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  • Elsevier  (4,223)
  • American Association for the Advancement of Science (AAAS)
  • American Chemical Society (ACS)
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  • 2020-2024  (4,375)
  • 1950-1954
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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physics Letters B 294 (1992), S. 466-478 
    ISSN: 0370-2693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Physics Letters B 317 (1993), S. 474-484 
    ISSN: 0370-2693
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2023-10-04
    Description: The current policy and goals aimed to conserve biodiversity and manage biodiversity change are often formulated at the global scale. At smaller scales however, biodiversity change is more nuanced leading to a plethora of trends in different metrics of alpha diversity and temporal turnover. Therefore, large-scale policy targets do not translate easily into local to regional management decisions for biodiversity. Using long-term monitoring data from the Wadden Sea (Southern North Sea), joining structural equation models and general dissimilarity models enabled a better overview of the drivers of biodiversity change. Few commonalities emerged as birds, fish, macroinvertebrates, and phytoplankton differed in their response to certain drivers of change. These differences were additionally dependent upon the biodiversity aspect in question and which environmental data were recorded in each monitoring program. No single biodiversity metric or model sufficed to capture all ongoing change, which requires an explicitly multivariate approaches to biodiversity assessment in local ecosystem management.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 4
    Publication Date: 2023-09-18
    Description: Habitat forming ecosystem engineers play critical roles in structuring coastal seascapes. Many ecosystem engineers, such as seagrasses and epifaunal bivalves, are known to have positive effects on sediment stability and increase coastal protection and ecosystem resilience. Others, such as bioturbating infaunal bivalves, may instead destabilize sediment. However, despite the common co-occurrence of seagrasses and bivalves in coastal seascapes, little is known of their combined effects on sediment dynamics. Here, we used wave flumes to compare sediment dynamics in monospecific and multispecific treatments of eelgrass, Zostera marina, and associated bivalves (infaunal Limecola balthica, infaunal Cerastoderma edule, epifaunal Magellana gigas) under a range of wave exposures. Eelgrass reduced bedload erosion rates by 25–50%, with digital elevation models indicating that eelgrass affected the sediment micro-bathymetry by decreasing surface roughness and ripple sizes. Effects of bivalves on sediment mobilization were species-specific; L. balthica reduced erosion by 25%, C. edule increased erosion by 40%, while M. gigas had little effect. Importantly, eelgrass modified the impacts of bivalves: the destabilizing effects of C. edule vanished in the presence of eelgrass, while we found positive additive effects of eelgrass and L. balthica on sediment stabilization and potential for mutual anchoring. Such interspecific interactions are likely relevant for habitat patch emergence and resilience to extreme wave conditions. In light of future climate scenarios where increasing storm frequency and wave exposure threaten coastal ecosystems, our results add a mechanistic understanding of sediment dynamics and interactions between ecosystem engineers, with relevance for management and conservation.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
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  • 5
    Publication Date: 2023-09-19
    Description: The last deglaciation was characterized by a sequence of abrupt climate events thought to be linked to rapid changes in Atlantic meridional overturning circulation (AMOC). The sequence includes a weakening of the AMOC after the Last Glacial Maximum (LGM) during Heinrich Stadial 1 (HS1), which ends with an abrupt AMOC amplification at the transition to the Bølling/Allerød (B/A). This transition occurs despite persistent deglacial meltwater fluxes that counteract vigorous North Atlantic deep-water formation. Using the Earth system model COSMOS with a range of deglacial boundary conditions and reconstructed deglacial meltwater fluxes, we show that deglacial CO2 rise and ice sheet decline modulate the sensitivity of the AMOC to these fluxes. While declining ice sheets increase the sensitivity, increasing atmospheric CO2 levels tend to counteract this effect. Therefore, the occurrence of a weaker HS1 AMOC and an abrupt AMOC increase in the presence of meltwater, might be explained by these effects, as an alternative to or in combination with changes in the magnitude or routing of meltwater discharge.
