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  • 1
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    Bacterial Community Composition in the Sea Surface Microlayer Off the Peruvian Coast (2018)
    Frontiers
    In:  Frontiers in Microbiology, 9 . Art.Nr. 2699.
    Details
    Publication Date: 2021-03-19
    Description: The sea surface microlayer (SML) is located at the air-sea interface, with microorganisms and organic matter in the SML influencing air-sea exchange processes. Yet understanding of the SML bacterial (bacterioneuston) community composition and assembly remains limited. Availability of organic matter, UV radiation and wind speed have previously been suggested to influence the community composition of bacterioneuston. Another mechanism potentially controlling bacterioneuston dynamics is bacterioplankton attached to gel-like particles that ascend through the water column into the SML. We analyzed the bacterial community composition, Transparent Exopolymer Particles (TEP) abundance and nutrient concentrations in the surface waters of the Peruvian upwelling region. The bacterioneuston and bacterioplankton communities were similar, suggesting a close spatial coupling. Four Bacteroidetes families were significantly enriched in the SML, two of them, the Flavobacteriaceae and Cryomorphaceae, were found to comprise the majority of SML-enriched operational taxonomic units (OTUs). The enrichment of these families was controlled by a variety of environmental factors. The SML-enriched bacterial families were negatively correlated with water temperature and wind speed in the SML and positively correlated with nutrient concentrations, salinity and TEP in the underlying water (ULW). The correlations with nutrient concentrations and salinity suggest that the enriched bacterial families were more abundant at the upwelling stations.
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  • 2
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    Benthic-pelagic coupling and isotopic fractionation of barium in Kiel Bight, SW Baltic Sea (2023)
    Frontiers
    Details
    Publication Date: 2024-02-07
    Description: Barium (Ba) isotopes are a promising new tracer for riverine freshwater input to the ocean and marine biogeochemical cycling. However, many processes that affect Ba cycling at continental margins have not yet been investigated with respect to Ba isotope fractionation. Here, we present a comprehensive data set of Ba concentration and isotope data for water column, pore water and sediment samples from Kiel Bight, a seasonally stratified and hypoxic fjord in the southwestern Baltic Sea. The surface water Ba concentration and Ba isotope inventory of the water column can generally be explained by mixing of riverine freshwater and Atlantic seawater. However, the deep-water below the seasonal pycnocline (10 - 15 m water depth) is characterized by a pronounced positive Ba concentration anomaly (up to 915 nM) that is accompanied by a δ138Ba of ~+0.25 ‰, which is lighter than expected from the seawater-freshwater mixing line (Ba: 77 nM, δ138Ba: +0.32 ‰ at a salinity of 18). Pore water profiles indicate a Ba flux across the sediment-water interface, which contributes to the enrichment in isotopically light Ba in the deep-water. Pore waters of surface sediments and deep-waters are oversaturated with respect to barite. Therefore, barite dissolution is unlikely to account for the benthic Ba flux. Water column Ba concentrations closely correlate with those of the nutrients phosphate and silica, which are removed from surface waters by biological processes and recycled from the sediment by diffusion across the sediment-water interface. As nutrient-to-Ba ratios differ among sites and from those observed in open-marine systems, we propose that Ba is removed from surface waters by adsorption onto biogenic particles (rather than assimilation) and regenerated within surface sediments upon organic matter degradation. Pore water data for subsurface sediments in Kiel Bight indicate preferential transfer of isotopically heavy Ba into an authigenic phase during early diagenesis. Quantifying the burial flux associated with this authigenic Ba phase along continental margins could potentially help to settle the isotopic imbalance between known Ba source and sink fluxes in the ocean.
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  • 3
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    Can Hydrocarbon Extraction From the Crust Enhance or Inhibit Seismicity in Tectonically Active Regions? A Statistical Study in Italy (2021)
    Frontiers
    Details
    Publication Date: 2021-07-07
    Description: A number of oil- and gas-producing leases have been operating in Italy in the last decades, many of which are located in the surroundings of tectonically active regions. Identifying human-induced seismicity in areas with high levels of natural seismicity is a difficult task for which virtually any result can be a source of controversy. We implemented a large-scale analysis aiming at tracking significant departures of background seismicity from a stationary behavior around active oil and gas development leases in Italy. We analyzed seismicity rates before and after hydrocarbon peak production in six oil-producing and 43 gas-producing leases, and evaluate the significance of possible seismicity rate changes. In a considerable number of cases seismicity rate results stationary. None of the observed cases of seismicity rate increase after the peak production is statistically significant (at a s.l. = 0.05). Conversely, considering cases of seismicity rate decrease after peak production, our results suggest that the seismicity rate reduction is statistically significant (s.l. = 0.05) around one oil-producing lease (Val d’Agri, Basilicata) and around a cluster of gas-producing leases in Sicily. Our results put in evidence correlated changes between the rates of shallow seismicity and hydrocarbon production in these areas, which are then identified as hotspots requiring more detailed research; assessing actual causal relationships between these processes will require further physically-based modelling. If a physical causative link between these processes exists, then the observed seismicity rate reduction could either be due to increased seismicity during the progressive increase in production before reaching its maximum, or to an actual seismicity rate reduction after that peak. Considering that there is evidence of seismicity occurring before the start of hydrocarbon production, which contrasts with the evident reduction of events observed after the peak production, we think it likely that the seismicity inhibition is a plausible hypothesis. Using a simple model we also calculate Coulomb stress changes in planes optimally oriented for failure, and we show that under some conditions the inhibition of seismicity is feasible in at least one of these cases. We conclude that more efforts to study the mechanisms and the possible consequences of anthropogenically-driven seismicity inhibition are required.
