Influence of settling organic matter quantity and quality on benthic nitrogen cycling

Albert, Séréna; Bonaglia, Stefano; Stjärnkvist, Nellie; Winder, Monika; Thamdrup, Bo; Nascimento, Francisco J. A.

doi:10.1002/lno.11730

Cited by 25 publications

(14 citation statements)

References 56 publications

(110 reference statements)

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“…The increases in primary production over time are combined with an increasing areal extent of AW, a decrease in ArW, loss of sea ice and weakening stratification. Our results suggest that these changes have led to an enhanced nitrate flux to the surface, but a higher uptake of nitrate by phytoplankton and higher primary production, therefore a decrease in summertime nutrients N-rich) to the sediments favours the recycling of nutrients back into the water column, thus reducing the loss of N from sediments through denitrification, compared to N-poor degraded material with high C:N ratios which may favour denitrification (Albert et al 2021).…”

Section: Benthic/pelagic Coupling and Loss Of N Via Denitrificationmentioning

confidence: 83%

Nutrient pathways and their susceptibility to past and future change in the Eurasian Arctic Ocean

Tuerena

Mahaffey

Henley

et al. 2021

Ambio

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Climate change is altering nutrient cycling within the Arctic Ocean, having knock-on effects to Arctic ecosystems. Primary production in the Arctic is principally nitrogen-limited, particularly in the western Pacific-dominated regions where denitrification exacerbates nitrogen loss. The nutrient status of the eastern Eurasian Arctic remains under debate. In the Barents Sea, primary production has increased by 88% since 1998. To support this rapid increase in productivity, either the standing stock of nutrients has been depleted, or the external nutrient supply has increased. Atlantic water inflow, enhanced mixing, benthic nitrogen cycling, and land–ocean interaction have the potential to alter the nutrient supply through addition, dilution or removal. Here we use new datasets from the Changing Arctic Ocean program alongside historical datasets to assess how nitrate and phosphate concentrations may be changing in response to these processes. We highlight how nutrient dynamics may continue to change, why this is important for regional and international policy-making and suggest relevant research priorities for the future.

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Section: Benthic/pelagic Coupling and Loss Of N Via Denitrificationmentioning

confidence: 83%

Nutrient pathways and their susceptibility to past and future change in the Eurasian Arctic Ocean

Tuerena

Mahaffey

Henley

et al. 2021

Ambio

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“…In addition, due to the short lifespan of messenger RNA (mRNA) transcripts, the measurements taken upon experiment termination only represent a snapshot of the functional response to OM quality. Nevertheless, previous studies did demonstrate increased denitrification rates in response to cyanobacteria amendment 33 , 39 . As cyanobacteria are typically rich in N, their settlement on the seafloor can lead to mineralization that releases large quantities of dissolved inorganic nitrogen (DIN), and ultimately fuels denitrification 39 .…”

Section: Discussionmentioning

confidence: 76%

“…Nevertheless, previous studies did demonstrate increased denitrification rates in response to cyanobacteria amendment 33 , 39 . As cyanobacteria are typically rich in N, their settlement on the seafloor can lead to mineralization that releases large quantities of dissolved inorganic nitrogen (DIN), and ultimately fuels denitrification 39 .…”

Section: Discussionmentioning

confidence: 76%

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Phytoplankton settling quality has a subtle but significant effect on sediment microeukaryotic and bacterial communities