    Repository Name: EPIC Alfred Wegener Institut
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  • 6
    Publication Date: 2023-09-22
    Description: Primary consumers in aquatic ecosystems are frequently limited by the quality of their food, often expressed as phytoplankton elemental and biochemical composition. However, the effects of these food quality indicators vary across studies, and we lack an integrated understanding of how elemental (e.g. nitrogen, phosphorus) and biochemical (e.g. fatty acid, sterol) limitations interactively influence aquatic food webs. Here, we present the results of a meta-analysis using 〉100 experimental studies, confirming that limitation by N, P, fatty acids, and sterols all have significant negative effects on zooplankton performance. However, effects varied by grazer response (growth vs. reproduction), specific manipulation, and across taxa. While P limitation had greater effects on zooplankton growth than fatty acids overall, P and fatty acid limitation had equal effects on reproduction. Furthermore, we show that: nutrient co-limitation in zooplankton is strong; effects of essential fatty acid limitation depend on P availability; indirect effects induced by P limitation exceed direct effects of mineral P limitation; and effects of nutrient amendments using laboratory phytoplankton isolates exceed those using natural field communities. Our meta-analysis reconciles contrasting views about the role of various food quality indicators, and their interactions, for zooplankton performance, and provides a mechanistic understanding of trophic transfer in aquatic environments.
    Repository Name: EPIC Alfred Wegener Institut
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  • 7
    Publication Date: 2023-09-22
    Description: Ecological stability refers to a range of concepts used to quantify how species and environments change over time and in response to disturbances. Most empirically tractable ecological stability metrics assume that systems have simple dynamics and static equilibria. However, ecological systems are typically complex and often lack static equilibria (e.g., predator–prey oscillations, transient dynamics, chaos). Failing to account for these factors can lead to biased estimates of stability, in particular, by conflating effects of observation error, process noise, and underlying deterministic dynamics. To distinguish among these processes, we combine three existing approaches: state space models; delay embedding methods; and particle filtering. Jointly, these provide something akin to a deterministically “detrended” version of the coefficient of variation, separately tracking variability due to deterministic dynamics versus stochastic perturbations. Moreover, these variability estimates can be used to forecast dynamics, classify underlying sources of stochastic dynamics, and estimate the “exit time” before a state change takes place (e.g., local extinction events). Importantly, the time-delay embedding methods that we employ make very few assumptions about the functions governing deterministic dynamics, which facilitates applications in systems with limited data and a priori biological knowledge. To demonstrate how complex dynamics without static equilibria can bias ecological stability estimates, we analyze simulated time series of abundance dynamics in a system with time-varying carrying capacity and empirically observed abundance dynamics of the green algae Chlamydomonas terricola grown in a diverse microcosm mixture under variable temperature conditions. We show that stability estimates based on raw observations greatly overestimate temporal variability and fail to accurately forecast time to extinction. In contrast, joint application of state space modeling, delay embedding, and particle filters were able to: (1) correctly quantify the contributions of deterministic versus stochastic variability; (2) successfully estimate “true” abundance dynamics; and (3) correctly forecast time to extinction. Our results therefore demonstrate the importance of accounting for effects of complex, nonstatic dynamics in studies of ecological stability and provide an empirically tractable and flexible toolkit for conducting these measurements.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
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  • 8
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    Elsevier
    In:  EPIC3Political Geography, Elsevier, 92, pp. 102581-102581, ISSN: 0962-6298
    Publication Date: 2023-10-30
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , peerRev
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  • 9
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    Elsevier
    In:  EPIC3Chemical Geology, Elsevier, 597, pp. 120795-120795, ISSN: 0167-6695
    Publication Date: 2023-10-30
