The fate of organic carbon in marine sediments - New insights from recent data and analysis

Earth-Science Reviews, Год журнала: 2020, Номер 204, С. 103146 - 103146

Опубликована: Фев. 29, 2020

Язык: Английский

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Connected macroalgal‐sediment systems: blue carbon and food webs in the deep coastal ocean

Ecological Monographs, Год журнала: 2019, Номер 89(3)

Опубликована: Май 23, 2019

Abstract Macroalgae drive the largest CO 2 flux fixed globally by marine macrophytes. Most of resulting biomass is exported through coastal ocean as detritus and yet almost no field measurements have verified its potential net sequestration in sediments. This gap limits scope for inclusion macroalgae within blue carbon schemes that support globally, understanding role their plays distal food webs. Here, we pursued three lines evidence (eDNA sequencing, Bayesian Stable Isotope Mixing Modeling, benthic‐pelagic process measurements) to generate needed, novel data addressing this gap. To end, a 13‐month study was undertaken at deep sedimentary site English Channel, surrounding shoreline Plymouth, UK. The eDNA sequencing indicated from most shores occurs deep, sediments, with supply reflecting seasonal ecology individual species. stable isotope mixing modeling [C N] highlighted vital supporting benthic web (22–36% diets), especially when other resources are seasonally low. magnitude uptake sediments varies seasonally, an average organic macroalgal 8.75 g C·m −2 ·yr −1 . particulate 58.74 , two rates corresponding 4–5% 26–37% those associated mangroves, salt marshes, seagrass beds, systems more readily identified habitats. These provide important first estimates help contextualize importance macroalgal‐sedimentary connectivity webs, measured fluxes constrain global can policy development. At time climate change mitigation foreground environmental development, embracing full regulation via necessity.

Язык: Английский

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Sediment oxygen consumption: Role in the global marine carbon cycle

Earth-Science Reviews, Год журнала: 2022, Номер 228, С. 103987 - 103987

Опубликована: Март 12, 2022

The seabed plays a key role in the marine carbon cycle as a) terminal location of aerobic oxidation organic matter, b) greatest anaerobic bioreactor, and c) repository for reactive on Earth. We compiled data oxygen uptake sediments with objective to understand constraints mineralization rates deposited matter their relation environmental parameters. database includes nearly 4000 O2 is available supplementary material. It also information bottom water concentration, penetration depth, geographic position, full sources. present different situ ex approaches measure total (TOU) diffusive (DOU) discuss robustness towards methodological errors statistical uncertainty. transport through benthic boundary layers, diffusion- fauna-mediated uptake, coupling respiration processes. Five regional examples are presented illustrate diversity seabed: Eutrophic seas, minimum zones, abyssal plains, mid-oceanic gyres, hadal trenches. A multiple correlation analysis shows that primarily controlled by ocean depth sea surface primary productivity. scales DOU according power law breaks down under gyres. developed model was used draw global map rates. Respiratory coefficients, differentiated regions ocean, were convert oxidation. resulting budget an 212 Tmol C yr−1 5-95% confidence interval 175-260 yr−1. comparison flux particulate (POC) from photic waters deep sea, determined sediment trap studies, suggests deficit sedimentation at 2000 m about 70% relative turnover underlying seabed. At margins, rivers vegetated coastal ecosystems contributes greatly may even exceed phytoplankton production inner continental shelf.

Язык: Английский

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The impact of mobile demersal fishing on carbon storage in seabed sediments

Global Change Biology, Год журнала: 2022, Номер 28(9), С. 2875 - 2894

Опубликована: Фев. 17, 2022

Abstract Subtidal marine sediments are one of the planet's primary carbon stores and strongly influence oceanic sink for atmospheric CO 2 . By far most widespread human activity occurring on seabed is bottom trawling/dredging fish shellfish. A global first‐order estimate suggested mobile demersal fishing activities may cause 0.16–0.4 Gt organic (OC) to be remineralized annually from sediment (Sala et al., 2021). There are, however, many uncertainties in this calculation. Here, we discuss potential drivers change OC due conduct a literature review, synthesizing studies where interaction has been directly investigated. Under certain environmental settings, hypothesize that would reduce lower production flora fauna, loss fine flocculent material, increased resuspension, mixing transport oxygen exposure. Reductions offset varying extents by reduced faunal bioturbation community respiration, off‐shelf increases resuspension nutrients. Studies which investigated impact stocks had mixed results. finding no significant effect was reported 61% 49 investigations; 29% activities, with 10% reporting higher OC. In relation remineralization rates within seabed, four investigations decreased remineralization, three rates. Patterns experimental characteristics between different outcomes were largely indistinct. More evidence urgently needed accurately quantify anthropogenic physical disturbance settings incorporate full evidence‐based considerations into management.

Язык: Английский

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Carbon on the Northwest European Shelf: Contemporary Budget and Future Influences

Frontiers in Marine Science, Год журнала: 2020, Номер 7

Опубликована: Март 18, 2020

A carbon budget for the northwest European continental shelf seas (NWES) was synthesised using available estimates coastal, pelagic and benthic stocks flows. Key uncertainties were identified effect of future impacts on assessed. The water contains between 210 230 Tmol absorbs 1.3 3.3 from atmosphere annually. Off-shelf transport burial in sediments account 60-100% 0-40% outputs NWES, respectively. Both these fluxes remain poorly constrained by observations resolving their magnitudes relative importance is a key research priority. Pelagic are dominated inorganic carbon. Shelf contain largest stock carbon, with 520 1600 stored top 0.1 m sea bed. Coastal habitats such as salt marshes mud flats large amounts per unit area but total small compared to due smaller spatial extent. will continue increase rising concentration atmospheric CO2, associated pH decrease. flows also likely be significantly affected increasing acidity temperature, circulation changes net impact uncertain. Benthic temperature acidity, decreasing oxygen concentrations, although interrelated uncertain major knowledge gap. bottom trawling unique amongst we consider that it widespread directly manageable, its vulnerable level rise strongly impacted management decisions. Local, national regional actions have potential protect or enhance storage, ultimately global governance, via controls emissions, has greatest influence long-term fate northwestern shelf.

