North Sea Oxygen Deficiency 1982 and Its Effects on the Bottom Fauna

In August and September 1982, two cruises were made in order to investigate the extent and effects of O2deficiencies in German and Danish coastal bottom waters. In two-thirds of the more than 15 000 km2covered, O2content below the distinct thermocline 10 to 15 m above the bottom was less than 4 ml/l (about 60 percent saturation); lowest values were near 1 ml/l. Low O2content coincided with low pH values (7.7 pH). In${\rm O}_{2}\text{-deficient}$areas ( O2saturation ca 12 percent) fish catches were low, and contained dead Agonus cataphractus, Pleuronectes platessa and Limanda limanda. Dead fish and dead benthic organisms were also detected by means of underwater TV and photography.