The netz-phytoplankton assemblage structure of Qingcaosha Reservoir adjacent waters

Abstract:

Changjiang River estuary is the major economic offshore fishing water. Construction of Qingcaosha Reservoir may become unfavorable factors of juvenile growth and complementary resources in Changjiang Delta. This may eventually lead to the degradation of estuarine spawning grounds and abnormal biological community structure, and may restrict the sustainable use of fishery resources. Ecological characteristics of phytoplankton are important indicators of environmental quality assessment of fisheries. A multidisciplinary study on netz-phytoplankton assemblage structure was carried out in Qingcaosha Reservoir adjacent waters during February to November, 2012. This study identified 7 phyla, including 46 genera and 71 species, in which diatoms dominated, and Cyanophyta, Chlorophyta, Dinoflagellates, Chrysophyta, Cryptophyta and Euglenophyta were also found. Skeletonema spp. was prevailed cross-season in the whole investigation period. Temperate coastal species were the major ecotype, while fresh water species were occasional. Cell abundance decreased in turn from spring, summer, autumn to winter and the average value of spring and winter were 548.09 and 2.19 ind/ml, respectively. The major factor of daily migration was tidal impact, while the seasonal variation was affected by diluted water. Seasonal variation patterns in the survey area were discriminated by the cluster analysis of the phytoplankton assemblages. The change in seasonal runoff of the river and direction transformation of Changjiang diluted water was responsible for the variations. The canonical correspondence analysis (CCA) showed that the environmental factors drive the assemblage variation during all seasons.