Nitrous oxide cycling in the water column and sediments of the oxygen minimum zone, eastern subtropical North Pacific, Southern California, and Northern Mexico (23°N-34°N)

Townsend‐Small, Amy; Prokopenko, Maria G.; Berelson, William M.

doi:10.1002/2013jc009580

Cited by 19 publications

(24 citation statements)

References 69 publications

(165 reference statements)

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“…Thus, the SMB water column oxygen gradient reported by Townsend‐Small et al. () likely captures the general pattern of oxygen availability that these time‐average foraminifera would have experienced, independent of seasonal or annual perturbations to the basin.…”

Section: Methodsmentioning

confidence: 69%

“…Water column samples, including near bottom‐waters (~892 m), were collected at 33°50.21′N, 119°01.75′W using a conductivity, temperature, and depth device. Water column measurements revealed hypoxic (<1.43 ml/L) conditions by ~600 m (Figure ; Townsend‐Small et al., ). In addition, because foraminifera were not stained, samples represent both living and recently dead individuals.…”

Section: Methodsmentioning

confidence: 95%

“…Accompanying dissolved oxygen and temperature data were compiled from a cruise to SMB in October 2009 (Townsend‐Small, Prokopenko, & Berelson, ). Water column samples, including near bottom‐waters (~892 m), were collected at 33°50.21′N, 119°01.75′W using a conductivity, temperature, and depth device.…”

Section: Methodsmentioning

confidence: 99%

“…Star marks the location where water column temperature and dissolved oxygen concentrations were measured by Townsend‐Small et al. (). (b) SMB depth profiles of water temperature (dashed line) and dissolved oxygen concentrations (solid line; Townsend‐Small et al., )…”

Section: Introductionmentioning

confidence: 99%

“…(). (b) SMB depth profiles of water temperature (dashed line) and dissolved oxygen concentrations (solid line; Townsend‐Small et al., )…”

Section: Introductionmentioning

confidence: 99%

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Ecophenotypic responses of benthic foraminifera to oxygen availability along an oxygen gradient in the California Borderland

Keating-Bitonti

Payne

2017

Marine Ecology

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Spatial variation in environmental conditions can elicit predictable size and morphological responses in marine organisms through influences on physiology. Thus, spatial and temporal variation in marine organism size and shape are often used to infer paleoenvironmental conditions, such as dissolved oxygen concentrations. Benthic foraminifera commonly serve as a tool for reconstructing past ocean oxygen levels. For example, benthic foraminiferal species assemblages, within‐ and among‐species patterns of test morphology, and geochemical analyses of carbonate tests are often employed to reconstruct past marine conditions. In this study, we measured the sizes and shapes of modern foraminifera representing four species that inhabit a steep oxygen gradient in the Santa Monica Basin on the Southern California Borderland with the aim of quantifying the influence of oxygen availability on foraminiferal morphology, both within and among species. Most foraminifera rely on aerobic respiration, but the four benthic foraminifera from the Santa Monica Basin do not show the predicted size and morphological responses to variations in dissolved oxygen concentrations based on first principles of cell physiology: Bolivina spissa shows no volume or volume‐to‐surface area response, Uvigerina peregrina increases in both test volume and volume‐to‐surface area ratio with decreasing dissolved oxygen concentrations, and both Bolivina argentea and Loxostomum pseudobeyrichi decrease in test volume, but only L. pseudobeyrichi shows a decrease in test volume‐to‐surface area ratio with decreasing oxygen concentrations as expected from physiological predictions. These findings imply that the morphological responses of individual foraminiferal species are not necessarily representative of the responses of other foraminiferal species within the community. Our findings further suggest that these species use physiological strategies such as depressed metabolic rates and alternative energy metabolisms to persist in low oxygen environments and, therefore, cannot be used in any simple way as paleo‐oxygen indicators. Should Proterozoic (1,000–542 million years ago) protists have possessed metabolic strategies similar to foraminifera, the sizes and shapes of protists in the fossil record may not usefully constrain ambient oxygen conditions during the appearance and initial taxonomic radiation of heterotrophic eukaryotes.

