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Sci Total Environ. 2015 Feb 1;505:435-45. doi: 10.1016/j.scitotenv.2014.10.012. Epub 2014 Oct 21.

Species sorting and seasonal dynamics primarily shape bacterial communities in the Upper Mississippi River.

Author information

1
BioTechnology Institute, University of Minnesota, St. Paul, MN, United States.
2
BioTechnology Institute, University of Minnesota, St. Paul, MN, United States; Biology Program, University of Minnesota, St. Paul, MN, United States.
3
Biology Program, University of Minnesota, St. Paul, MN, United States.
4
Department of Ecology, Evolution and Behavior, University of Minnesota, St. Paul, MN, United States.
5
BioTechnology Institute, University of Minnesota, St. Paul, MN, United States; Department of Soil, Water and Climate, University of Minnesota, St. Paul, MN, United States. Electronic address: sadowsky@umn.edu.

Abstract

Bacterial community structure (BCS) in freshwater ecosystems varies seasonally and due to physicochemical gradients, but metacommunity structure of a major river remains understudied. Here we characterize the BCS along the Mississippi River and contributing rivers in Minnesota over three years using Illumina next-generation sequencing, to determine how changes in environmental conditions as well as inputs from surrounding land and confluences impacted community structure. Contributions of sediment to water microbial diversity were also evaluated. Long-term variation in community membership was observed, and significant shifts in relative abundances of major freshwater taxa, including α-Proteobacteria, Burkholderiales, and Actinomycetales, were observed due to temporal and spatial variations. Environmental parameters (e.g. temperature, rainfall, and nutrient concentrations) primarily contributed to differences in phyla abundances (88% of variance), with minimal influence from spatial distance alone (<1% of variance). Furthermore, an annually-recurrent BCS was observed in late summer, further suggesting that seasonal dynamics strongly influence community composition. Sediment communities differed from those in the water, but contributed up to 50% to community composition in the water column. Among water sampling sites, 34% showed significant variability in BCS of replicate samples indicating variability among riverine communities due to heterogeneity in the water column. Results of this study highlight the need for a better understanding of spatial and temporal variations in riverine bacterial diversity associated with physicochemical gradients and reveal how communities in sediments, and potentially other environmental reservoirs, impact waterborne BCS. Techniques used in this study may prove useful to determine sources of microbes from sediments and soils to waterways, which will facilitate best management practices and total maximum daily load determinations.

KEYWORDS:

Bacterial community structure; High-throughput sequencing; Metacommunity theory; Microbial ecology; Mississippi River; Recreational water

PMID:
25461045
DOI:
10.1016/j.scitotenv.2014.10.012
[Indexed for MEDLINE]

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