Annual variation of phytoplankton communities and its driving environmental factors in a subtropical mussel-fish integrated pond in China

In this study, phytoplankton communities as well as environmental factors in a subtropical mussel-fish integrated pond in China were investigated during December 2012 to November 2013. Phytoplankton showed distinct seasonal density shifts in community structure at both taxonomic and functional levels. Cryptophyta was the dominant assemblage in low and moderate temperature, especially in January, April and May. Cryptophyta was gradually replaced by Cyanophyta with increase in temperature and formed cyanobacterial bloom in July. Chlorophyta became the most dominant group in the following six months with the second dominant assemblages of Cyanophyta, Cryptophyta and Bacillariophyta every two months in turn. Bacillariophyta was the dominant assemblage in March with low temperature and nutrients concentration. It appeared that water temperature and total nitrogen (TN) were the most critical factors driving phytoplankton community shift in terms of density and biomass, respectively.