GLORIA

GEOMAR Library Ocean Research Information Access

X

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Online Resource
    Online Resource
    Impact of dust addition on the metabolism of Mediterranean plankton communities and carbon export under present and future conditions of pH and temperature
    Copernicus GmbH ; 2021
    In:  Biogeosciences Vol. 18, No. 19 ( 2021-10-06), p. 5423-5446
    Details
    In: Biogeosciences, Copernicus GmbH, Vol. 18, No. 19 ( 2021-10-06), p. 5423-5446
    Abstract: Abstract. Although atmospheric dust fluxes from arid as well as human-impacted areas represent a significant source of nutrients to surface waters of the Mediterranean Sea, studies focusing on the evolution of the metabolic balance of the plankton community following a dust deposition event are scarce, and none were conducted in the context of projected future levels of temperature and pH. Moreover, most of the experiments took place in coastal areas. In the framework of the PEACETIME project, three dust-addition perturbation experiments were conducted in 300 L tanks filled with surface seawater collected in the Tyrrhenian Sea (TYR), Ionian Sea (ION) and Algerian basin (FAST) on board the R/V Pourquoi Pas? in late spring 2017. For each experiment, six tanks were used to follow the evolution of chemical and biological stocks, biological activity and particle export. The impacts of a dust deposition event simulated at their surface were followed under present environmental conditions and under a realistic climate change scenario for 2100 (ca. +3 ∘C and −0.3 pH units). The tested waters were all typical of stratified oligotrophic conditions encountered in the open Mediterranean Sea at this period of the year, with low rates of primary production and a metabolic balance towards net heterotrophy. The release of nutrients after dust seeding had very contrasting impacts on the metabolism of the communities, depending on the station investigated. At TYR, the release of new nutrients was followed by a negative impact on both particulate and dissolved 14C-based production rates, while heterotrophic bacterial production strongly increased, driving the community to an even more heterotrophic state. At ION and FAST, the efficiency of organic matter export due to mineral/organic aggregation processes was lower than at TYR and likely related to a lower quantity/age of dissolved organic matter present at the time of the seeding and a smaller production of DOM following dust addition. This was also reflected by lower initial concentrations in transparent exopolymer particles (TEPs) and a lower increase in TEP concentrations following the dust addition, as compared to TYR. At ION and FAST, both the autotrophic and heterotrophic community benefited from dust addition, with a stronger relative increase in autotrophic processes observed at FAST. Our study showed that the potential positive impact of dust deposition on primary production depends on the initial composition and metabolic state of the investigated community. This impact is constrained by the quantity of nutrients added in order to sustain both the fast response of heterotrophic prokaryotes and the delayed one of primary producers. Finally, under future environmental conditions, heterotrophic metabolism was overall more impacted than primary production, with the consequence that all integrated net community production rates decreased with no detectable impact on carbon export, therefore reducing the capacity of surface waters to sequester anthropogenic CO2.
    Type of Medium: Online Resource
    ISSN: 1726-4189
    URL: Article
    URL: Article
    DOI: 10.5194/bg-18-5423-2021
    DOI: 10.5194/bg-18-5423-2021-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2021
    detail.hit.zdb_id: 2158181-2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 2
    Online Resource
    Online Resource
    Marine isoprene production and consumption in the mixed layer of the surface ocean – a field study over two oceanic regions
    Copernicus GmbH ; 2018
    In:  Biogeosciences Vol. 15, No. 2 ( 2018-02-01), p. 649-667
    Details
    In: Biogeosciences, Copernicus GmbH, Vol. 15, No. 2 ( 2018-02-01), p. 649-667
    Abstract: Abstract. Parameterizations of surface ocean isoprene concentrations are numerous, despite the lack of source/sink process understanding. Here we present isoprene and related field measurements in the mixed layer from the Indian Ocean and the eastern Pacific Ocean to investigate the production and consumption rates in two contrasting regions, namely oligotrophic open ocean and the coastal upwelling region. Our data show that the ability of different phytoplankton functional types (PFTs) to produce isoprene seems to be mainly influenced by light, ocean temperature, and salinity. Our field measurements also demonstrate that nutrient availability seems to have a direct influence on the isoprene production. With the help of pigment data, we calculate in-field isoprene production rates for different PFTs under varying biogeochemical and physical conditions. Using these new calculated production rates, we demonstrate that an additional significant and variable loss, besides a known chemical loss and a loss due to air–sea gas exchange, is needed to explain the measured isoprene concentration. We hypothesize that this loss, with a lifetime for isoprene between 10 and 100 days depending on the ocean region, is potentially due to degradation or consumption by bacteria.
