Study On The Temporal And Spatial Distribution Of Algae In Poyang Lake

Algal distribution characteristics is closely related with water bloom and research on distribution characteristics of the algae in Poyang lake has practical significance for the prevention and control of water bloom. In the study, field research and laboratory simulation are used to investigate the temporal and spatial of algae in Poyang Lake, as well as the analysis of bloom prone areas and high risk period. Hydrological conditions is the main factor influence on the the dominant algae distribution in Poyang lake, so with the method of laboratory simulation to observe the growth situation of typical water-bloom algae on different disturbance and study on the hydrodynamic effects on algal growth, in order to give the mechanism of the change of water environment that caused by river-lake relation changes effect on algae provide a basis. The results showed that:1. The research analysed the characteristic of spatial and temporal distribution of algae by the field monitoring and laboratory experiments during wet season.mid-dry and dry season and high risk of algae bloom in Poyang lake in order to reveal the effect of algae bloom risk by the change of river-lake relationship. The results showed that there were8phylum and101genera of algae were identified.,51genera of Chlorophyta accounted for50%of the total and16genera of Bacillariophyta accountde for16%of the total.Mainly in the Chlorophyta and Bacillariophyta dominated,followed by Cyanophyta. The major group of algae were Bacillariophyceae(28%),Cryptophyta(26%),Pyrrophyta (21%) and Chlorophyta(17%), especially to Bacillariophyceae on the population biomass. Cyanophyta had the highest density.The biomass from high to low were the south lake district, the central lake district and the channel lake outlet in the spatial distribution. The biomass from high to low were May, September and November in the temporal distribution. Temperature, suspended solids and transparency were the main factors affecting the temporal and spatial distribution of the algae.There were good hydrodynamic and low risk of algae bloom in a whole Poyang Lake, except the central and south region. October was the high risk period and the southern region was prone areas of algae bloom in Poyang lake. 2.The investigation was carried on to study the effects of disturbance on logarith mic growth period growth of Microcystis wesenbegii,Scenedesmus quadricauda and Nitzschia by means of indoor simulated experiment.The result showed that:when carbon sourcesufficient the disturbance had little influence on the growth of cyanobacteria and green algae at pH≤8.3,there is the positive effect on the0.1m/sbut not so significant,and had promote effect on diatoms in0.2m/s and0.5m/s. When carb on source insufficient,three kinds of algae growth rate were accelerated in0.5m/s at p H>8.3,it was indicated that the increasing of carbon source was one of the reasons the disturbance for algae growth,hydrodynamic factors have little effect on the growth of cyanobacteria reducing hydrodynamic a major cause of algal bloom.