Redox effects on the microbial degradation of refractory organic matter in marine sediments

Reimers, Clare E.; Alleau, Yvan; Bauer, James E.; Delaney, Jennifer A.; Girguis, Peter R.; Schrader, Paul S.; Stecher, Hilmar A.

doi:10.1016/j.gca.2013.08.004

Cited by 51 publications

(32 citation statements)

References 83 publications

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“…Consequently, the reduced gradient of oxygen in seawater near the top inhibits the diffusion of oxygen from the sediment surface to the deeper depth and a relatively reduced environment is formed in a shallower depth of the sediment. Other electron acceptors, such as NO 3 ‐ , Fe 3+ , Mn 4+ , and SO 4 2‐ , may be subsequently reduced and play more important roles in the acquisition of carbon and energy by microorganisms (Reimers et al, ). Moreover, a greater proportion of Deltaproteobacteria related to sulfate reduction (e.g., NB1‐j) and syntrophic sulfate reduction ( Syntrophobacteales ) were detected at the same layer, an indicator of low or depleted oxygen in the sediment (Baumgartner et al, ; Orcutt et al, ).…”

Section: Discussionmentioning

confidence: 99%

Bacterial Community on a Guyot in the Northwest Pacific Ocean Influenced by Physical Dynamics and Environmental Variables

Liu

Huo

et al. 2019

JGR Biogeosciences

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Bacterial communities in sediments of the Caiwei Seamount, a typical guyot located in the northwest Pacific Ocean, were investigated. A total of 727,879 16S ribosomal RNA gene sequences were retrieved from eight sediment samples of the top (mean depth = 1,407 m) and the base (mean depth = 5,525 m) of the guyot through pyrosequencing of V6 hypervariable region and clustered into 32,844 operational taxonomic units. Abundant‐weighted UniFrac metric partitioned bacterial assemblies into two categories (the top community and the base community) by principal coordinates analysis, consisting with the grouping of sampling stations by environmental variables. Differences in depth and physicochemical properties of the surrounding environment (e.g., concentrations of dissolved oxygen and geochemical elements) between the top and the base of the guyot may cause this partition of bacterial communities, whereas the typical fluid flow around the guyot may potentially contribute to the bacterial dispersal and environmental homogeneity along the same layer, resulting in the similarity of bacterial community structure within the same region (the top or the base). The surface sediment on the top of the guyot harbored the bacterial communities with greater diversity and evenness, represented by Gamma‐ and Deltaproteobacteria involved in sulfur cycling. At the base of the guyot, Gammaproteobacteria related to sulfur‐oxidizing and Chloroflexi functioning in the decomposition of refractory organic matter dominated, suggesting that the redox condition at the interface of the sediment and the water can influence bacteria‐mediated elemental cycling, eventually shaping the physicochemical and geological characteristics of a guyot.

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Section: Discussionmentioning

confidence: 99%

Bacterial Community on a Guyot in the Northwest Pacific Ocean Influenced by Physical Dynamics and Environmental Variables

Liu

Huo

et al. 2019

JGR Biogeosciences

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“…These observations and the fact that the benthic O 2 consumption exceeds the local primary production strongly suggest that terrestrial carbon supply was important in sustaining the benthic community and that the turnover of refractory organic material was stimulated in these sediments. Sediment reworking and dynamic redox conditions have been shown to stimulate degradation of organic material (Aller 1994;Kristensen and Holmer 2001;Reimers et al 2013;Aller 2014). The numerous burrows being intensively irrigated by A. filiformis induce highly dynamic redox conditions in the upper sediment layers, and this may indeed have facilitated further degradation of terrestrial material than would otherwise be expected in these high-deposition environments.…”