    Type of Medium: Online Resource
    ISSN: 1726-4189
    URL: Article
    URL: Article
    DOI: 10.5194/bg-15-649-2018
    DOI: 10.5194/bg-15-649-2018-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2018
    detail.hit.zdb_id: 2158181-2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 3
    Online Resource
    Online Resource
    Deep maxima of phytoplankton biomass, primary production and bacterial production in the Mediterranean Sea
    Copernicus GmbH ; 2021
    In:  Biogeosciences Vol. 18, No. 5 ( 2021-03-15), p. 1749-1767
    Details
    In: Biogeosciences, Copernicus GmbH, Vol. 18, No. 5 ( 2021-03-15), p. 1749-1767
    Abstract: Abstract. The deep chlorophyll maximum (DCM) is a ubiquitous feature of phytoplankton vertical distribution in stratified waters that is relevant to our understanding of the mechanisms that underpin the variability in photoautotroph ecophysiology across environmental gradients and has implications for remote sensing of aquatic productivity. During the PEACETIME (Process studies at the air-sea interface after dust deposition in the Mediterranean Sea) cruise, carried out from 10 May to 11 June 2017, we obtained 23 concurrent vertical profiles of phytoplankton chlorophyll a, carbon biomass and primary production, as well as heterotrophic prokaryotic production, in the western and central Mediterranean basins. Our main aims were to quantify the relative role of photoacclimation and enhanced growth as underlying mechanisms of the DCM and to assess the trophic coupling between phytoplankton and heterotrophic prokaryotic production. We found that the DCM coincided with a maximum in both the biomass and primary production but not in the growth rate of phytoplankton, which averaged 0.3 d−1 and was relatively constant across the euphotic layer. Photoacclimation explained most of the increased chlorophyll a at the DCM, as the ratio of carbon to chlorophyll a (C:Chl a) decreased from ca. 90–100 (g:g) at the surface to 20–30 at the base of the euphotic layer, while phytoplankton carbon biomass increased from ca. 6 mg C m−3 at the surface to 10–15 mg C m−3 at the DCM. As a result of photoacclimation, there was an uncoupling between chlorophyll a-specific and carbon-specific productivity across the euphotic layer. The ratio of fucoxanthin to total chlorophyll a increased markedly with depth, suggesting an increased contribution of diatoms at the DCM. The increased biomass and carbon fixation at the base of the euphotic zone was associated with enhanced rates of heterotrophic prokaryotic activity, which also showed a surface peak linked with warmer temperatures. Considering the phytoplankton biomass and turnover rates measured at the DCM, nutrient diffusive fluxes across the nutricline were able to supply only a minor fraction of the photoautotroph nitrogen and phosphorus requirements. Thus the deep maxima in biomass and primary production were not fuelled by new nutrients but likely resulted from cell sinking from the upper layers in combination with the high photosynthetic efficiency of a diatom-rich, low-light acclimated community largely sustained by regenerated nutrients. Further studies with increased temporal and spatial resolution will be required to ascertain if the peaks of deep primary production associated with the DCM persist across the western and central Mediterranean Sea throughout the stratification season.
