澜沧江真核浮游生物的空间格局及其多样性

Spatial Distribution of Eukaryotic Plankton in the Lancang River Basin and Its Diversity

目前关于澜沧江浮游生物的研究多局限于浮游植物,缺乏从整个真核生物群落的角度进行探讨的研究。为填补相关方面的研究空白,于2020年10月在澜沧江近2 000 km的区域布设了36个样点进行样品采集,基于18S rRNA宏条形码技术探究了真核浮游生物群落的空间分布差异及其对环境因子的响应。测序共得到1 269个OTU,涵盖了45门284属,测序深度足够反映物种多样性。NMDS和ANOSIM分析显示澜沧江真核浮游生物群落依据地理空间分布可划分为3个分组:上游的自然河道段、中游的乌弄龙电站和功果桥电站之间区域、下游的功果桥电站以下区域。根据多样性及群落组成数据发现:属于自然河道段的上游群落组成最为均匀,金藻门和硅藻门广泛分布于该区域;属于水库段的中游和下游多样性类似且均低于上游,隐藻门广泛分布于该区域。影响澜沧江真核浮游生物群落结构变化的环境因子主要为水温和碱度。上、中、下游的环境驱动因子有所不同,电导率是影响上游真核浮游生物群落结构的关键环境因子,水温是影响中游的关键环境因子,而下游则主要受总磷的影响。

Current research on plankton in the Lancang River is mostly limited to phytoplankton;discussion from the perspective of the whole eukaryotic community is in lack.To fill the blank in the research area, the eukaryotic plankton diversity and its response to environmental factors were explored by using 18S rRNA metabarcoding technology based on water samples collected from 36 locations covering an area of nearly 2 000 kilometers of Lancang River in October 2020.Overall, 1 269 OTUs were obtained from the samples;the eukaryotic plankton species detected in these samples cover 45 phyla and 284 genera, reflecting the majority of the diversity.Based on NMDS and ANOSIM analysis, the eukaryotic community can be divided into three spatial groups: the natural channel in the upstream area, the midstream area between Wunonglong hydropower station and Gongguoqiao hydropower station, and the downstream area of Gongguoqiao hydropower station.According to the diversity and community composition data, the upstream area sees the most evenly distributed eukaryotic community, with Chrysophyte and Bacillariophyta broadly distributed;the midstream and the downstream features similar diversity, both lower than that in the upstream, with Cryptophyta most broadly distributed.Water temperature and alkalinity are dominant environmental factors that affect the structural change of eukaryotic plankton community in the Lancang River.Driving factors vary among the upstream, midstream, and downstream: electrical conductivity is the key environmental factor affecting the community structure of eukaryotic plankton in the upstream area, while water temperature in the midstream, and total phosphorus concentration in the downstream.