K. DOCHIN and A. IVANOVA
Institute of Fisheries and Aquaculture, BG – 4003 Plovdiv, Bulgaria
DOCHIN, K. and A. IVANOVA, 2015. Study of phytoplankton diversity and hydrochemical regime of Bistrica Dam Lake. Bulg. J. Agric. Sci., Supplement 1, 21: 137–146
Taxonomic structure of phytoplankton community and dynamics of hydrochemical regime as determining factors of trophic conditions were studied in Bistrica Dam Lake. Seventy seven taxa in six divisions of planktonic algae were found: Cyanoprokaryota (8 species, 10.38%), Chlorophyta (34 species, 44.15%), Euglenophyta (6 species, 7.79%), Streptophyta (3 species, 2.59%), Pyrrhophyta (3 species, 3.88%), Ochrophyta (24 species) including class Synurophyceae (3 species, 3.89%) and class Bacillariophyceae (21 species, 27.27%). Dominant and sub-dominant species were identified and seasonal dynamic of phytoplankton community was established of Bistrica Dam Lake. Diatoms – Synedra acus Kützing, Aulacoseira granulata (Ehrenberg) Simonsen and Stephanodiscus hantzschii Grunow predominated in May Scenedesmus communis (Breb.) Hegewald, Scenedesmus acuminatus (Lagerheim) Chodat and Hyaloraphidium contortum Pascher and Korshikov were the majority in the summer-time populations, while diatoms – Asterionella formosa Hassall Stephanodiscus hantzschii Grunow and Synedra ulna (Nitzsch) Ehrenberg were the sub-dominant species. Stephanodiscus hantzschii Grunowand Aulacoseira granulata (Ehrenberg) species increased their numbers again in the autumn. The average phytoplankton biomass for the studied period (0.333 mg.l–1) determined the oligothrophic status of the Bistrica Dam Lake.