[Seasonal variation of chlorophyll a and its potential relationship with various algal species in Xiaojiang River backwater area, Three Gorges Reservoir].

The seasonal variation of Chlorophyll a (Chla) in Xiaojiang river backwater area from May 2007 to April 2008 with 115 water samples was studied. Three trophic states i.e. Chla < or = 5 microg x L(-1), 5 microg x L(-1) < Chla < or = 19 microg x L(-1) and Chla >19 microg x L(-1), were applied to represent the potential relationship of Chla, algal cell density (CellD) and biomass (BioM) in Xiaojiang river backwater area. The results showed that the algal cell density, biomass and Chla had significantly positive correlations (r > 0.70, Sig. < or = 0.01) and their seasonal variation processes are synchronous. The average values of Chla and biomass of chlorophyta, diatoms, cyanobacteria, dinoflagellate during the study period in Xiaojiang river backwater area were (9.58 +/- 10.77), (1605 +/- 647), (707 +/- 124), (511 +/- 266) and (4019 +/- 1345) microg x L(-1), respectively. When Chla < or = 5 microg x L(-1), chlorophyta, diatoms and Chla were significantly positively correlated; while under 5 microg x L(-1) < Chla < or = 19 microg x L(-1) level, only cyanophytes and Chla showed a significantly positive correlation; At Chla > 19 microg x L(-1) level, Chla was positively correlated to dinoflagellate, and there were no significant correlations among Chla and other algae.