BOUNDARY-LAYER CHARACTERISTICS OF THE CONTINENTAL-MARGIN OF THE WESTERN BARENTS SEA

Characteristics of suspended particulate matter in the benthic boundary layer of the continental margin of the western Barents Sea were studied during three cruises in July 1990, Winter and Summer 1991 by collecting water samples 10, 15, 25, 40 and 500 cm above the sea-floor. At all stations gradients of oxygen and particulate matter within the benthic boundary layer were evident. Oxygen varied between 266 and 376 mu mol l(-1) and did not correlate with height above the sea-floor. Total particulate matter concentrations ranged from 0.75 to 11.3 mg l(-1) Particulate organic carbon concentrations ranged from 16 to 107 mu g l(-1) and chlorophyll equivalent concentrations ranged from 0.0 to 0.18 mu g l(-1). Bacterial biomass measured at 5 stations varied between 0.05 and 2.07 mu g bacterial organic carbon l(-1) with highest values at 25 and 40 cm height above sea-floor. From 10 to 40 cm above the sea-floor the distribution of individual bacterial volume-shifts to higher size classes. 10 to 30 cm above the bed 35 to 65 % of the bacteria were particle-associated, while more than 85 % of the bacteria were free-living 500 cm above the sea-floor: Data from the Barents Sea site indicate that, within the suspended matter in the near-bottom water layers, particle stratification due to hydrodynamic sorting occurred. Generally, particulate organic carbon increased from the sea bed into the water column with decreasing values between 40 and 500 cm above the seafloor. Chlorophyll equivalents decrease above the sea bed into the water column. Chlorophyll equivalent / particulate organic carbon ratio in the near-bottom water did not exeed 0.5 %.