The best of both worlds: A combined approach for analyzing microalgal diversity via metabarcoding and morphology-based methods.

Sophie Groendahl,Maria Kahlert,Patrick Fink,Hideyuki Doi

doi:10.1371/journal.pone.0172808

Abstract

An increasing number of studies use next generation sequencing (NGS) to analyze complex communities, but is the method sensitive enough when it comes to identification and quantification of species? We compared NGS with morphology-based identification methods in an analysis of microalgal (periphyton) communities. We conducted a mesocosm experiment in which we allowed two benthic grazer species to feed upon benthic biofilms, which resulted in altered periphyton communities. Morphology-based identification and 454 (Roche) pyrosequencing of the V4 region in the small ribosomal unit (18S) rDNA gene were used to investigate the community change caused by grazing. Both the NGS-based data and the morphology-based method detected a marked shift in the biofilm composition, though the two methods varied strongly in their abilities to detect and quantify specific taxa, and neither method was able to detect all species in the biofilms. For quantitative analysis, we therefore recommend using both metabarcoding and microscopic identification when assessing the community composition of eukaryotic microorganisms.

Highlights

During the last century biodiversity has declined due to anthropogenic influences [1]
We find great discrepancies between the methods; the next generation sequencing (NGS) approach provided us with valuable information regarding species richness, whereas the morphology-based method provided species abundance and biodiversity measurements
Considerable progress has recently been made in DNA metabarcoding, many challenges remain

Summary

Introduction

During the last century biodiversity has declined due to anthropogenic influences [1]. This results in reduced ecosystem stability, functioning and provision of ecosystem services [2,3,4]. As microalgae are the base of aquatic food webs [5, 6], a reduction in algal diversity may have great repercussions for higher trophic levels. Most studies on the diversity, distribution, and abundance of algae were based on morphological characteristics e.g.

Methods

Results

Conclusion