Albert

Hedberg

Motwani

et al. 2021

Sci Rep

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In coastal aphotic sediments, organic matter (OM) input from phytoplankton is the primary food resource for benthic organisms. Current observations from temperate ecosystems like the Baltic Sea report a decline in spring bloom diatoms, while summer cyanobacteria blooms are becoming more frequent and intense. These climate-driven changes in phytoplankton communities may in turn have important consequences for benthic biodiversity and ecosystem functions, but such questions are not yet sufficiently explored experimentally. Here, in a 4-week experiment, we investigated the response of microeukaryotic and bacterial communities to different types of OM inputs comprising five ratios of two common phytoplankton species in the Baltic Sea, the diatom Skeletonema marinoi and filamentous cyanobacterium Nodularia spumigena. Metabarcoding analyses on 16S and 18S ribosomal RNA (rRNA) at the experiment termination revealed subtle but significant changes in diversity and community composition of microeukaryotes in response to settling OM quality. Sediment bacteria were less affected, although we observed a clear effect on denitrification gene expression (nirS and nosZ), which was positively correlated with increasing proportions of cyanobacteria. Altogether, these results suggest that future changes in OM input to the seafloor may have important effects on both the composition and function of microbenthic communities.

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“…To our knowledge, no investigation has dissociated and quantified the respective effects of OM quantity and source on the sediment biodegradability. Recently, Albert et al, 2021 have attempted to highlight the prevalent role of the OM quality on the benthic processes in coastal sediments, but in a context dominated rather uniform OM source materials (spring and summer plankton).…”

Section: Introductionmentioning

confidence: 99%

Linking sediment biodegradability with its origin in shallow coastal environments

Louis

Laverman

Jardé

et al. 2021

Preprint

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Abstract. In coastal areas and estuaries, such as those encountered in the western part of France (Brittany region), the recycling of carbon and nutrients from sediments can participate in the development of micro and macro-algal blooms with harmful consequences for these ecosystems. One of the main processes controlling this recycling is the microbial mineralization of sedimentary organic matter (SOM). Mineralization is controlled by the origin, quantity and accessibility of the SOM, three factors whose relative importance remain, however, poorly quantified, mainly due to the great diversity of OM sources in coastal areas. The first objective of the present work was to assess the variability of the SOM origin at the regional scale representative of the complexity of the sources likely to be involved. The second objective was to determine the link between the SOM origin and its biodegradability, and how the OM sources can drive nutrient dynamics at the sediment-water interface. To this end, a broad sediment sampling campaign was carried out on Brittany mudflats, particularly affected by the eutrophication, during the spring period. A total of 200 samples were collected at 45 sites. They were characterized by their porosity and grain-size, as well as their chemical composition through elemental, isotopic and molecular biomarker analysis. A wide range of OM sources were identified in the sediments, including both natural (bacteria, algae, macrophytes, terrestrial plants), and anthropogenic (combustion products, crude oil, petroleum products – e.g. from the processing of crude oil at refineries- and fecal matter) sources. Sediment slurry incubations were carried out to determine the spatial variability of potential mineralization rates under oxic conditions. In addition, the measurements of NH4+ and PO4 fluxes at the sediment-water interface were made from sediment core incubations under realistic redox conditions of sediment. The physical and chemical sedimentary characteristics explained 58 % of the variability of mineralization rates under oxic conditions, with a negligible independent effect of the SOM origin (3 %). Conversely, under insitu redox conditions, the prevalent role of SOM origin over quantity/accessibility on the sediment biodegradability was highlighted with a significant effect 5 and 1.5 fold higher on the PO4 and NH4+ fluxes respectively. The anthropogenic inputs from the watershed to the coastal sediment, through agricultural runoff and/or sewages discharge, seem to significantly drive the nutrient dynamics at the sediment-water interface. Higher values of NH4+ and PO4 fluxes were measured for the sediment with a chemical composition impacted by human activities.

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Influence of settling organic matter quantity and quality on benthic nitrogen cycling

Cited by 25 publications

References 56 publications

Nutrient pathways and their susceptibility to past and future change in the Eurasian Arctic Ocean

Nutrient pathways and their susceptibility to past and future change in the Eurasian Arctic Ocean

Phytoplankton settling quality has a subtle but significant effect on sediment microeukaryotic and bacterial communities

Linking sediment biodegradability with its origin in shallow coastal environments

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