Язык: Английский

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Soothsaying DOM: A Current Perspective on the Future of Oceanic Dissolved Organic Carbon

Frontiers in Marine Science, Год журнала: 2020, Номер 7

Опубликована: Май 25, 2020

The vast majority of freshly produced oceanic dissolved organic carbon (DOC) is derived from marine phytoplankton, then rapidly recycled by heterotrophic microbes. A small fraction this DOC survives long enough to be routed the interior ocean, which houses largest and oldest reservoir. reactivity depends upon its intrinsic chemical composition extrinsic environmental conditions. Therefore, recalcitrance an emergent property that analytically difficult constrain. New isotopic techniques track flow through individual molecules show promise in unveiling specific biosynthetic or degradation pathways control metabolic turnover accumulation deep ocean. However, a multivariate approach required constrain current fluxes so we may better predict how cycling will altered with continued climate change. Ocean warming, acidification, oxygen depletion upset balance between primary production reworking DOC, thus modifying amount and/or recalcitrant DOC. Climate change anthropogenic activities enhance mobilization terrestrial stimulate coastal waters, but it unclear would affect flux open Here, assess knowledge on cycle identify research gaps must addressed successfully implement use global scale models.

Язык: Английский

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Quality Not Quantity: Prioritizing the Management of Sedimentary Organic Matter Across Continental Shelf Seas

Geophysical Research Letters, Год журнала: 2022, Номер 49(5)

Опубликована: Март 8, 2022

Abstract Disturbance of marine sediments results in the remineralization sedimentary organic matter (OM) and impacts upon natural burial processes. Management interventions which restrict or remove activities that cause seabed disturbance may offer effective strategies to protect most vulnerable these shelf sea OM stores, offering new opportunities deliver climate mitigation actions. While largest quantities are often stored expansive offshore regions continental shelves might therefore suggest appropriate zones for management our highlight generally contain low reactivity. Conversely, inshore coastal store significant highly reactive is at greater risk when disturbed. The marked spatial disparities between reactivity across environments highlights need focus emergent policy future toward protection sediments.

Язык: Английский

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A global assessment of the mixed layer in coastal sediments and implications for carbon storage

Nature Communications, Год журнала: 2022, Номер 13(1)

Опубликована: Авг. 20, 2022

Abstract The sediment-water interface in the coastal ocean is a highly dynamic zone controlling biogeochemical fluxes of greenhouse gases, nutrients, and metals. Processes sediment mixed layer (SML) control transfer reactivity both particulate dissolved matter interfaces. Here we map global distribution SML based on excess 210 Pb ( ex ) profiles then use neural network model to upscale these observations. We show that regions such as large estuaries have thicker SMLs than most oceanic sediments. Organic carbon preservation are inversely related mixing stimulates oxidation sediments which enhances organic decomposition. Sites with thickness >60 cm usually lower accumulation rates (<50 g C m −2 yr −1 total carbon/specific surface area ratios (<0.4 mg ). Our scale observations reveal reworking can accelerate degradation reduce storage

Язык: Английский

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The Microbial Ecology of Estuarine Ecosystems

Annual Review of Marine Science, Год журнала: 2023, Номер 16(1), С. 335 - 360

Опубликована: Июль 7, 2023

Human civilization relies on estuaries, and many estuarine ecosystem services are provided by microbial communities. These include high rates of primary production that nourish harvests commercially valuable species through fisheries aquaculture, the transformation terrestrial anthropogenic materials to help ensure water quality necessary support recreation tourism, mutualisms maintain blue carbon accumulation storage. Research ecology underlies in estuaries has expanded greatly across a range environments, including water, sediment, biofilms, biological reefs, stands seagrasses, marshes, mangroves. Moreover, application new molecular tools improved our understanding diversity genomic functions microbes. This review synthesizes recent research habitats contributions microbes food webs, elemental cycling, interactions with plants animals, highlights novel insights advances genomics.

Язык: Английский

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Key role of bacteria in the short‐term cycling of carbon at the abyssal seafloor in a low particulate organic carbon flux region of the eastern Pacific Ocean

Limnology and Oceanography, Год журнала: 2018, Номер 64(2), С. 694 - 713

Опубликована: Ноя. 16, 2018

Abstract The cycling of carbon (C) by benthic organisms is a key ecosystem function in the deep sea. Pulse‐chase experiments are designed to quantify this process, yet few studies have been carried out using abyssal (3500–6000 m) sediments and only handful undertaken situ. We undertook eight situ pulse‐chase three strata (4050–4200 m water depth) separated tens hundreds kilometers eastern Clarion‐Clipperton Fracture Zone (CCFZ). These demonstrated that bacteria dominated consumption phytodetritus over short (~ 1.5 d) time scales, with metazoan macrofauna playing minor role. results contrast other comparable study, where assimilation (2.5 scales eutrophic NE Atlantic. also were capable converting dissolved inorganic C into biomass showed process can occur at rates as high bacterial algal‐derived organic C. This demonstrates potential importance uptake ecosystems region. It alludes possibility some incorporation our algal‐addition may resulted from labeled initially respired unstudied organisms. Our findings reveal short‐term habitats CCFZ provide important information on functioning an area targeted for commercial‐scale, deep‐sea mining activities.

Язык: Английский

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