Preliminary study on <i>in situ</i> growth rate of dominant algae species in Pengxi River of the Three Gorges Reservoir

Abstract

本文提出了两种原位培养装置(培养笼、培养桶)并采用这两种装置在澎溪河高阳平湖断面进行原位培养实验,旨在研究澎溪河典型优势藻的原位生长速率.研究期间主要生境特征为营养物丰足、光热条件优越、生境条件相对稳定,适宜于藻类生长,为水华形成的敏感期;在此期间代表CR型生长策略的湖北小环藻和兼具C、R、S生长策略的卵形隐藻的原位生长速率总体呈逐渐下降趋势,代表CS型生长策略的水华鱼腥藻和空球藻的原位生长速率则先增加后又有所下降,代表S型生长策略的铜绿微囊藻的原位生长速率虽然前期都为负,但总体呈现逐渐增加的趋势;并测得培养笼和培养桶中各藻种的最大比生长速率分别为湖北小环藻0.31、0.21 d^-1;铜绿微囊藻0.09、0.03 d^-1;空球藻0.16、0.42 d^-1;水华鱼腥藻0.30、0.26 d^-1;卵形隐藻0.49、0.95 d^-1.本研究中,不同生长策略藻种生长速率的变化在一定程度上体现了不同生长策略藻种的生长趋势.另外,就装置性能实验及原位培养实验结果综合分析,认为两种原位培养装置均能够满足对天然水域藻类原位生长速率的测试要求,但装置的构造对藻类实际生长过程仍存在一定影响.;In situ growth rates of the typical dominant algae species in Pengxi River were investigated using two kinds of in situ incubation devices (incubation cage and incubation bucket) for field incubation experiment in Lake Gaoyang of Pengxi River. Adequate nutrients, superior solar-thermal and relatively stable hydrodynamic conditions are the main characteristic of the habitat during the study. The selected environment was suitable for the algal growth and the period chosen was sensitive for the occurrence of algal blooms. During this period, in situ growth rates of Cyllotella and Cryptomonas representing phytoplankton with CR and CRS growth strategies, respectively, were both gradually declined, and those of Anabaena and Eudorina which both represent the CS growth strategies increased firstly and then declined. The in situ growth rate of Microcystis which represents the S growth strategy was negative in early days, however, the general trend of growth rate was increased. The maximum specific growth rate of each species in the incubation cage and incubation bucket were Cyllotella hubeiana 0.31, 0.21 d^-1, Microcystis aeruginosa 0.09, 0.03 d^-1, Eudorina elegans 0.16, 0.42 d^-1, Anabaena flos-aquae 0.30, 0.26 d^-1, Cryptomonas ovata 0.49, 0.95 d^-1, respectively. In this study, changes in the algae growth rates of the different growth strategies to a certain extent reflected the different growth trend. In addition, comprehensive analysis of the results of the performance test and in situ incubation experiment suggested that both of the two devices were able to meet the testing requirements of in situ growth rate of algae in natural water. There were potential impacts of the incubation devices on the in situ growth of phytoplankton.