| At present,there are many researches on water environmental factors and phytoplankton functional groups,but there are few researches on phytoplankton functional groups,especially on zooplankton functional groups.Therefore,this paper aims to study the effects of water environmental factors and zooplankton functional groups on phytoplankton functional groups.Therefore,this paper investigates phytoplankton,zooplankton and water environmental factors in spring(May),summer(July)and autumn(September)in 2022,and studies the species composition,biomass and functional groups of phytoplankton and zooplankton.The characteristics of dominant functional groups of phytoplankton and zooplankton in each season were studied,and the relationship between phytoplankton functional groups,water environmental factors and zooplankton functional groups was analyzed,and the influence on phytoplankton functional groups in Xiaobei Lake was analyzed,especially the influence on the growth and functional groups of cyanobacteria was analyzed,so as to provide theoretical basis for further control of eutrophication in Xiaobei Lake.Based on the monitoring results and RDA analysis,a total of 96 species(including varieties)of7 phyla were identified in Xiaobei Lake waters through the survey results of 3 seasons,including 37 species of chlorophyta,30 species of diatoms,and 13 species of cyanophyta,with the remaining phyla occupying a small proportion.In addition,the survey found that the seasonal abundance and biomass were also dominated by these three categories,and seasonal succession occurred.A total of22 common species were identified in 6 phyla in 3 seasons,including Anabaena variabilis,a nitrogen-fixing fish in the phyla cyanobacteria.Melosira granulata,Synedra acus,Cyclotella meneghiniana from the diatomata,Chlamydomonas globosa,Ankistrodesmus angustus and Dictyosphaerium pulchellum were common species in each season.A total of 13 dominant phytoplankton species were identified in 4 phyla,among which Anabaena variabilis in cyanophyta and Cyclotella meneghiniana in Diophyta were dominant species in all seasons during the survey period.Anabaena variabilis(Anabaena variabilis)occupied the highest position with a dominance of0.77 in summer.According to the classification basis of functional group theory proposed by Reynolds and Padisak,these 96 species of phytoplankton were divided into 22 different functional groups of phytoplankton.According to the biomass occupation of any of the functional groups,when the seasonal total biomass accounted for more than 10%,the dominant functional groups were determined,and a total of 3 dominant functional groups were obtained,namely H1,P and X2.The functional groups of phytoplankton in Xiaobei Lake changed significantly with the succession of seasons.In spring(May),summer(July)and autumn(September),the dominant functional groups of phytoplankton showed a trend of P+H1→H1+X2→P+X2+H1.In summer(July),the dominant functional group P was gradually replaced by functional group H1,and the biomass ratio was as high as 66.01%.Phytoplankton functional groups,in addition to zooplankton functional groups RF,PF and RC,are mainly affected by water environmental factors.In addition to the upstream effect of water environmental factors,they are also affected by the downward effect of zooplankton functional groups.The multivariate statistical analysis of RDA shows that: In addition to RF,PF and RC zooplankton functional groups,water environmental factors BOD5,TP,TN,CODMn,SD,p H and WT were the main environmental factors affecting phytoplankton functional groups.The main functional group of rapid growth of cyanobacteria HI was positively correlated with the functional groups of RF,PF,PC and other zooplankton.There was a significant negative correlation with LCF,SCF and other zooplankton functional groups.The zooplankton functional groups mainly affect the small zooplankton functional groups RF,PF and RC,while the large zooplankton functional groups do not affect the phytoplankton functional groups,so comprehensive analysis is needed.Meanwhile,the influence relationship of H1 functional groups should be emphasized to analyze the reasons for the rapid growth of cyanobacteria in Xiaobei Lake.The biomass of phytoplankton,Shannon-Wiener diversity index and water environment factors were used to evaluate the water quality of Xiaobei Lake.The three sampling points of Daliushu River(13#～15#),which entered the lake,were all in poor trophic state in each season,and the water quality was good.The water quality of Xiaobei Lake is good in spring,except 3#,5# and 7# are poor nutrition,the rest are medium nutrition.The water quality decreased significantly in summer and autumn,especially in the upper reaches of the lake(1#～5#).In autumn,the water eutrophication in the middle reaches(5#～10#)is more serious... |