    Type of Medium: Online Resource
    ISSN: 1726-4189
    URL: Article
    URL: Article
    DOI: 10.5194/bg-18-1749-2021
    DOI: 10.5194/bg-18-1749-2021-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2021
    detail.hit.zdb_id: 2158181-2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 4
    Online Resource
    Online Resource
    Eukaryotic community composition in the sea surface microlayer across an east–west transect in the Mediterranean Sea
    Copernicus GmbH ; 2021
    In:  Biogeosciences Vol. 18, No. 6 ( 2021-03-23), p. 2107-2118
    Details
    In: Biogeosciences, Copernicus GmbH, Vol. 18, No. 6 ( 2021-03-23), p. 2107-2118
    Abstract: Abstract. The sea surface microlayer (SML) represents the boundary layer at the air–sea interface. Microbial eukaryotes in the SML potentially influence air–sea gas exchange directly by taking up and producing gases and indirectly by excreting and degrading organic matter, which may modify the viscoelastic properties of the SML. However, little is known about the distribution of microbial eukaryotes in the SML. We studied the composition of the microbial community, transparent exopolymer particles and polysaccharides in the SML during the PEACETIME cruise along a west–east transect in the Mediterranean Sea, covering the western basin, Tyrrhenian Sea and Ionian Sea. At the stations located in the Ionian Sea, fungi – likely of continental origin and delivered by atmospheric deposition – were found in high relative abundances, making up a significant proportion of the sequences recovered. Concomitantly, bacterial and picophytoplankton counts decreased from west to east, while transparent exopolymer particle (TEP) abundance and total carbohydrate (TCHO) concentrations remained constant in all basins. Our results suggest that the presence of substrates for fungi, such as Cladosporium, known to take up phytoplankton-derived polysaccharides, in combination with decreased substrate competition by bacteria, might favor fungal dominance in the neuston of the Ionian Sea and other low-nutrient, low-chlorophyll (LNLC) regions.
    Type of Medium: Online Resource
    ISSN: 1726-4189
    URL: Article
    URL: Article
    URL: Article
    DOI: 10.5194/bg-18-2107-2021
    DOI: 10.5194/bg-18-2107-2021-supplement
    DOI: 10.5194/bg-18-2107-2021-corrigendum
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2021
    detail.hit.zdb_id: 2158181-2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 5
    Online Resource
    Online Resource
    Data_Sheet_1.pdf
    Frontiers Media SA ; 2019
    In:  Frontiers in Microbiology Vol. 10 ( 2019-4-12)
    Details
    In: Frontiers in Microbiology, Frontiers Media SA, Vol. 10 ( 2019-4-12)
    Type of Medium: Online Resource
    ISSN: 1664-302X
    URL: Article
    URL: Article
    DOI: 10.3389/fmicb.2019.00758
    DOI: 10.3389/fmicb.2019.00758.s001
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2019
    detail.hit.zdb_id: 2587354-4
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 6
    Online Resource
    Online Resource
    The Ocean's Vital Skin: Toward an Integrated Understanding of the Sea Surface Microlayer
    Frontiers Media SA ; 2017
    In:  Frontiers in Marine Science Vol. 4 ( 2017-05-30)
    Details
    In: Frontiers in Marine Science, Frontiers Media SA, Vol. 4 ( 2017-05-30)
    Type of Medium: Online Resource
    ISSN: 2296-7745
    URL: Article
    DOI: 10.3389/fmars.2017.00165
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2017
    detail.hit.zdb_id: 2757748-X
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 7
    Online Resource
    Online Resource
    Bacterial communities associated with individual transparent exopolymer particles (TEP)
    Oxford University Press (OUP) ; 2019
    In:  Journal of Plankton Research Vol. 41, No. 4 ( 2019-07-26), p. 561-565
    Details
    In: Journal of Plankton Research, Oxford University Press (OUP), Vol. 41, No. 4 ( 2019-07-26), p. 561-565
    Abstract: Transparent exopolymer particles (TEP) are polysaccharide-rich microgels that are prevalent in the marine environment and have important roles in the aggregation of organic matter and carbon export from the euphotic zone. TEP are readily colonized by bacteria and utilized by specialized taxa, such as Alteromonadaceae. However, bacterial community composition specifically attached to natural TEP remains largely unknown. In this study, we isolated individual TEP from Plymouth Sound (UK) and performed DNA sequencing of the TEP-attached bacterial communities. We also sampled the cognate bulk seawater total bacterial communities for comparison. The bacterial communities associated with individual TEP showed distinct differences compared to the total bulk bacterioplankton communities, with Alteromonadaceae significantly more abundant on TEP. The TEP-associated Alteromonadaceae consisted of two operational taxonomic units that were closely related to Marinobacter and Glaciecola, both previously associated with biogenic aggregates and microgel-rich habitats. This study provides novel insight into marine bacterial–microgel interactions.
