Seasonal occurrence of silica-scaled chrysophytes under eutrophic conditions

The seasonal occurrence of silica-scaled chrysophytes (Paraphysomonadaceae and Mallomonadaceae) in the eutrophic lake Tystrup Sø, was examined during 1979–1981 in relation to temperature and to overall phytoplankton biomass and composition. The 33 species recorded represent three seasonality types, with occurrence in spring alone, spring and autumn, and during a greater or lesser part of the whole year, including summer. The great majority of the species have their main occurrence in early spring and at low temperatures, perhaps due to effects of the high phytoplankton biomass, especially cyanophytes, during summer and autumn.