Diversity of phytoplankton of the Rivers Ciulucul Mare, Ciulucul de Mijloc, and Ciulucul Mic in the sub-basin of the Răut river

The article presents the results of investigations on the taxonomic composition of phytoplankton in the rivers Ciulucul Mare, Ciulucul de Mijloc and Ciulucul Mic from the River Răut sub-basin. The phytoplankton composition was represented by a total of 80 species and varieties of planktonic algae belonging to 6 taxonomic groups: Cyanophyta (Cyanobacteria), Bacillariophyta, Heterokontophyta, Dinoflagellata, Euglenophyta, and Chlorophyta. The richest diversity of phytoplankton was attested in the River Ciulucul Mare (55 species). The values of saprobic indices, estimated on the basis of indicator species (48 species from the total number of 80), of which 56\% are typically beta-mesosaprobic, confirm the following: the water quality was satisfactory for the development of phytoplankton and was mainly assigned to quality classes II-III (good-moderately polluted).