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  • 2020-2024  (23)
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  • 11
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    KOSMOS mesocosm experiment Gran Canaria 2019 on testing the effect of nutrient composition (Si:N) during artificial upwelling: phytoplankton microscopy (2023)
    PANGAEA
    Details
    Publication Date: 2024-06-12
    Description: Abundance and biovolume data of the community of larger phytoplankton from the mesocosm experiment conducted in the Canary Islands in autumn 2019. Depth-integrated (0-2.5m) water samples were taken in 2-days intervals over the course of 33 days and autotrophic taxa assessed to the lowest taxonomic level possible using Utermöhl microscopy. Only taxa larger than approx. 〉5 µm could be considered with this method. Biovolume was calculated based on geometrical measurements (dominant taxa) or the literature (rare taxa). Carbon biomass estimates were purposefully not provided, as the standard literature conversion factors from biovolume to carbon biomass did not apply to many of our samples, likely due to low carbon density within cells. Predominantly mixotrophic or heterotrophic taxa are not provided in this dataset. The upwelling treatment started on day 6. Methodological details in Goldenberg et al. (doi:10.3389/fmars.2022.1015188).
    Keywords: Amphora sp.; Amphora sp., biovolume; AQUACOSM; artificial upwelling; Calculated; Canarias Sea; carbon dioxide removal; CDRmare; Cerataulina pelagica; Cerataulina pelagica, biovolume; Chaetoceros cf. aequatorialis; Chaetoceros cf. aequatorialis, biovolume; Chaetoceros cf. compressus; Chaetoceros cf. compressus, biovolume; Chaetoceros cf. curvisetus; Chaetoceros cf. curvisetus, biovolume; Chaetoceros cf. lauderi; Chaetoceros cf. lauderi, biovolume; Chaetoceros cf. lorenzianus; Chaetoceros cf. lorenzianus, biovolume; Chaetoceros cf. tenuissimus; Chaetoceros cf. tenuissimus, biovolume; Chaetoceros decipiens; Chaetoceros decipiens, biovolume; Chaetoceros densus; Chaetoceros densus, biovolume; Chrysochromulina sp.; Chrysochromulina sp., biovolume; Climacodium cf. frauenfeldianum; Climacodium cf. frauenfeldianum, biovolume; Coccolithophoridae, biovolume; Coccolithophoridae, total; Coscinodiscus cf. pavillardii; Coscinodiscus cf. pavillardii, biovolume; Coscinodiscus sp.; Coscinodiscus sp., biovolume; Cylindrotheca closterium; Cylindrotheca closterium, biovolume; Cylindrotheca sp.; Cylindrotheca sp., biovolume; Dactyliosolen cf. blavyanus; Dactyliosolen cf. blavyanus, biovolume; Dactyliosolen cf. fragilissimus; Dactyliosolen cf. fragilissimus, biovolume; DAM CDRmare - Test-ArtUp: Road testing ocean artificial upwelling; DATE/TIME; Day of experiment; diatoms; Diatoms; Diatoms, biovolume; Dictyocha fibula; Dictyocha fibula, biovolume; Diploneis sp.; Diploneis sp., biovolume; Event label; Flagellates; Flagellates, biovolume; Flagellates indeterminata, oval; Flagellates indeterminata, oval, biovolume; GC2019; Guinardia delicatula; Guinardia delicatula, biovolume; Guinardia striata; Guinardia striata, biovolume; Hemiaulus cf. sinensis; Hemiaulus cf. sinensis, biovolume; KOSMOS; KOSMOS_2019; KOSMOS_2019_Mesocosm-M1; KOSMOS_2019_Mesocosm-M2; KOSMOS_2019_Mesocosm-M3; KOSMOS_2019_Mesocosm-M4; KOSMOS_2019_Mesocosm-M5; KOSMOS_2019_Mesocosm-M6; KOSMOS_2019_Mesocosm-M7; KOSMOS_2019_Mesocosm-M8; KOSMOS Gran Canaria; Leptocylindrus danicus; Leptocylindrus danicus, biovolume; Leptocylindrus minimus; Leptocylindrus minimus, biovolume; Licmophora sp.; Licmophora sp., biovolume; MESO; Mesocosm experiment; Mesocosm label; Microscopy; Minutocellus polymorphus; Minutocellus polymorphus, biovolume; negative emission technology; Network of Leading European AQUAtic MesoCOSM Facilities Connecting Mountains to Oceans from the Arctic to the Mediterranean; Nitzschia cf. acicularis; Nitzschia cf. acicularis, biovolume; Number of taxa; Ocean Artificial Upwelling; Ocean-artUp; ocean fertilization; Phaeocystis cf. globosa; Phaeocystis cf. globosa, biovolume; Phaeocystis sp.; Phaeocystis sp., biovolume; Phase