Seasonal dynamics of algal biodiversity and water quality assessment of Jiangsu Shilianghe reservoir in China

Analysis of 4 sampling surveys on Jiangsu Shilianghe reservoir in May, July and October of 2011 and January of 2012, 109 species of algae belonging to 7 divisions were totally identified. The green algae and diatoms were the main species while Euglena and Cryptomonas were rare. The algal cell density in each season was compared as follows: summer (63.77 x 1000000 / L) > autumn (61.87 x 1000000 / L) > spring (43.31 x 1000000 / L) > winter (37.922 x 1000000 / L). Algae Shannon-Wiener index and Pielou indexes of each season were compared and described as follows: summer (2.71, 0.41) > winter (2.09, 0.32) > autumn (2.05, 0.31) > spring (1.85, 0.28). The Margalef indexes of each season were compared as follows: summer (1.51) > spring (1.38) > autumn (1.19) > winter (0.86). The water quality was assessed as alpha-medium pollution according to biological indicators. Sand mining, cages and obstruction between rivers and lakes may be the main reasons that lead to high algal cell density and low index of species diversity.