Ward
Bess B.
Ward
Bess B.
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ArticleIdeas and perspectives: a strategic assessment of methane and nitrous oxide measurements in the marine environment(European Geosciences Union, 2020-11-26) Wilson, Samuel T. ; Al-Haj, Alia N. ; Bourbonnais, Annie ; Frey, Claudia ; Fulweiler, Robinson W. ; Kessler, John D. ; Marchant, Hannah K. ; Milucka, Jana ; Ray, Nicholas E. ; Suntharalingam, Parvadha ; Thornton, Brett F. ; Upstill-Goddard, Robert C. ; Weber, Thomas S. ; Arévalo-Martínez, Damian L. ; Bange, Hermann W. ; Benway, Heather M. ; Bianchi, Daniele ; Borges, Alberto V. ; Chang, Bonnie X. ; Crill, Patrick M. ; del Valle, Daniela A. ; Farías, Laura ; Joye, Samantha B. ; Kock, Annette ; Labidi, Jabrane ; Manning, Cara C. ; Pohlman, John W. ; Rehder, Gregor ; Sparrow, Katy J. ; Tortell, Philippe D. ; Treude, Tina ; Valentine, David L. ; Ward, Bess B. ; Yang, Simon ; Yurganov, Leonid N.In the current era of rapid climate change, accurate characterization of climate-relevant gas dynamics – namely production, consumption, and net emissions – is required for all biomes, especially those ecosystems most susceptible to the impact of change. Marine environments include regions that act as net sources or sinks for numerous climate-active trace gases including methane (CH4) and nitrous oxide (N2O). The temporal and spatial distributions of CH4 and N2O are controlled by the interaction of complex biogeochemical and physical processes. To evaluate and quantify how these mechanisms affect marine CH4 and N2O cycling requires a combination of traditional scientific disciplines including oceanography, microbiology, and numerical modeling. Fundamental to these efforts is ensuring that the datasets produced by independent scientists are comparable and interoperable. Equally critical is transparent communication within the research community about the technical improvements required to increase our collective understanding of marine CH4 and N2O. A workshop sponsored by Ocean Carbon and Biogeochemistry (OCB) was organized to enhance dialogue and collaborations pertaining to marine CH4 and N2O. Here, we summarize the outcomes from the workshop to describe the challenges and opportunities for near-future CH4 and N2O research in the marine environment.
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ArticleNitrite oxidation exceeds reduction and fixed nitrogen loss in anoxic Pacific waters(Elsevier, 2020-08-20) Babbin, Andrew ; Buchwald, Carolyn ; Morel, Francois M. M. ; Wankel, Scott D. ; Ward, Bess B.The diversity of nitrogen-based dissimilatory metabolisms in anoxic waters continues to increase with additional studies to the marine oxygen deficient zones (ODZs). Although the microbial oxidation of nitrite (NO2–) has been known for over a century, studies of the pathways and microbes involved have generally proceeded under the assumption that nitrite oxidation to nitrate requires dioxygen (O2). Anaerobic NO2– oxidation until now has been conclusively shown only for anammox bacteria, albeit only as a limited sink for NO2– in their metabolism compared to the NO2– reduced to N2. Here, using direct experimental techniques optimized for replicating in situ anoxic conditions, we show that NO2– oxidation is substantial, widespread, and consistent across the ODZs of the eastern tropical Pacific Ocean. Regardless of the specific oxidant, NO2– oxidation rates are up to an order of magnitude larger than simultaneous N2 production rates for which these zones are known, and cannot be explained by anammox rates alone. Higher rates of NO2– oxidation over reduction in anoxic waters are paradoxical but help to explain how anammox rates can be enhanced over denitrification in shallow anoxic waters (σθ < 26.4) at the edge of the ODZs but not within the ODZ core. Furthermore, nitrite oxidation may be the key to reconciliation of the perceived imbalance of the global fixed nitrogen loss budget.
