The influence of habitat heterogeneity on freshwater bacterial community composition and dynamics (original) (raw)
Related papers
Interannual dynamics and phenology of bacterial communities in a eutrophic lake
Limnology and Oceanography, 2007
We investigated patterns of intra-and interannual change in pelagic bacterial community composition (BCC, assessed using automated ribosomal intergenic spacer analysis) over six years in eutrophic Lake Mendota, Wisconsin. A regular phenology was repeated across years, implying that freshwater bacterial communities are more predictable in their dynamics than previously thought. Seasonal events, such as water column mixing and trends in water temperature, were most strongly related to BCC variation. Communities became progressively less similar across years between the months of May and September, when the lake was thermally stratified. Dissolved oxygen and nitrate + nitrite concentrations were highly correlated to BCC change within and across seasons. The relationship between BCC and seasonal drivers suggests that trajectories of community change observed over long time series will reflect large-scale climate variation.
PLoS ONE, 2014
The diversity and composition of ecological communities often co-vary with ecosystem productivity. However, the relative importance of productivity, or resource abundance, versus the spatial distribution of resources in shaping those ecological patterns is not well understood, particularly for the bacterial communities that underlie most important ecosystem functions. Increasing ecosystem productivity in lakes has been shown to influence the composition and ecology of bacterial communities, but existing work has only evaluated the effect of increasing resource supply and not heterogeneity in how those resources are distributed. We quantified how bacterial communities varied with the trophic status of lakes and whether community responses differed in surface and deep habitats in response to heterogeneity in nutrient resources. Using ARISA fingerprinting, we found that bacterial communities were more abundant, richer, and more distinct among habitats as lake trophic state and vertical heterogeneity in nutrients increased, and that spatial resource variation produced habitat specific responses of bacteria in response to increased productivity. Furthermore, changes in communities in high nutrient lakes were not produced by turnover in community composition but from additional taxa augmenting core bacterial communities found in lower productivity lakes. These data suggests that bacterial community responses to nutrient enrichment in lakes vary spatially and are likely influenced disproportionately by rare taxa.
Transitions in microbial communities along a 1600 km freshwater trophic gradient
Journal of Great Lakes Research, 2019
This study examined vertically-resolved patterns in microbial community structure across a freshwater trophic gradient extending 1600 km from the oligotrophic waters of Lake Superior to the eutrophic waters of Lake Erie, the most anthropogenically influenced of the Laurentian Great Lakes system. Planktonic bacterial communities clustered by Principal Coordinates Analysis (PCoA) on UniFrac distance matrices into four groups representing the epilimnion and hypolimnion of the upper Great Lakes (Lakes Superior and Huron), Lake Superior's northern bays (Nipigon and Black bays), and Lake Erie. The microbes within the upper Great Lakes hypolimnion were the most divergent of these groups with elevated abundance of Planctomycetes and Chloroflexi compared to the surface mixed layer. Statistical tests of the correlation between distance matrices identified temperature and sample depth as the most influential community structuring parameters, reflecting the strong UniFrac clustering separating mixed-layer and hypolimnetic samples. Analyzing mixed-layer samples alone showed clustering patterns were correlated with nutrient concentrations. Operational taxonomic units (OTU) which were differentially distributed among these conditions often accounted for a large portion of the reads returned. While limited in coverage of temporal variability, this study contributes a detailed description of community variability that can be related to other large freshwater systems characterized by changing trophic state.
PLOS ONE, 2017
Many freshwater lakes undergo seasonal stratification, where the formation of phototrophic blooms in the epilimnion and subsequent sedimentation induces hypoxia/anoxia in the thermocline and hypolimnion. This autochthonously produced biomass represents a major seasonal organic input that impacts the entire ecosystem. While the limnological aspects of this process are fairly well documented, relatively little is known regarding the microbial community response to such events, especially in the deeper anoxic layers of the water column. Here, we conducted a spatiotemporal survey of the particle-associated and free-living microbial communities in a warm monomictic freshwater reservoir (Grand Lake O' the Cherokees) in northeastern Oklahoma, USA. Pre-stratification samples (March) harbored a homogeneous community throughout the oxygenated water column dominated by typical oligotrophic aquatic lineages (acl clade within Actinobacteria, and Flavobacterium within the Bacteroidetes). The onset of phototrophic blooming in June induced the progression of this baseline community into two distinct trajectories. Within the oxic epilimnion, samples were characterized by the propagation of phototrophic (Prochlorococcus), and heterotrophic (Planctomycetes, Verrucomicrobia, and Beta-Proteobacteria) lineages. Within the oxygendeficient thermocline and hypolimnion, the sedimentation of surface biomass induced the development of a highly diverse community, with the enrichment of Chloroflexi, "Latescibacteria", Armatimonadetes, and Delta-Proteobacteria in the particle-associated fraction, and Gemmatimonadetes and "Omnitrophica" in the free-living fraction. Our work documents the development of multiple spatially and temporally distinct niches during lake stratification, and supports the enrichment of multiple yet-uncultured and poorly characterized lineages in the lake's deeper oxygen-deficient layers, an ecologically relevant microbial niche that is often overlooked in lakes diversity surveys.
