Molecular and microscopic diversity of planktonic eukaryotes in the oligotrophic Lake Stechlin (Germany)

Abstract

The aim of this study was to compare a molecular and a microscopic approach to study the planktonic eukaryotic diversity of an oligotrophic lake. Plankton samples from the temperate Lake Stechlin were assessed in winter and summer 2008 by comparison of 18S rRNA gene clone libraries to light microscopic evaluations. For both approaches identical samples were used. There were remarkable differences between the main groups recovered by the contrasting methods. The microscopic analyses showed predominance of autotrophic planktonic organisms, whereas most of them could not be discovered by the molecular method which resulted in a higher diversity of heterotrophic flagellates. The microscopic survey revealed high diversity of Chlorophyta and Cryptophyta as well as the Stramenopiles groups of Bacillariophyceae and Chrysophyceae. The clone libraries, based on full-length 18S rRNA gene sequences, displayed highest diversity of Alveolata belonging to seven different subclades. Notably, Antarctic Dinophyta-related clones were detected. The occurrence of the marine phagotrophic flagellate Telonema was also documented. Comparing the two sampling seasons, rich diversity suggests that flagellates played an important role in late winter (February), however, there is relatively low diversity in summer (August). The newly discovered molecular diversity of planktonic eukaryotes in Stechlin will help to understand the biodiversity patterns in freshwater lakes.

High habitat-specificity in fungal communities in oligo-mesotrophic, temperate Lake Stechlin (North-East Germany)

“…The proportion of fungal sequences in all samples classified as FPOM was significantly lower (Figure 3). Previous results from Lake Stechlin also reported a low proportion of fungi in water samples (Luo et al 2011), which may be related to the fact that we did not enrich for fungi by prefiltration or by primer selection. Lefèvre et al (2012) provided a summary of fungal and chytrid percentages ranging from 1-50% in water samples, relating these observations to prefiltration and primer pair used.…”

“…Lake Stechlin is part of the global lake ecological observatory network (GLEON) and has been monitored since 1959 (Casper 1985). Of the many publications from Lake Stechlin, few have examined the fungi (Casper 1965;Luo et al 2011;Wurzbacher et al 2014). This study thus represents the first attempt to characterize Lake Stechlin's mycobiota.…”

Temporal variation of the small eukaryotic community in two freshwater lakes: emphasis on zoosporic fungi

“…With the exception of 1 study (Richards et al 2005), zoosporic fungi have been systematically detected in lakes (Lefranc et al 2005, Lefèvre et al 2007, Lepère et al 2008, Genitsaris et al 2009, Luo et al 2011, Monchy et al 2011. Because some previous studies comparing aquatic systems differing in their trophic status found that zoosporic fungal diversity was higher in oligotrophic waters (Lefranc et al 2005, Chen et al 2008, Monchy et al 2011, the oligotrophic LT was expected to harbor a higher zoosporic fungal diversity than the mesoeutrophic LL.…”

“…Photos: MJ Powell, PM Letcher, E Lefèvre where fungi in general have rarely been factored in as a component of the microbial food web (Wetzel 2001, Sigee 2005, a high diversity of zoosporic fungal sequences has been unexpectedly recovered in recent studies (Lefranc et al 2005, Slapeta et al 2005, Lefèvre et al 2007, Lepère et al 2008, Chen et al 2008, Luo et al 2011, Monchy et al 2011). …”

“…Previous similar studies used the SSU gene (Lefranc et al 2005, Richards et al 2005, Slapeta et al 2005, Lefèvre et al 2007, Chen et al 2008, Lepère et al 2008, Genitsaris et al 2009, Luo et al 2011, Monchy et al 2011. Nevertheless, some of the general results obtained in our study are in accordance with the findings of previous studies: (1) the most represented taxa in our genetic libraries were fungi, alveolates, stramenopiles and cryptophytes, (2) heterotrophs were phylogenetically the most diverse among the small eukaryotic community, (3) Cryptophyta was the most diverse taxon among the small phototrophic eukaryotes, and (4) only few taxa were found in common in the 2 lakes studied.…”