Studies on phytoplankton in the lakes of Netiesa range. – Botanica Lithuanica, 4(2): 169–186

Phytoplankton in the lakes of Netiesa range was investigated in July, 1996. Totally 196 algae species, 45 varieties and 11 forms were recorded. 11 species were identified up to the genus rank. Green algae (Chlorophyta) and diatoms (Bacillariophyta) dominated in the studied phytoplankton, respectively they comprised 44.4 % and 30.7 % of the recorded taxa. Other groups are presented in a decreasing order: Cyanophyta – 13.6 %, Euglenophyta – 4.94 %, Chrysophyta – 3.04 %, Pyrrophyta – 2.28 %, Xanthophyta – 0.76 %. The most frequent species (44 ), found in more than 50 % of all examined lakes, were as follows: Asterionella formosa Hassall, Ceratium hirundinella (O. F. Müller) Schrank, Cocconeis placentula Ehrenb., Dinobryon divergens Imhof, Epithemia turgida (Ehrenb.) Kützing, Fragilaria crotonensis Kitton, Gomphonemaacuminatum Ehrenb., Rhopalodia gibba (Ehrenb.) O. F. Müller, Synedra capitata Ehrenb. Most of all recorded algae species (155) were rare ones, which were found only in one lake. These species comprised 59 % of all recorded taxa (e.g., Surirella robustra Ehrenb., Cosmarium pseudoprotuberans Kirchner, Tetradesmusscenedesmoides (G. M. Smith) Chodat, etc). Gomphonema clevei Fricke was found for the first time in Lithuania.

Keywords: phytoplankton, species structure, distribution, abundance, level of trophy, lakes of the Netiesa range, Dz?kija National Park, Lithuania.