Microhabitats shape diversity-productivity relationships in freshwater bacterial communities
bioRxiv (Cold Spring Harbor Laboratory), 2017
Eukaryotic communities commonly display a positive relationship between biodiversity and ecosystem function (BEF). Based on current studies, it remains uncertain to what extent these findings extend to bacterial communities. An extrapolation from eukaryotic relationships would predict there to be no BEF relationships for bacterial communities because they are generally composed of an order of magnitude more taxa than the communities in most eukaryotic BEF studies. Here, we sampled surface water of a freshwater, estuarine lake to evaluate BEF relationships in bacterial communities across a natural productivity gradient. We assessed the impact of habitat heterogeneity-an important factor influencing eukaryotic BEFs-on the relationship between species richness, evenness, phylogenetic diversity, and heterotrophic productivity by sampling co-occurring free-living (more homogenous) and particle-associated (more heterogeneous) bacterial habitats. Diversity measures, and not environmental variables, were the best predictors of particles-associated heterotrophic production. There was a strong, positive, linear relationship between particle-associated bacterial richness and heterotrophic productivity that was strengthened when considering evenness. There were no observable BEF trends in free-living bacterial communities. In contrast, per-capita but not community-wide heterotrophic productivity increased across both habitats as communities were composed of taxa that were more phylogenetically clustered. This association indicates that communities with more phylogenetically related taxa have higher per-capita heterotrophic production than communities of phylogenetically distantly related taxa. Our findings show that lake heterotrophic bacterial productivity can be positively affected by evenness and richness, negatively by phylogenetic diversity, and that BEF relationships are contingent on microhabitats. These results .
Seasonal and Episodic Lake Mixing Stimulate Differential Planktonic Bacterial Dynamics
Microbial Ecology, 2010
Yuan Yang Lake (YYL), Taiwan, experiences both winter and typhoon-initiated mixing, and each type of mixing event is characterized by contrasting environmental conditions. Previous work suggested that after typhoon mixing, bacterial communities in YYL reset to a pioneer composition and then follow a predictable trajectory of change until the next typhoon. Our goal was to continue this investigation by observing bacterial community change after a range of mixing intensities, including seasonal winter mixing. We fingerprinted aquatic bacterial communities in the epilimnion and hypolimnion using automated ribosomal intergenic spacer analysis and then assessed community response using multivariate statistics. We found a significant linear relationship between water column stability and the epilimnion to hypolimnion divergences. In comparison to the summer, we found the winter community had a distinct composition and less variation.
Environmental Microbiology Reports, 2013
With this work we intend to stress the importance of considering discrete depth sampling for bacterial community analysis of stratified aquatic systems. Depth is a very important parameter to consider when sampling bacterial communities, as their abundance and composition can change within the distinct water layers. Stratified lakes are good model systems to study these connections since changes in environmental parameters can occur on a cm-scale at the thermo-and/or chemocline. Lake Grosse Fuchskuhle was sampled at discrete fine-scale depths at three time points covering a stage in which the lake was stratified and the beginning of winter mixing. In this paper we present the most abundant bacterial groups at the different depths sampled and also the most abundant operational taxonomic units (OTUs). Overall, oxygen was found to be an important factor shaping the microbial community composition.
FEMS Microbiology Ecology
Seasonal environmental variation is a leading driver of microbial planktonic community assembly and interactions. However, departures from usual seasonal trends are often reported. To understand the role of local stressors in modifying seasonal succession, we sampled fortnightly throughout three seasons five nearby shallow soda lakes exposed to identical seasonal and meteorological changes. We characterised their microeukaryotic and bacterial communities by amplicon sequencing of the 16S and 18S rRNA gene, respectively. Biological interactions were inferred by analyses of synchronous and time-shifted interaction networks, and the keystone taxa of the communities were topologically identified. The lakes showed similar succession patterns during the study period with spring being characterised by relevance of trophic interactions and certain level of community stability followed by a more dynamic and variable summer-autumn period. Adaptation to general seasonal changes happened throug...
FEMS Microbiology Ecology, 2020
Eukaryotic communities commonly display a positive relationship between biodiversity and ecosystem function (BEF) but the results have been mixed when assessed in bacterial communities. Habitat heterogeneity, a factor in eukaryotic BEFs, may explain these variable observations but it has not been thoroughly evaluated in bacterial communities. Here, we examined the impact of habitat on the relationship between diversity assessed based on the (phylogenetic) Hill diversity metrics and heterotrophic productivity. We sampled co-occurring free-living (more homogenous) and particle-associated (more heterogeneous) bacterial habitats in a freshwater, estuarine lake over three seasons: spring, summer and fall. There was a strong, positive, linear relationship between particle-associated bacterial richness and heterotrophic productivity that strengthened when considering dominant taxa. There were no observable BEF trends in free-living bacterial communities for any diversity metric. Biodiversity, richness and Inverse Simpson's index, were the best predictors of particle-associated production whereas pH was the best predictor of free-living production. Our findings show that heterotrophic productivity is positively correlated with the effective number of taxa and that BEF relationships are associated with microhabitats. These results add to the understanding of the highly distinct contributions to diversity and functioning contributed by bacteria in free-living and particle-associated habitats.