Dynamics of the phytoplankton community in mesotrophic Lake Borówno

The phytoplankton in Lake Borówno has never been included in phycological studies. The objective of our research was qualitative and quantitative analysis with reference to physicochemical parameters. Qualitative and quantitative analysis of phytoplankton assemblages were performed in 2004 and 2009. A total of 117 taxa were identified in Lake Borówno: Cyanoprocaryota — 35, Cryptophyta — 2, Euglenophyta — 1, Pyrophyta — 3, Chrysophyceae — 4, Bacillariophyceae — 25, Chlorophyta — 47. The bottom of the shallow water was covered with meadows of Charophyceae, with the dominant species Chara vulgaris L.

Biomass of the phytoplankton varied from 1.23 mg dm−3 in April to 5.74 mg dm−3 in August 2009. Ceratium hirundinella (O.F.Müller) Bergh was the dominant taxon during the whole season, but during summer another co-dominant taxon, Microcystis aeruginosa (Kütz.)Kütz., occurred.

The quality parameters, phytoplankton biomass, chlorophyll-a concentration and TSI indicate the mesotrophic character of the lake. The blue-green algae blooms, which are the major problem for preserving the good conditions of water in lakes, were not observed either in 2004 or 2009.