Methane oxidation in Saanich inlet during summer stratification

Ward, Bettie; Kilpatrick, K. A.; Wopat, Ann E.; Minnich, Elizabeth; Lidstrom, Mary E.

doi:10.1016/0278-4343(89)90083-6

Cited by 62 publications

(49 citation statements)

References 21 publications

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“…This conventional model is clearly inconsistent with the observations of a methane maximum in the pycnocline of the open ocean (Scranton & Brewer 1977, refs. in Rudd & Taylor 1980, with our microbiological data from stratified upper Chesapeake Bay (Sieburth 1993, Sieburth et al 1993a, with that of stratified fjords (Lidstrom 1983, Ward et al 1989) and with the data presented here.…”

Section: Discussionsupporting

confidence: 77%

See 1 more Smart Citation

Planktonic methane production and oxidation within the algal maximum of the pycnocline: seasonal fine-scale observations in an anoxic estuarine basin

Sieburth¹,

Donaghay²

1993

Mar. Ecol. Prog. Ser.

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High resolution profiles of methane concentration and potential methane-oxidation rates were used to test the importance of in situ production and oxidation in controlling methane structure and dynamics in the southern anoxic basin of the Pettaquamscutt Estuary, Rhode Island, USA. Profiles conducted in both April and August showed low but increasing methane concentrations in the surface oxic layer, a minor maximum about 0.75 m above the Eh = 0 boundary, a methane minimum just above Eh = 0, and a rapid increase to a major maximum about 0.75 m below Eh = 0. Methane concentrations in both maxima increased between April and August while concentrations in the methane minimum decreased. This methane minimum in the suboxic zone was strongly associated with a minor oxygen maximum and a major peak in chlorophyll due to the oxygenic alga Euglena proxima. April incubations in the presence of added oxygen at 2°C supported oxidation rates as high as 9% d-' in and just below the methane minimum at the Eh = 0 boundary, due to psychrophilic methane-oxidation. Similar experiments conducted in August at 22°C showed a similar narrow peak in potential methaneoxidation rates in and just below the methane minimum at the Eh = 0 boundary, suggesting that the boundary was now dynamically controlled by rapid mesophilic methane-oxidation. Analysis of the August incubations at 2°C showed a decline in methane at the depths of the major methane maximum for 4 d, followed by a 4 d increase in methane concentration at the same depths, due presumably to the exhaustion of dissolved oxygen and the cessation of the masking oxidation. These results indicate that the seasonal increase in the major methane maximum is generated Ln situ by psychrophilic methaneproduction, a production that IS largely masked by a concomitant psychrophilic methane-oxidation. The shift from an initial dominance of methane-oxidation to a final dominance of methane-production in the same water sample bottles indicates just how sensitive the structure of the major methane maximum is to the bacterial processes of methanogenesis and methanotrophy, changes in water temperature, and oxygen inputs by in situ primary production and physical intrusions. Such processes have made it bfficult to document a major production of methane in the pycnocllne.

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Section: Discussionsupporting

confidence: 77%

“…Such outliers are commonly observed in methane profiles near the Eh boundary (e.g. Atkinson & Richards 1967, Ward et al 1987Ward et al , 1989. As an example, we have redrawn a profile from Atkinson & Richards (1967), also obtained from a n anoxic captive water column of a British Colunlbian fjord, and show it as Fig.…”

Section: Discussionmentioning

confidence: 95%

Planktonic methane production and oxidation within the algal maximum of the pycnocline: seasonal fine-scale observations in an anoxic estuarine basin

Sieburth¹,

Donaghay²

1993

Mar. Ecol. Prog. Ser.

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“…In contrast, methane-oxidation rates were highest (2.6 ± 0.7 nM d −1 ) at the top of the anoxic zone below the oxycline (90 m), but below detection deeper in the water column. This pattern is consistent with the periphery of OMZs as sites of active methane consumption (Ward et al, 1989;Sansone et al, 2001;Naqvi et al, 2010;Pack et al, 2015), potentially with methanotrophs at these transition depths adapted for both aerobic and anaerobic methane oxidation to accommodate fluctuation in oxycline depth or oxygen intrusions. Here, metagenomic data, interpreted alongside 16S rRNA amplicon sequences and phylogenetic analyses, identify an OPU3 bacterium as a dominant member of the anoxic GD community.…”

supporting

confidence: 74%

Metagenomic Binning Recovers a Transcriptionally Active Gammaproteobacterium Linking Methanotrophy to Partial Denitrification in an Anoxic Oxygen Minimum Zone

et al. 2017

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Diverse planktonic microorganisms play a crucial role in mediating methane flux from the ocean to the atmosphere. The distribution and composition of the marine methanotroph community is determined partly by oxygen availability. The low oxygen conditions of oxygen minimum zones (OMZs) may select for methanotrophs that oxidize methane using inorganic nitrogen compounds (e.g., nitrate, nitrite) in place of oxygen. However, environmental evidence for methane-nitrogen linkages in OMZs remains sparse, as does our knowledge of the genomic content and metabolic capacity of organisms catalyzing OMZ methane oxidation. Here, binning of metagenome sequences from a coastal anoxic OMZ recovered the first near complete (95%) draft genome representing the methanotroph clade OPU3. Phylogenetic reconstruction of concatenated single copy marker genes confirmed the OPU3-like bacterium as a divergent member of the type Ia methanotrophs, with an estimated genome size half that of other sequenced taxa in this group. The proportional abundance of this bacterium peaked at 4% of the total microbial community at the top of the anoxic zone in areas of nitrite and nitrate availability but low methane concentrations. Genes mediating dissimilatory nitrate and nitrite reduction were identified in the OPU3 genome, and transcribed in conjunction with key enzymes catalyzing methane oxidation to formaldehyde and the ribulose monophosphate (RuMP) pathway for formaldehyde assimilation, suggesting partial denitrification linked to methane oxidation. Together, these data provide the first field-based evidence for methanotrophic partial denitrification by the OPU3 cluster under anoxic conditions, supporting a role for OMZs as key sites in pelagic methane turnover.

