CHLOROPHYTES AND THEIR ECOLOGY IN 3 MACEDONIAN LAKES, GREECE

The ecology of planktic chlorophytes was studied in three productive l akes of Macedonia (L. Volvi, L. Mikri Prespa and L. Vegoritis), which differ significantly in morphometry, physical and chemical features. C hlorophytes constituted almost half of the phytoplankton species in th e lakes Volvi (50.8%) and Vegoritis (47.3%) and contributed considerab ly (38.9%) to the phytoplankton of L.M. Prespa. Although rarely domina nt, for they made up only a small part of the phytoplankton biomass (< 15%), they played an important role in the structure of the phytoplan kton communities encountered in these lakes. In L. Volvi, desmids were much more abundant than in the other two lakes, where coccal green al gae consisted the significant part of the chlorophyte biomass. Clear p atterns of seasonality emerged for several green algae in the warm mon omictic lakes Volvi and Vegoritis in contrast to the lack of periodici ty for many of the chlorophytes in the unstably stratified, shallow la ke M. Prespa.