.