    Description: This study was performed with the support of Clypea, the Innovation Network for Future Energy financed by the Italian Ministry of Economic Development, Direzione Generale per le Infrastrutture e la Sicurezza dei Sistemi Energetici e Geominerari (MISE—DGISSEG)
    Description: Published
    Description: 673124
    Description: 4T. Sismicità dell'Italia
    Description: JCR Journal
    Keywords: regional seismicity ; hydrocarbon production ; correlation analysis ; seismicity rate changes ; Italy, ; anthropogenic hazards ; 04. Solid Earth
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 4
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    Characterization of Shiga toxin-producing Escherichia coli O130:H11 and O178:H19 isolated from dairy cows (2013)
    Frontiers
    Details
    Publication Date: 2013-03-09
    Description: Daniel Fernández, Alejandra Krüger, Rosana Polifroni, Ana V. Bustamante, A. Mariel Sanso, Analía I. Etcheverría, Paula M. A. Lucchesi, Alberto E. Parma and Nora L. Padola
    Electronic ISSN: 1664-302X
    Topics: Biology
    Published by Frontiers
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  • 5
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    Coastal upwelling systems as dynamic mosaics of bacterioplankton functional specialization (2024)
    Frontiers
    Details
    Publication Date: 2024-01-30
    Description: Coastal upwelling areas are extraordinarily productive environments where prokaryotic communities, the principal remineralizers of dissolved organic matter (DOM), rapidly respond to phytoplankton bloom and decay dynamics. Nevertheless, the extent of variability of key microbial functions in such dynamic waters remains largely unconstrained. Our metatranscriptomics analyses of 162 marker genes encoding ecologically relevant prokaryotic functions showed distinct spatial-temporal patterns in the NW Iberian Peninsula upwelling area. Short-term (daily) changes in specific bacterial functions associated with changes in biotic and abiotic factors were superimposed on seasonal variability. Taxonomic and functional specialization of prokaryotic communities, based mostly on different resource acquisition strategies, was observed. Our results uncovered the potential influence of prokaryotic functioning on phytoplankton bloom composition and development (e.g., Cellvibrionales and Flavobacteriales increased relative gene expression related to vitamin B12 and siderophore metabolisms during Chaetoceros and Dinophyceae summer blooms). Notably, bacterial adjustments to C- or N-limitation and DMSP availability during summer phytoplankton blooms and different spatial-temporal patterns of variability in the expression of genes with different phosphate affinity indicated a complex role of resource availability in structuring bacterial communities in this upwelling system. Also, a crucial role of Cellvibrionales in the degradation of DOM (carbohydrate metabolism, TCA cycle, proteorhodopsin, ammonium, and phosphate uptake genes) during the summer phytoplankton bloom was found. Overall, this dataset revealed an intertwined mosaic of microbial interactions and nutrient utilization patterns along a spatial-temporal gradient that needs to be considered if we aim to understand the biogeochemical processes in some of the most productive ecosystems in the world´s oceans.
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  • 6
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    Combined Carbohydrates Support Rich Communities of Particle-Associated Marine Bacterioplankton (2017)
    Frontiers
    In:  Frontiers in Microbiology, 8 . Art.Nr. 65.
    Details
    Publication Date: 2020-02-06
    Description: Carbohydrates represent an important fraction of labile and semi-labile marine organic matter that is mainly comprised of exopolymeric substances derived from phytoplankton exudation and decay. This study investigates the composition of total combined carbohydrates (tCCHO; 〉1 kDa) and the community development of free-living (0.2–3 μm) and particle-associated (PA) (3–10 μm) bacterioplankton during a spring phytoplankton bloom in the southern North Sea. Furthermore, rates were determined for the extracellular enzymatic hydrolysis that catalyzes the initial step in bacterial organic matter remineralization. Concentrations of tCCHO greatly increased during bloom development, while the composition showed only minor changes over time. The combined concentration of glucose, galactose, fucose, rhamnose, galactosamine, glucosamine, and glucuronic acid in tCCHO was a significant factor shaping the community composition of the PA bacteria. The richness of PA bacteria greatly increased in the post-bloom phase. At the same time, the increase in extracellular β-glucosidase activity was sufficient to explain the observed decrease in tCCHO, indicating the efficient utilization of carbohydrates by the bacterioplankton community during the post-bloom phase. Our results suggest that carbohydrate concentration and composition are important factors in the multifactorial environmental control of bacterioplankton succession and the enzymatic hydrolysis of organic matter during phytoplankton blooms.
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  • 7
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    Drivers of pelagic and benthic microbial communities on Central Arctic seamounts (2023)
    Frontiers
    Details
    Publication Date: 2024-02-07
    Description: Seamounts are abundant features on the seafloor that serve as hotspots and barriers for the dispersal of benthic organisms. The primary focus of seamount ecology has typically been on the composition and distribution of faunal communities, with far less attention given to microbial communities. Here, we investigated the microbial communities in the water column (0-3400 m depth) and sediments (619-3883 m depth, 0-16 cm below seafloor) along the ice-covered Arctic ridge system called the Langseth Ridge. We contextualized the microbial community composition with data on the benthic trophic state (i.e., organic matter, chlorophyll- a content, and porewater geochemistry) and substrate type (i.e., sponge mats, sediments, basaltic pebbles). Our results showed slow current velocities throughout the water column, a shift in the pelagic microbial community from a dominance of Bacteroidia in the 0-10 m depth towards Proteobacteria and Nitrososphaeria below the epipelagic zone. In general, the pelagic microbial communities showed a high degree of similarity between the Langseth Ridge seamounts to a northern reference site. The only notable differences were decreases in richness between ~600 m and the bottom waters (~10 m above the seafloor) that suggest a pelagic-benthic coupling mediated by filter feeding of sponges living on the seamount summits. On the seafloor, the sponge spicule mats, and polychaete worms were the principal source of variation in sedimentary biogeochemistry and the benthic microbial community structure. The porewater signature suggested that low organic matter degradation rates are accompanied by a microbial community typical of deep-sea oligotrophic environments, such as Proteobacteria, Acidimicrobiia, Dehalococcoidia, Nitrospira, and archaeal Nitrososphaeria. The combined analysis of biogeochemical parameters and the microbial community suggests that the sponges play a significant role for pelagic-benthic coupling and acted as ecosystem engineers on the seafloor of ice-covered seamounts in the oligotrophic central Arctic Ocean.
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  • 8
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    Ecosystem-based fisheries management increases catch and carbon sequestration through recovery of exploited stocks: The western Baltic Sea case study (2022)
    Frontiers
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    Publication Date: 2024-02-07
    Description: Legal requirement in Europe asks for Ecosystem-Based Fisheries Management (EBFM) in European seas, including consideration of trophic interactions and minimization of negative impacts of fishing on food webs and ecosystem functioning. This study presents the first mass-balanced ecosystem model focused on the western Baltic Sea (WBS). Results show that heavy fishing pressure exerted on the WBS has forced top predators such as harbour porpoise and cod to cover their dietary needs by shifting from forage fish to other prey or find food outside of the model area. The model was then developed to explore the dynamics of four future fishery scenarios: (1) business as usual (BAU), (2) maximum sustainable fishing (F = FMSY), (3) half of FMSY, and (4) EBFM with F = 0.5 FMSY for forage fish and F = 0.8 FMSY for other fish. Simulations show that BAU would perpetuate low catches from depleted stocks with a high risk of extinction for harbour porpoise. In contrast, the EBFM scenario would allow the recovery of harbour porpoise, forage fish and cod with increases in catch of herring and cod. EBFM promotes ecosystem resilience to eutrophication and ocean warming, and through the rebuilding of commercial stocks increases by more than three times carbon sequestration compared to BAU. The model provides an interrelated assessment of trophic guilds in the WBS, as required by European law to assess whether European seas are in good environmental status.
