Communities Of Phytoplankton And Periphytic Diatoms In Reservoirs With Short Water Retention Time:A Comparative Study Of Two Tropical Reservoirs

To understand seasonal variation of phytoplankton community and its relationship with environmental factors in reservoirs with short warter retention time,and the reasonality of biological monitoring by using periphytic diatom,phytoplankton or periphytic diatom were sampled monthly in A reservoir and B reservoir which have short warter rention time in 2016-2017.We analyse water quality,structure of phytoplankton community,structure of periphytic diatom community,structure of planktonic diatom community,and summarized the main conclusions as follows: 1.A total of 131 and 103 phytoplankton species were detected in the two reservoirs,the structure of phytoplankton community had an obvious seasonal variation,and less variation between sampling sites.The structure of phytoplankton community and diversity were most mainly affected by water temperature in both reservoirs.2.A reservoir is a through-flowing reservoir with water retention time of less than 15 days.The intensive inflow and rapid water flow contributed to the rather low standing abundance of phytoplankton.The seasonal shift of dominant phytoplankton species and their abundances well demonstrated the change in water environmental factors and water quality.3.A total of 138 periphytic diatom species of 36 generas,belonging to 10 families,and 31 planktonic diatom species were detected in A reservoir.Navicula minima and Nitzschia palea in Pennatae are the dominant species in of periphytic diatoms.Melosira granulate and Cyclotella in Centrica are the dominant species of planktonic diatoms.The spatial variation in the aboundance of the dominant periphytic diatom well presented the environmental change.The periphytic diatom species could indicate specific environmental variables.The community structure of planktonic diatoms had a lower correlation with the environmental factors than that with the periphytic diatom.4.Based on application to A reservoir,the Q evaluation index of phytoplankton is a better index for ecological evaluation of the through-flowing reservoirs.In genneral,combining the responses of phytoplankton community and the periphytic diatom community,we can comprehensively understand the change in the environmental conditions in through-flowing reservoirs.