汉江中下游硅藻群落时空分布及其影响因素研究

为研究汉江中下游水体和沉积物硅藻的时空分布特征及其影响因素, 于2014年春、秋两季对汉江中下游5个监测断面的硅藻群落进行监测。基于18S rRNA Illumina Miseq高通量测序技术的鉴定结果, 共得到硅藻3纲28目49科111属160种, 其中沉积物硅藻占98.6%。物种丰度显著多于已有研究的结果, 体现了高通量测序技术在硅藻物种鉴定上的优势。水体和沉积物硅藻群落组成和优势种有显著差异, 水体中硅藻优势种为Pinnularia, Cyclotella和Nitzschia, 沉积物中硅藻优势种为Pinnularia, Nitzschia和Navicula。汉江中下游硅藻群落多样性的时空差异明显, 硅藻多样性存在空间异质性, 且沉积物硅藻比水体硅藻多样性丰富; 在季节影响方面, 表现为秋季硅藻物种多样性比春季丰富。总氮、氨氮、硝态氮和总磷等环境因素对硅藻群落组成影响较大, 因此氮磷控制对避免汉江中下游硅藻水华发生具有重要意义。

Spatiotemporal Distribution and Its Influence Factors of Diatoms in the Middle and Lower Reaches of Hanjiang River

To study the temporal and spatial distribution and its influence factors of diatoms in the middle and lower reaches of Hanjiang River, diatom in water and sediment were sampled from 5 monitoring sites in Spring and Fall, 2014. Based on 18S rRNA Illumina Miseq high-throughput sequencing technology, 160 species belonging to 111 genuses, 49 families, 28 orders and 3 classes were identified, of which sediment diatom genuses accounted for 98.6%. The species abundance was higher than that of the previous studies, suggesting the significant advantage of high-throughput sequencing technology in diatom identification. The community composition and dominant species in water and sediment were remarkably different, i.e., Pinnularia, Cyclotella and Nitzschia were the dominant species in water, while the dominant species in sediment were Pinnularia, Nitzschia and Navicula. Meanwhile, there exists obvious difference in temporal and spatial distribution of diatom community, due to the fact that Shannon diversity index displayed apparent spatial heterogeneity and diatom species in sediment were higher than that in water; from the view of season changes, the Shannon diversity index in fall were higher than that in spring. Furthermore, total nitorgen, ammonia nitrogen, nitrate and total phosphorus displayed great impact on diatom community composition. As results, controlling nitrogen and phosphorus concentration in the middle and lower reaches of Hanjiang River will be of great importance to avoid diatom blooms.