CHARACTERIZATION OF PHYTOPLANKTON COMMUNITIES IN REARING PONDS OF ONE SUMMER OLD FISH FROM BRATES LAKE

Magdalena Tenciu, Elena-Eugenia Mocanu, Veta Nistor, Marilena-Florentina Lăcătuş, Liliana-Blondina Athanasopoulos, Maria-Desimira Stroe, Viorica Savin, Al.-I. Angheluţă, N. Patriche

Abstract
   The objective of this paper was to analyze the composition of phytoplankton communities in summer growth ponds, in the Brateș Experimental Base between April and September 2018. Sampling of phytoplankton was performed monthly. For the study of phytoplankton, the water was collected in glass bottles with a volume of 300 ml, from the surface horizon of the water (0 m). After sampling the samples were preserved with Lugol's fixative and sodium acetate (Utermöhl), in the following proportion 0.15 - 0.25 ml solution per 100 ml / sample. At the same time with the phytoplankton samples, water samples were taken to analyze the physico-chemical parameters of the water from the analyzed ponds. The interpretation of the results was done in accordance with the provisions of the Normative regarding the classification of surface water quality in order to establish the ecological status of the water bodies (MMGA Ord. no. 161/2006) and correlated with the data from the specialized literature for the waters with fish use.
   Following the analysis of the composition of phytoplankton communities in the growth ponds in summer I, in the Brateș Experimental Base, we observe a seasonal dynamics both in number of species and in abundance. the stage in which the different groups of algae winter, the water temperature and the presence or absence of certain substances in the water winter.
   Phytoplankton is represented by: diatoms, chlorophylls, cyanophyses and euglenophyses. Chlorophylls predominate quantitatively and qualitatively and develop throughout the year which reveals a high trophic level of the lake, during the hot period of the year the cyanophysics develop, sometimes with "flowering" phenomena. Diatoms have a smaller development compared to other groups of algae, and euglins are poorly represented throughout the study.
   From a chemical point of view, the parameters analyzed in the water samples fall into the second class of surface water quality, according to Ord. 161/2006.

Key words: phytoplankton, pond, algal communities