Comparative analysis of freshwater phytoplankton communities in two lakes of Burabay National Park using morphological and molecular approaches

Dmitry V Malashenkov,Ivan A Vorobjev,Veronika Dashkova,Natasha S Barteneva,Kymbat Zhakupova

doi:10.1038/s41598-021-95223-z

Dmitry V Malashenkov, Ivan A Vorobjev + Show 3 more

Open Access

https://doi.org/10.1038/s41598-021-95223-z

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Abstract

We analyzed phytoplankton assemblages’ variations in oligo-mesotrophic Shchuchie and Burabay lakes using traditional morphological and next-generation sequencing (NGS) approaches. The total phytoplankton biodiversity and abundance estimated by both microscopy and NGS were significantly higher in Lake Burabay than in Lake Shchuchie. NGS of 16S and 18S rRNA amplicons adequately identify phytoplankton taxa only on the genera level, while species composition obtained by microscopic examination was significantly larger. The limitations of NGS analysis could be related to insufficient coverage of freshwater lakes phytoplankton by existing databases, short algal sequences available from current instrumentation, and high homology of chloroplast genes in eukaryotic cells. However, utilization of NGS, together with microscopy allowed us to perform a complete taxonomic characterization of phytoplankton lake communities including picocyanobacteria, often overlooked by traditional microscopy. We demonstrate the high potential of an integrated morphological and molecular approach in understanding the processes of organization in aquatic ecosystem assemblages.

Highlights

We analyzed phytoplankton assemblages’ variations in oligo-mesotrophic Shchuchie and Burabay lakes using traditional morphological and next-generation sequencing (NGS) approaches
Traditional approaches assessing phytoplankton diversity, distribution, and abundance of phytoplankton taxa, based on morphological characteristics obtained by light m icroscopy[21,22,23,24] have a number of limitations: (1) labor intensity that limits the size of the quantified sample to hundred(s) of cellular events and a relatively low number of samples to be processed; (2) accurate diagnostics of taxa and their abundances are hampered by undifferentiated morphologies, unidentified early-life algal stages and numerous cryptic species[25,26]; and (3) incomplete description of the changes in biodiversity based on a limited number of morphologically identified taxa
Morphological diversity of phytoplankton based on microscopy and FlowCam analysis

Summary

Introduction

We analyzed phytoplankton assemblages’ variations in oligo-mesotrophic Shchuchie and Burabay lakes using traditional morphological and next-generation sequencing (NGS) approaches. During the last two decades, cytometric methods (flow cytometry (FCM) and imaging flow cytometry (IFC)) have been recognized as a powerful tool to study seasonal and spatial trends of p hytoplankton[27,28] It is noteworthy, that conventional cytometry may not be allowed to isolate and characterize all plankton species and colonial forms identified by traditional microscopy due to size limitations of flow cells typically within a 150 μm limit[29]. Despite the fast development of high-throughput sequencing (HTS), it is not yet clear to what extent the results of a traditional light microscopy-based taxonomic approach can be consistent in comparison with the results of NGS analysis[42]. Comparative methodological studies are required to evaluate different algal taxa, such as diatoms and c yanobacteria[40,44,47,48,49,50,51]

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