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  • 9
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    Framework for Assessing the Feasibility of Carbon Dioxide Removal Options Within the National Context of Germany (2022)
    Frontiers
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    Publication Date: 2024-02-07
    Description: Removal of carbon dioxide from the atmosphere will be required over the next decades to achieve the Paris Agreement goal of limiting global warming to well below 2°C aiming at not exceeding 1.5°C. Technological and ecosystem-based options are considered for generating negative emissions through carbon dioxide removal (CDR) and several nations have already included these in their Long-Term Low Greenhouse Gas Emission Development Strategies. However, strategies for development, implementation, and upscaling of CDR options often remain vague. Considering the scale at which CDR deployment is envisioned in emission pathways for limiting global warming to 1.5°C, significant environmental, social, and institutional implications are to be expected and need to be included in national feasibility assessments of CDR options. Following a multi-disciplinary and comprehensive approach, we created a framework that considers the environmental, technological, economic, social, institutional, and systemic implications of upscaling CDR options. We propose the framework as a tool to help guide decision-relevant feasibility assessments of CDR options, as well as identify challenges and opportunities within the national context. As such, the framework can serve as a means to inform and support decision makers and stakeholders in the iterative science-policy process of determining the role of CDR options in national strategies of achieving net-zero carbon emissions.
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  • 10
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    Gastrointestinal Tract As Entry Route for Hantavirus Infection (2017)
    Frontiers
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    Publication Date: 2017-09-09
    Description: Peter T. Witkowski, Casey C. Perley, Rebecca L. Brocato, Jay W. Hooper, Christian Jürgensen, Jörg-Dieter Schulzke, Detlev H. Krüger, Roland Bücker
    Electronic ISSN: 1664-302X
    Topics: Biology
    Published by Frontiers
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  • 11
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    Hydrocarbon Degradation in Caspian Sea Sediment Cores Subjected to Simulated Petroleum Seepage in a Newly Designed Sediment-Oil-Flow-Through System (2017)
    Frontiers
    In:  Frontiers in Microbiology, 8 (763).
    Details
    Publication Date: 2020-02-06
    Description: The microbial community response to petroleum seepage was investigated in a whole round sediment core (16 cm length) collected nearby natural hydrocarbon seepage structures in the Caspian Sea, using a newly developed Sediment-Oil-Flow-Through (SOFT) system. Distinct redox zones established and migrated vertically in the core during the 190 days-long simulated petroleum seepage. Methanogenic petroleum degradation was indicated by an increase in methane concentration from 8 μM in an untreated core compared to 2300 μM in the lower sulfate-free zone of the SOFT core at the end of the experiment, accompanied by a respective decrease in the δ13C signal of methane from -33.7 to -49.5‰. The involvement of methanogens in petroleum degradation was further confirmed by methane production in enrichment cultures from SOFT sediment after the addition of hexadecane, methylnapthalene, toluene, and ethylbenzene. Petroleum degradation coupled to sulfate reduction was indicated by the increase of integrated sulfate reduction rates from 2.8 SO42-m-2 day-1 in untreated cores to 5.7 mmol SO42-m-2 day-1 in the SOFT core at the end of the experiment, accompanied by a respective accumulation of sulfide from 30 to 447 μM. Volatile hydrocarbons (C2–C6 n-alkanes) passed through the methanogenic zone mostly unchanged and were depleted within the sulfate-reducing zone. The amount of heavier n-alkanes (C10–C38) decreased step-wise toward the top of the sediment core and a preferential degradation of shorter (〈C14) and longer chain n-alkanes (〉C30) was seen during the seepage. This study illustrates, to the best of our knowledge, for the first time the development of methanogenic petroleum degradation and the succession of benthic microbial processes during petroleum passage in a whole round sediment core.
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  • 12
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    Influence of Natural Oxygenation of Baltic Proper Deep Water on Benthic Recycling and Removal of Phosphorus, Nitrogen, Silicon and Carbon (2017)
    Frontiers
    In:  Frontiers in Marine Science, 4 (27).
    Details
    Publication Date: 2020-02-06
    Description: At the end of 2014, a Major Baltic Inflow (MBI) brought oxygenated, salty water into the Baltic proper and reached the long-term anoxic Eastern Gotland Basin (EGB) by March 2015. In July 2015, we measured benthic fluxes of phosphorus (P), nitrogen (N) and silicon (Si) nutrients and dissolved inorganic carbon (DIC) in situ using an autonomous benthic lander at deep sites (170-210 m) in the EGB, where the bottom water oxygen concentration was 30-45 μM. The same in situ methodology was used to measure benthic fluxes at the same sites in 2008-2010, but then under anoxic conditions. The high efflux of phosphate under anoxic conditions became lower upon oxygenation, and turned into an influx in about 50% of the flux measurements. The C:P and N:P ratios of the benthic solute flux changed from clearly below the Redfield ratio (on average about 70 and 3-4, respectively) under anoxia to approaching or being well above the Redfield ratio upon oxygenation. These observations demonstrate retention of P in newly oxygenated sediments. We found no significant effect of oxygenation on the benthic ammonium, silicate and DIC flux. We also measured benthic denitrification, anammox, and dissimilatory nitrate reduction to ammonium (DNRA) rates at the same sites using isotope-pairing techniques. The bottom water of the long-term anoxic EGB contained less than 0.5 μM nitrate in 2008-2010, but the oxygenation event created bottom water nitrate concentrations of about 10 μM in July 2015 and the benthic flux of nitrate was consistently directed into the sediment. Nitrate reduction to both dinitrogen gas (denitrification) and ammonium (DNRA) was initiated in the newly oxygenated sediments, while anammox activity was negligible. We estimated the influence of this oxygenation event on the magnitudes of the integrated benthic P flux (the internal P load) and the fixed N removal through benthic and pelagic denitrification by comparing with a hypothetical scenario without the MBI. Our calculations suggest that the oxygenation triggered by the MBI in July 2015, extrapolated to the basin-wide scale of the Baltic proper, decreased the internal P load by 23% and increased the total (benthic plus pelagic) denitrification by 18%.
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  • 13
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    Linking Ecology to Genetics to Better Understand Adaptation and Evolution: A Review in Marine Macrophytes (2020)
    Frontiers
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    Publication Date: 2023-02-08
    Description: Ecological processes and intra-specific genetic diversity reciprocally affect each other. While the importance of uniting ecological variables and genetic variation to understand species’ plasticity, adaptation, and evolution is increasingly recognized, only few studies have attempted to address the intersection of population ecology and genetics using marine macrophyte as models. Representative empirical case studies on genetic diversity are reviewed that explore ecological and evolutionary processes in marine macrophytes. These include studies on environment-induced phenotypic plasticity and associated ecological adaptation; population genetic variation and structuring driven by ecological variation; and ecological consequences mediated by intraspecific and interspecific diversity. Knowledge gaps are also discussed that impede the connection of ecology and genetics in macrophytes and possible approaches to address these issues. Finally, an eco-evolutionary perspective is advocated, by incorporating structural-to-functional genomics and life cycle complexity, to increase the understanding of the adaptation and evolution of macrophytes in response to environmental heterogeneity.
