The Effects of Oxygen Transition on Community Respiration and Potential Chemoautotrophic Production in a Seasonally Stratified Anoxic Estuary

Lee, Dong Y.; Owens, Michael S.; Doherty, Mary K.; Eggleston, Erin M.; Hewson, Ian; Crump, Byron C.; Cornwell, Jeffrey C.

doi:10.1007/s12237-014-9803-8

Cited by 22 publications

(21 citation statements)

References 82 publications

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“…Despite interannual differences in the extent of stratification and hypoxic volume, we observed similar patterns of geochemical constituents compared to previous studies (Gavis and Grant, 1986;Lee et al, 2015), suggesting conserved residents or recurring populations in bacterioplankton communities. The vertical patterns of respiration and autotrophic dark 14 CO 2 fixation, elevated near the maximum stratification, also suggest that some subset of the microbial community was optimally adapted to the interface.…”

Section: Discussionsupporting

confidence: 77%

“…Previous studies have suggested spatiotemporal variability in microbial phylogenetic and functional composition reflects the diversity of metabolic processes in the Chesapeake Bay during seasonal anoxic events (Crump et al, 2007;Eggleston et al, 2015;Hewson et al, 2014;Lee et al, 2015). For example, occasional high production of dissolved inorganic carbon ðDIC ¼ ½H 2 CO 3 þ ½HCO 3 À þ ½CO 3 2À Þ near the top of oxyclines and net consumption of DIC in the oxic/ anoxic interface suggested not only close proximity between aerobic heterotrophs and chemoautotrophs, but also the formation of a secondary microbial food web.…”

Section: Introductionmentioning

confidence: 99%

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Elevated microbial CO2 production and fixation in the oxic/anoxic interface of estuarine water columns during seasonal anoxia

Lee

Owens

Crump

et al. 2015

Estuarine, Coastal and Shelf Science

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a b s t r a c tGradients of dissolved oxygen concentrations in stratified estuarine water columns directly influence microbial composition and metabolic pathways, resulting in vertical and axial chemical gradients of redox-active species. Understanding such microbial responses to changing geochemical conditions and elucidating the diversity of microbially-mediated processes are needed to comprehensively identify ecosystem functions. We tested the hypothesis that microbial metabolic processes in the vicinity of the oxic/anoxic interface in Chesapeake Bay would be elevated due to the coincidence of oxidized and reduced compounds. We measured rates of microbial redox processes associated with carbon cycles and quantified geochemical constituents. The transition from oxic to anoxic to oxic conditions was correlated with the pattern of dissolved nitrogen species, with the most reducing conditions comprising the highest concentrations of dissolved chemical compounds. The vertical distribution of community respiration was measured with changes in dissolved inorganic carbon concentrations and was related to water column stratification, with the highest median and variability (1.2 ± 1.4 mmol L À1 h À1 ) in the most stratified conditions. Rates of CO 2 fixation under dark conditions, a measure of chemoautotrophy, were elevated at the base of oxyclines and significantly correlated with a gradient of density and some reduced compounds. Although vertical interpolation must be made with caution due to high vertical variability, chemoautotrophic production averaged 0.5 mmol m À2 h À1 from May to August and added 5.8% to autochthonous organic carbon production in the mesohaline Chesapeake Bay. Overall, our results suggest that anaerobic community metabolism and chemoautotrophy in the oxic/anoxic interface exert a small impact on estuarine carbon cycles.