description; Phytoplankton, biovolume; Phytoplankton, total; Pielou evenness index; plankton community; Pleurosigma sp.; Pleurosigma sp., biovolume; Proboscia sp.; Proboscia sp., biovolume; Pseudo-nitzschia delicatissima; Pseudo-nitzschia delicatissima, biovolume; Pseudo-nitzschia pungens; Pseudo-nitzschia pungens, biovolume; Pseudo-nitzschia sp.; Pseudo-nitzschia sp., biovolume; Pseudo-nitzschia subcurvata; Pseudo-nitzschia subcurvata, biovolume; Research Mission of the German Marine Research Alliance (DAM): Marine carbon sinks in decarbonisation pathways; Rhizosolenia cf. imbricata; Rhizosolenia cf. imbricata, biovolume; Rhizosolenia cf. setigera; Rhizosolenia cf. setigera, biovolume; Rhizosolenia sp.; Rhizosolenia sp., biovolume; Shannon Diversity Index; Si:N; silicic acid; Skeletonema sp.; Skeletonema sp., biovolume; Striatella cf. unipunctata; Striatella cf. unipunctata, biovolume; Sum; Test-ArtUp; Treatment
    Type: Dataset
    Format: text/tab-separated-values, 14416 data points
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    DATA PANGAEA
  • 12
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    KOSMOS mesocosm experiment Gran Canaria 2019 on testing the effect of nutrient composition (Si:N) during artificial upwelling: export flux and sinking particle properties (2023)
    PANGAEA
    Details
    Publication Date: 2024-06-12
    Description: Export data from the mesocosm experiment conducted in the Canary Islands in autumn 2019. Sinking matter was collected in 2-days intervals over the course of 33 days from the mesocosm sediment traps (4 m depth). Sediment samples were processed and subsampled for duplicate measurements of particulate organic carbon (POC), nitrogen (PON), phosphorus (POP) and biogenic silica (BSi). Elemental mass fluxes in µmol L-1 were calculated by normalizing to the mesocosm volume. They were then either normalized to the time between sample collection (48 h) to obtain daily mass fluxes (µmol L-1 d-1), or added up to obtain cumulative mass fluxes (µmol L-1). Another set of sediment subsamples was analyzed for particle sinking velocities, sizes and porosities (bidaily) and microbial remineralization rates (every 4 days).
    Keywords: AQUACOSM; artificial upwelling; Biogenic silica, flux, cumulative; Biogenic silica, flux per day; Biogenic silica, weight fraction; Canarias Sea; Carbon, organic, particulate, flux, cumulative; Carbon, organic, particulate, flux per day; Carbon/Nitrogen, molar ratio; carbon dioxide removal; CDRmare; DAM CDRmare - Test-ArtUp: Road testing ocean artificial upwelling; DATE/TIME; Day of experiment; DEPTH, water, experiment; diatoms; Equivalent spherical diameter; Event label; GC2019; KOSMOS; KOSMOS_2019; KOSMOS_2019_Mesocosm-M1; KOSMOS_2019_Mesocosm-M2; KOSMOS_2019_Mesocosm-M3; KOSMOS_2019_Mesocosm-M4; KOSMOS_2019_Mesocosm-M5; KOSMOS_2019_Mesocosm-M6; KOSMOS_2019_Mesocosm-M7; KOSMOS_2019_Mesocosm-M8; KOSMOS Gran Canaria; MESO; Mesocosm experiment; Mesocosm label; negative emission technology; Network of Leading European AQUAtic MesoCOSM Facilities Connecting Mountains to Oceans from the Arctic to the Mediterranean; Nitrogen, organic, particulate, flux, cumulative; Nitrogen, organic, particulate, flux per day; Nitrogen/Phosphorus, molar ratio; Ocean Artificial Upwelling; Ocean-artUp; ocean fertilization; Particle porosity; Phase description; Phosphorus, organic, particulate, flux, cumulative; Phosphorus, organic, particulate, flux per day; Remineralisation rate of carbon per day; Research Mission of the German Marine Research Alliance (DAM): Marine carbon sinks in decarbonisation pathways; Si:N; silicic acid; Silicon/Nitrogen, molar ratio; Sinking velocity; Size fraction 100-250 µm; Size fraction 250-1000 µm; Size fraction 40-100 µm; Test-ArtUp; Treatment
    Type: Dataset
    Format: text/tab-separated-values, 3164 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 13
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    Coastal N 2 fixation rates coincide spatially with N loss in the Humboldt Upwelling System off Peru (2023)
