A team of researchers was able to reconstruct hundreds of microbial genomes from complex soil samples to show that soils bounded by individual river meanders capture processes that occur in soils bounded by other meanders along the river corridor. A paper describing their study was recently published in the journal Microbiome.
Their study focuses on the East River watershed, a pristine, high elevation, snow-dominated headwater basin of the Colorado River and part of the Watershed Function Scientific Focus Area (SFA) program that is exploring how disturbances in mountain systems – such as floods, drought, changing snowpack and earlier snowmelt – impact the downstream delivery of water, nutrients, carbon, and metals. Ken Williams, deputy director for the Watershed SFA program, contributed to the journal publication, as did EESA faculty scientist and UC Berkeley professor Jillian Banfield.
Meander-bound floodplains appear to serve as scaling motifs that predict aggregate capacities for biogeochemical transformations in floodplain soils. The team reconstructed 248 draft quality genomes (at the sub-species level) from the upper, middle, and lower reaches of the East River in Colorado at the Watersed SFA research site. Despite the very high microbial diversity and complexity of the soils, ~15% of species were detected in two consecutive years, and approximately one third of the representative genomes were detected with similar levels of abundance across all three locations.
This work is important, given that there is a need to understand microbially mediated biogeochemical transformations, which occur at the millionth of a meter scale, at the tens to hundreds of kilometer scale of watershed ecosystems. According to the researchers, the presence of the same bacteria (~ 15%) over two consecutive years, combined with differences between common capacities and important capacities at the time of sampling, suggests that the floodplain soil microbiome is versatile and can respond to natural disturbances (e.g., flooding resulting from spring snowmelt).