Significance of tintinnid grazing during blooms of Phaeocystis pouchetii (haptophyceae) in Dutch coastal waters

Abstract

Extremely dense populations of tintinnids (24 000 to 118 000·dm −3) were found during the spring bloom of the alga Phaeocystis pouchetii in the Dutch Wadden Sea and coastal North Sea. Microscopic observations showed that these Protozoa grazed on the single-cell stage of the colony-forming Phaeocystis. At the end of the bloom, the biovolume of the tintinnid population equalled or even exceeded that of the Phaeocystis population, indicating that microfaunal grazing prevented further growth of the Phaeocystis spring bloom.