Seasonal variation of microbial eukaryotic community composition in the large, shallow, subtropical Taihu Lake, China

Abstract

Microbial eukaryotic community (0.8-20 lm) composition and its seasonal variation were investigated in large, shallow, subtropical Lake Taihu located in Southeast China. The water samples were collected monthly from August 2006 to July 2007 at two sites distantly located in Meiliang Bay and Lake Center, which differed strongly in their trophic status and sediment resuspension. The microbial eukaryotic community compositions (MECC) were measured using denaturing gradient gel electrophoresis (DGGE) of PCR-amplified eukaryotic 18S rRNA gene fragments. Seasonal variations were related to environmental factors by means of redundancy analysis (RDA) in order to reveal the most important regulating factors. At both sites, the structures and Shannon-Wiener indices of the microbial eukaryotic communities displayed apparent seasonal variations, which were significantly related to environmental variables. There were significant intrahabitat differences in environmental factors regulating MECC, as well as in the seasonal dynamics of the two sites during the study period. At Meiliang Bay, the variations of total phosphorus concentration and cladocera abundance had the most profound impacts on the microbial eukaryotic community composition, while at Lake Center, the total nitrogen concentration and conductivity were most influential. Our results suggest that the DGGE method is a cost-effective way to analyze the seasonal dynamics of MECC and their interaction with environmental variables, which will provide new insights into the diversity and dynamics of MECC.

Vertical structure of small eukaryotes in three lakes that differ by their trophic status: a quantitative approach

“…Our results suggesting a structuring impact linked to trophic level and depth are consistent with the recent conclusions reported by Chen et al (2009). It appears here a specificity of small eukaryote structure in the eutrophic lake and in the deepest zones close to the sediments.…”

“…However, using FISH (CHLO02 probe), Mangot et al (2009) showed during a 1-year study that Chlorophyta were well represented, accounting for 17.9% of small eukaryotes in Lake Bourget. Similarly, Chen et al (2009) observed, by morphological observations, that some pigmented taxa, such as Tetraedron sp., were abundant in the Meiliang Bay, but were not detected by molecular analysis. All these data suggest that 18S rRNA gene-based studies may underestimate pigmented cells in samples, and because of their limitations, molecular approaches based on PCR may not reflect the real diversity.…”

“…Vertical structure of small eukaryotes C Lepère et al Chlorophyta and Haptophyta sequences were always present at a very low proportion in clone libraries (Richards et al, 2005;Chen et al, 2009;Lefèvre et al, 2008;Lepère et al, 2008). In Lake Bourget, only one Haptophyta and five Chlorophyta sequences were retrieved in libraries constituted from epilimnic samples (Lepère et al, 2008).…”

Seasonal and Spatial Changes of Planktonic Bacterial Communities Inhabiting the Natural Thermal Lake Hévíz, Hungary

“…This method provides the possibility to identify the community members by reamplifying and sequencing of the excised bands. Previously, DGGE technique was successfully applied to reveal the alterations of bacterial or total microbial communities in freshwater and seawater habitats infl uenced by different environmental factors [10,11,12,13,14]. According to the UPGMA dendrogram based on the DGGE patterns, signifi cant seasonal changes with less spatial differences were found among the total planktonic bacterial communities of Lake Hévíz (Fig.…”

“…Some of these bacteria were revealed mainly from still water (lakes, ponds, reservoirs), e.g. Aquiluna rubra, Rheinheimera aquatica, Polynucleobacter cosmopolitanus, Polynucleobacter acidiphobus from which 'Candidatus Aquiluna rubra' and both Polynucleobacter species are typical planktonic freshwater microbes [14,17,18,19]. Others, e.g.…”