Correlations between phytoplankton, organic detritus and carbon in North Sea waters during the Fladenground Experiment (FLEX' 76)

Quantitative analysis of phytoplankton, organic detritus and dissolved organic carbon was carried out, during the spring bloom, in a specific North Sea area (58° 55′ N, O° 32′ E) in the course of an international and multidisciplinary marine investigation (FLEX' 76). An attempt was made to correlate the fluctuations of these variables; the analysis, however, was complicated by massive water movements. A maximum of the phytoplankton bloom coincided with a maximum of organic detritus, while both variables turned out to be inversely correlated with the dissolved organic carbon content. The initial, high amount of dissolved organic carbon declined at a daily rate of ca. 13% during a period of non-interference by water movements. Two thirds of the dissolved organic carbon content are assumed to be transformed into particulate organic matter whilst the rest disappears through still unknown channels.