Study on phytoplankton situation in Neor Lake after the arrival of the Carassius gibelio

 Phytoplankton groups have specific role in the water quality of Neor Lake for living of fishes in Ardabil province. So, in order to study water quality and fish stocks assessment of Neor Lake after entering Carassius gibelio, primary products of this lake at first should be evaluated.This investigation carried out in 5 stations and 8 months during 2014. Phytoplankton sampled by 1 liter Ruttner. After that the sample fixed by formalin and after homogenizing the sample in laboratory, 5 milliliters of it precipitated for 24hr in order to further evaluation and enumeration by invert microscope 400X. According to the results, 6 phyla and 68 genera have been identified, mainly. Totally, 24, 25, 11, 2, 4, & 2 genus identified that belong to phyla Bacillariophyta, Chlorophyta, Cyanophyta, Pyrrophyta, Euglenophyta and Chrysophyta, respectively. The results show that stations 1 (Dareh Khersi) and 5 (Robero Mobish) have the most and least density of phytoplankton with annual mean of 132300500 ± 31011000 and 118575560 ± 45165997, respectively, compared to other stations. Station 3 (Mameli Dash) has the least phytoplankton density, 76071333 ± 20606342.  Phyla Cyanophyta and Bacillariophyta specially genus Oscillatoria and Synedra were dominant in all stations. Commonly, in fall, the mean density of phytoplankton is more than other seasons and in winter it is at least. According to statistical analysis Kruskal Wallis, phytoplankton density show significant differences in different months and seasons of year (P<0.05). However, there is no significant differences among stations (P>0.05). Significant differences observed in density of phyla, too (P<0.05). Generally, Neor Lake is eutrophic from nutrient material and phytoplankton density point of view after entering Carassius gibelio. The Carassius gibelio stock as the only fish of this ecosystem were 12.91 tons in 2014.