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  • 1
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    KOSMOS 2018 Gran Canaria mesocosm study: particle flux data from sediment trap (2021)
    PANGAEA
    Details
    Publication Date: 2024-03-06
    Description: The data set compiles sinking flux data collected during a KOSMOS mesocosm experiment carried out in the frame work of the Ocean Artificial Upwelling project. The experiment was performed in the North-East Atlantic Ocean off the coast of Gran Canaria in autumn 2018 and lasted for 39 days. In this study we investigated the effect of different intensities of artificial upwelling combined with two upwelling modes (recurring additions versus one singular addition) on POC export and its potential transfer efficiency to depth. The data set includes the amounts of surface water that were exchanged with nutrient-rich deep water (from ~300 m depth). It also contains particle flux data, i.e. POC flux, PON flux, BSi flux and the corresponding C:N and C:Si ratios, as well as the carbon-specific remineralization rates, sinking velocities, porosities and remineralization length scales of sinking particles.
    Keywords: artificial upwelling; Biogenic silica, flux per day; Canarias Sea; Carbon, organic, particulate, flux, cumulative; Carbon, organic, particulate, flux per day; Carbon/Nitrogen ratio; Carbon/Silicon ratio; carbon sequestration; DATE/TIME; Deep water exchange, total; DEPTH, water, experiment; Event label; Experiment day; export flux; KOSMOS_2018; KOSMOS_2018_Mesocosm-M1; KOSMOS_2018_Mesocosm-M2; KOSMOS_2018_Mesocosm-M3; KOSMOS_2018_Mesocosm-M4; KOSMOS_2018_Mesocosm-M5; KOSMOS_2018_Mesocosm-M6; KOSMOS_2018_Mesocosm-M7; KOSMOS_2018_Mesocosm-M8; KOSMOS_2018_Mesocosm-M9; KOSMOS Gran Canaria; MESO; Mesocosm experiment; Mesocosm label; mesocosm study; Nitrogen, organic, particulate, flux, cumulative; Nitrogen, organic, particulate, flux per day; Ocean Artificial Upwelling; Ocean-artUp; Particle porosity; particle properties; Remineralisation length scale; Remineralisation rate of carbon per day; remineralization depth; remineralization rate; sinking velocity; Sinking velocity; Treatment
    Type: Dataset
    Format: text/tab-separated-values, 2473 data points
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    DATA PANGAEA
  • 2
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    KOSMOS 2018 Gran Canaria mesocosm study: water column biogeochemistry (2021)
    PANGAEA
    Details
    Publication Date: 2024-03-06
    Description: The data set compiles biogeochemical water column collected during a KOSMOS mesocosm experiment carried out in the frame work of the Ocean Artificial Upwelling project. The experiment was performed in the North-East Atlantic Ocean off the coast of Gran Canaria in autumn 2018 and lasted for 39 days. In this study we investigated the effect of different intensities of artificial upwelling combined with two upwelling modes (recurring additions versus one singular addition) on POC export and its potential transfer efficiency to depth. The data set includes the amounts of surface water that were exchanged with nutrient-rich deep water (from ~300 m depth), primary production and chlorophyll a, elemental composition of suspended particulate matter (POC, PON, C:N) and prokaryotic heterotrophic production.
    Keywords: artificial upwelling; Canarias Sea; Carbon, organic, particulate; Carbon/Nitrogen ratio; carbon sequestration; Chlorophyll a; DATE/TIME; Deep water exchange, total; DEPTH, water, experiment; Event label; Experiment day; export flux; KOSMOS_2018; KOSMOS_2018_Mesocosm-M1; KOSMOS_2018_Mesocosm-M2; KOSMOS_2018_Mesocosm-M3; KOSMOS_2018_Mesocosm-M4; KOSMOS_2018_Mesocosm-M5; KOSMOS_2018_Mesocosm-M6; KOSMOS_2018_Mesocosm-M7; KOSMOS_2018_Mesocosm-M8; KOSMOS_2018_Mesocosm-M9; KOSMOS Gran Canaria; MESO; Mesocosm experiment; Mesocosm label; mesocosm study; Nitrogen, organic, particulate; Ocean Artificial Upwelling; Ocean-artUp; particle properties; Primary production; Primary production, cumulative; Prokaryotic heterotrophic production; remineralization depth; remineralization rate; sinking velocity; Treatment
    Type: Dataset
    Format: text/tab-separated-values, 2094 data points
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    DATA PANGAEA
  • 3
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    Viability of pico- and nanophytoplankton in the Baltic Sea during spring (2019)
    Springer
    Details
    Publication Date: 2019-11-11
    Print ISSN: 1386-2588
    Electronic ISSN: 1573-5125
    Topics: Biology
    Published by Springer
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    PAPER CURRENT
  • 4
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    Effect of Intensity and Mode of Artificial Upwelling on Particle Flux and Carbon Export (2021)
    Frontiers Media
    Details
    Publication Date: 2021-10-27
