title: Groundwater-surface water mixing shifts ecological assembly processes and stimulates organic carbon turnover.
abstract: Environmental transitions often result in resource mixtures that overcome limitations to microbial metabolism, resulting in biogeochemical hotspots and moments. Riverine systems, where groundwater mixes with surface water (the hyporheic zone), are spatially complex and temporally dynamic, making development of predictive models challenging. Spatial and temporal variations in hyporheic zone microbial communities are a key, but understudied, component of riverine biogeochemical function. Here, to investigate the coupling among groundwater-surface water mixing, microbial communities and biogeochemistry, we apply ecological theory, aqueous biogeochemistry, DNA sequencing and ultra-high-resolution organic carbon profiling to field samples collected across times and locations representing a broad range of mixing conditions. Our results indicate that groundwater-surface water mixing in the hyporheic zone stimulates heterotrophic respiration, alters organic carbon composition, causes ecological processes to shift from stochastic to deterministic and is associated with elevated abundances of microbial taxa that may degrade a broad suite of organic compounds.
authors.affiliation: Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, Richland, Washington 99352, USA.
authors.forename: James C
authors.initials: JC
authors.lastname: Stegen
authors.affiliation: Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, Richland, Washington 99352, USA.
authors.forename: James K
authors.initials: JK
authors.lastname: Fredrickson
authors.affiliation: Department of Microbiology, The Ohio State University, Columbus, Ohio 43210, USA.|School of Earth Sciences, The Ohio State University, Columbus, Ohio 43210, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Wilkins
authors.affiliation: Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, Richland, Washington 99352, USA.
authors.forename: Allan E
authors.initials: AE
authors.lastname: Konopka
authors.affiliation: Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, Richland, Washington 99352, USA.
authors.forename: William C
authors.initials: WC
authors.lastname: Nelson
authors.affiliation: Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, Richland, Washington 99352, USA.
authors.forename: Evan V
authors.initials: EV
authors.lastname: Arntzen
authors.affiliation: Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, Richland, Washington 99352, USA.
authors.forename: William B
authors.initials: WB
authors.lastname: Chrisler
authors.affiliation: Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, Richland, Washington 99352, USA.
authors.forename: Rosalie K
authors.initials: RK
authors.lastname: Chu
authors.affiliation: Department of Microbiology, The Ohio State University, Columbus, Ohio 43210, USA.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Danczak
authors.affiliation: Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, Richland, Washington 99352, USA.
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Fansler
authors.affiliation: Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, Richland, Washington 99352, USA.
authors.forename: David W
authors.initials: DW
authors.lastname: Kennedy
authors.affiliation: Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, Richland, Washington 99352, USA.
authors.forename: Charles T
authors.initials: CT
authors.lastname: Resch
authors.affiliation: Pacific Northwest National Laboratory, 902 Battelle Boulevard, P.O. Box 999, Richland, Washington 99352, USA.
authors.forename: Malak
authors.initials: M
authors.lastname: Tfaily
mesh_terms: D001419:Bacteria / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D001673:Biodegradation, Environmental; D002244:Carbon / Q000737:chemistry* / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics*; D017753:Ecosystem; D060587:Groundwater / Q000737:chemistry* / Q000382:microbiology; D059013:Microbial Consortia / Q000502:physiology*; D045483:Rivers / Q000737:chemistry* / Q000382:microbiology; D017422:Sequence Analysis, DNA; D014861:Washington; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000378:metabolism
chemical_list: D004269:DNA, Bacterial; D014874:Water Pollutants, Chemical; D002244:Carbon