Temporal And Spatial Succession Of Phytoplankton Taxonomic Functional Groups And Water Quality Evaluation In Jingpo Lake Basin

To understand the seasonal dynamics of phytoplankton community structure in Jingbo Lake basins, the survey was carried out in spring and autumn in 2013. The research set up three different sampling area: catchment area, lake area and drainage area, including 10 sampling sites. Phytoplankton samples were collected, at the same time, physical and chemical variables(water temperature, dissolved oxygen, transparency, p H, ammonia nitrogen, total nitrogen, total phosphorus, potassium permanganate index and chlorophyll a)were monitored. In order to provide astrategy for the water quality management of the local department,the characteristics ofphytoplankton community and its functional groups were analyzed. The water quality of Jingbo Lake basin was evaluated by the nutrition state index and biological index.A total of 81 phytoplankton species that belonged to 7 phyla were identified and the dominantphyla were Bacillariophyta and Chlorophyta. Bacillariophyta included 39 species(genus), accounting for 48% of the total number of phytoplankton, Chlorophyta 31 species(genus), accounting for 38% of the total number of species, other algae accounting for only 14% of the total number of species. The dominant species in Jingbo Lake basin during the survey period mainly belonged to Bacillariophyta and Chlorophyta species, such as Synedra spp., Nitzschia spp., Hornidium subtile and Ankistrodesmus falcatus etc. The seasonal pattern of phytoplankton abundance in Jingbo Lake basin was different. Phytoplankton abundance in spring was significantly higher than in autumn. From the perspective of the spatial variation of phytoplankton abundance, the lake areawas significantly higher than that of other areas.While in autumn, catchment area was higher than other areas.The Shannon-Wiener diversity index rangedfrom 0.855 to 3.259 in Jingbo Lake basin, with the highest values in S3 in autumn,and the lowest in S6 in autumn. Shannon Wiener diversity index in springwas higher than autumn. The Margalef index ranged from 0.681 to 2.993, with the highest values in autumn of S3, the lowest in spring of S9.No significant differences were observed in seasonal dynamics of Margalef species richness index. Pielou evenness index ranged from 0.285 ~ 0.948,with the highest values in spring of S9 and lowest in autumn of S6. Pielou evenness index in spring is higher than in autumn.Multidimensional scaling analysis showed that phytoplankton community composition was highly different between different areas. Phytoplankton community similarity in Spring(P < 0.05) and autumn(P < 0.05) in different regions were different, the similarity of phytoplankton community in different regions in spring was higher than autumn.The classification of phytoplankton functional groups were identified according to Padisák(2009). Seventeen phytoplankton functional groups were classed, and 9 and 5 main functional groups were identified in spring and autumn, respectively. The temporal and spatial pattern of phytoplankton functional groups were significant different in Jingbo Lake basin.The abundanceof phytoplanktonfunctional groups in spring was higher than autumn. From the perspective of the spatial variation of Jingbo Lake basin, the abundanceof phytoplankton functional groups was catchment area > lake area>drainage area.We used comprehensive nutrition state index, biodiversity index(Shannon Wiener index, Margalef index and Pielou evenness index) and phytoplankton functional groupsto evaluate the water quality in Jingbo Lake basin. The evaluation results of comprehensive nutrition state index and diversity index showed that thewater quality was in meso-trophic state, The seasonal pattern of water quality was spring > autumn, while the spatial pattern was catchment area >drainage area > lake area. Phytoplankton functional groups evaluation results showed that most of function groups are adaptive to eutrophic waterbody environment.Water quality evaluation result from all methods exhibit a high degree of consistency, reflecting an artificial interference and a trend of eutrophication in Jingbo Lake basin.RDA analysis of the relationship between phytoplankton and environment variablesin Jingbo Lake basin showed that environmental factors in different periods had different influence on phytoplankton community and functional groups.The main environmentalfactors affecting phytoplankton community structure was water temperature, p H and nutrients.The main physical and chemical environmental factors affecting phytoplankton functional groups were nutrients and water temperature.