Annual Dynamics Of Characteristics Of Community Structures Of Phytoplankton In The Jiuduansha Inshore Waters Of The Yangtze River Estuary

Jiuduansha Wetland National Nature Reserve is located in the mouth of theYangtze River, which is the largest piece of carbon sinks in shanghai.The total area ofthe wetland is420km2.It also plays an integral role in the conservation ofbiodiversity and maintenance of ecological balance.The great effect JiuduanshaWetland Nature Reserve makes is not limited to the mouth of the Yangtze River, butalso affect the entire Yangtze River Estuary. As typical estuarine ecosystems, theresearch of the characteristic of phytoplankton community of Jiuduansha wetland isimportant. But the research on the Jiuduansha inshore waters and accumulation arenot enough. The community structure of phytoplankton in9sites was investigatedfrom October2010to October2012. Statistical Program for Social Science (SPSS)was used for correlation between physicochemical parameters and cell abundance ofphytoplankton. Redundancy analysis (RDA) was applied to further explore thecorrelation between phytoplankton and environmental factors using CANOCO4.5.Through statistical analysis of large number of original data to analyze thephytoplankton community species composition and seasonal variation, cellabundance of temporal and spatial distribution of phytoplankton diversity dynamicchanges and phytoplankton diversity and environmental factors related.To providebasic information for the status quo of Jiuduansha wetland ecosystem andenvironmental monitoring, and as a useful supplement for environmentally safe of theYangtze Estuary and long-term dynamic monitoring and research.The main results as below:1. A total of137species and varieties of phytoplankton were found in theJiuduansha inshore waters, which belong to65genera of6phyla. Bacillariophytawere the most important component, the species was98, belonged to45genera,which accounted for71.53percent. Second in species number was Chlorophyta amounted16.79percent, the species number was23belong to11genera. Thephytoplankton types of changes with the seasons change in two years. Bacillariophytadoor the highest proportion in the spring. The maximum number of Chlorophytaoccurred in summer. Pyrrophyta、Cyanophyta、Euglenophyta and Chrysophyta hadlittle change in the type of season.2. According to its ecotype and habitat,the phytoplankton can be groupedinto freshwater、coastal and eurysalinity and oceanic species in the Jiuduanshainshore waters. Skeletonema costatum absolutely dominated in the Jiuduansha inshore waters, which cell abundance was (81.72±27.26)×10~4cell/L and(49.42±32.25)×10~4cell/L, accounting for95.27%and93.94%of the annual average cell abundance of total phytoplankton respectively in two years.3. The horizontal distribution of annual cell abundance of phytoplankton in theJiuduansha inshore waters was (85.78±28.31)×10~4cell/L and（52.61±20.07）×10~4cell/L.The characteristics of horizontal distribution of cell abundance ofphytoplankton were similar in two years.4. The seasonal variation of annual cell abundance of phytoplankton in theJiuduansha inshore waters was (73.07±22.71)×10~4cell/L an（d52.61±31.64）×10~4cell/L.It was higher in spring and summer, lower in autumn and winter in the year of2010-2011. It was higher in spring and autumn, lower in summer and winter in theyear of2010-2011.5. The horizontal distribution of annual phytoplankton diversity index in theJiuduansha inshore waters was (0.54±0.23) and (0.79±0.30). The horizontaldistribution of phytoplankton evenness in the Jiuduansha inshore waters was(0.14±0.05) and (0.2±0.07).6. The seasonal variation of annual phytoplankton diversity index in theJiuduansha inshore waters was (0.54±0.27) and (0.79±0.37). The seasonal variationof annual phytoplankton evenness in the Jiuduansha inshore waters was (0.14±0.07)and (0.2±0.09). The characteristics of seasonal variation of phytoplankton diversityindex and evenness in two years were similar. Overall higher in summer and winter,lower in spring and autumn.7. Water temperature、total nitrogen and suspended solids had great impact onthe phytoplankton community in the Jiuduansha inshore waters in the year of2011-2012. H′and J had a significant negative correlation with salinity in spring and summer. H′and J had a significant positive correlation with total nitrogen in spring.The number of phytoplankton species had a significant positive correlation withsalinity.