    AGU (American Geophysical Union) | Wiley
    Details
    Publication Date: 2024-02-07
    Description: Marine nitrogen (N2) fixation supports significant primary productivity in the global ocean. However, in one of the most productive regions of the world ocean, the northern Humboldt Upwelling System (HUS), the magnitude and spatial distribution of this process remains poorly characterized. This study presents a spatially resolved dataset of N2 fixation rates across six coastal transects of the northern HUS off Peru (8°S – 16°S) during austral summer. N2 fixation rates were detected throughout the waters column including within the OMZ between 12°S and 16°S. N2 fixation rates were highest where the subsurface Oxygen Minimum Zone (OMZ, O2 〈20 µmol L-1) was most intense and estimated nitrogen (N) loss was highest. There, rates were measured throughout the water column. Hence the vertical and spatial distribution of rates indicates colocation of N2 fixation with N loss in the coastal productive waters of the northern HUS. Despite high phosphate and total dissolvable iron (TdFe) concentrations throughout the study area, N2 fixation was still generally low (1.19 ± 3.81 nmol L-1 d-1) and its distribution could not be directly explained by these two factors. Our results suggest that the distribution was likely influenced by a complex interplay of environmental factors including phytoplankton biomass and organic matter availability, and potentially iron, or other trace metal (co)-limitation of both N2 fixation and primary production. In general, our results support previous conclusions that N2 fixation in the northern HUS plays a minor role as a source of new N and to replenish the regional N loss. Key Points: A north-to-south pattern in N2 fixation rates was observed implying increased N turnover between 12°S and 16°S where N loss was pronounced Highest N2 fixation rates were measured in coastal productive waters above and within the OMZ, showing no clear relationship with Fe or P The magnitude of N2 fixation was low compared to predictions, estimated to account for ∼0.3% of primary production and 〈2% of local N loss
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 14
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    Counteracting effects of nutrient composition (Si:N) on export flux under artificial upwelling (2023)
    Frontiers
    Details
    Publication Date: 2024-02-07
    Description: To keep global warming below 1.5 °C, technologies that remove carbon from the atmosphere will be needed. Ocean artificial upwelling of nutrient-rich water stimulates primary productivity and could enhance the biological carbon pump for natural CO2 removal. Its potential may depend on the Si availability in the upwelled water, which regulates the abundance of diatoms that are key carbon exporters. In a mesocosm experiment, we tested the effect of nutrient composition (Si relative to N) in artificially upwelled waters on export quantity and quality in a subtropical oligotrophic environment. Upwelling led to a doubling of exported particulate matter and increased C:N ratios to well beyond Redfield (9.5 to 11.1). High Si availability stimulated this carbon over-consumption further, resulting in a temporary ~5-fold increase in POC export and ~30% increase in C:N ratios compared to Si-scarce upwelling. Whilst the biogenic Si ballast of the export flux increased more than 3.5-fold over the Si:N gradient, these heavier particles did not sink faster. On the contrary, sinking velocity decreased considerably under high Si:N, most likely due to reduced particle size. Respiration rates remained similar across all treatments indicating that biogenic Si did not protect particles against microbial degradation. Si availability thus influenced key processes of the biological carbon pump in counteracting ways by increasing the export magnitude and associated C:N ratios but decreasing the efficiency of carbon transfer to depth. These opposing effects need to be considered when evaluating the potential of artificial upwelling as negative emission technology.
