The Research On The Community Structure Of Phytoplankton In Huayang River-lake Group And Shengjin Lake

Huayang river-lake group and Shengjin Lake as a natural reserve what are Yangtze River-conncted lake.The phytoplankton community sructur and its impact fator resach is importance for biological diversity in natural reserve.In the present study,we examined species composition, the dominant species,density and the temporal and spatial distribution of the phytoplankton community to understand the phytoplankton community structure characteristics from 2014 in the Shengjin Lake and from 2015 in the Huayang river-lake group. Pearson correlations and Redundancy analysis (RDA) method were used to analyze the main environmental factors affecting phytoplankton community structure.1 A total of 183 species (with varietas and metatype) of phytoplankton be longing to 8 phyla and 84 genera were identified in the Huayang river-lake gr oup.Chlorophyta accounted for 45.60% of total number algae species,which had 83 species belonging to 34 genera.Bacillariophyta accounted for 23.63% of tota 1 number algae species,which had 30 species belonging to 14 genera.The phyt oplankton dominant species were Fragilaria capucina,Cyclotella meneghinian a.Asterionella Formosa, Melosira granulate, Melosira granulata var. angustissima, Gymnodinium aeruginosum.Oscillatoria chlorine,Merismopedia minima,Anabaena variabilis,Schroederia spiralis.Ankistrodesmus angustus,Pediastrum simplex,Crypto monas erosa.A total of 210 species of phytoplankton belonging to 8 phyla and 91 gene ra were identified in the shengjin Lake.Chlorophyta accounted for 41.20% of to tal number algae species,which had 89 species belonging to 36 genera.Bacillari ophyta accounted for 28.70% of total number algae species,which had 32 speci es belonging to 14 genera.The phytoplankton dominant species were Synedr a ulna,Melosira granulata var. angustissima,Cyclotella meneghiniana,Dinobryon bavaricum,Merismopedia minima,Chlamydomonas,Scenedesmus quadricauda,Chro omonas acuta,Cryptomonas ovate.2 The phytoplankton cells density of Huayang river-lake group was in the range of 0.33×105～1.06×108 cells/L.The yearly total cells density was 86.92×105cells/L.The highest density in the summer,Cyanophyta accounted for 96% of total density The phytoplankton cells biomass of Huayang river-lake group was in the range of 0.12～43.15 mg/L.The yearly total biomass is 1.26mg/L.Cyanophyta in the summer and Bacillariophyta in the spring and autumu and Bacillariophyta in the winter which was highest biomass.The yearly total biomass of Shengjin Lake was 10.72mg/L,As for seasonal change from high to low was summer,autumu,spring,winter. The yearly total densitys of Shengjin Lake was 140.61×105 cells/L,As for seasonal change from high to low was summer,spring,autumu,winter.The phytoplankton biomass and abundance showed a similar increasing trend.3 The Shannon Wiener diversity index varied from0.48～6.60 with an average of 2.92 in the Huayang river-lake group;Pielou evenness index varied from 0.10～1.19 with an average of 0.60 in the Huayang river-lake group;Margalef index varied from 1.92～5.43with an average of 3.29 in the Huayang river-lake group.The Shannon Wiener diversity index varied from 2.56-8.05 with an average of 5.21 in the shengjin Lake;Pielou evenness index varied from 0.40～1.78 with an average of 0.74 in the shengjin Lake; Margalef index varied from 1.77～9.99with an average of 3.89 in the shengjin Lake.The diversity indices of phytoplankton community in Shengjin Lake and Huayang river-lake group revealed obviously temporal and spatial variations.4 The yearly average temperature of Huayang river-lake group is 16.91 degrees, the variable span is from 8.90～23.60.For three lakes,The highest temperature in the huangdahu lake.The yearly average Dissolved Oxygen was 10.72mg/L.There was no difference on transprancy between differents sites, the highest transprancy centimetres in the huangdahu lake of autumu,the chlorophyll-a was higher in winter than in spring.For chemical indexes,The highest total nitrogen in the summerand the total phosphorus in autumn.The yearly average temperature of Shengjin Lake was 19.66 degrees,the variable span is from 10.60～34.00 degrees.The yearly average Dissolved Oxygen was 10.72mg/L.there is no difference on transprancy between differents sites, the average was 67.76cm centimetres,the chlorophyll-a was higher in summer and autumn than in winter and spring.For chemical indexes,The total nitrogen and total phosphorus and ammonia nitrogen have smaller change and the lowest in autumn.5 Pearson correlations revealed that:The phytoplankton biomass and abundance showed a similar increasing trend to environmental factor.total phytoplankton abundance and biomass showed a significant positive correlation with T,pH,ammonia nitrogen,TN,crustacean zooplankton (P<0.01); but a negative one with DO, turbidity, SW and NO2--N,TN (P<0.01).Redundancy analysis (RDA) and Pearson correlations in Shengjin Lake.It revealed that:total phytoplankton showed a significant positive correlation with DO,ammonia nitrogen T, SD.