The dynamics and importance of picoplankton in shallow, dystrophic lake in comparison with surface waters of two deep lakes with contrasting trophic status

The abundance, biovolume and seasonal patterns of autotrophicpicoplankton and larger phytoplankton were studied in 1993 intheshallow, dystrophic Lake Flosek and in the epilimnion of up to5 min two non-dystrophic, deep lakes: mesotrophic Lake Majcz andeutrophic Lake Mikołajskie. In all the three lakespicoplanktonexhibited well visible seasonal patterns. In non-dystrophiclakesspring/early summer abundance peaks were observed while inLakeFlosek two abundance peaks occurred: a smaller one in springandsecond, bigger, in autumn.It was noticed that maximal picoplankton abundances did notcoincided with abundance peaks of larger phytoplankton. Theshareof picoplankton in the total phytoplankton community in twolessproductive lakes (Flosek and Majcz) varied between 7 and 24%during picoplankton abundance peaks and about 5% during therestof the vegetation season. In Lake Mikołajskiepicoplankton's share was noticeable only during the abundance peak (13–6%)whileit was insignificant (about 1% of the total phytoplanktonbiovolume) during the rest of the season.