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 15
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    Counting (on) blue carbon—Challenges and ways forward for carbon accounting of ecosystem-based carbon removal in marine environments (2023)
    Public Library of Science (PLOS)
    Details
    Publication Date: 2024-02-07
    Description: The latest IPCC assessment report highlights once more the need for negative emissions via carbon dioxide removal (CDR) measures to reach ambitious mitigation goals. In particular ecosystem-based CDR measures are currently the focus of national net-zero strategies and novel carbon crediting efforts. Blue carbon dioxide removal (blueCDR) options are anthropogenic activities that aim to enhance such ecosystem-based carbon sinks in the marine environment. The protection and conservation of existing marine ecosystems that naturally sequester carbon, does not qualify as CDR. Using blueCDR as an example, we highlight key challenges concerning the monitoring and evaluation of marine carbon fluxes for carbon crediting. Challenges specific to ecosystem-based CDR measures are i) the definition of baseline natural carbon fluxes, which is necessary for ii) clear anthropogenic CDR signal attribution, as well as iii) accounting for possible natural or anthropogenic disturbances of the carbon stock and hence an assessment for the durability of the carbon storage. In addition, the marine environment poses further monitoring and evaluation challenges due to i) temporal and spatial decoupling of the carbon capturing and sequestration processes, combined with ii) signal dilution due to high ecosystem connectivity, and iii) large pre-existing carbon stocks which makes any human-made increase in carbon stocks even harder to quantify. To increase the scientific rigour and ensure additionality behind issued carbon credits, we support the current trend of focusing monitoring efforts on carbon sequestration rather than on capturing processes, and on establishing a baseline for natural carbon sequestration in diverse marine ecosystems. Finally, we believe that making carbon credits subject to dynamic adjustments over time, will increase their credibility.
    Type: Article , PeerReviewed
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 16
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    A Winter-to-Summer Transition of Bacterial and Archaeal Communities in Arctic Sea Ice (2022)
    MDPI
    Details
    Publication Date: 2024-02-07
    Description: The Arctic is warming 2–3 times faster than the global average, leading to a decrease in Arctic sea ice extent, thickness, and associated changes in sea ice structure. These changes impact sea ice habitat properties and the ice-associated ecosystems. Sea-ice algal blooms provide various algal-derived carbon sources for the bacterial and archaeal communities within the sea ice. Here, we detail the transition of these communities from winter through spring to early summer during the Norwegian young sea ICE (N-ICE2015) expedition. The winter community was dominated by the archaeon Candidatus Nitrosopumilus and bacteria belonging to the Gammaproteobacteria (Colwellia, Kangiellaceae, and Nitrinocolaceae), indicating that nitrogen-based metabolisms, particularly ammonia oxidation to nitrite by Cand. Nitrosopumilus was prevalent. At the onset of the vernal sea-ice algae bloom, the community shifted to the dominance of Gammaproteobacteria (Kangiellaceae, Nitrinocolaceae) and Bacteroidia (Polaribacter), while Cand. Nitrosopumilus almost disappeared. The bioinformatically predicted carbohydrate-active enzymes increased during spring and summer, indicating that sea-ice algae-derived carbon sources are a strong driver of bacterial and archaeal community succession in Arctic sea ice during the change of seasons. This implies a succession from a nitrogen metabolism-based winter community to an algal-derived carbon metabolism-based spring/ summer community.
    Type: Article , PeerReviewed
    Format: text
    Format: archive
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 17
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    Nutrient composition (Si:N) as driver of plankton communities during artificial upwelling (2022)
    Frontiers
    Details
    Publication Date: 2024-02-07
    Description: Artificial upwelling brings nutrient-rich deep water to the sun-lit surface to boost fisheries or carbon sequestration. Deep water sources under consideration range widely in inorganic silicon (Si) relative to nitrogen (N). Yet, little is known about how such differences in nutrient composition may influence the effectiveness of the fertilization. Si is essential primarily for diatoms that may increase food web and export efficiency via their large size and ballasting mineral shells, respectively. With a month-long mesocosm study in the subtropical North Atlantic, we tested the biological response to artificial upwelling with varying Si:N ratios (0.07-1.33). Community biomass increased 10-fold across all mesocosms, indicating that basic bloom dynamics were upheld despite the wide range in nutrient composition. Key properties of these blooms, however, were influenced by Si. Photosynthetic capacity and nutrient-use efficiency doubled from Si-poor to Si-rich upwelling, leading to C:N ratios as high as 17, well beyond Redfield. Si-rich upwelling also resulted in 6-fold higher diatom abundance and mineralized Si and a corresponding shift from smaller towards larger phytoplankton. The pronounced change in both plankton quantity (biomass) and quality (C:N ratio, size and mineral ballast) for trophic transfer and export underlines the pivotal role of Si in shaping the response of oligotrophic regions to upwelled nutrients. Our findings indicate a benefit of active Si management during artificial upwelling with the potential to optimize fisheries production and CO2 removal.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 18