    Description: Ocean environmental conditions can be inferred from the chemical composition of bamboo coral skeletons. The high magnesium calcite internodes of these long-living octocorals may therefore represent a potential archive for seawater properties such as salinity or temperature where instrumental time series are absent. To extend these time series into the past using a natural archive the principles of temperature and salinity signal incorporation into cold-water coral skeletal material need to be investigated. Since skeletal Na and S concentrations have been proposed as environmental proxies, we mapped the spatial distribution and concentration of these elements in two Atlantic specimens of Keratoisis grayi (family Isididae). These measurements were conducted with an electron microprobe applying a spatial resolution of 4 μm. The mean apparent distribution coefficient of Na/Ca for the two samples was within 2.5 and 2.8*10−4, while that of S shows a similar depletion relative to seawater with 3.8 and 3.6*10−3. The two elements show an inverse correlation in bamboo coral skeletons. The mean apparent distribution coefficient of Na is similar to that of abiotic calcites. This similarity can be interpreted as the absence of significant vital effects for skeletal Na/Ca. Hence it corroborates the idea that the average skeletal composition of bamboo corals holds the potential to record past seawater conditions. In contrast, it appears unlikely that the spatial variations of the element distribution of seemingly simultaneously precipitated material along growth rings are exclusively controlled by environmental factors. We further exclude Rayleigh fractionation, ion-specific pumping, and Ca/proton exchange as the driver of Na and S distribution in bamboo corals. Instead, we adapt a calcification model originally proposed for scleractinians to bamboo corals. This model can explain the observed distribution of Na and S in the skeleton by a combination of Ca/proton pumping, bicarbonate active transport, and the formation of an organic skeletal matrix. The adapted model can further be used to predict the theoretical behaviour of other elements and disentangle vital effects from external factors influencing compositional features. It is therefore a useful tool for future studies on the potential of bamboo corals as environmental archives.
    Repository Name: EPIC Alfred Wegener Institut
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  • 10
    Publication Date: 2023-11-16
    Description: Although often speculated, the link between theMiddle Triassic shoshonitic magmatismat the NE margin of the Adria plate and the subduction-related metasomatismof the Southern Alps Sub-Continental Lithospheric Mantle (SCLM) has never been constrained. In this paper, a detailed geochemical and petrological characterization of the lavas, dykes and ultramafic cumulates belonging to the shoshonitic magmatic event that shaped the Dolomites (Southern Alps) was used tomodel the composition and evolution of the underlying SCLMin the time comprised between the Variscan subduction and the opening of the Alpine Tethys. Geochemical models and numerical simulations enabled us to define that 5–7% partial melting of an amphibole + phlogopite-bearing spinel lherzolite, similar to the Finero phlogopite peridotite, can account for the composition of the primitive Mid-Triassic SiO2- saturated to -undersaturated melts with shoshonitic affinity (87Sr/86Sri = 0.7032–0.7058; 143Nd/144Ndi = 0.51219–0.51235; Mg # ~ 70; ~1.1 wt% H2O). By taking into account the H2O content documented in mineral phases from the Finero phlogopite peridotite, it is suggested that the Mid-Triassic SCLM source was able to preserve a significant enrichment and volatile content (600–800 ppm H2O) for more than 50 Ma, i.e. since the slab-related metasomatismconnected to the Variscan subduction. The partialmelting of a Finero-like SCLM represents the exhaustion of the subduction-related signature in the Southern Alps lithosphere that predated the Late Triassic-Early Jurassic asthenospheric upwelling related to the opening of the Alpine Tethys.
    Description: Published
    Description: 105856
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 11
    Publication Date: 2023-11-16
    Description: Excessive nonphysical energy dissipation is a problem in Smoothed Particle Hydrodynamics (SPH) when modeling free surface waves, resulting in a significant decrease in wave amplitude within a few wavelengths for progressive waves. This dissipation poses a limitation to the physical scale of SPH applications involving water wave propagation. Some prior solutions to this wave decay problem rely on elaborate schemes, which require a complex, or non-straightforward, implementation. Other approaches demand large smoothing lengths that lead to longer simulation times and potential degradation of the results. In this work we present an approach based on a kernel gradient correction. Our scheme is fully 3D and solves the main known drawbacks of kernel gradient corrections, such as instabilities and lack of momentum conservation. The latter is ensured by adopting an averaged correction matrix, so as to conserve reciprocity during particle interactions. We test our model with a standing wave in a basin and a progressive wave train in a wave tank, and in both cases no nonphysical decay occurs. A comparison to an approach based on large smoothing factors shows advantages both in quality of the results and simulation time.
