Abstract
The aim of the research was to determine the effect of irradiance on the content of carotenoids in the natural algae community occurring in the Baltic Sea: diatom Skeletonema marinoi, cryptophytes Teleaulax sp., Rhodomonas sp., and dinoflagellate Heterocapsa triquetra.
In the natural population of Skeletonema marinoi, the highest fucoxanthin content was observed in the morning and afternoon, unlike with diatoxanthin+diadinoxanthin, where a mean of 0.008 pg cell-1 was found at dawn and at dusk, whereas maximum values were observed at noon (mean 0.017 pg cell-1). Similar tendencies related to diurnal variations in the content of xanthophylls involved in the xanthophyll cycle occurred also in dinoflagellate Heterocapsa triquetra.
In cryptophytes Teleaulax sp. and Rhodomonas sp., no carotenoids of the xanthophyll cycle were detected. The content of alloxanthin showed diurnal variation from 0.048 pg cell-1 to 0.085 pg cell-1 and was not clearly correlated with the irradiance.