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  • 14
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    Linking Internal Carbonate Chemistry Regulation and Calcification in Corals Growing at a Mediterranean CO2 Vent (2019)
    Frontiers
    In:  Frontiers in Marine Science, 6 (699).
    Details
    Publication Date: 2022-01-31
    Description: Corals exert a strong biological control over their calcification processes, but there is a lack of knowledge on their capability of long-term acclimatization to ocean acidification (OA). We used a dual geochemical proxy approach to estimate the calcifying fluid pH (pHcf) and carbonate chemistry of a Mediterranean coral (Balanophyllia europaea) naturally growing along a pH gradient (range: pHTS 8.07–7.74). The pHcf derived from skeletal boron isotopic composition (δ11B) was 0.3–0.6 units above seawater values and homogeneous along the gradient (mean ± SEM: Site 1 = 8.39 ± 0.03, Site 2 = 8.34 ± 0.03, Site 3 = 8.34 ± 0.02). Also carbonate ion concentration derived from B/Ca was homogeneous [mean ± SEM (μmol kg–1): Site 1 = 579 ± 34, Site 2 = 541 ± 27, Site 3 = 568 ± 30] regardless of seawater pH. Furthermore, gross calcification rate (GCR, mass of CaCO3 deposited on the skeletal unit area per unit of time), estimated by a “bio-inorganic model” (IpHRAC), was homogeneous with decreasing pH. The homogeneous GCR, internal pH and carbonate chemistry confirm that the features of the “building blocks” – the fundamental structural components – produced by the biomineralization process were substantially unaffected by increased acidification. Furthermore, the pH up-regulation observed in this study could potentially explain the previous hypothesis that less “building blocks” are produced with increasing acidification ultimately leading to increased skeletal porosity and to reduced net calcification rate computed by including the total volume of the pore space. In fact, assuming that the available energy at the three sites is the same, this energy at the low pH sites could be partitioned among fewer calicoblastic cells that consume more energy given the larger difference between external and internal pH compared to the control, leading to the production of less building blocks (i.e., formation of pores inside the skeleton structure, determining increased porosity). However, we cannot exclude that also dissolution may play a role in increasing porosity. Thus, the ability of scleractinian corals to maintain elevated pHcf relative to ambient seawater might not always be sufficient to counteract declines in net calcification under OA scenarios.
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  • 15
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    Major Bottom Water Ventilation Events Do Not Significantly Reduce Basin-Wide Benthic N and P Release in the Eastern Gotland Basin (Baltic Sea) (2017)
    Frontiers
    In:  Frontiers in Marine Science, 4 (18).
    Details
    Publication Date: 2020-02-06
    Description: Redox-sensitive mobilization of nutrients from sediments strongly affects the eutrophic state of the central Baltic Sea; a region associated with the spread of hypoxia and almost permanently anoxic and sulfidic conditions in the deeper basins. Ventilation of these basins depends on renewal by inflow of water enriched in oxygen (O2) from the North Sea, occurring roughly once per decade. Benthic fluxes and water column distributions of dissolved inorganic nitrogen species, phosphate (PO43-), dissolved inorganic carbon (DIC), sulfide (HS-), and total oxygen uptake (TOU) were measured along a depth gradient in the Eastern Gotland Basin (EGB). Campaigns were conducted during euxinic conditions of the deep basin in Aug./Sept. 2013 and after two inflow events in July/Aug. 2015 and March 2016 when O2 concentrations in deep waters reached 60 μM. The intrusion of O2-rich North Sea water into the EGB led to an approximate 33 and 10% reduction of the seabed PO43- and ammonium (NH4+) release from deep basin sediments. Post-inflow, the deep basin sediment was rapidly colonized by HS- oxidizing bacteria tentatively assigned to the family Beggiatoaceae, and HS- release was completely suppressed. The presence of a hypoxic transition zone (HTZ) between 80 and 120 m water depth was confirmed not only for euxinic deep-water conditions during 2013 but also for post-inflow conditions. Because deep-water renewal did not ventilate the HTZ, where PO43- and NH4+ fluxes were highest, high seabed nutrient release there was relatively unchanged. Extrapolation of the in situ nutrient fluxes indicated that, overall, the reduction in PO43- and NH4+ release in response to deep-water renewal can be considered as minor, reducing the internal nutrient load by 2 and 12% only, respectively. Infrequent inflow events thus have a limited capacity to sustainably reduce internal nutrient loading in the EGB and mitigate eutrophication.
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  • 16
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    Mechanisms of P* Reduction in the Eastern Tropical South Pacific (2017)
    Frontiers
    Details
    Publication Date: 2023-09-19
    Description: Water masses influenced by oxygen minimum zones (OMZ) feature low inorganic nitrogen (N) to phosphorus (P) ratios. The surplus of P over N is thought to favor non-Redfield primary production by bloom-forming phytoplankton species. Additionally, excess phosphate (P*) is thought to provide a niche for nitrogen fixing organisms. In order to assess the effect of low inorganic nutrient ratios on the stoichiometry and composition of primary producers, biogeochemical measurements were carried out in 2012 during a research cruise in the eastern tropical South Pacific (ETSP). Based on pigment analyses, a succession of different phytoplankton functional groups was observed along onshore—offshore transects with diatoms dominating the productive upwelling region, and prymnesiophytes, cryptophytes, and Synechococcus prevailing in the oligotrophic open ocean. Although inorganic nutrient supply ratios were below Redfield proportions throughout the sampling area, the stoichiometry of particulate organic nitrogen to phosphorus (PON:POP) generally exceeded ratios of 16:1. Despite PON:POP ≥ 16, high P*-values in the surface layer (0–50 m) above the shelf rapidly decreased as water masses were advected offshore. There are three mechanisms which can explain these observations: (1) non-Redfield primary production, where the excess phosphorus in the biomass is directly released as dissolved organic phosphorus (DOP), (2) non-Redfield primary production, which is masked by a particulate organic matter pool mainly consisting of P-depleted detrital biomass, and/or (3) Redfield primary production combined with dinitrogen (N2) fixation. Our observations suggest that the three processes occur simultaneously in the study area; quantifying the relative importance of each of these mechanisms needs further investigation. Therefore, it remains uncertain whether the ETSP is a net sink for bioavailable N or whether the N-deficit in this area is replenished locally.
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  • 17
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    Microbial communities under distinct thermal and geochemical regimes in axial and off-axis sediments of Guaymas Basin (2021)
    Frontiers
    In:  EPIC3Frontiers in microbiology, Frontiers, 12, pp. 110
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    Publication Date: 2021-10-20
    Repository Name: EPIC Alfred Wegener Institut
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  • 18
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    Microbial Community Response to Simulated Petroleum Seepage in Caspian Sea Sediments (2017)
    Frontiers
    In:  Frontiers in Microbiology, 8 (764).
