High diversity of protistan plankton communities in remote high mountain lakes in the European Alps and the Himalayan mountains

Abstract

We analyzed the genetic diversity (V4 region of the 18S rRNA) of planktonic microbial eukaryotes in four high mountain lakes including two remote biogeographic regions (the Himalayan mountains and the European Alps) and distinct habitat types (clear and glacier-fed turbid lakes). The recorded high genetic diversity in these lakes was far beyond of what is described from high mountain lake plankton. In total, we detected representatives from 66 families with the main taxon groups being Alveolata (55.0% OTUs97%, operational taxonomic units), Stramenopiles (34.0% OTUs97%), Cryptophyta (4.0% OTUs97%), Chloroplastida (3.6% OTUs97%) and Fungi (1.7% OTUs97%). Centrohelida, Choanomonada, Rhizaria, Katablepharidae and Telonema were represented by <1% OTUs97%. Himalayan lakes harbored a higher plankton diversity compared to the Alpine lakes (Shannon index). Community structures were significantly different between lake types and biogeographic regions (Fisher exact test, P < 0.01). Network analysis revealed that more families of the Chloroplastida (10 vs 5) and the Stramenopiles (14 vs 8) were found in the Himalayan lakes than in the Alpine lakes and none of the fungal families was shared between them. Biogeographic aspects as well as ecological factors such as water turbidity may structure the microbial eukaryote plankton communities in such remote lakes.

Geographic distance and mountain ranges structure freshwater protist communities on a European scalе

“…Keeping this in mind, the community composition corresponded to those known from other studies (e.g. Lange et al 2015, Kammerlander et al 2015, Filker et al 2016.…”

“…Considerable research effort has been focused on marine diversity (Countway et al 2005,Countway et al 2007, Campo et al 2016, Lovejoy et al 2006, López-García et al 2001, Massana and Pedrós-Alió 2008, Worden et al 2006. Despite the global importance of freshwater resources and the heterogeneity of freshwater systems, their biological diversity has been comparatively neglected (Filker et al 2016, Grossmann et al 2016a, Kammerlander et al 2015, Lepère et al 2007, Taib et al 2013, Triadó-Margarit and Casamayor 2012, Slapeta et al 2005. Our study revealed a high diversity of microbial freshwater eukaryotes and a high level of regional separation.…”

“…Most, if not all, microbial ecologists meanwhile agree that at least some single-celled organisms have limited distribution patterns (Filker et al 2016, Kammerlander et al 2015, van der Gast 2014, Wu et al 2009) and that on a larger scale, historical and geographic factors may also affect protist distribution and dispersal (Filker et al 2016, Izaguirre et al 2015. However, despite indications of large-scale variation between protist communities, geographical factors are considered to be of minor importance at short to intermediate distances (Beisner et al 2006, Filker et al 2016.…”

Novel Diversity of Deeply Branching Holomycota and Unicellular Holozoans Revealed by Metabarcoding in Middle Paraná River, Argentina

“…These clean reads were then clustered into Operational Taxonomic Units (OTUs) using UPARSE with a 97% similarity threshold, resulting in a total of 4,598 OTUs for V4 and 4,176 OTUs for V8-9 region. Even though there is no clear consensus on the optimal threshold to use in clustering algorithms Brown et al, 2015), we decided to use 97% because it has been widely used (Stoeck et al, 2010;Kammerlander et al, 2015;Massana et al, 2015;Giner et al, 2016;Kim et al, 2016). We are aware that this threshold might group species or even genus into the same OTU.…”

“…For example, mountain lakes have been shown to harbor an extensive diversity within large eukaryotic lineages and a high proportion of unclassified sequences (Triadó-Margarit and Casamayor, 2012;Kammerlander et al, 2015;Filker et al, 2016;Boenigk et al, 2018). This is remarkable given the extreme oligotrophic condition of some of these lakes.…”