<i>In situ</i> research of relationship between cellular N/P of dominate algae species and limitation evaluation in Pengxi River of the Three Gorges Reservoir

Abstract

本文通过选取水华鱼腥藻（Anabaena flos-aquae）、铜绿微囊藻（Microcystis aeruginosa）、空球藻（Eudorina sp.）和湖北小环藻（Cyclotella hubeiana）为三峡库区流域中典型的优势藻，在澎溪河进行原位培养试验，跟踪监测了三峡水库不同运行时期4种典型优势藻细胞氮（Cell-N）、磷（Cell-P）浓度以及环境水体中的总氮（TN）、总磷（TP）浓度，并且结合团队之前的研究成果，根据临界（供应）N/P摩尔比、细胞N/P摩尔比和Guildford的TN/TP摩尔比评价标准对库区水体的营养限制状态进行了评价，为进一步揭示三峡水库运行下支流水域富营养化过程与生理特征的限制性评价提供研究基础.原位试验结果表明：3个评价标准下水体的营养（氮或磷）限制状态基本相同，低水位时期水体无机磷营养盐比较贫乏，在试验初期没有显著的营养盐限制而在末期受到了磷的相对限制；高水位试验初期和末期均未呈现显著的营养盐限制；泄水期营养盐变动频繁，试验初期表现为氮限制而末期表现为磷限制.虽然各藻种在不同时期会表现出不同的营养盐限制性，但总的来看，临界N/P比和细胞N/P比的阈值范围具有一定指示作用，能够从藻类细胞生理的角度对水体的营养状况作出初步评价.;This paper present in situ experiments in Pengxi River of the Three Gorges Reservoir by selecting Anabaena flos-aquae, Microcystis aeruginosa, Eudorina sp. and Cyclotella hubeiana as dominate algae species, monitoring nitrogen (Cell-N) and phosphorus (Cell-P) concentrations of these algae cells in three operating periods, and measuring total nitrogen (TN) together with total phosphorus (TP) concentrations in ambient water body. Combined with our previous findings, the state of nutrient limitation is evaluated via critical (supply) N/P ratio, cellular N/P ratio and Guildford's TN/TP ratio evaluating standard, providing research foundation of limitation evaluation for revealing the eutrophication processes as well as algae physiological characteristics of tributary waters in the Three Gorges Reservoir. The results of in situ research showed that these three evaluation standards presented the same state of nutrient (nitrogen or phosphorus) limitation. Specifically, in low water period, phosphorus was deficient, and no obvious nutrient limitation were presented at initial cultivation stage while phosphorus limitation was appeared at last cultivation stage. In high water period, both initial and last cultivation phase observed no obvious nutrient limitations. In discharge period the initial stage showed nitrogen limitation while the final stage appeared phosphorus limitation because of the frequent change of nutrient. Though each algae in different water periods presented various nutrient limitations, on the whole, the threshold range of critical N/P ratio and cellular N/P ratio have significantly and promisingly indicative effect, the nutrient state of water body can be preliminarily evaluated from the perspective of physiology of algae cells.