Section: Benthic Carbon and Nutrient Turnover In A Highly Irrigated Cmentioning

confidence: 99%

Benthic Carbon Mineralization and Nutrient Turnover in a Scottish Sea Loch: An Integrative In Situ Study

et al. 2016

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Based on in situ microprofiles, chamber incubations and eddy covariance measurements, we investigated the benthic carbon mineralization and nutrient regeneration in a *65-m-deep sedimentation basin of Loch Etive, UK. The sediment hosted a considerable amount of infauna that was dominated by the brittle star A. filiformis. The numerous burrows were intensively irrigated enhancing the benthic in situ O 2 uptake by *50 %, and inducing highly variable redox conditions and O 2 distribution in the surface sediment as also documented by complementary laboratory-based planar optode measurements. The average benthic O 2 exchange as derived by chamber incubations and the eddy covariance approach were similar (14.9 ± 2.5 and 13.1 ± 9.0 mmol m -2 day -1 ) providing confidence in the two measuring approaches. Moreover, the non-invasive eddy approach revealed a flow-dependent benthic O 2 flux that was partly ascribed to enhanced ventilation of infauna burrows during periods of elevated flow rates. The ratio in exchange rates of RCO 2 and O 2 was close to unity, confirming that the O 2 uptake was a good proxy for the benthic carbon mineralization in this setting. The infauna activity resulted in highly dynamic redox conditions that presumably facilitated an efficient degradation of both terrestrial and marine-derived organic material. The complex O 2 dynamics of the burrow environment also concurrently stimulated nitrification and coupled denitrification rates making the sediment an efficient sink for bioavailable nitrogen. Furthermore, bioturbation mediated a high efflux of dissolved phosphorus and silicate. The study documents a high spatial and temporal variation in benthic solute exchange with important implications for benthic turnover of organic carbon and nutrients. However, more long-term in situ investigations with like approaches are required to fully understand how environmental events and spatio-temporal variations interrelate to the overall biogeochemical functioning of coastal sediments.

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“…3a). The largest decrease was observed at the 1.0-2.0 and 2.0-4.0 cm depth intervals spanning the approximate depth of the oxic-anoxic interface, one of the most active zones of organic-matter mineralization by heterotrophic mi- croorganisms (Reimers et al, 2013). Vertical profiles of TN and the C : N on days 0 and 14 followed a similar trend with the most marked changes occurring at the 1.0-2.0 and 2.0-4.0 cm depth intervals.…”

Section: Sediment Characteristics and Remineralization Ratiosmentioning

confidence: 97%

Response to Reviewer 2

Anonymous

2017

Preprint

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The treatment of organic wastes remains one of the key sustainability challenges facing the growing global aquaculture industry. Bioremediation systems based on coupled bioturbation-microbial processing offer a promising route for waste management. We present, for the first time, a combined biogeochemical-molecular analysis of the short-term performance of one such system that is designed to receive nitrogen-rich particulate aquaculture wastes. Using sea cucumbers (Holothuria scabra) as a model bioturbator we provide evidence that adjusting the waste C : N from 5 : 1 to 20 : 1 promoted a shift in nitrogen cycling pathways towards the dissimilatory nitrate reduction to ammonium (DNRA), resulting in net NH + 4 efflux from the sediment. The carbon amended treatment exhibited an overall net N 2 uptake, whereas the control receiving only aquaculture waste exhibited net N 2 production, suggesting that carbon supplementation enhanced nitrogen fixation. The higher NH + 4 efflux and N 2 uptake was further supported by meta-genome predictions that indicate that organic-carbon addition stimulated DNRA over denitrification. These findings indicate that carbon addition may potentially result in greater retention of nitrogen within the system; however, longer-term trials are necessary to determine whether this nitrogen retention is translated into improved sea cucumber biomass yields. Whether this truly constitutes a remediation process is open for debate as there remains the risk that any increased nitrogen retention may be temporary, with any subsequent release potentially raising the eutrophication risk. Longer and larger-scale trials are required before this approach may be validated with the complexities of the in-system nitrogen cycle being fully understood.

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Redox effects on the microbial degradation of refractory organic matter in marine sediments

Cited by 51 publications

References 83 publications

Bacterial Community on a Guyot in the Northwest Pacific Ocean Influenced by Physical Dynamics and Environmental Variables

Bacterial Community on a Guyot in the Northwest Pacific Ocean Influenced by Physical Dynamics and Environmental Variables

Benthic Carbon Mineralization and Nutrient Turnover in a Scottish Sea Loch: An Integrative In Situ Study

Response to Reviewer 2

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