    Description: Reduction of anthropogenic CO2 emissions alone will not sufficiently restrict global warming and enable the 1.5°C goal of the Paris agreement to be met. To effectively counteract climate change, measures to actively remove carbon dioxide from the atmosphere are required. Artificial upwelling has been proposed as one such carbon dioxide removal technique. By fueling primary productivity in the surface ocean with nutrient-rich deep water, it could potentially enhance downward fluxes of particulate organic carbon (POC) and carbon sequestration. In this study we investigated the effect of different intensities of artificial upwelling combined with two upwelling modes (recurring additions vs. one singular addition) on POC export, sinking matter stoichiometry and remineralization depth. We carried out a 39 day-long mesocosm experiment in the subtropical North Atlantic, where we fertilized oligotrophic surface waters with different amounts of deep water. The total nutrient inputs ranged from 1.6 to 11.0 μmol NO3– L–1. We found that on the one hand POC export under artificial upwelling more than doubled, and the molar C:N ratios of sinking organic matter increased from values around Redfield (6.6) to ∼8–13, which is beneficial for potential carbon dioxide removal. On the other hand, sinking matter was remineralized at faster rates and showed lower sinking velocities, which led to shallower remineralization depths. Particle properties were more favorable for deep carbon export in the recurring upwelling mode, while in the singular mode the C:N increase of sinking matter was more pronounced. In both upwelling modes roughly half of the produced organic carbon was retained in the water column until the end of the experiment. This suggests that the plankton communities were still in the process of adjustment, possibly due to the different response times of producers and consumers. There is thus a need for studies with longer experimental durations to quantify the responses of fully adjusted communities. Finally, our results revealed that artificial upwelling affects a variety of sinking particle properties, and that the intensity and mode with which it is applied control the strength of the effects.
    Electronic ISSN: 2296-7745
    Topics: Biology
    Published by Frontiers Media
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  • 5
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    Particle fluxes by subtropical pelagic communities under ocean alkalinity enhancement (2023)
    Copernicus Publications (EGU)
    Details
    Publication Date: 2023-12-21
    Description: Ocean alkalinity enhancement (OAE) has been proposed as a carbon dioxide removal technology (CDR) allowing for long term storage of carbon dioxide in the ocean. By changing the carbonate speciation in seawater, OAE may potentially alter marine ecosystems with implications for the biological carbon pump. Using mesocosmsthe subtropical North Atlantic, we provide first empirical insights into impacts of carbonate-based OAE on the vertical flux and attenuation of sinking particles in an oligotrophic plankton community. We enhanced total alkalinity (TA) in increments of 300 μmol kg-1, reaching up to ΔTA = 2400 µmol kg-1 compared to ambient TA. We applied a pCO2-equilibrated OAE approach, i.e. dissolved inorganic carbon (DIC) was raised simultaneously with TA to maintain seawater pCO2 in equilibrium with the atmosphere, thereby keeping perturbations of seawater carbonate chemistry moderate. The vertical flux of major elements including carbon, nitrogen, phosphorus and silicon, as well as their stoichiometric ratios (e.g. carbon-to-nitrogen) remained unaffected over 29 days of OAE. The particle properties controlling the flux attenuationinking velocities and remineralization rates also remained unaffected by OAE. However, we observed abiotic mineral precipitation at high OAE levels (ΔTA = 1800 μmol kg-1 and higher) that resulted in a substantial increase in PIC formation. The associated consumption of alkalinity reduces the efficiency of CO2 removal and emphasizes the importance of maintaining OAE within a carefully defined operating range. Our findings suggest that carbon export by oligotrophic plankton communities is insensitive to OAE perturbations using a CO2 pre-equilibrated approach. The integrity of ecosystem services is a prerequisite for large-scale application and should be further tested across a variety of nutrient-regimes and for less idealized OAE approaches.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
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    PAPER (OCEANREP)
  • 6
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    Effect of Intensity and Mode of Artificial Upwelling on Particle Flux and Carbon Export (2021)
    Frontiers
    Details
    Publication Date: 2024-02-07
    Description: Reduction of anthropogenic CO2 emissions alone will not sufficiently restrict global warming and enable the 1.5°C goal of the Paris agreement to be met. To effectively counteract climate change, measures to actively remove carbon dioxide from the atmosphere are required. Artificial upwelling has been proposed as one such carbon dioxide removal technique. By fueling primary productivity in the surface ocean with nutrient-rich deep water, it could potentially enhance downward fluxes of particulate organic carbon (POC) and carbon sequestration. In this study we investigated the effect of different intensities of artificial upwelling combined with two upwelling modes (recurring additions vs. one singular addition) on POC export, sinking matter stoichiometry and remineralization depth. We carried out a 39 day-long mesocosm experiment in the subtropical North Atlantic, where we fertilized oligotrophic surface waters with different amounts of deep water. The total nutrient inputs ranged from 1.6 to 11.0 μmol NO3– L–1. We found that on the one hand POC export under artificial upwelling more than doubled, and the molar C:N ratios of sinking organic matter increased from values around Redfield (6.6) to ∼8–13, which