Pigment composition in relation to phytoplankton community structure and nutrient content in the Baltic Sea

The concentration of chlorophylls and carotenoids with respect to communities of characteristic phytoplankton species and hydrological parameters, such as temperature, salinity and nutrients were analysed. Samples from the southern Baltic were taken during three periods: spring 1999, autumn 1999 and 2000 during cruises of r/v 'Oceania' in this area. The seasonal differences between the phytoplankton species composition and pigmentation of samples (measured by HPLC) were noted. The total biomass of the spring phytoplankton population was 11-15 times greater than that of the autumn populations. However, the phytoplankton community was more diverse in the two autumns, whereas the spring population was almost mono-taxonomic: > 80% of the total biomass consisted of dinophytes. The total content of chlorophylls (a, b, c1 + c2) was about 20 times higher in spring. Moreover, in spring the concentrations of photosynthetic carotenoids (with dominant perdinin) were 2-4 times higher than those of the photoprotecting carotenoids (with dominant diadinoxanthin), whereas in the two autumns the situation was reversed: PPC concentrations (with dominant zeaxanthin and diadinoxanthin) exceeded those of PSC (with dominant fucoxanthin) by c. 3-10 times. Pigment markers have proved to be extremely useful biomarkers for elucidating the composition of phytoplankton populations in natural samples.