SPETIAL DISTRIBUTION, ABUNDANCE AND HETEROGENETY OF THE POPULATIONS OF PICOPLANKTON CYANOBACTERIA SYNECHOCOCCUS SP. IN THE BLACK-SEA

We have revealed high abundance of the phycoerythrin-containing unicel lular picocyanobacteria Synechococcus spp. in the Black Sea in summer at the well stratified water. We showed varied picoplankton communitie s at the regions with different hydrological structer, Distinct subsur face maxima in cell concentration and nutrients have been observed at the base of the thermocline with irradiance level about 1% at the open -sea stations; the dominant forms ware coccoids with deameter 1.0-1.6 mkm and high intencivity of fluorescens which increas with depth and m aximum was in eufotic zone. Near-surface maxima of cyanobacteria have been founded at the shell stations at irradiance levels 50-100% and a wide variety of forms, We met not only coccoid, but rod-shap cyanobact eria with very deme flurorescens. Nontipical for oceans abundance of p hycocyanin-containing picocyanobacteria was observed at inshore area o f Northwest region. It is possible that variation between vertical pro files results from domination of genetically different populations wit h different pigment composition in these water masses.