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Section: Methodsmentioning

confidence: 69%

Section: Methodsmentioning

confidence: 95%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…(). (b) SMB depth profiles of water temperature (dashed line) and dissolved oxygen concentrations (solid line; Townsend‐Small et al., )…”

Section: Introductionmentioning

confidence: 99%

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Ecophenotypic responses of benthic foraminifera to oxygen availability along an oxygen gradient in the California Borderland

Keating-Bitonti

Payne

2017

Marine Ecology

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Particulate δ¹⁵N in laminated marine sediments as a proxy for mixing between the California Undercurrent and the California Current: A proof of concept

Tems

Berelson

Prokopenko

2015

Geophysical Research Letters

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The measurements of particulate δ 15 N in coastal marine laminated sediments provide a high-resolution proxy for fluctuations in the intensity of denitrification in the water column. In the eastern tropical North Pacific oxygen minimum zone, this denitrification signal is transported northward by the California Undercurrent, thus serving as a tracer of ocean circulation. This is verified through comparisons between salinity in the thermocline off Southern California (Santa Monica Basin) and the difference between δ 15 N sed within age equivalent sediments from a southern (Pescadero Slope) and northern (Santa Monica

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Decadal to centennial fluctuations in the intensity of the eastern tropical North Pacific oxygen minimum zone during the last 1200 years

et al. 2016

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Oxygen minimum zones (OMZs), located below highly productive marine regions, are sites of microbially mediated denitrification and biogeochemical cycling that have global significance. The intensity of OMZs fluctuates naturally; however, the degree of these fluctuations and a comprehensive understanding of the factors that drive these fluctuations on decadal to centennial time scales is lacking. Our high-resolution (near-annual) record of δ 15 N sed from laminated sediments at the Pescadero Slope in the Gulf of California (eastern tropical North Pacific) fluctuates between maximum values of 10.5‰ and minimum values of 8.0‰ over the past 1200 years. An analysis of the relationship between δ 15 NO 3 À and [O 2 ] in the water column suggests that the observed range of δ 15 N sed values is equivalent to an approximately 8 μM fluctuation in O 2 content and that these changes can occur in less than 25 years. Our findings show that the OMZ typically intensifies quickly and contracts gradually; the average rate of OMZ intensification (À0.24 μM O 2 /yr) is twice as fast as the rate of OMZ reoxygenation. Spectral analyses of the δ 15 N sed record and Br/Cl counts, with the latter are used as a proxy for organic carbon preservation, suggest that the Pacific Decadal Oscillation and the Suess (deVries) solar cycle (solar irradiance) may influence the intensity of the OMZ and carbon production/export during the late Holocene. Coherence between δ 15 N sed and weight percent organic carbon also suggests that similar mechanisms influence both OMZ fluctuations and variation in organic carbon production/export.

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Nitrous oxide cycling in the water column and sediments of the oxygen minimum zone, eastern subtropical North Pacific, Southern California, and Northern Mexico (23°N-34°N)

Cited by 19 publications

References 69 publications

Ecophenotypic responses of benthic foraminifera to oxygen availability along an oxygen gradient in the California Borderland

Ecophenotypic responses of benthic foraminifera to oxygen availability along an oxygen gradient in the California Borderland

Particulate δ¹⁵N in laminated marine sediments as a proxy for mixing between the California Undercurrent and the California Current: A proof of concept

Decadal to centennial fluctuations in the intensity of the eastern tropical North Pacific oxygen minimum zone during the last 1200 years

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Nitrous oxide cycling in the water column and sediments of the oxygen minimum zone, eastern subtropical North Pacific, Southern California, and Northern Mexico (23°N-34°N)

Cited by 19 publications

References 69 publications

Ecophenotypic responses of benthic foraminifera to oxygen availability along an oxygen gradient in the California Borderland

Ecophenotypic responses of benthic foraminifera to oxygen availability along an oxygen gradient in the California Borderland

Particulate δ15N in laminated marine sediments as a proxy for mixing between the California Undercurrent and the California Current: A proof of concept

Decadal to centennial fluctuations in the intensity of the eastern tropical North Pacific oxygen minimum zone during the last 1200 years

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Product

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Particulate δ¹⁵N in laminated marine sediments as a proxy for mixing between the California Undercurrent and the California Current: A proof of concept