Comparing sediment bacterial communities in the macrophyte-dominated and algae-dominated areas of eutrophic Lake Taihu, China

Abstract

Bacterial community structure and the effects of several environmental factors on bacterial community distribution were investigated in the sediment of the macrophyte-dominated and algae-dominated areas in a large, shallow, eutrophic freshwater lake (Lake Taihu, China). Surface sediment samples were collected at 6 sampling sites (3 sites from each of the 2 areas) on 15 February and 15 August 2009. Based on cluster analysis of the DGGE banding patterns, there were significant seasonal variations in the structure of the sediment bacterial community in the macrophyte- and algae-dominated areas, and site-specific variation within an area and between 2 areas. However, there were no significant between-area variations due to the large within-area variation. Analysis of DNA sequences showed that there were differences in the species composition of the sediment bacteria between the macrophyte- and algae-dominated area clone libraries. In the macrophyte-dominated area library, the bacterial community was dominated by Deltaproteobacteria, Verrucomicrobia, Acidobacteria, Bacteroidetes, Gammaproteobacteria, and Betaproteobacteria. OP10 was found in the library of this area but not in the algae-dominated area library. The algae-dominated area library was dominated by Betaproteobacteria, Deltaproteobacteria, Gammaproteobacteria, and Acidobacteria. Cyanobacteria, Alphaproteobacteria, and Planctomycetes were found in this area library but not in the macrophyte-dominated area library. Canonical correspondence analysis demonstrated that total phosphorus and water temperature were the dominant environmental factors affecting bacterial community composition in the sediment.

Sediment prokaryote communities in different sites of eutrophic Lake Taihu and their interactions with environmental factors

“…These changes might be related to the responds of these bacteria to the nutrient conditions of the sediments during different bloom stages, since they have been described as the degraders of organic nutrient in marine sediment (Sinkko et al 2013). Our results demonstrated that the Alphaproteobacteria were more abundant during the algal bloom, which is similar to the findings elsewhere (Eiler et al 2006;Shao et al 2011;Ye et al 2009). The changes of anaerobic phototrophic bacteria Chlorobi and Chloroflexi might be related to the turbidity of the water body, since the bloom can block the transmission of light to the surface of sediments.…”

“…However, the Betaproteobacteria as the most dominant bacterial group in all the sediments sampled in the four periods from different sites of Taihu was a result different from the observation in a previous study (Shao et al 2011), in which Shao et al (2011 reported that Deltaproteobacteria was the most dominant classes in macrophyte-dominated areas and Betaproteobacteria was the most dominant classes in algaedominated areas of the Lake Taihu. This difference might be due to the fact that DGGE and sequencing methods were used in Shao et al (2011), which have less resolution than the pyrosequencing technique. In addition, Shao et al (2011) reported that Epsilonproteobacteria (21.1 %) were the second dominant group of sediment bacteria in the macrophyte-dominated state, but not in the algaedominated state.…”

“…This difference might be due to the fact that DGGE and sequencing methods were used in Shao et al (2011), which have less resolution than the pyrosequencing technique. In addition, Shao et al (2011) reported that Epsilonproteobacteria (21.1 %) were the second dominant group of sediment bacteria in the macrophyte-dominated state, but not in the algaedominated state. In our present study, Epsilonproteobacteria were detected in both the sites 16 and 24 as a relatively abundant group (5.5 and 3.6 %, respectively), but not in the center of the lake (site 7), implying that they might come from the soils surrounding the lake (see Fig.…”

“…In this study, the sediment and overlaying water were sampled from seven sites presenting different levels of contamination based upon previous observations (Shao et al 2011): sites 1, 6, 10 and 16 were located in the algaedominated areas characterized by high water turbidity and strong algal bloom; site 7 and sites 21 were located in the center of the Lake, an area influenced slightly by human activities, with lower algal bloom; site 24 was located in a grass-bottom area (macrophyte-dominated area) characterized by clear water and diverse communities of fishes and invertebrates. The location of these sites is presented in Fig.…”

“…has extended its coverage and persistence throughout the summer (Guo 2007;Deng et al 2014;Qin et al 2007), similar to other shallow lakes in the world, such as Lake Okeechobee (USA) (James et al 2009) and Lake Engelsholm (Denmark) (Søndergaard et al 2013). In order to understand and control the eutrophication, some studies have been performed in Taihu, mainly focused on three aspects: (1) the physical and chemical changes in the water body and sediment (Han et al 2013;Liu et al 2013); (2) the algal community and algal toxin production changes Zhai et al 2013); (3) the microbial community changes in water body and sediment (Chen et al 2008;Hou et al 2013a;Shao et al 2013;Wu et al 2007;Ye et al 2009), which showed vertical variation of bacterial community (Ye et al 2009) and significant seasonal variation in February and August in sediment (Shao et al 2011). However, further study on the microbial communities by the molecular methods, in coupling with the physicochemical characterization of water and sediment could enable a better understanding about the interactions among the environment factors, the prokaryotic communities and the algal bloom.…”