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Factors affecting phytoplankton extracellular release in the Southern Bight of the North Sea

par Lancelot, Christiane
Référence Marine ecology. Progress series, 12, page (115-121)
Publication Publié, 1983-05-30

Article révisé par les pairs

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Résumé :

Phytoplankton extra cellular release of organic substances was studied in the Southern Bight of the North Sea in relation to changes in growth conditions (light intensity and inorganic nitrogen concentration) and in taxonomie phytoplankton composition. Light intensity had no effect on percent extracellular release (PER). A high negative correlation between PER and mineraI nitrogen concentration was found during spring bloom wh en phytoplankton were dominated by flagellates (Phaeocystis poucheti in the Southern Bight; dinoflagellates in the oligotrophic English Channel). The physiological response of the flagellate.populations to shortage of nutrients differed. High PER was measured during the decline of the bloom with lower values in oligotrophic (46 %) than eutrophie waters (70 to 80 %). On the other hand, no significant correlation was found between PER and mineraI nitrogen for diatoms which dominate the phytoplankton population outside the spring period. PER values were unchangeably low (0 to 14 %) over a large range of mineraI nitrogen concentrations (0 to 50 µg at N 1-1).