    Type of Medium: Online Resource
    ISSN: 0142-7873 , 1464-3774
    URL: Article
    DOI: 10.1093/plankt/fbz022
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2019
    detail.hit.zdb_id: 756271-8
    detail.hit.zdb_id: 1474909-9
    SSG: 12
    SSG: 21,3
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 8
    Online Resource
    Online Resource
    Spatial patterns of ectoenzymatic kinetics in relation to biogeochemical properties in the Mediterranean Sea and the concentration of the fluorogenic substrate used
    Copernicus GmbH ; 2021
    In:  Biogeosciences Vol. 18, No. 7 ( 2021-04-09), p. 2301-2323
    Details
    In: Biogeosciences, Copernicus GmbH, Vol. 18, No. 7 ( 2021-04-09), p. 2301-2323
    Abstract: Abstract. Ectoenzymatic activity, prokaryotic heterotrophic abundances and production were determined in the Mediterranean Sea. Sampling was carried out in the sub-surface, the deep chlorophyll maximum layer (DCM), the core of the Levantine intermediate waters and in the deeper part of the mesopelagic layers. Michaelis–Menten kinetics were assessed using a large range of concentrations of fluorogenic substrates (0.025 to 50 µM). As a consequence, Km (Michaelis–Menten half-saturation constant) and Vm (maximum hydrolysis velocity) parameters were determined for both low- and high-affinity enzymes for alkaline phosphatase, aminopeptidase (LAP) and β-glucosidase (βGLU). Based on the constant derived from the high-LAP-affinity enzyme (0.025–1 µM substrate concentration range), in situ hydrolysis of N proteins contributed 48 % ± 30 % to the heterotrophic bacterial nitrogen demand within the epipelagic layers and 180 % ± 154 % in the Levantine intermediate waters and the upper part of the mesopelagic layers. The LAP hydrolysis rate was higher than bacterial N demand only within the deeper layer and only when considering the high-affinity enzyme. Based on a 10 % bacterial growth efficiency, the cumulative hydrolysis rates of C proteins and C polysaccharides contributed on average 2.5 % ± 1.3  % to the heterotrophic bacterial carbon demand in the epipelagic layers sampled (sub-surface and DCM). This study clearly reveals potential biases in current and past interpretations of the kinetic parameters for the three enzymes tested based on the fluorogenic-substrate concentration used. In particular, the LAP / βGLU enzymatic ratios and some of the depth-related trends differed between the use of high and low concentrations of fluorogenic substrates.
