Genetic Diversity of Small Eukaryotes in Lakes Differing by Their Trophic Status

Abstract

Small eukaryotes, cells with a diameter of less than 5 m, are fundamental components of lacustrine planktonic systems. In this study, small-eukaryote diversity was determined by sequencing cloned 18S rRNA genes in three libraries from lakes of differing trophic status in the Massif Central, France: the oligotrophic Lake Godivelle, the oligomesotrophic Lake Pavin, and the eutrophic Lake Aydat. This analysis shows that the least diversified library was in the eutrophic lake (12 operational taxonomic units [OTUs]) and the most diversified was in the oligomesotrophic lake (26 OTUs). Certain groups were present in at least two ecosystems, while the others were specific to one lake on the sampling date. Cryptophyta, Chrysophyceae, and the strictly heterotrophic eukaryotes, Ciliophora and fungi, were identified in the three libraries. Among the small eukaryotes found only in two lakes, Choanoflagellida and environmental sequences (LKM11) were not detected in the eutrophic system whereas Cercozoa were confined to the oligomesotrophic and eutrophic lakes. Three OTUs, linked to the Perkinsozoa, were detected only in the Aydat library, where they represented 60% of the clones of the library. Chlorophyta and Haptophyta lineages were represented by a single clone and were present only in Godivelle and Pavin, respectively. Of the 127 clones studied, classical pigmented organisms (autotrophs and mixotrophs) represented only a low proportion regardless of the library's origin. This study shows that the small-eukaryote community composition may differ as a function of trophic status; certain lineages could be detected only in a single ecosystem.

Effect of pyrene on denitrification activity and abundance and composition of denitrifying community in an agricultural soil

“…However, the diversity indices for nirS gene in our study were lower than those in a flooded paddy field reported by Yoshida et al (2009). There are substantial evidences that the diversity and composition of soil bacterial communities can be influenced by a wide range of biotic and abiotic factors including vegetation, trophic status, salinity, soil pH and heavy metals (McArthur et al, 1988;Lefranc et al, 2005;Lozupone and Knight, 2007;Fierer and Jackson, 2006;Gans et al, 2005).…”

Composition and genetic diversity of picoeukaryotes in subtropical coastal waters as revealed by 454 pyrosequencing

“…In this study, both parametric rarefaction curves and nonparametric richness estimators revealed a higher diversity of picoeukaryotes in the oligomesotrophic MB than in the eutrophic TH (Table 3, Figure 2). This finding is in good agreement with that of Lefranc et al (2005) and provides further evidence on the classic unimodal diversity-productivity relationship.…”

“…Recent analysis of a global data set has revealed a similar pattern between marine phytoplankton diversity and phytoplankton biomass (Irigoien et al, 2004). Lefranc et al (2005) used the cloning and sequencing method to study the genetic diversity of small eukaryotes (o5 mm) in three lakes in France and reported a higher diversity in the oligomesotrophic lake than in the oligotrophic and eutrophic lakes. In this study, both parametric rarefaction curves and nonparametric richness estimators revealed a higher diversity of picoeukaryotes in the oligomesotrophic MB than in the eutrophic TH (Table 3, Figure 2).…”

The Environmental Clade LKM11 and Rozella Form the Deepest Branching Clade of Fungi

“…1). The LKM11 (AJ130849) sequence branched within this group, as well as other environmental sequences classified in other studies as related to it (Lefranc et al 2005;Luo et al 2005;Šlapeta et al 2005;Van Hannen et al 1999). Given the high statistical support in our phylogenetic analyses for the Rozella/LKM11 clade, we propose here to name this group ''Rozellida'', in reference to the genus Rozella.…”