Investigations of algal bloom in “Yerevanyan Lich” reservoir Biology

Abstract

During investigations carried out in “Yerevanyan Lich” reservoir from 2015 to 2016 water bloom with different groups of algae was registered. The change of dominant groups from dominance by diatoms to cyanobacteria was observed in the phytoplankton community of reservoir during the study period. High quantitative values of diatomic algae were the result of quantitative growth of Melosira varians, Fragilaria crotonensis and Stephanodiscus hantzschii species. High quantitative values of blue-green algae were the result of quantitative qrowth of Anabaena cylindrica and Oscillatoria limnetica species. The values of saprobic index in the reservoir in the study period fluctuated from 1.5 to 1.99. The saprobity in the reservoir was changed from α-oligosaprob to β-mezosaprob level. The highest value of the Shannon biodiversity index was recorded in May of 2015, and the lowest in September of 2016, which shows that there was quantitatively monodominancy of blue-green algae Oscilatoria limnetica, which is pressing diversity of algae in the reservoir.