Optical measurements for biomass determination in limnological studies of eutrophication

An optical technique for determining phytoplankton biomass in lakes and reservoirs is described. By making measurements of light intensity over relatively short intervals of depth the absorption coefficient can be calculated. This permits a determination of the biomass. Good correspondence between values of the biomass using this method and other methods of sampling has been obtained. The procedure is rapid and yields results without the necessity of transporting water samples to a laboratory to make microscope cell counts.