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This paper is about the structure of phytoplankton communities in the autumn of 2010 in Anxing Wetland,Heilongjiang Province,China.The abundance of phytoplankton communities,cell density and dominant species were analyzed.In total,146 taxa were identified from nine sampling sites.The 146 taxa included 6 divisions,8 classes,12 orders,25 families,45 genera,128 species,17 varieties and 1 form.Chlorophyta were dominant and accounted for 39.7% of the total phytoplankton,while Euglenophyta and Bacillariophyta accounted for 30.8% and 21.9%,respectively.The abundance of phytoplankton was 181.4×106 cells/L.Dominance analysis showed that there were more than three dominant species at each sampling site,including Trachelomonas granulosa Playf.,Cyclotella meneghiniana Kutz.and Trachelomonas granulosa var.crenulatocollis(Szab.)Hub.-Pest..Cluster and non-metric Multi Dimensional Scaling analysis showed that nine sampling sites were divided into five groups and the composition of phytoplankton communities were significant different spatially when the similarity of the phytoplankton community reached to 60%.That was related to different ecological characteristics of each site.Canonical Correspondence Analysis showed that dominant specie change was mainly influenced by temperature and pH.In addition,a large number of β-mesosaprobic zone indicators and lower diversity index were monitored in Anxing Wetland,suggesting that the water quality from the wetlands might have been polluted.

Monthly algae samples in Hulanhe Wetland,Heilongjiang Province,were collected from May to October,2009.A total of 158 taxa,belonging to 7 phyla,8 classes,14 orders,23 families,50 genera,148 species and 10 varieties,were identified.The abundance of algae ranged from 469.55×105-847.35×105cells/L.They were predominantly Bacillariophyta and Chlorophyta.The composition and biomass of the algae varied with the studying periods.Most of the algae were found in the site II.While the biomass in sites I and V was greater than that of other sites.Results showed that most taxa were common species and several indicator species for eutrophication and pollution were also found.According to the assessments using saprobic indicator,Shannon-Wiener diversity index and Pielou evenness index,the water in Hulanhe Wetland was of different degrees of pollution.

The algal community was studied in Heihe channel in Heilongjiang River during May to October of 2006-2007, according to the taxon and relations between algal assemblage structures and environmental variables based on data from six monitor stations, and was analyzed by use of Canonical correspondence analysis. It revealed that biology oxygen demand, total phosphorus, water temperature and chemical oxygen demand from 7 water environmental variables are significant fractions of the distribution and variation of algal community. CCA result indicates that, the algal community and space distribution are correlated with environmental variables, the variety of the algal community may become a useful monitor for river environments.

The species of Epithemia ocellata (Ehr.) Kutz. from Northeastern China were observed by scanning electron microscopy (SEM). The studies on silica valve formation in different stages were made. At the early stage, a Y-shaped raphe sternum was found. Areolae were made from virgae and vimines. In immature valves, the canal formation before the raphe fissure is visible. The raphe system, virgae and vimines (areolae) might be the early siliceous elements of the valve during morphogenesis. The formations of virgae and vimines are similar to that of Gephyria media W. Arnott. Rows of silica papillae formed gradually on the face of the valve. After the areolae were covered with silica and form rows of papillae, the outer valve surface could become mature. Details of the internal costae were observed in mature valves.

The authors discribed a new polystigmate combination,Gomphonema turris Ehr. var.okamurae (Skv.) Fan et Bao. comb. nov., and two new varieties,Gomphonema turris Ehr. var.latum Fan et Wang. var. nov. andGomphonema acuminatum var.obtusum Fan et Bao, var. nov., that were distinguished by frustule morphology under LM. The samples were collected from freshwater of Heilongjiang Province, China.