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DatasetChlorophyll-a concentrations from CTD cast deployments and underway seawater inflow from Endeavor 532 and Endeavor 538 cruises in 2013 and 2014(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2022-05-04) Ward, Bess B. ; Allen, Andrew E ; Sigman, Daniel M.Chlorophyll-a concentrations from CTD cast deployments and underway seawater inflow from Endeavor 532 and Endeavor 538 cruises in 2013 (August and September) and 2014 (April and May). For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/651784
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DatasetBottle data from CTD casts conducted on R/V Sally Ride cruise SR1805 in the Eastern Tropical North Pacific Ocean from March to April 2018(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2021-06-21) Ward, Bess B. ; Casciotti, Karen L.This dataset includes bottle data from CTD casts conducted on R/V Sally Ride cruise SR1805 in the Eastern Tropical North Pacific Ocean from March to April 2018. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/854091
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DatasetCast data from cruise R/V Hugh R. Sharp HRS2110 in the Chesapeake Bay from August 2021 (NO2Ox_OMZs project)(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2022-02-09) Ward, Bess B.Cast data from cruise R/V Hugh R. Sharp HRS2110 in the Chesapeake Bay from August 2021 associated with the Nitrate Oxidation in Oxygen Minimum Zones project. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/868879
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ArticleAcidification alters the composition of ammonia‑oxidizing microbial assemblages in marine mesocosms(Inter-Research, 2013-10-31) Bowen, Jennifer L. ; Kearns, Patrick J. ; Holcomb, Michael ; Ward, Bess B.Increasing atmospheric CO2 concentrations are causing decreased pH over vast expanses of the ocean. This decreasing pH may alter biogeochemical cycling of carbon and nitrogen via the microbial process of nitrification, a key process that couples these cycles in the ocean, but which is often sensitive to acidic conditions. Recent reports have indicated a decrease in oceanic nitrification rates under experimentally lowered pH. How the composition and abundance of ammonia-oxidizing bacteria (AOB) and archaea (AOA) assemblages respond to decreasing oceanic pH is unknown. We sampled microbes from 2 different acidification experiments and used a combination of qPCR and functional gene microarrays for the ammonia monooxygenase gene (amoA) to assess how acidification alters the structure of ammonia oxidizer assemblages. We show that despite widely different experimental conditions, acidification consistently altered the community composition of AOB by increasing the relative abundance of taxa related to the Nitrosomonas ureae clade. In one experiment, this increase was sufficient to cause an increase in the overall abundance of AOB. There were no systematic shifts in the community structure or abundance of AOA in either experiment. These different responses to acidification underscore the important role of microbial community structure in the resiliency of marine ecosystems.
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PreprintMicrobial community composition in sediments resists perturbation by nutrient enrichment( 2010-11) Bowen, Jennifer L. ; Ward, Bess B. ; Morrison, Hilary G. ; Hobbie, John E. ; Valiela, Ivan ; Deegan, Linda A. ; Sogin, Mitchell L.Functional redundancy in bacterial communities is expected to allow microbial assemblages to survive perturbation by allowing continuity in function despite compositional changes in communities. Recent evidence suggests, however, that microbial communities change both composition and function as a result of disturbance. We present evidence for a third response: resistance. We examined microbial community response to perturbation caused by nutrient enrichment in salt marsh sediments using deep pyrosequencing of 16S rRNA and functional gene microarrays targeting the nirS gene. Composition of the microbial community, as demonstrated by both genes, was unaffected by significant variations in external nutrient supply, despite demonstrable and diverse nutrient–induced changes in many aspects of marsh ecology. The lack of response to external forcing demonstrates a remarkable uncoupling between microbial composition and ecosystem-level biogeochemical processes and suggests that sediment microbial communities are able to resist some forms of perturbation.
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DatasetAmmonium, total nitrate and nitrite, nitrite, and flow cytometry profiles in the Eastern Tropical North Pacific from March to April 2018.(Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu, 2021-04-23) Ward, Bess B.Ammonium, total nitrate and nitrite, nitrite, and flow cytometry profiles in the Eastern Tropical North Pacific from March to April 2018. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/774855
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ArticleIsotopomer labeling and oxygen dependence of hybrid nitrous oxide production(Copernicus Publications, 2024-07-17) Kelly, Colette L. ; Travis, Nicole M. ; Baya, Pascale A. ; Frey, Claudia ; Sun, Xin ; Ward, Bess B. ; Casciotti, Karen L.Nitrous oxide (N2O) is a potent greenhouse gas and ozone depletion agent, with a significant natural source from marine oxygen-deficient zones (ODZs). Open questions remain, however, about the microbial processes responsible for this N2O production, especially hybrid N2O production when ammonia-oxidizing archaea are present. Using 15N-labeled tracer incubations, we measured the rates of N2O production from ammonium (NH), nitrite (NO), and nitrate (NO) in the eastern tropical North Pacific ODZ and the isotopic labeling of the central (α) and terminal (β) nitrogen (N) atoms of the N2O molecule. We observed production of both doubly and singly labeled N2O from each tracer, with the highest rates of labeled N2O production at the same depths as the near-surface N2O concentration maximum. At most stations and depths, the production of 45N2Oα and 45N2Oβ were statistically indistinguishable, but at a few depths there were significant differences in the labeling of the two nitrogen atoms in the N2O molecule. Implementing the rates of labeled N2O production in a time-dependent numerical model, we found that N2O production from NO dominated at most stations and depths, with rates as high as 1600 ± 200 pM N2O d−1. Hybrid N2O production, one of the mechanisms by which ammonia-oxidizing archaea produce N2O, had rates as high as 230 ± 80 pM N2O d−1 that peaked in both the near-surface and deep N2O concentration maxima. Based on the equal production of 45N2Oα and 45N2Oβ in the majority of our experiments, we infer that hybrid N2O production likely has a consistent site preference, despite drawing from two distinct substrate pools. We also found that the rates and yields of hybrid N2O production were enhanced at low dissolved oxygen concentrations ([O2]), with hybrid N2O yields as high as 20 % at depths where [O2] was below detection (880 nM) but nitrification was still active. Finally, we identified a few incubations with [O2] up to 20 µM where N2O production from NO was still active. A relatively high O2 tolerance for N2O production via denitrification has implications for the feedbacks between marine deoxygenation and greenhouse gas cycling.