THE PHYTOPLANKTON OF A SMALL LOWLAND DAM LAKE PART OF THE NATURE 2000 USED FOR AQUA PRODUCTION

K. Dochin, A. Ivanova

Abstract: During the study of phytoplankton in the “Konush” dam lake 113 taxa of planktonic algae represented in 6 divisions have been identified: Cyanoprokaryota (17, 15.04%); Chlorophyta (47, 51.09%); Streptophyta (6, 5.3%); Euglenophyta (13, 11.5%); Pyrrhophyta (4, 3.53%) and division Ochrophyta (class Bacillariophyceae) (26, 23%). The most numerous are the species of the green algae (47) of the Division Chlorophyta, which are an integral part of the dominant complexes throughout the survey period. The identified seasonal variations in the quantitative development of the phytoplankton is probably mainly due to the introduction of organic matter, which is a consequence of the exploitation of the basin by aquaculture production and changes in the water regime of the researched dam lake. The average values of phytoplankton biomass (1.364 mg.l-1) determine “Konush” dam lake as mesotrophic to eutrophic. The results of our survey indicate that the “Konush” dam lake is at a process of eutrophication, the reasons for this being due to a number of factors, among which are the changes in water regimes, nutrient loads from aquaculture and last but not least of anthropogenic pressure.

Keywords: aquaculture; biomass; eutrophication; hydrological regime; phytoplankton

Date published: 2017-12-20