Submitted to: Journal of Great Lakes Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/3/2013
Publication Date: 6/3/2013
Publication URL: http://handle.nal.usda.gov/10113/56968
Citation: Bouzat, J., Hostel, M., Looft, T.P. 2013. Spatial patterns of microbial community composition within Lake Erie sediments. Journal of Great Lakes Research. 39(2):344-351. Interpretive Summary: Lake Erie is an important freshwater ecosystem with regions of differing amounts of nutrient and pollution inputs. To evaluate the effects of these spatial differences on the bacteria in the lake sediment, bacterial communities were profiled for comparisons. Eleven locations across the lake, including a large area of low oxygen “dead zone” were used. The abundance of bacteria within each location revealed groups capable of metabolizing a wide range of organic matter were found more abundant within inshore sites of the Central and Western basins compared to the Eastern basin. Community analyses showed microbial community spatial structuring, with the Central basin, with the dead zone, being the most unique. Results from this study provide evidence for the local adaptation of microbial communities, with differential levels of dissolved organic matter potentially driving these differences.
Technical Abstract: Lake Erie is a large freshwater ecosystem with three distinct basins that exhibit an east-west gradient of increasing productivity, as well as allochthonous inputs of nutrients and xenobiotics. To evaluate microbial community composition throughout this ecosystem, 435 16S rDNA environmental clones were sequenced from 11 sediment samples throughout the Western, Central, and Eastern basins, as well as the hypoxic “dead zone” of Lake Erie in the hypolimnetic region of the Central basin. Rank abundance of bacterial taxa within each location revealed that gamma- and betaproteobacteria, microbes, capable of metabolizing a wide range of organic matter pools, comprised a much greater fraction of the microbial community within inshore sites of the Central and Western basins compared to the Eastern basin. Although levels of species diversity among regions were not significant, the Central and Eastern basins showed moderately higher species richness. Fast Unifrac analyses revealed microbial community spatial structuring, with the Central basin showing higher phylogenetic uniqueness of microbial lineages. Principal component analyses based on phylogenetic distances consistently grouped the dead zone with the Central basin, and highlighted the distinctiveness of microbial communities from the Eastern basin. Results from this study provide evidence for the local adaptation of microbial communities, with differential levels of dissolved organic matter potentially modulating species richness. These results are consistent with previous functional studies on microbial community metabolism, which showed that differences in DOM and heavy metal concentrations play an important role in the local adaptation of microbial communities.