    Details
    Publication Date: 2020-02-06
    Description: Anaerobic microbial hydrocarbon degradation is a major biogeochemical process at marine seeps. Here we studied the response of the microbial community to petroleum seepage simulated for 190 days in a sediment core from the Caspian Sea using a sediment-oil-flow-through (SOFT) system. Untreated (without simulated petroleum seepage) and SOFT sediment microbial communities shared 43% bacterial genuslevel 16S rRNA-based operational taxonomic units (OTU0:945) but shared only 23% archaeal OTU0:945. The community differed significantly between sediment layers. The detection of fourfold higher deltaproteobacterial cell numbers in SOFT than in untreated sediment at depths characterized by highest sulfate reduction rates and strongest decrease of gaseous and mid-chain alkane concentrations indicated a specific response of hydrocarbon-degrading Deltaproteobacteria. Based on an increase in specific CARD-FISH cell numbers, we suggest the following groups of sulfate-reducing bacteria to be likely responsible for the observed decrease in aliphatic and aromatic hydrocarbon concentration in SOFT sediments: clade SCA1 for propane and butane degradation, clade LCA2 for mid- to long-chain alkane degradation, clade Cyhx for cycloalkanes, pentane and hexane degradation, and relatives of Desulfobacula for toluene degradation. Highest numbers of archaea of the genus Methanosarcina were found in the methanogenic zone of the SOFT core where we detected preferential degradation of long-chain hydrocarbons. Sequencing of masD, a marker gene for alkane degradation encoding (1-methylalkyl)succinate synthase, revealed a low diversity in SOFT sediment with two abundant species-level MasD OTU0:96.
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  • 19
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    Microbial Diversity and Connectivity in Deep-Sea Sediments of the South Atlantic Polar Front (2019)
    Frontiers
    In:  Frontiers in Microbiology, 10 (Article number 665).
    Details
    Publication Date: 2022-01-31
    Description: Ultraslow spreading ridges account for one-third of the global mid-ocean ridges. Their impact on the diversity and connectivity of benthic deep-sea microbial assemblages is poorly understood, especially for hydrothermally inactive, magma-starved ridges. We investigated bacterial and archaeal diversity in sediments collected from an amagmatic segment (10∘–17∘E) of the Southwest Indian Ridge (SWIR) and in the adjacent northern and southern abyssal zones of similar water depths within one biogeochemical province of the Indian Ocean. Microbial diversity was determined by 16S ribosomal RNA (rRNA) gene sequencing. Our results show significant differences in microbial communities between stations outside and inside the SWIR, which were mostly explained by environmental selection. Community similarity correlated significantly with differences in chlorophyll a content and with the presence of upward porewater fluxes carrying reduced compounds (e.g., ammonia and sulfide), suggesting that trophic resource availability is a main driver for changes in microbial community composition. At the stations in the SWIR axial valley (3,655–4,448 m water depth), microbial communities were enriched in bacterial and archaeal taxa common in organic matter-rich subsurface sediments (e.g., SEEP-SRB1, Dehalococcoida, Atribacteria, and Woesearchaeota) and chemosynthetic environments (mainly Helicobacteraceae). The abyssal stations outside the SWIR communities (3,760–4,869 m water depth) were dominated by OM1 clade, JTB255, Planctomycetaceae, and Rhodospirillaceae. We conclude that ultraslow spreading ridges create a unique environmental setting in sedimented segments without distinct hydrothermal activity, and play an important role in shaping microbial communities and promoting diversity, but also in connectivity among deep-sea habitats.
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    Microbial Sulfide Filter along a Benthic Redox Gradient in the Eastern Gotland Basin, Baltic Sea (2017)
    Frontiers
    In:  Frontiers in Microbiology, 8 (169).
    Details
    Publication Date: 2020-02-06
    Description: The sediment-water interface is an important site for material exchange in marine systems and harbor unique microbial habitats. The flux of nutrients, metals, and greenhouse gases at this interface may be severely dampened by the activity of microorganisms and abiotic redox processes, leading to the “benthic filter” concept. In this study, we investigate the spatial variability, mechanisms and quantitative importance of a microbially-dominated benthic filter for dissolved sulfide in the Eastern Gotland Basin (Baltic Sea) that is located along a dynamic redox gradient between 65 and 173 m water depth. In August-September 2013, high resolution (0.25 mm minimum) vertical microprofiles of redox-sensitive species were measured in surface sediments with solid-state gold-amalgam voltammetric microelectrodes. The highest sulfide consumption (2.73–3.38 mmol m−2 day−1) occurred within the top 5 mm in sediments beneath a pelagic hypoxic transition zone (HTZ, 80–120 m water depth) covered by conspicuous white bacterial mats of genus Beggiatoa. A distinct voltammetric signal for polysulfides, a transient sulfur oxidation intermediate, was consistently observed within the mats. In sediments under anoxic waters (〉140 m depth), signals for Fe(II) and aqueous FeS appeared below a subsurface maximum in dissolved sulfide, indicating a Fe(II) flux originating from older sediments presumably deposited during the freshwater Ancylus Lake that preceded the modern Baltic Sea. Our results point to a dynamic benthic sulfur cycling in Gotland Basin where benthic sulfide accumulation is moderated by microbial sulfide oxidation at the sediment surface and FeS precipitation in deeper sediment layers. Upscaling our fluxes to the Baltic Proper; we find that up to 70% of the sulfide flux (2281 kton yr−1) toward the sediment-seawater interface in the entire basin can be consumed at the microbial mats under the HTZ (80–120 m water depth) while only about 30% the sulfide flux effuses to the bottom waters (〉120 m depth). This newly described benthic filter for the Gotland Basin must play a major role in limiting the accumulation of sulfide in and around the deep basins of the Baltic Sea.
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  • 21
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    Molecular Ontogeny of First-Feeding European Eel Larvae (2018)
    Frontiers
    In:  Frontiers in Physiology, 9 . Art.Nr. 1477.