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    Oligotrophic Phytoplankton Community Effectively Adjusts to Artificial Upwelling Regardless of Intensity, but Differently Among Upwelling Modes (2022)
    Frontiers
    Details
    Publication Date: 2024-02-07
    Description: Artificial upwelling has been proposed as a means of enhancing oceanic CO2 sequestration and/or raising fishery yields through an increase in primary production in unproductive parts of the ocean. However, evidence of its efficacy, applicability and side effects is scarce. Here we present part of the results of a 37-day mesocosm study conducted in oligotrophic waters off the coast of Gran Canaria. The goal was to assess in situ the effects of artificial upwelling on the pelagic community. Upwelling was simulated via two modes: i) a singular deep-water pulse and ii) a recurring supply every 4 days; each mode at four different intensities defined by the total amount of nitrate added: approx. 1.5, 3, 5.7, and 11 µmol L-1. In this study we focus on the phytoplankton response through size-fractionated 14C primary production rates (PP), Chlorophyll a and biomass. We observed increases in PP, accumulated PP, Chlorophyll a and biomass that scaled linearly with upwelling intensity. Upwelling primarily benefitted larger phytoplankton size fractions, causing a shift from pico- and nano- to nano- and microphytoplankton. Recurring deep-water addition produced more biomass under higher upwelling intensities than a single pulse addition. It also reached significantly higher accumulated PP per unit of added nutrients and showed a stronger reduction in percentage extracellular release with increasing upwelling intensity. These results demonstrate that oligotrophic phytoplankton communities can effectively adjust to artificial upwelling regardless of upwelling intensity, but differently depending on the upwelling mode. Recurring supply of upwelled waters generated higher efficiencies in primary production and biomass build-up than a single pulse of the same volume and nutrient load.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 19
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    Oceanographic structuring of the mucous-mesh grazer community in the Humboldt Current off Peru (2023)
    Inter Research
    Details
    Publication Date: 2024-03-25
    Description: The Humboldt Upwelling System (HUS) supports high levels of primary production and has the largest single-stock fishery worldwide. The high fish production is suggested to be related to high trophic transfer efficiency in the HUS. Mucous-mesh grazers (pelagic tunicates and gastropods) are mostly of low nutritious value and might reduce trophic transfer efficiency when they are locally abundant. Unfortunately, little is known about the spatial dynamics of mucous-mesh grazers from Peruvian waters, limiting our understanding of their potential ecological role(s). We provide a spatial assessment of mucous-mesh grazer abundance from the Peruvian shelf in austral summer 2018/2019 along six cross-shelf transects spanning from 8.5 to 16° S latitude. The community was dominated by appendicularians and doliolids. Salps occurred in high abundance but infrequently and pelagic gastropods were mostly restricted to the North. At low latitudes, the abundance of mucous-mesh grazers was higher than some key species of crustacean mesozooplankton. Transects in this region had stronger Ekman-transport, higher temperature, lower surface turbidity and a broader oxygenated upper water layer compared to higher-latitude transects. Small-scale lateral intrusions of upwelled water were potentially associated with high abundances of doliolids at specific stations. The high abundance and estimated ingestion rates of mucous-mesh grazers in the northern HUS suggest that a large flux of carbon from lower trophic levels is shunted to tunicates in recently upwelled water masses. The data provide important information on the ecology of mucous mesh grazers and stress the relevance to increase research effort on investigating their functioning in upwelling systems.
    Type: Article , PeerReviewed
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  • 20
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    Diatom-mediated food web functioning under ocean artificial upwelling (2024)
    Nature Research
    Details
    Publication Date: 2024-05-29
    Description: Enhancing ocean productivity by artificial upwelling is evaluated as a nature-based solution for food security and climate change mitigation. Fish production is intended through diatom-based plankton food webs as these are assumed to be short and efficient. However, our findings from mesocosm experiments on artificial upwelling in the oligotrophic ocean disagree with this classical food web model. Here, diatoms did not reduce trophic length and instead impaired the transfer of primary production to crustacean grazers and small pelagic fish. The diatom-driven decrease in trophic efficiency was likely mediated by changes in nutritional value for the copepod grazers. Whilst diatoms benefitted the availability of essential fatty acids, they also caused unfavorable elemental compositions via high carbon-to-nitrogen ratios (i.e. low protein content) to which the grazers were unable to adapt. This nutritional imbalance for grazers was most pronounced in systems optimized for CO 2 uptake through carbon-to-nitrogen ratios well beyond Redfield. A simultaneous enhancement of fisheries production and carbon sequestration via artificial upwelling may thus be difficult to achieve given their opposing stoichiometric constraints. Our study suggest that food quality can be more critical than quantity to maximize food web productivity during shorter-term fertilization of the oligotrophic ocean.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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