Zhao Lina, Zhang Xue, Xu Mengyue, Mao Ying, Huang Yuan
College of Life Sciences, Shaanxi Normal University, Xian, Shaanxi, China.
PeerJ. 2021 Mar 19;9:e11057. doi: 10.7717/peerj.11057. eCollection 2021.
Zooplankton is an important component of aquatic organisms and has important biological and economical significance in freshwater ecosystems. However, traditional methods that rely on morphology to classify zooplankton require expert taxonomic skills. Moreover, traditional classification methods are time-consuming and labor-intensive, which is not practical for the design of conservation measures and ecological management tools based on zooplankton diversity assessment.
We used DNA metabarcoding technology with two different markers: the nuclear small subunit ribosomal RNA (18S rRNA) and mitochondrial cytochrome c oxidase (COI), to analyze 72 zooplankton samples collected in 4 seasons and 9 locations from the Sanmenxia Reservoir. We investigated seasonal changes in the zooplankton community and their relationship with water environmental factors.
A total of 190 species of zooplankton were found, belonging to 12 phyla, 24 classes, 61 orders, 111 families, and 174 genera. Protozoa, especially ciliates, were the most diverse taxa. Richness and relative abundance of zooplankton showed significant seasonal changes. Both alpha and beta diversity showed seasonal trends: the diversity in summer and autumn was higher than that in winter and spring. The zooplankton diversity was most similar in winter and spring. By correlating metabarcoding data and water environmental factors, we proved that water temperature, chemical oxygen demand, total nitrogen and ammoniacal nitrogen were the main environmental factors driving the seasonal changes in zooplankton in the Sanmenxia Reservoir. Water temperature, followed by total nitrogen, were the most influential factors. This study highlights the advantages and some limitations of zooplankton molecular biodiversity assessment using two molecular markers.
浮游动物是水生生物的重要组成部分，在淡水生态系统中具有重要的生物学和经济意义。然而，依靠形态学对浮游动物进行分类的传统方法需要专业的分类技能。此外，传统分类方法耗时费力，对于基于浮游动物多样性评估的保护措施设计和生态管理工具而言并不实用。
我们使用DNA宏条形码技术，采用两种不同的标记：核小亚基核糖体RNA（18S rRNA）和线粒体细胞色素c氧化酶（COI），对从三门峡水库4个季节和9个地点采集的72个浮游动物样本进行分析。我们研究了浮游动物群落的季节变化及其与水环境因子的关系。
共发现190种浮游动物，隶属于12个门、24个纲、61个目、111个科和174个属。原生动物，尤其是纤毛虫，是种类最多的类群。浮游动物的丰富度和相对丰度呈现出显著的季节变化。α多样性和β多样性均呈现出季节趋势：夏秋季节的多样性高于冬春季节。冬春季节浮游动物多样性最为相似。通过将宏条形码数据与水环境因子进行关联，我们证明水温、化学需氧量、总氮和氨氮是驱动三门峡水库浮游动物季节变化的主要环境因子。水温是最具影响力的因素，其次是总氮。本研究凸显了使用两种分子标记评估浮游动物分子生物多样性的优势和一些局限性。