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“…Farias, unpublished). The zonal distribution of N 2 O flux across Lilley et al (1982); Ward et al (1989) a Except stations located very close to coast sampled by Yayanos (1992, 1993) where surface and subsurface values reached up to ∼1200 nM and 1400 nM, respectively, with sea-to-air fluxes as high as 4350 µmol m −2 d −1 . Cohen (1978) eastern South Pacific along latitude 32.5 • S (Charpentier et al, 2010) also shows a very large increase (by a factor of 30) in N 2 O emissions within the coastal zone off Chile.…”

Section: Off Central Chile (30 • -40 • S)mentioning

confidence: 99%

Marine hypoxia/anoxia as a source of CH<sub>4</sub> and N<sub>2</sub>O

Naqvi

Bange

Farı́as³

et al. 2010

Biogeosciences

349

240

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Abstract. We review here the available information on methane (CH 4 ) and nitrous oxide (N 2 O) from major marine, mostly coastal, oxygen (O 2 )-deficient zones formed both naturally and as a result of human activities (mainly eutrophication). Concentrations of both gases in subsurface waters are affected by ambient O 2 levels to varying degrees. Organic matter supply to seafloor appears to be the primary factor controlling CH 4 production in sediments and its supply to (and concentration in) overlying waters, with bottom-water O 2 -deficiency exerting only a modulating effect. High (micromolar level) CH 4 accumulation occurs in anoxic (sulphidic) waters of silled basins, such as the Black Sea and Cariaco Basin, and over the highly productive Namibian shelf. In other regions experiencing various degrees of O 2 -deficiency (hypoxia to anoxia), CH 4 concentrations vary from a few to hundreds of nanomolar levels. Since coastal O 2 -deficient zones are generally very productive and are sometimes located close to river mouths and submarine hydrocarbon seeps, it is difficult to differentiate any O 2 -deficiency-induced enhancement from in situ production of CH 4 in the water column and its inputs through freshwater runoff or seepage from sediments. While the role of bottom-water O 2 -deficiency in CH 4 formation appears to be secondary, even when CH 4 accumulates in O 2 -deficient subsurface waters, methanotrophic activity severely restricts its diffusive efflux to the atmosphere. As a result, an intensification or expansion of coastal O 2 -deficient zones will probably Correspondence to: S. W. A. Naqvi (naqvi@nio.org) not drastically change the present status where emission from the ocean as a whole forms an insignificant term in the atmospheric CH 4 budget. The situation is different for N 2 O, the production of which is greatly enhanced in low-O 2 waters, and although it is lost through denitrification in most suboxic and anoxic environments, the peripheries of such environments offer most suitable conditions for its production, with the exception of enclosed anoxic basins. Most O 2 -deficient systems serve as strong net sources of N 2 O to the atmosphere. This is especially true for coastal upwelling regions with shallow O 2 -deficient zones where a dramatic increase in N 2 O production often occurs in rapidly denitrifying waters. Nitrous oxide emissions from these zones are globally significant, and so their ongoing intensification and expansion is likely to lead to a significant increase in N 2 O emission from the ocean. However, a meaningful quantitative prediction of this increase is not possible at present because of continuing uncertainties concerning the formative pathways to N 2 O as well as insufficient data from key coastal regions.

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Methane oxidation in Saanich inlet during summer stratification

Cited by 62 publications

References 21 publications

Planktonic methane production and oxidation within the algal maximum of the pycnocline: seasonal fine-scale observations in an anoxic estuarine basin

Planktonic methane production and oxidation within the algal maximum of the pycnocline: seasonal fine-scale observations in an anoxic estuarine basin

Metagenomic Binning Recovers a Transcriptionally Active Gammaproteobacterium Linking Methanotrophy to Partial Denitrification in an Anoxic Oxygen Minimum Zone

Marine hypoxia/anoxia as a source of CH<sub>4</sub> and N<sub>2</sub>O

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Methane oxidation in Saanich inlet during summer stratification

Cited by 62 publications

References 21 publications

Planktonic methane production and oxidation within the algal maximum of the pycnocline: seasonal fine-scale observations in an anoxic estuarine basin

Planktonic methane production and oxidation within the algal maximum of the pycnocline: seasonal fine-scale observations in an anoxic estuarine basin

Metagenomic Binning Recovers a Transcriptionally Active Gammaproteobacterium Linking Methanotrophy to Partial Denitrification in an Anoxic Oxygen Minimum Zone

Marine hypoxia/anoxia as a source of CH&lt;sub&gt;4&lt;/sub&gt; and N&lt;sub&gt;2&lt;/sub&gt;O

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Marine hypoxia/anoxia as a source of CH<sub>4</sub> and N<sub>2</sub>O