Hydrography, micronutrients, and phytoplankton at four stations in Hjeltefjorden, western Norway

Abstract

Abstract The study covers the period February to August 1978. The hydrography differed little from that of the coastal water in general, possibly with the exception of a more stable surface layer. Salinities at the surface ranged from 27.7‰ to 32.9‰ in the bottom water (250 m) from 34.4 to 34.9‰. The highest temperature was 14.5° C at 0 m in August and the lowest was 4° C at 0 m at the end of March. At 250 m depth the temperature decreased from 7.7° C in February to 6.7° C in July. Oxygen saturation was above 100% during the phytoplankton growth period down to a depth of la-3D m. In the deep water oxygen saturation was 86–88%. Two blooms were recorded, one in March-April and Onein June, both dominated by Skeletonema costatum. The highest cell numbers, 105–1071-1, the highest chlorophyll a concentrations, 2.6–3.3 mg m-3, and the highest carbon assimilation rates, 10–20 mg C m-3h-1 (100 μE m-2sec-1 )-1, were all round during the blooms, At other times cell numbers were low, and chlorophyll a concentrations ...