Spatio-temporal variation in phytoplankton community and its influencing factors in Danjiangkou Reservoir

Abstract

为研究丹江口浮游植物的群落特征，探讨影响浮游植物时空分布的环境因子，于2014年5月-2015年4月对丹江口水库进行了为期1年的调查.此次调查共采集到浮游植物66种，隶属于7门21科38属.浮游植物全年平均生物量为0.35 mg/L，平均密度为9.08×10⁵ cells/L.优势种为脆杆藻、小环藻、直链藻和栅藻，其中脆杆藻所占比例最大，平均生物量为0.089 mg/L，占总生物量的25.43%.近些年丹江口水库营养水平的提高可能是脆杆藻生物量升高的主要原因.绿藻和蓝藻在夏季大量繁殖，硅藻为春、秋和冬季优势门类.汉江库区浮游植物生物量大于丹江库区，两个库区的浮游植物种类组成存在明显的差异，丹江库区优势门类为硅藻门，而汉江库区为绿藻门.浮游植物生物量与环境因子的相关分析表明，浮游植物生物量的主要影响因子是总磷浓度、pH值和溶解氧浓度.RDA分析表明，影响浮游植物组成的主要环境因子是溶解氧浓度、pH值、总磷浓度和水温.为控制浮游植物的生物量，防止其异常增殖造成水华，应严格控制外源营养盐特别是磷元素的输入.本研究可为丹江口水库的水质改善及富营养化防治提供一定的科学依据.;In order to explore the spatiotemporal variations in phytoplankton community and its influencing factors in Danjiangkou Reservoir, we conducted a one-year survey from May 2014 to April 2015. Sixty-six species, including 38 genera, 21 families and 7 phyla, were identified in the survey. The average biomass of phytoplankton is 0.35 mg/L, while the average density is 9.08×10⁵ cells/L. Dominant species are Fragilaria spp., Cyclotella spp., Melosira spp., and Scenedesmus spp.. Fragilaria spp. is the most dominant specie, and its average biomass is 0.089 mg/L, making up 25.43% of total biomass. In recent years, high level of nutrient may be the main cause of increasement in Fragilaria biomass in Danjiangkou Reservoir. Chlorophyta and cyanobacteria bloomed in summer, while diatom dominated in spring, autumn and winter. Total phytoplankton biomass in Han Reservoir is greater than that of Dan Reservoir. There were significant differences in phytoplankton composition between these two reservoirs. The dominant phylum of Dan Reservoir is Bacillariophyta, while the dominant phylum of Han Reservoir is Chlorophyta. There was significant correlation of the phytoplankton biomass with phosphorus, pH and dissolved oxygen, respectively. RDA analysis showed that the major environmental factors affecting phytoplankton community were dissolved oxygen, pH, phosphorus and temperature. For preventing the algae blooms, strict measures should be taken to control the input of exogenous nutrient especially phosphorus. This study provides scientific basis for water quality improvement and control of eutrophication at Danjiangkou Reservoir.