For oxygen determination samples were analysed on board immediately after collection with the Winkler method according to Carpenter (1965a, 1965b). Titration was done with a Metrohm Dosimat 665 automatic burette. Precision of the method is estimated at 0.05 ml O2/l.Apparent oxygen utilisation (AOU) was calculated according to difference of measured oxygen values and oxygen saturation given by the equations of Benson and Krause (1984), which are recommended by Millero (1986).Percentage of oxygen saturation in water was calculated from the following equation (at temperature 0-40ºC and salinity 0-40 promille): %O2 = (O2/O2') X100, where O2 is oxygen concentration in a sample, O2' is oxygen solubility in sea water at the same temperature and salinity as in the sample.Samples for determination of nutrients were collected in 100 ml polyethylene bottles and kept continuously under deep freeze (-20°C ) until analysis in the laboratory. Nitrate and nitrite were analysed by a Bran and Luebbe Autoanalyser II according to the procedure of Treguer and Le Corre (1975). Phosphate was measured by a Perkin Elmer Lambda 2S UV/VIS Spectrometer according to the method described by Murphy and Riley (1962). Precision is estimated at ±0.1 µmol/l for nitrate and ±0.02 µmol/l for phosphate and nitrite. Detection limit was 0.08 µmol/l for nitrate and nitrite and 0.01 µmol/l for phosphate.