Abstract
Planktonic algal samples were collected from lakes with different salinity (Salt Lake Brăila, Amara Lake, Fundata Lake,
Techirghiol Lake and Black Lake-Sovata), in which mud used in balneary therapy is formed. A total of 189 species were
recorded: 35 Cyanobacteria, 10 Euglenophyceae, 96 Bacillariophyceae, 33 Chlorophyceae, 3 Chrysophyceae, 2 Cryptophyceae, 1
Xantophyceae and 9 Dinophyceae. The highest number of phytoplankton species was recorded in Techirghiol lake (127 species)
and the lowest number in Black Lake-Sovata and Salt Lake Brăila (23 species). The species diversity of microalgae was
compared in different pelogenous lakes. In the case of Cyanobacteria and Bacillariophyceae, the calculated values for the
Sorensen similarity coefficient reflect a weak association of species in the pelogenous lakes, while in the case of
Euglenophyceae, Chrysophyceae, Crysophyceae, Dinophyceae, Xanthophyceae classes, the comparison of the species diversity
was impossible because they were not found in all the studied biotopes. The composition of the Chlorophyceae class was similar
in the plankton of two clusters: cluster 1- Techirghiol lake and Black lake-Sovata; cluster 2- Salt lake- Brăila, Fundata lake. The
hypersaline lake Techirghiol was the most algologically productive habitat, here forming the mud with the highest content of
organic substance. Salt Lake Brăila and Black Lake-Sovata were the least algologically productive ecosystems; in both lakes mud
with mineral developed fraction and organic component in small percentage are formed, although they are biotopes with different
salinity, one being hypersaline, the other brackish.