    Details
    Publication Date: 2021-02-08
    Description: Digestive system functionality of fish larvae relies on the onset of genetically pre-programmed and extrinsically influenced digestive functions. This study explored how algal supplementation (green-water) until 14 days post hatch (dph) and the ingestion of food [enriched rotifer (Brachionus plicatilis) paste] from 15 dph onward affects molecular maturation and functionality of European eel larval ingestion and digestion mechanisms. For this, we linked larval biometrics to expression of genes relating to appetite [ghrelin (ghrl), cholecystokinin (cck)], food intake [proopiomelanocortin (pomc)], digestion [trypsin (try), triglyceride lipase (tgl), amylase (amyl)], energy metabolism [ATP synthase F0 subunit 6 (atp6), cytochrome-c-oxidase 1 (cox1)], growth [insulin-like growth factor (igf1)] and thyroid metabolism [thyroid hormone receptors (thrαA, thrβB)]. Additionally, we estimated larval nutritional status via nucleic acid analysis during transition from endogenous and throughout the exogenous feeding stage. Results showed increased expression of ghrl and cck on 12 dph, marking the beginning of the first-feeding window, but no benefit of larviculture in green-water was observed. Moreover, expression of genes relating to protein (try) and lipid (tgl) hydrolysis revealed essential digestive processes occurring from 14 to 20 dph. On 16 dph, a molecular response to initiation of exogenous feeding was observed in the expression patterns of pomc, atp6, cox1, igf1, thrαA and thrβB. Additionally, we detected increased DNA contents, which coincided with increased RNA contents and greater body area, reflecting growth in feeding compared to non-feeding larvae. Thus, the here applied nutritional regime facilitated a short-term benefit, where feeding larvae were able to sustain growth and better condition than their non-feeding conspecifics. However, RNA:DNA ratios decreased from 12 dph onward, indicating a generally low larval nutritional condition, probably leading to the point-of-no-return and subsequent irreversible mortality due to unsuccessful utilization of exogenous feeding. In conclusion, this study molecularly identified the first-feeding window in European eel and revealed that exogenous feeding success occurs concurrently with the onset of a broad array of enzymes and hormones, which are known to regulate molecular processes in feeding physiology. This knowledge constitutes essential information to develop efficient larval feeding strategies and will hopefully provide a promising step toward sustainable aquaculture of European eel.
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    MtDNA-Based Phylogeography of the Red Alga Agarophyton vermiculophyllum (Gigartinales, Rhodophyta) in the Native Northwest Pacific (2020)
    Frontiers
    Details
    Publication Date: 2023-02-08
    Description: The repeated transgression and regression of coastlines mediated by the late Quaternary glacial–interglacial cycles make the northwest Pacific a hot spot to study marine speciation and population diversity. The red alga Agarophyton vermiculophyllum is an ecologically important species native to the northwest Pacific, capturing considerable research interest due to its wide-range invasiveness in Europe and North America. However, the knowledge of phylogeographic structure and intraspecific genetic diversity across the entire native range was still scarce. Here, we used 1,214-bp of mitochondrial cytochrome c oxidase subunit 1 (cox1) to explore phylogeographic patterns, lineage structure, and population genetic differentiation of 48 A. vermiculophyllum populations in the northwest Pacific. Our DNA data revealed overall high haplotype diversity and low nucleotide diversity and five phylogeographically structured genetic lineages that diverged significantly from each other. S-DIVA analysis showed the ancestors of A. vermiculophyllum originating from multiple areas encompassing the Japan–Pacific coast, East and South China Seas. This combined evidence indicates that A. vermiculophyllum might have survived in multiple scattered glacial refugia during the late Quaternary climate oscillations in the northwest Pacific. Such knowledge may help to better understand how palaeoclimate interacted with contemporary environments to contribute to intraspecific genetic variation and provide a new perspective for conserving natural resource of A. vermiculophyllum in the northwest Pacific.
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  • 23
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    Navigating Potential Hype and Opportunity in Governing Marine Carbon Removal (2021)
    Frontiers
    Details
    Publication Date: 2024-02-07
    Description: As the technical and political challenges of land-based carbon dioxide removal (CDR) approaches become more apparent, the oceans may be the new “blue” frontier for carbon drawdown strategies in climate governance. Drawing on lessons learnt from the way terrestrial carbon dioxide removal emerged, we explore increasing overall attention to marine environments and mCDR projects, and how this could manifest in four entwined knowledge systems and governance sectors. We consider how developments within and between these “frontiers” could result in different futures—where hype and over-promising around marine carbon drawdown could enable continued time-buying for the carbon economy without providing significant removals, or where reforms to modeling practices, policy development, innovation funding, and legal governance could seek co-benefits between ocean protection, economy, and climate.
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  • 24
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    On synchronous supereruptions (2022)
    Frontiers
    Details
    Publication Date: 2024-02-07
    Description: The Youngest Toba Tuff (YTT) supereruption from Toba Caldera in Sumatra at ca. 74,000 years BP is the largest volcanic event recorded in the Pleistocene. Intriguingly, recent radioisotopic dating of the near antipodal Los Chocoyos (LCY) supereruption from the Atitlán caldera in Guatemala finds an identical age within uncertainties to that of YTT. This opens the question of whether these synchronous supereruptions may be a coincidence or could be a consequence of each other? Using the known eruptive record from the past 2 Myr, we find that the likelihood of having two near antipodal supereruptions (〉1,000 km3 tephra volume) within centuries (〈400 years), as suggested by volcanic proxies and annual counting layer chronology in the ice core records, is very small (0.086%), requiring a non-random cause and effect. Considering this analysis, we speculate that one potential physical mechanism that could explain the temporal relationship between these supereruptions is that seismic energy released during YTT eruption focused on the antipodal region, where concentrated stresses ultimately promoted the eruption of the perched LCY magma system (or vice versa). This supereruption “double-whammy” may thus be the more compelling source of the significant environmental impacts often attributed individually to the YTT supereruption. Improving the existing age information of YTT and LCY, and a better understanding of caldera collapse events will enable further testing of the hypothesis that synchronous supereruptions do not result by pure chance.
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  • 25
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    Particulate Organic Carbon Deconstructed: Molecular and Chemical Composition of Particulate Organic Carbon in the Ocean (2020)
    Frontiers
    Details
    Publication Date: 2023-02-08
    Description: The dynamics of the particulate organic carbon (POC) pool in the ocean are central to the marine carbon cycle. POC is the link between surface primary production, the deep ocean, and sediments. The rate at which POC is degraded in the dark ocean can impact atmospheric CO2 concentration. Therefore, a central focus of marine organic geochemistry studies is to improve our understanding of POC distribution, composition, and cycling. The last few decades have seen improvements in analytical techniques that have greatly expanded what we can measure, both in terms of organic compound structural diversity and isotopic composition, and complementary molecular omics studies. Here we provide a brief overview of the autochthonous, allochthonous, and anthropogenic components comprising POC in the ocean. In addition, we highlight key needs for future research that will enable us to more effectively connect diverse data sources and link the identity and structural diversity of POC to its sources and transformation processes.
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    Practical Issues in Monitoring a Hydrocarbon Cultivation Activity in Italy: The Pilot Project at the Cavone Oil Field (2021)
    Frontiers
    Details
    Publication Date: 2021-11-12
    Description: In this paper we describe the results of an experimental implementation of the recent guidelines issued by the Italian regulatory body for monitoring hydrocarbon production activities. In particular, we report about the pilot study on seismic, deformation, and pore pressure monitoring of the Mirandola hydrocarbon cultivation facility in Northern Italy. This site hosts the Cavone oil field that was speculated of possibly influencing the 2012 ML 5.8 Mirandola earthquake source. According to the guidelines, the monitoring center should analyse geophysical measurements related to seismicity, crustal deformation and pore pressure in quasi real-time (within 24–48 h). A traffic light system would then be used to regulate underground operations in case of detecting significant earthquakes (i.e., events with size and location included in critical ranges). For these 2-year period of guidelines experimentation, we analysed all different kinds of available data, and we tested the existence of possible relationship between their temporal trends. Despite the short time window and the scarce quantity of data collected, we performed the required analysis and extracted as much meaningful and statistically reliable information from the data. We discuss here the most important observations drawn from the monitoring results, and highlight the lessons learned by describing practical issues and limitations that we have encountered in carrying out the tasks as defined in the guidelines. Our main goal is to contribute to the discussion about how to better monitor the geophysical impact of this kind of anthropogenic activity. We point out the importance of a wider seismic network but, mostly, of borehole sensors to improve microseismic detection capabilities. Moreover, the lack of an assessment of background seismicity in an unperturbed situation -due to long life extraction activities- makes it difficult to get a proper picture of natural background seismic activity, which would be instead an essential reference information for a tectonically-active regions, such as Northern Italy.
