Study On The Characters Of Phytoplankton Community Structure And Its Indication For Aquatic Environment Of Suburb Rivers In Shanghai

The community structure of phytoplankton and physico-chemical factors ofqualitywere surveyed in7rivers located in7districts of Shanghai in4seasons in theperiod of May,2011, to February,2012. PCA and CCA method applied to analyze therelation between phytoplankton density and environmental factors. Sequent resultsshowed as follows.1.Qualitycharacteristics and Comprehensive evaluation of water qualityof7rivers:The water quality of seven rivershas seasonal changes,ranged from III toinferior class Ⅴ.In general,water quality is better in winter and spring than insummer and autumn.The large number discharge of industrial, sewage andagricultural waste water may be the evidence of obvious alkalinity in summer.Theconcentration of TN ranged from1.62to4.09mg/L, TP ranged from0.21to0.77mg/L, and NH4+-N changed in1.09to3.52mg/L in spring;in summer,theconcentration of TN ranged from1.59～8.44mg/L, TP ranged from0.24～0.87mg/L,and NH4+-N changed in0.79～6.56mg/L;When in fall, TN ranged from0.98to5.20mg/L, TP ranged from0.23to0.81mg/L, and NH4+-N changed in0.77to4.19mg/L;In winter, TN ranged from1.45to4.31mg/L, TP ranged from0.12to0.42mg/L, andNH4+-N changed in0.38to3.18mg/L.2.In phytoplankton survey,296taxa of phytoplankton belonging to8phylumwere identified, including36species of cyanophyta,127species of chlorophyta,83species of bacillariophyta,35species of euglenophyta,6species of xanthophyta,4species of pyrrophyta,3species of cryptophyta,2species of chrysophyte. Fourseasons(spring, summer, fall and winter) were respectively135、189、130and145species.Cyanophyta, chlorophyta and bacillariophyta took dominance of speciesnumber in each season, in the contrast pyrrophyta,cryptophyta and chrysophyteappeared occasionally, occurrence of euglenophytawasfrequent in winter. Speciesnumber and density of phytoplankton.3.The assessment result of three bio-diversity indexs (Shannon-weaver’s index, Magerf’s index, Pielou’s index) had great difference with quality evaluation,thismaybe that some other factors influenced phytoplankton community such as sewagedisposal, throttling and recovery of aquatic macrophytes. So many indexes should beconsidered to make comprehension water evaluation.4.Phytoplankton density increased in base of nutrient whose number anddistribution affected dynamic variationof algae community structure.Correlationanalysis between water quality and phytoplankton showed that: cyanobacteria celldensity had a significant positive correlated with T/P(p<0.05). In this paper,phytoplankton number had a closely connection with nutrients especially N,P content.Most blue and green algae had a negative correlated with TP.5.Althoughbio-diversity index were not appropriate for the water evaluation ofsuburban river, some pollution indicator species in phytoplankton can providetheoretical basis for development of suburban river ecological evaluationsystem.According to theresults,rhaphidioides,CryptomonaserosaandChroomonasacutaserveas indicator speciesinsummersuburban river rich nutritional (α-ms)water;Cyclotellamenighiniana,MelosiragranulateandOscillatoriaprincepsserveas indicatorspecies in summer suburban river rich nutritional (β-α-ms)water;lagerheim,pandorinamorum and scenedesmusquadricaudaserveas indicator species insummer suburban river rich nutritional (β-ms) water.