Dynamics of Phytoplankton Community in Relation to Environmental Factors in a Tropical Pumped-Water Storage Reservoir

Abstract

Phytoplankton and environmental variables were measured every 2 months in 2005 in Dajingshan, a subtropical pumped-water reservoir in South China. Phytoplankton community structure and its relationship with environmental factors including hydrological and chemical variables were explored by multivariate analysis. In total, over 100 species of algae were identified. Total abundance ranged from 0.85 × 10⁶ to 106.27 × 10⁶ cells/L, and total biomass from 1.0 to 16.8 mg/L (mean 6.94 mg/L). The community was dominated by Pseudanabaena limnetica, but in spring, Synedra ulna and P. limnetica were co-dominant. The community was relatively stable, but change rates of community structure in autumn and summer were higher than in winter and spring. Ordination by canonical correspondence analysis (CCA) divided all samples into four groups, distributed in the four districts formed by axes 1 and 2, corresponding to the four seasons: winter, spring, summer and autumn. Most samples were located in the summer and autumn districts. Fifty-four main species of phytoplankton were selected for CCA. Cyanophyta (Cyanobacteria), Bacillariophyta and Euglenophyta were restricted to the districts at the left of axis 1, but most Chlorophyta, Chrysophyta and Cryptophyta were to the right. CCA revealed that temperature and precipitation were important in driving dynamics of species composition and phytoplankton abundance.