四川丘陵区水库浮游植物功能群季节演替特征及驱动因子

SEASONAL SUCCESSION OF PHYTOPLANKTON FUNCTIONAL GROUPS AND ITS DRIVING FACTORS IN RESERVOIRS IN HILLY REGIONS OF SICHUAN PROVINCE

为了解四川丘陵水库浮游植物群落结构、演替规律和影响因素,于2016—2017年分4个季节对该区域10个中小型水库的浮游植物功能类群演替与水环境变化关系进行了分析。研究期间10个水库共检出浮游植物9门104属188种,分属于24个功能群;在全年或各季节占优势的功能群,多为喜高营养或喜静水,耐低光、不耐冲刷和高光的类群,包括低光静水类群S1、S2、S_(N)和Y,高营养静水类群T_(C)、X1和X2,高营养低光类群J和C,及具有广适性的L_(O)。其中,全年优势度指数Y>0.02的功能群有6个,高低依次为S1>T_(C)>S_(N)>S2>L_(O)>J。单因素方差分析表明:不同季节优势功能群存在明显差异(P<0.05),其中夏季为S1+T_(C)+S_(N)+L_(O)+S2,秋季为S1+S2+J+S_(N)+X1+L_(O)+X2,冬季为S1+X2+C+X1+J+Y,春季为S1+S_(N)+H1+J+X1+X2。丝状蓝藻的种类组成(包括S1、S2、S_(N)、T_(C)和H1)在四季间有所更替,但其优势度并未改变;季节间水库分层的形成与打破,及水体光照强度、牧食强度和营养水平等因素的变化,导致了该地区水库浮游植物功能群之间的此消彼长。RDA分析显示,浮游植物功能群季节演替主要受水温(WT)、营养水平(包括总氮TN、总磷TP、氨氮NH4-N和硝态氮NO3-N)、高锰酸盐指数(CODMn)和透明度(SD)等环境因子的驱动。研究发现,优势功能群现存量均表现出随营养水平和水温的升高而增加的趋势,因此为防止丝状蓝藻在高营养水平与全球气候变暖的双重促进下发生暴发性增殖,需要对该地区水库水质进行有效管理与修复。

The community structure and succession of phytoplankton are strongly related to water quality and affects the structure,function and utilization of aquatic ecosystem,especially in reservoirs.Seasonal annual surveys on 10 typical reservoirs in hilly regions of Sichuan Province were conducted from 2016 to 2017,with the aim to expL_(O)re the annual changes,succession rules and influencing factors of phytoplankton community structure in this area.Phytoplankton functional classification and redundancy analysis were used.24 phytoplankton functional groups were identified in total,which are dominated by the 6 groups of S1,T_(C),S_(N),S2,L_(O)and J.Furthermore,the seasonal succession patterns for the dominant functional groups of phytoplankton in investigated reservoirs were identified as folL_(O)ws:S1+T_(C)+S_(N)+L_(O)+S2 in summer,S1+S2+J+S_(N)+X1+L_(O)+X2 in autumn,S1+X2+C+X1+J+Y in winter and S1+S_(N)+H1+J+X1+X2 in spring.The results showed that the phytoplankton is always dominated by filamentous cyanobacteria whose composition changed from season to season.The formation and breaking of reservoir stratification,changes of light intensity,grazing intensity and nutrient level in water in different seasons led to the fluctuation of phytoplankton functional groups.Redundancy analysis indicated that water temperature,total nitrogen,total phosphorus,ammonia nitrogen,Nitrate nitrogen,permanganate index and Secchi depth were the main environmental factors that influencing the functional groups.Although the filamentous cyanobacteria were seasonally different in terms of its dominant species,its abundance increased with the increase of nutrient level and water temperature.In order to ensure the safety of life and production in this area,it is recommended that the water quality of the reservoirs should be effectively managed and immediately repaired to prevent the expL_(O)sive proliferation of filamentous cyanobacteria under the dual promotion of high nutritional level and gL_(O)bal warming.