    Description: “Convenzione tra il comune di San Possidonio e l’Istituto Nazionale di Geofisica e Vulcanologia -I.N.G.V.- per l’attuazione del monitoraggio nella concessione di coltivazione idrocarburi “Mirandola” finalizzata alla messa in opera di attività di monitoraggio di sperimentazione degli indirizzi e linee guida per i monitoraggi ILG ed assunzione funzioni di Struttura Preposta al Monitoraggio di cui all’art. 6 del Protocollo Operativo”
    Description: Published
    Description: 685300
    Description: 3SR TERREMOTI - Attività dei Centri
    Description: JCR Journal
    Keywords: Italian guidelines for monitoring industrial activities ; induced seismicity ; pore pressure monitoring ; deformation monitoring ; seismic monitoring ; 04.06. Seismology ; 05.09. Miscellaneous ; 04.02. Exploration geophysics ; 04.03. Geodesy
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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    Relevance of Nutrient-Limited Phytoplankton Production and Its Bacterial Remineralization for Carbon and Oxygen Fluxes in the Baltic Sea (2019)
    Frontiers
    In:  Frontiers in Marine Science, 6 . Art.Nr. 581.
    Details
    Publication Date: 2022-01-31
    Description: The Baltic Sea is prone to oxygen deficiency due to the restricted water exchange with the North Sea in coincidence with a high biological oxygen demand. The partitioning of organic carbon between respiration, accumulation and export is co-determined by phytoplankton primary production and its subsequent bacterial remineralization. Here, we investigated net phytoplankton primary production, heterotrophic bacterial biomass production and dark CO2 fixation by on-board incubations with radiolabeled tracers in the Baltic Proper and in the Gulf of Riga after the main spring bloom. Results show that low phytoplankton standing stocks of ≤1.6 μg chlorophyll a L–1 sustained net primary production of 161–724 mg C m–2 d–1 under nitrogen limitation. Estimates of bacterial carbon remineralization suggest that freshly produced organic carbon was supplied to the aphotic zone at all stations. In the southern Baltic Proper, net primary production exceeded the bacterial carbon demand in the surface mixed layer, suggesting that organic matter derived from nutrient-limited primary production was available for export to bacterial communities below the oxycline. On average, 46% of heterotrophic bacterial production was mediated in oxygen minimum zones, revealing the high importance of organic matter recycling under hypoxic and anoxic conditions for the carbon budget. Dark CO2 fixation of up to 4.33 μg C L–1 d–1 in sulfide-free waters equaled 9–54% of the co-inciding heterotrophic bacterial carbon demand and may have provided another organic carbon source for heterotrophic activity. Substantially higher dark CO2 fixation up to 25.46 μg C L–1 d–1 was determined in sulfidic waters. Since our study was conducted 5 months after the major Baltic inflow event in winter 2014/2015, potential effects of deep water ventilation could be investigated. In the Gotland Basin, heterotrophic bacterial production in renewed oxygen-rich bottom water was similar to that in the uplifted oxygen-deficient former bottom water, while it was significantly reduced in sulfidic waters. Hence, our results suggest that the removal of hydrogen sulfide by inflow events has a high potential to increase bacterial carbon remineralization.
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    Salinity Driven Selection and Local Adaptation in Baltic Sea Mytilid Mussels (2021)
    Frontiers
    Details
    Publication Date: 2024-02-07
    Description: Baltic blue mussels can colonise and dominate habitats with far lower salinity (〈 10 psu) than other Mytilus congeners. Pervasive gene flow was observed between Western Baltic Mytilus edulis living at high salinity conditions and Eastern Baltic M. trossulus living at lower salinites, with highest admixture proportions within a genetic transition zone located at intermediate salinities (Darss Sill area). Yet, we do not understand the impacts of low salinity on larval performance, and how salinity may act as an early selective pressure during passive larval drift across salinity gradients. This study tested whether larvae originating from two different populations along the natural salinity cline in the Baltic Sea have highest fitness at their native salinities. Our results suggest that Eastern Baltic M. trossulus (Usedom, 7 psu) and Western Baltic M. edulis (Kiel, 16 psu) larvae display better performance (fitness components: growth, mortality, settlement success) when reared at their respective native salinities. This suggests that these populations are adapted to their local environment. Additionally, species diagnostic markers were used for genetic analyses of transition zone (Ahrenshoop, 11 psu) mussel larvae exposed to low salinity. This revealed that low salinity selection resulted in a shift towards allele frequencies more typical for Eastern Baltic M. trossulus. Thus, salinity acts as a selective pressure during the pre-settlement phase and can shape the genetic composition of Baltic mussel populations driving local adaptation to low salinity. Future climate change driven desalination, therefore, has the potential to shift the Baltic Sea hybrid gradient westward with consequences for benthic ecosystem structure.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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    Surface impacts and associated mechanisms of a moisture intrusion into the Arctic observed in mid-April 2020 during MOSAiC (2023)
    Frontiers
    In:  EPIC3Frontiers in Earth Science, Frontiers, 11, pp. 1147848-1147848, ISSN: 2296-6463
    Details
    Publication Date: 2023-09-15
    Description: Distinct events of warm and moist air intrusions (WAIs) from mid-latitudes have pronounced impacts on the Arctic climate system. We present a detailed analysis of a record-breaking WAI observed during the MOSAiC expedition in mid-April 2020. By combining Eulerian with Lagrangian frameworks and using simulations across different scales, we investigate aspects of air mass transformations via cloud processes and quantify related surface impacts. The WAI is characterized by two distinct pathways, Siberian and Atlantic. A moist static energy transport across the Arctic Circle above the climatological 90th percentile is found. Observations at research vessel Polarstern show a transition from radiatively clear to cloudy state with significant precipitation and a positive surface energy balance (SEB), i.e., surface warming. WAI air parcels reach Polarstern first near the tropopause, and only 1–2 days later at lower altitudes. In the 5 days prior to the event, latent heat release during cloud formation triggers maximum diabatic heating rates in excess of 20 K d-1. For some poleward drifting air parcels, this facilitates strong ascent by up to 9 km. Based on model experiments, we explore the role of two key cloud-determining factors. First, we test the role moisture availability by reducing lateral moisture inflow during the WAI by 30%. This does not significantly affect the liquid water path, and therefore the SEB, in the central Arctic. The cause are counteracting mechanisms of cloud formation and precipitation along the trajectory. Second, we test the impact of increasing Cloud Condensation Nuclei concentrations from 10 to 1,000 cm-3 (pristine Arctic to highly polluted), which enhances cloud water content. Resulting stronger longwave cooling at cloud top makes entrainment more efficient and deepens the atmospheric boundary layer. Finally, we show the strongly positive effect of the WAI on the SEB. This is mainly driven by turbulent heat fluxes over the ocean, but radiation over sea ice. The WAI also contributes a large fraction to precipitation in the Arctic, reaching 30% of total precipitation in a 9-day period at the MOSAiC site. However, measured precipitation varies substantially between different platforms. Therefore, estimates of total precipitation are subject to considerable observational uncertainty.
