Chlorophyll a was measured fluorometrically by use of laboratory fluorometer constracted on the base of spectrophotometer Specol, fitted with a red sensitive photomultiplier, blue lamp, blue filter and red filter. Accuracy: lower limit = 0.01 mg/m**3 and the error of Chl determination is 10-15% (calculated from 10-15 repeatings). Primary production was measured by C14 simulated in situ method. Accuracy: 20 %, from experimens.