Full Length Research Paper

Spatio-temporal variations of phytoplankton community composition assayed by morphological observation and photosynthetic pigment analyses in Lake Taihu (China)

Xiao Tan, Fan-xiang Kong*, Yang Yu and Min Zhang

State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China.

*Corresponding author. E-mail: kongfanxiang@gmail.com. Tel.: 86-25-86882191. Fax: 86-25-57714759.

Abbreviations: Chl a, Chlorophyll a; Chl b, chlorophyll b; PC, phycocyanin.

Accepted 25 September, 2009

   Abstract

Spatio-temporal variations of phytoplankton were assayed by morphological observation and photosynthetic pigment analyses at four sites in Lake Taihu from September 2007 to June 2008. Results showed that cyanobacteria abundance in water column decreased from autumn to winter but increased in the sediment; in spring, cyanobacteria abundance decreased in sediment but increased in water column. Since phycocyanin in the sediment fluctuated during the year with maxima in March and minima in September, vertical migration and recruitment of cyanobacteria were apparent. Algal abundance and composition changed in the water column. Chlorophytes dominated phytoplankton community initially and were replaced by cyanobacteria especially Microcystis spp., which underwent a colony-enlargement process and evolved from colonies with a few cells to those with dozens or hundreds of cells before blooming in late June.

Key words: Colony enlargement, cyanobacteria, Lake Taihu, morphological observation, Microcystis spp., photosynthetic pigment.