    Repository Name: EPIC Alfred Wegener Institut
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    Tephra without borders: Far-reaching clues into past explosive eruptions (2015)
    Frontiers
    In:  Frontiers in Earth Science, 3 (83).
    Details
    Publication Date: 2016-01-08
    Description: This review is intended to highlight recent exciting advances in the study of distal (〉100 km from the source) tephra and cryptotephra deposits and their potential application for volcanology. Geochemical correlations of tephra between proximal and distal locations have extended the geographical distribution of tephra over tens of millions square kilometers. Such correlations embark on the potential to reappraise volume and magnitude estimates of known eruptions. Cryptotephra investigations in marine, lake and ice-core records also give rise to continuous chronicles of large explosive eruptions many of which were hitherto unknown. Tephra preservation within distal ice sheets and varved lake sediments permit precise dating of parent eruptions and provide new insight into the frequency of eruptions. Recent advances in analytical methods permit an examination of magmatic processes and the evolution of the whole volcanic belts at distances of hundreds and thousands of kilometers from source. Distal tephrochronology has much to offer volcanology and has the potential to significantly contribute to our understanding of sizes, recurrence intervals and geochemical make-up of the large explosive eruptions.
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    Tephrostratigraphy of Pleistocene-Holocene deposits from the Detroit Rise eastern slope (northwestern Pacific) (2023)
    Frontiers
    Details
    Publication Date: 2024-02-07
    Description: The main goal of the study is to establish the spatial and temporal distribution of pyroclastic material from large explosive eruptions of the volcanoes of Kamchatka, the Kuril, and Aleutian Islands to create a generalized tephrochronological model and reveal patterns of explosive activity in this region. This paper presents new data on the composition of volcanic ash (tephra) found in the Pleistocene deposits of the northwestern Pacific from the eastern slope of the Detroit Rise (northwestern part of the Imperial Ridge), 450–550 km east of the Kamchatka Peninsula. Eleven layers and lenses of tephra aged from 28 to 245 ka, which were previously unknown, were studied in the core Lv63-4-2. Their stratigraphic position and age were determined based on age models developed in this study. Based on the geochemical composition of volcanic glass (determined using an electron microprobe), seven layers were correlated with tephra from several cores in the northwestern Pacific and the Bering Sea. The obtained results supplement the information on large explosive eruptions of volcanoes in the region and their periods of activity. They also allow the development of a generalized tephrochronological model of Quaternary deposits, which is necessary for stratigraphic correlation, and of paleooceanological and paleogeographic reconstructions.
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    The Essentials of Marine Biotechnology (2021)
    Frontiers
    Details
    Publication Date: 2024-02-07
    Description: Coastal countries have traditionally relied on the existing marine resources (e.g., fishing, food, transport, recreation, and tourism) as well as tried to support new economic endeavors (ocean energy, desalination for water supply, and seabed mining). Modern societies and lifestyle resulted in an increased demand for dietary diversity, better health and well-being, new biomedicines, natural cosmeceuticals, environmental conservation, and sustainable energy sources. These societal needs stimulated the interest of researchers on the diverse and underexplored marine environments as promising and sustainable sources of biomolecules and biomass, and they are addressed by the emerging field of marine (blue) biotechnology. Blue biotechnology provides opportunities for a wide range of initiatives of commercial interest for the pharmaceutical, biomedical, cosmetic, nutraceutical, food, feed, agricultural, and related industries. This article synthesizes the essence, opportunities, responsibilities, and challenges encountered in marine biotechnology and outlines the attainment and valorization of directly derived or bio-inspired products from marine organisms. First, the concept of bioeconomy is introduced. Then, the diversity of marine bioresources including an overview of the most prominent marine organisms and their potential for biotechnological uses are described. This is followed by introducing methodologies for exploration of these resources and the main use case scenarios in energy, food and feed, agronomy, bioremediation and climate change, cosmeceuticals, bio-inspired materials, healthcare, and well-being sectors. The key aspects in the fields of legislation and funding are provided, with the emphasis on the importance of communication and stakeholder engagement at all levels of biotechnology development. Finally, vital overarching concepts, such as the quadruple helix and Responsible Research and Innovation principle are highlighted as important to follow within the marine biotechnology field. The authors of this review are collaborating under the European Commission-funded Cooperation in Science and Technology (COST) Action Ocean4Biotech – European transdisciplinary networking platform for marine biotechnology and focus the study on the European state of affairs.
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    The invasive alga Gracilaria vermiculophylla in the native northwest Pacific under ocean warming: Southern genetic consequence and northern range expansion (2022)
    Frontiers
    Details
    Publication Date: 2024-02-07
    Description: Ocean warming is one of the most important factors in shaping the spatial distribution and genetic biodiversity of marine organisms worldwide. The northwest Pacific has been broadly illustrated as an essential seaweed diversity hotspot. However, few studies have yet investigated in this region on whether and how past and ongoing climate warming impacted the distribution and genetic pools of coastal seaweeds. Here, we chose the invasive species Gracilaria vermiculophylla as a model, and identified multiple genetic lineages in the native range through genome-scale microsatellite genotyping. Subsequently, by reconstructing decadal trends of sea surface temperature (SST) change between 1978 and 2018, we found that SST in northern Japan and the East China Sea indeed increased broadly by 0.25-0.4°C/decade. The projections of species distribution models (SDMs) under different future climate change scenarios (RCP 2.6, RCP 4.5, RCP 6.0 and RCP 8.5) indicated that a unique genetic pool of G. vermiculophylla at its current southern range limit (i.e. the South China Sea) is at high risk of disappearance, and that the populations at its current northern range limit (i.e. in Hokkaido region) will undergo poleward expansions, particularly by the year 2100. Such responses, along with this species’ limited dispersal potential, may considerably alter the contemporary distribution and genetic composition of G. vermiculophylla in the northwest Pacific, and ultimately threaten ecological services provided by this habitat-forming species and other associated functional roles.
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