E. Tryfon et al., PHYTOPLANKTON AND PHYSICAL-CHEMICAL FEATURES OF THE SHALLOW LAKE MIKRI-PRESPA, MACEDONIA, GREECE, Archiv fur Hydrobiologie, 131(4), 1994, pp. 477-494
The structure and dynamics of phytoplankton assemblages in the shallow
Lake Mikri Prespa were studied during the period from May 1990 to Sep
tember 1992. Biomass values varied between 1.2 and 38.0 g m-3 and reve
aled one autumnal and one vernal peak. Cyanophytes, the most important
algal group (mean annual contribution was 78.6% and 49.8% in 1990-199
1 and 1991-1992, respectively) remained dominant almost throughout the
year. Diatoms, the second abundant group (mean annual contribution wa
s 15.3% and 34.9% in the successive years, respectively) dominated in
winter and spring. All other classes contributed to a small degree to
the total biomass. The periodicity of the phytoplankton and the height
of annual peaks resembled those of many temperature eutrophic lakes b
ut the absence of a summer maximum was opposed to the PEG model statem
ent that eutrophic systems are characterized by increased summer bioma
ss. Temperature, dissolved inorganic nitrogen and dissolved silica app
eared to be the main of the studied factors controlling the developmen
t of cyanophytes and diatoms. Changes in weather conditions, especiall
y rainfall, seemed to have a strong impact on the species seasonality.