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Section: Discussionsupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Elevated microbial CO2 production and fixation in the oxic/anoxic interface of estuarine water columns during seasonal anoxia

Lee

Owens

Crump

et al. 2015

Estuarine, Coastal and Shelf Science

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“…Anaerobic environments pose different challenges, and aeration of cores changes the redox dynamics at the sediment-water interface. We seal up cores with stirring tops immediately after collection and start the fluxes without replacing the water column completely 30 . Our experiments with illuminated sediments typically have saturating or near-saturating levels of illumination 31 , and thus maximize the effect of benthic microalgae.…”

Section: Discussionmentioning

confidence: 99%

The Benthic Exchange of O<sub>2</sub>, N<sub>2</sub> and Dissolved Nutrients Using Small Core Incubations

Owens

Cornwell

2016

JoVE

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The measurement of sediment-water exchange of gases and solutes in aquatic sediments provides data valuable for understanding the role of sediments in nutrient and gas cycles. After cores with intact sediment-water interfaces are collected, they are submerged in incubation tanks and kept under aerobic conditions at in situ temperatures. To initiate a time course of overlying water chemistry, cores are sealed without bubbles using a top cap with a suspended stirrer. Time courses of 4-7 sample points are used to determine the rate of sediment water exchange. Artificial illumination simulates day-time conditions for shallow photosynthetic sediments, and in conjunction with dark incubations can provide net exchanges on a daily basis. The net measurement of N 2 is made possible by sampling a time course of dissolved gas concentrations, with high precision mass spectrometric analysis of N 2 :Ar ratios providing a means to measure N 2 concentrations. We have successfully applied this approach to lakes, reservoirs, estuaries, wetlands and storm water ponds, and with care, this approach provides valuable information on biogeochemical balances in aquatic ecosystems.

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“…The DIC samples were preserved with mercuric chloride (HgCl2) for initial conditions, while biochemical oxygen demand (BOD) bottles were incubated in a temperature-controlled environmental chamber (±1 °C of in 5 situ water temperatures). After 24 h, samples were siphoned from the vials, preserved with HgCl2, and respiration rates were determined as the difference in DIC between initial and final samples divided by the 24 hours (Lee et al, 2015b).…”

Section: Sample Acquisition and Processingmentioning

confidence: 99%

“…was measured with an automated infrared analyzer (Apollo SciTech, Newark, DE) as previously reported (Lee et al, 2015b).…”

Section: Analytical Proceduresmentioning

confidence: 99%

Nitrogen and oxygen availabilities control water column nitrous oxide production during seasonal anoxia in the Chesapeake Bay

Ji¹,

Frey²,

Sun³

et al. 2018

Preprint

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Abstract. Nitrous oxide (N2O) is a greenhouse gas and an ozone depletion agent. One of the major uncertainties in the global N2O budget is the contribution of the coastal region, including estuaries, which can be sites of intense N2O efflux.Incubation experiments with nitrogen stable isotope tracer ( 15 N) enabled the investigation of the environmental controls of 10 N2O production in the water column of Chesapeake Bay, the largest estuary in North America. The highest potential rates of N2O production (7.5±1.2 nmol-N L -1 hr -1 ) were detected during summer anoxia, during which oxidized nitrogen species (nitrate and nitrite) were absent from the water column. At the top of the anoxic layer, N2O production from denitrification was stimulated by addition of nitrate and nitrite. The relative contribution of nitrate and nitrite to N2O production was positively correlated with the ratio of nitrate to nitrite concentrations. Increased oxygen availability, up to 7 µM oxygen 15 inhibited both N2O production and the reduction of nitrate to nitrite. Therefore, reducing the nitrogen input into the Chesapeake Bay has two potential impacts on the N2O efflux: In the short-term, N2O emission will be mitigated due to nitrogen deficiency. In the long-run, eutrophication will be alleviated and subsequent re-oxygenation of the bay will further inhibit N2O production.

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The Effects of Oxygen Transition on Community Respiration and Potential Chemoautotrophic Production in a Seasonally Stratified Anoxic Estuary

Cited by 22 publications

References 82 publications

Elevated microbial CO2 production and fixation in the oxic/anoxic interface of estuarine water columns during seasonal anoxia

Elevated microbial CO2 production and fixation in the oxic/anoxic interface of estuarine water columns during seasonal anoxia

The Benthic Exchange of O<sub>2</sub>, N<sub>2</sub> and Dissolved Nutrients Using Small Core Incubations

Nitrogen and oxygen availabilities control water column nitrous oxide production during seasonal anoxia in the Chesapeake Bay

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