三峡水库大宁河春季水华藻类分布及影响因子

以三峡水库支流大宁河2010年3月中旬的水华调查数据为依据,分析浮游藻类分布规律,并探讨其影响因子。结果表明,在容易暴发水华的库湾开阔地带之外,狭窄的峡谷地带亦会暴发严重水华,并且持续时间更长;河口区域的浮游藻类则表现出比其他区域更好的群落稳定性和生物均匀性。在此次水华的前、中期,浮游藻类的群落稳定性随生物量增大而降低;后期则随其增大而增加。通过对样品的定量分析,共鉴定浮游藻类7门24属,主要为绿藻和甲藻,第一优势种为拟多甲藻,占到总藻类的38%,其次为小球藻和衣藻。观察到藻类群体有垂直迁移现象,可能因藻类有趋光性所致。拟多甲藻水华的暴发会降低水体氮磷比,而随着水华的消退,水体氮磷比会较迅速地恢复到一个较高水平。在水华前期,总磷与浮游藻类群落稳定性呈现高度负相关,在中、后期其相关性减弱。

Distribution of algae and its influencing factors in Daning River in Three Gorges Reservoir during period of spring algal bloom

Based on investigation data of the algal bloom in the Daning River, which is the tributary of the Three Gorges Reservoir, in the middle of March, 2010, the spatial and temporal distribution of algae and its influencing factors were studied. The results show that algal blooms not only occur in wide reservoir bays, but also in narrow valley belts, where there exist significant algal blooms that last longer periods of time. The planktonic algae in the estuary region show greater community stability and biological uniformity than other regions. With the increase of plankton biomass, the community stability of the planktonic algae decreased during the early and middle periods of the algal bloom and increased during the late period of the algal bloom. Through quantitative analysis of samples from the period of the algal bloom, the planktonic algae were classified as 24 genera of seven phyla, mainly including Chlorophyta and Pyrrophyta. The first dominant species were Peridiniopsis sp., accounting for 38% of the total algae, followed by C. vulgaris and Chlamydomonas. During the period of the algal bloom, the vertical migration of algae groups was observed, which might be due to the change of illumination and the phototaxis of algae. The algal bloom of Peridiniopsis sp. reduced the N/P ratio of the water body. With the retrogression of the algal bloom, the N/P ratio quickly recovered to a relatively high level. The total phosphorus and the community stability of planktonic algae had a highly negative correlation during the early period of the algal bloom, and this correlation weakened during the middle and late periods.