    Type of Medium: Online Resource
    ISSN: 1726-4189
    URL: Article
    URL: Article
    DOI: 10.5194/bg-18-2301-2021
    DOI: 10.5194/bg-18-2301-2021-supplement
    Language: English
    Publisher: Copernicus GmbH
    Publication Date: 2021
    detail.hit.zdb_id: 2158181-2
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 9
    Online Resource
    Online Resource
    Variations of microbial communities and substrate regimes in the eastern Fram Strait between summer and fall
    Wiley ; 2022
    In:  Environmental Microbiology Vol. 24, No. 9 ( 2022-09), p. 4124-4136
    Details
    In: Environmental Microbiology, Wiley, Vol. 24, No. 9 ( 2022-09), p. 4124-4136
    Abstract: Seasonal variations in day length and temperature, in combination with dynamic factors such as advection from the North Atlantic, influence primary production and the microbial loop in the Fram Strait. Here, we investigated the seasonal variability of biopolymers, microbial abundance and microbial composition within the upper 100 m during summer and fall. Flow cytometry revealed a shift in the autotrophic community from picoeukaryotes dominating in summer to a 34‐fold increase of Synechococcus by fall. Furthermore, a significant decline in biopolymers concentrations covaried with increasing microbial diversity based on 16S rRNA gene sequencing along with a community shift towards fewer polymer‐degrading genera in fall. The seasonal succession in the biopolymer pool and microbes indicates distinct metabolic regimes, with a higher relative abundance of polysaccharide‐degrading genera in summer and a higher relative abundance of common taxa in fall. The parallel analysis of DOM and microbial diversity provides an important baseline for microbe–substrate relationships over the seasonal cycle in the Arctic Ocean.
    Type of Medium: Online Resource
    ISSN: 1462-2912 , 1462-2920
    URL: Issue
    URL: Article
    DOI: 10.1111/emi.v24.9
    DOI: 10.1111/1462-2920.16036
    Language: English
    Publisher: Wiley
    Publication Date: 2022
    detail.hit.zdb_id: 2020213-1
    SSG: 12
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 10
    Online Resource
    Online Resource
    The MILAN Campaign: Studying Diel Light Effects on the Air–Sea Interface
    American Meteorological Society ; 2020
    In:  Bulletin of the American Meteorological Society Vol. 101, No. 2 ( 2020-02), p. E146-E166
    Details
    In: Bulletin of the American Meteorological Society, American Meteorological Society, Vol. 101, No. 2 ( 2020-02), p. E146-E166
    Abstract: The sea surface microlayer (SML) at the air–sea interface is 〈 1 mm thick, but it is physically, chemically, and biologically distinct from the underlying water and the atmosphere above. Wind-driven turbulence and solar radiation are important drivers of SML physical and biogeochemical properties. Given that the SML is involved in all air–sea exchanges of mass and energy, its response to solar radiation, especially in relation to how it regulates the air–sea exchange of climate-relevant gases and aerosols, is surprisingly poorly characterized. MILAN (Sea Surface Microlayer at Night) was an international, multidisciplinary campaign designed to specifically address this issue. In spring 2017, we deployed diverse sampling platforms (research vessels, radio-controlled catamaran, free-drifting buoy) to study full diel cycles in the coastal North Sea SML and in underlying water, and installed a land-based aerosol sampler. We also carried out concurrent ex situ experiments using several microsensors, a laboratory gas exchange tank, a solar simulator, and a sea spray simulation chamber. In this paper we outline the diversity of approaches employed and some initial results obtained during MILAN. Our observations of diel SML variability show, for example, an influence of (i) changing solar radiation on the quantity and quality of organic material and (ii) diel changes in wind intensity primarily forcing air–sea CO 2 exchange. Thus, MILAN underlines the value and the need of multidiciplinary campaigns for integrating SML complexity into the context of air–sea interaction.
    Type of Medium: Online Resource
    ISSN: 0003-0007 , 1520-0477
    URL: Article
    URL: Article
    DOI: 10.1175/BAMS-D-17-0329.1
    DOI: 10.1175/bams-d-17-0329.2
    Language: Unknown
    Publisher: American Meteorological Society
    Publication Date: 2020
    detail.hit.zdb_id: 2029396-3
    detail.hit.zdb_id: 419957-1
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...