Inventory of the benthic eukaryotic diversity in the oldest European lake.

Benjamin Wilden,Walter Traunspurger,Stefan Geisen

doi:10.1002/ece3.7907

Benjamin Wilden, Walter Traunspurger + Show 1 more

Open Access

https://doi.org/10.1002/ece3.7907

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Abstract

We have profound knowledge on biodiversity on Earth including plants and animals. In the recent decade, we have also increased our understanding on microorganisms in different hosts and the environment. However, biodiversity is not equally well studied among different biodiversity groups and Earth's systems with eukaryotes in freshwater sediments being among the least known. In this study, we used high‐throughput sequencing of the 18S rRNA gene to investigate the entire diversity of benthic eukaryotes in three distinct habitats (littoral sediment and hard substrate, profundal sediment) of Lake Ohrid, the oldest European lake. Eukaryotic sequences were dominated by annelid and arthropod animals (54% of all eukaryotic reads) and protists (Ochrophyta and Ciliophora; together 40% of all reads). Eukaryotic diversity was 15% higher in the deep profundal than on either near‐surface hard substrates or littoral sediments. The three habitats differed in their taxonomic and functional community composition. Specifically, heterotrophic organisms accounted for 92% of the reads in the profundal, whereas phototrophs accounted for 43% on the littoral hard substrate. The profundal community was the most homogeneous, and its network was the most complex, suggesting its highest stability among the sampled habitats.

Highlights

While the biodiversity of higher plants and animals has long been appreciated (Larsen et al, 2017), the importance of the biodiversity of microorganisms in different hosts and in the environment has been recognized relatively recently (Thompson et al, 2017)
We used high- throughput sequencing of the 18S rRNA gene to investigate the entire diversity of benthic eukaryotes in three distinct habitats of Lake Ohrid, the oldest European lake
Eukaryotic diversity was 15% higher in the deep profundal than on either near-surface hard substrates or littoral sediments

Summary

| INTRODUCTION

While the biodiversity of higher plants and animals has long been appreciated (Larsen et al, 2017), the importance of the biodiversity of microorganisms in different hosts and in the environment has been recognized relatively recently (Thompson et al, 2017). Biodiversity is essential for ecosystem functioning (Loreau et al, 2001), but its decline due to anthropogenic impacts has made its documentation across the Earth's living systems all the more urgent (Johnson et al, 2017; Mihoub et al, 2017; Veresoglou et al, 2015) Those in freshwater habitats, their biodiversity has yet to be examined in detail (Cazzolla Gatti, 2016; Leray & Knowlton, 2016; Xiong et al, 2021). Within the littoral, hard substrates such as the surfaces of stones are highly exposed to environmental variations and covered by periphyton It mainly comprises algae and heterotrophic components, including bacteria, fungi, protists, and small metazoans, as well as dead organic material (Weitere et al, 2018; Wetzel, 2001). We hypothesized that profundal sediments host a stable community characterized by a higher network complexity, in contrast to littoral networks, which are subject to constant fluctuations and will be less connected

| METHODS

| Sampling procedure

Findings

| DISCUSSION