is beneficial for potential carbon dioxide removal. On the other hand, sinking matter was remineralized at faster rates and showed lower sinking velocities, which led to shallower remineralization depths. Particle properties were more favorable for deep carbon export in the recurring upwelling mode, while in the singular mode the C:N increase of sinking matter was more pronounced. In both upwelling modes roughly half of the produced organic carbon was retained in the water column until the end of the experiment. This suggests that the plankton communities were still in the process of adjustment, possibly due to the different response times of producers and consumers. There is thus a need for studies with longer experimental durations to quantify the responses of fully adjusted communities. Finally, our results revealed that artificial upwelling affects a variety of sinking particle properties, and that the intensity and mode with which it is applied control the strength of the effects
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
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    PAPER (OCEANREP)
  • 7
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    Respiration rate scales inversely with sinking speed of settling marine aggregates (2023)
    Public Library of Science
    Details
    Publication Date: 2024-02-07
    Description: Sinking marine aggregates have been studied for a long time to understand their role in carbon sequestration. Traditionally, sinking speed and respiration rates have been treated as independent variables, but two recent papers suggest that there is a connection albeit in contrasting directions. Here we collected recently formed (〈2 days old) aggregates from sediment traps mounted underneath mesocosms during two different experiments. The mesocosms were moored off Gran Canaria, Spain (~ 27.9 N; 15.4 E) in a coastal, sub-tropical and oligotrophic ecosystem. We determined the respiration rates of organisms (mainly heterotrophic prokaryotes) attached to aggregates sinking at different velocities. The average respiration rate of fast sinking aggregates (〉100 m d-1) was 0.12 d-1 ± 0.08 d-1 (SD). Slower sinking aggregates (〈50 m d-1) had on average higher (p 〈0.001) and more variable respiration rates (average 0.31 d-1 ± 0.16 d-1, SD). There was evidence that slower sinking aggregates had higher porosity than fast sinking aggregates, and we hypothesize that higher porosity increase the settlement area for bacteria and the respiration rate. These findings provide insights into the efficiency of the biological carbon pump and help resolve the apparent discrepancy in the recent studies of the correlation between respiration and sinking speed. © 2023 Spilling et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 8
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    Microzooplankton communities and their grazing of phytoplankton under artificial upwelling in the oligotrophic ocean (2023)
    Frontiers
    Details
    Publication Date: 2024-02-07
    Description: Ocean artificial upwelling has been suggested to boost primary production and increase harvestable resources such as fish. Yet, for this ecosystem-based approach to work, an effective energy transfer up the food web is required. Here, we studied the trophic role of microzooplankton under artificial upwelling via biomass and community composition as well as grazing rates on phytoplankton. Using mesocosms in the oligotrophic ocean, we supplied nutrient-rich deep water at varying intensities (low to high) and addition modes (a Singular large pulse or smaller Recurring pulses). Deep-water fertilization created a diatom-dominated bloom that scaled with the amount of inorganic nutrients added, but also Synechococcus -like cells, picoeukaryotes and nanophytoplankton increased in abundance with added nutrients. After 30 days, towards the end of the experiment, coccolithophores bloomed under recurring upwelling of high intensity. Across all upwelling scenarios, the microzooplankton community was dominated by ciliates, dinoflagellates (mixo- and heterotrophic) and radiolarians. Under the highest upwelling intensity, the average grazing rates of Synechococcus -like cells, picoeukaryotes and nanophytoplankton by microzooplankton were 0.35 d -1 ± 0.18 (SD), 0.09 d -1 ± 0.12 (SD), and 0.11 d -1 ± 0.13 (SD), respectively. There was little temporal variation in grazing of nanophytoplankton but grazing of Synechococcus -like cells and picoeukaryotes were more variable. There were positive correlations between abundance of these groups and grazing rates, suggesting a response in the microzooplankton community to prey availability. The average phytoplankton to microzooplankton ratio (biovolume) increased with added deep water, and this increase was highest in the Singular treatment, reaching ~30 (m 3 m -3 ), whereas the phytoplankton to total zooplankton biomass ratio (weight) increased from ~1 under low upwelling to ~6 (g g -1 ) in the highest upwelling but without a difference between the Singular and the Recurring mode. Several smaller, recurring upwelling events increased the importance of microzooplankton compared with one large pulse of deep water. Our results demonstrate that microzooplankton would be an important component for trophic transfer if artificial upwelling would be carried out at scale in the oligotrophic ocean.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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