Phytoplankton diversity of a natural karst lake combining morphological and molecular approaches

Phytoplankton are considered to be one of the most sensitive indicators of the lake ecological status. Nowadays, it is essential to recognize the prospects of the molecular approach (eDNA metabarcoding) in the phytoplankton community assessments and combine them with the exist-ing traditional microscopy-based morphological approach before its standardization. In this study, we aimed to characterize the phytoplankton community of a natural karstic lake by combining and comparing the morphological and molecular approach to check the applicability of eDNA metabarcoding as a biomonitoring tool. The comparability of both approaches in describing phytoplankton community is evident in the designation of centric diatoms, dinoflagellates and cryptophytes as descriptive taxa. Also, both approaches proved reliable in detecting functional groups (Lo, C, X2, X3) with similar ecological demands. Moreover, the results have shown that euphotic zone samples can be reliably exchanged by composite samples to provide an accurate characterization of phytoplankton community in the euphotic zone. We confirmed that eDNA metabarcoding is an applicable tool for biodiversity monitoring of a natural karst lake and should be used as a feasible supplement to traditional microscopy in the phytoplankton community assessments, with regards to drawbacks of each method.

浮游植物被视为湖泊生态状况最为敏感的指示生物之一。如今，充分认识分子检测方法（eDNA metabarcoding）在浮游植物群落评估中的应用前景，并在该方法实现标准化之前，将其与现有基于显微镜观测的传统形态学方法相结合，具有重要意义。本研究旨在通过结合并对比形态学与分子检测方法，对一处天然喀斯特湖泊的浮游植物群落进行表征，以验证eDNA metabarcoding作为生物监测工具的适用性。两种方法在描述浮游植物群落时的可比性，体现在将中心硅藻、甲藻与隐藻划定为特征分类群的结果中。此外，两种方法在检测具有相似生态需求的功能群（Lo、C、X2、X3）时均表现可靠。研究结果还表明，可通过混合样品替代真光层样品，以准确表征真光层内的浮游植物群落。我们证实，eDNA metabarcoding可作为天然喀斯特湖泊生物多样性监测的适用工具，且考虑到两种方法各自的局限性，其可作为传统显微镜观测方法在浮游植物群落评估中的可行补充手段。