南亚热带河流型水库浮游植物群落的季节变化：以广东飞来峡水库为例

Seasonal Variation in Phytoplankton Community in a Tropical Riverine Reservoir： A Case Study of Feilaixia Reservoir

摘要:

于2003年4—12月调查了广东省飞来峡水库的水文、营养盐分布状况和浮游植物种类与数量，分析了浮游植物群落的种类及数量组成与动态特征，探讨了其动态变化的驱动因子。结果表明，飞来峡水库是一个典型的河流型大型水库，水力滞留时间短，年均值低于15 d；降雨量主要集中于夏季，最短水力滞留时间只有8 d。水温全年没有分层现象。丰水期营养盐和叶绿素a高于枯水期。浮游植物生物量低，细胞密度在21.7×10³-808×10³cells L^-1之间变化，没有超过10⁶cells L^-1，叶绿素a的平均浓度为2 μgL^-1。浮游植物种类较多，4次采样共检到140种。种类组成上有较大变化，4月份有83种，以硅藻为主：7月和9月超过90种，以绿藻为主：12月有51种，蓝藻、绿藻和硅藻种类数量相当。优势种类的构成上与温带水库不同，硅藻仅在低水温时期为优势类群，而在丰水期则以蓝藻、绿藻和硅藻共同占优势。硅藻的主要优势种是变异直链藻（Melosira varians）、梅尼小环藻（Cyclotella menighiniana）和针杆藻（Synedra spp．）。绿藻种类组成季节变化较大，没有明显的优势种类。丰度相对较高的有美丽胶网藻（Dictyosphaerium pulchellum）、集星藻（Actinastrum hantzschii）和空球藻（Eudorina elegans）等。蓝藻的优势种以粘球藻（Gloeocapsa sp．）、优美平列藻（Merismopedia elegans）和伪鱼腥藻（Pseudoanabaena sp．）为主。与绿藻不同的是蓝藻的优势种在全年均可出现。隐藻只在水力滞留时间较长、温度较低的12月份占优势，主要优势种为啮蚀隐藻（Cryptomonas erosa）、尖尾蓝隐藻（Chroomonas acuta）。

Abstract:

Phytoplankton, water quality and hydrology in Feilaixia reservoir, Guangdong, were investigated to understand temporal pattern ofphytoplankton community. The reservoir, located in the southern tropic region, is a typical riverine reservoir with a short residence time, averaging 15 days a year. Total cell abundance of phytoplankton was measured to be less than 10⁶ cells L^-1, and the concentration of chlorophyll a varied between 1 and 5 μg L^-1. In total, 140 taxa were observed in all samplings in various seasons, in April 83 taxa, in July 92, in September 96 and in December 51. The variation in species composition of phytoplankton was mainly contributed by green algae and diatoms. In the dry season, diatoms were the important groups, which were mainly composed of Melosira variant, Cyclotella menighiniana and Syaedra spp.. Cryptophyta were the most important groups,dominated by Cryptomonas erosa and Chroomonas acuta, which appeared in relatively long residence time of water in reservoir （67 days） in December. Green algae, cyanophyta and diatoms were rich in flood season with high water temperature and high nutrient concentration. However, there was no significant differences in seasonal composition of green algae, in which no obvious dominant species were observed. Such green algae were Dictyosphaerium pulchellum. Actinastrum hantzschii and Scenedesmus bijuga. The cyanophyta were dominated by Gloeocapsa sp.. Merismopedia elegans and Pseudoanabaena sp..