| The water samples were collected from ten typical sampling stations in River area from Dou yin River part to Mudanjiang River entrance in May, July, Serptember and November 2009. Stations represented a range of inorganic nitrogen and phosphorus, which was reflected in the spatial variability in phytoplankton biomass and community composition. Phytoplankton was studied of fixed quantity and fixed qualitative, and monitored the correlated water environmental factors. Besides, phytoplankton communities and biodiversity were examined with multivariate statistic analysis. The Pearson analysis and grey association analysis were used to detect the correlation between phytoplankton and environmental factors. The purpose of this paper was to provide a guideline of protection and abatement, and restoration of the ecosystem in the water source place of Mudanjiang.Total of 8 phyla 208 species were identified, among which, the majority are Bacillariophyta (97) and Chlorophyta (77), Cyanophyta (25). Followed by Xanthophyta (8), Euglenophyta (6), Cryptophyta (2), Dinophyta (2) and Chrysophyta (1). The total mean abundance and biomass were 174.84×105 ind./L and 38.98 mg/L. There was significant change in species number, abundance and biomass between season and sampling stations by ANOVA(p<0.01,p<0.05).There were different ranges in different diversity index, Shanno-Wiener index from 2.50 to 3.85, Margalef index from 2.21 to 4.46, Pielou' index from 0.43 to 0.83 in the whole year change respectively. Seasonal variation of Shannon-Wiener index was autumn> summer> spring> winter, Pielou index was autumn> summer> winter> spring, and Margalef index was summer> autumn> winter> spring. From the spatial distribution of Shanno-Wiener index, Margalef index and Pielou index, the NO.10 highest, NO.8 and NO.9 lowest.Based on Pearson analysis, the results showed that the phytoplankton abundance and biomass positively correlated with the changes of environmental factors (p<0.01, p<0.05).Except diaphaneity and pH were no correlation with the phytoplankton abundance and biomass. All environmental factors were positiveiy correlated with the phytoplankton.In spring, the phytoplankton abundance and biomass were positively correlated with water temperature, DO, COD, TN and TP (p<0.01, p<0.05). But in summer the phytoplankton abundance and biomass were negatively related with the changes of environmental factors, just DO and COD were positively correlation (p<0.01, p<0.05). In autumn and winter, TN and TP were significant related with the phytoplankton abundance and biomass (p<0.01, p<0.05).The result of grey relational analysis suggested that the chl-a content can be well reflected in the phytoplankton biomass and cell density, In spring, the biggest environment factor to the phytoplankton is the water temperature, next is TN;In summer,COD is the biggest envirment facrors,next is DO. In autumn and winter,TNand TP are all in top row.The nutritional status of Hailanghe River water quality was evaluated comprehensively of Hailanghe River's water quality by using trophic status indices. The evaluation result showed that significant differences between different seasons and stations. From the seasonal variation, spring has the highest level, in summer and autumn the water quality was much better,best in winter; from the spatial variation of different stations view, the branch river NO.8, NO.9 stations were at high eutrophication level, the lowest level of upstream NO.10 was at light eutrophication level, the others were at eutrophication level. TN and TP were the most corrected environmental factors,Thus, it is important to control the exogenous nutrient to maintain ecosystem healthiness of Hailang River.
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