Microbial controls on climate active trace gas cycling in a model oxygen minimum zone
EMSL Project ID
47981
Abstract
Dissolved oxygen (O2) concentration is a critical organizing principle within marine ecosystems. As oxygen levels decline, energy is increasingly diverted away from higher trophic levels into microbial pathways leading to fixed nitrogen loss and greenhouse gas production. Although respiratory O2 consumption is an intrinsic outcome of a productive surface ocean, global warming induced stratification intensifies this process with unconstrained feedback on nutrient cycling and the climate system. Nowhere is this more evident than in the phenomenon of oxygen minimum zone (OMZ) expansion and intensification induced by ocean warming trends. Within OMZs, nitrate and nitrite are used as terminal electron acceptors in dissimilatory nitrate reduction (denitrification) and anaerobic ammonium oxidation (anammox) resulting in greenhouse gas production and fixed-nitrogen loss in the forms of nitrous oxide and dinitrogen gas respectively. Recent studies also posit an essential role for sulfur cycling in OMZs, coupling the production and consumption of reduced sulfur compounds to dissimilatory nitrate-reduction and dark CO2 fixation. The integration of C, N and S cycles represents a recurring theme within the O2-deficient water column, where electron donors and acceptors are actively recycled between lower and higher oxidation states forming distributed networks of metabolite exchange between microbial community members. Determining how these networks form, function, and change over time promises to reveal otherwise hidden linkages between microbial diversity and higher order ecological and biogeochemical processes with important implications for nutrient and climate active trace gas cycling. While nitrogen loss processes in OMZs have been the focus of intensive field and laboratory studies the environmental and genetic regulation of climate active trace gas cycling in relation to microbial community structure and water column chemistry remain poorly understood. Indeed, CH4 flux from OMZs is estimated to approach 1 Tg each year. To address this knowledge gap we will use isotopic labeling and incubation studies coupled with imaging and gene expression studies spanning multiple levels of biological information flow (RNA, protein, and metabolites) to link dark CO2 fixation and CH4 oxidation rates with specific microbial agents along defined gradients of oxygen, nitrate and sulfide. In the process we will constrain the metabolic pathways and trophic interactions coupling climate active trace gas production and consumption with cryptic sulfur cycling and nitrogen loss processes in OMZs with single cell resolution.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2013-10-01
End Date
2015-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Hawely AK, M Torres Beltran, M Bhatia, E Zaikova, DA Walsh, A Mueller, M Scofield, S Kheirandish, C Payne, L Pakhomova, O Shevchuk, EA Gies, D Fairley, S Malfatti, AD Norbeck, HM Brewer, L Pasa Tolic, T Glavina del Rio, CA Suttle, PD Tortell, S Tringe, and SJ Hallam. 2017. "A compendium of multi-omic sequence information from the Saanich Inlet water column." Scientific Data 170160. doi:10.1038/sdata.2017.160
Hawley AK, HM Brewer, AD Norbeck, L Pasa-Tolic, and SJ Hallam. 2014. "Metaproteomics reveals differential modes of metabolic coupling among ubiquitous oxygen minimum zone microbes." Proceedings of the National Academy of Sciences of the United States of America 111(31):11395-11400. doi:10.1073/pnas.1322132111