    Description: Published
    Description: 104018
    Description: 3IT. Calcolo scientifico
    Description: JCR Journal
    Keywords: WCSPH ; Wave propagation ; Coastal engineering ; Kernel correction ; Decay
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 12
    Publication Date: 2023-11-16
    Description: The attention and demand for greater social protection is increasing among the populations of all European countries. It is difficult to identify which of the structures and infrastructures, sectors and regional budgets are inefficient and/or negligent in respect of providing more social protection. In the political sphere the problem is examined from a qualitative point of view, because it is essential to have a valid decisional support system that provides useful information for structural and economic intervention programs devised to improve social protection. Regional spending on social protection is a fundamental component of individual well-being. This work is precisely aimed at assessing individual well-being in terms of technical expenses efficiency in the Italian Regions. Stochastic frontier analysis and a nonparametric deterministic model structure are the tools used to investigate the social protection determinants in the paper.
    Description: Published
    Description: 100965
    Description: 4TM. Web e Social
    Description: JCR Journal
    Keywords: Data envelopment analysis ; Technical efficiency ; Efficiency analysis
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 13
    Publication Date: 2023-11-16
    Description: The geometry, rates and kinematics of active faulting in the region close to the tip of a major crustal-scale normal fault in the Gulf of Corinth, Greece, are investigated using detailed fault mapping and new absolute dating. Fault offsets have been dated using a combination of 234U/230Th coral dates and in situ 36Cl cosmogenic exposure ages for sediments and wave-cut platforms deformed by the faults. Our results show that deformation in the tip zone is distributed across as many as eight faults arranged within ~700 m across strike, each of which deforms deposits and landforms associated with the 125 ka marine terrace of Marine Isotope Stage 5e. Summed throw-rates across strike achieve values as high as 0.3–1.6 mm/yr, values that are comparable to those at the centre of the crustal-scale fault (2–3 mm/yr from Holocene palaeoseismology and 3–4 mm/yr from GPS geodesy). The relatively high deformation rate and distributed deformation in the tip zone are discussed in terms of stress enhancement from rupture of neighbouring crustal-scale faults and in terms of how this should be considered during fault-based seismic hazard assessment.
    Description: Published
    Description: 104063
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Keywords: Crustal Deformation ; Active Faults ; Absolute Dating ; Marine terraces
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 14
    Publication Date: 2023-11-24
    Description: During the middle Eocene to early Oligocene Earth transitioned from a greenhouse to an icehouse climate state. The interval comprises the Middle Eocene Climatic Optimum (MECO; ~40 Ma) and a subsequent long-term cooling trend that culminated in the Eocene-Oligocene transition (EOT; ~34 Ma) with the Oi-1 glaciation. Here, we present a refined calcareous nannofossil biostratigraphy and an orbitally tuned age model for the Monte Cagnero (MCA) section spanning the middle Eocene to the early Oligocene (~41 to ~33 Ma). Spectral analysis of magnetic susceptibility (MS) data displays strong cyclicities in the orbital frequency band allowing us to tune the identified 405 kyr eccentricity minima in the MS record to their equivalents in the astronomical solution. Our orbitally tuned age model allows us to estimate the position and duration of polarity chrons (C18 to C13) and compare them with other standard and orbitally tuned ages. We were also able to constrain the timing and duration of the MECO event, which coincides with a minimum in the 2.4 Myr and 405 kyr eccentricity cycles. Our study corroborates the previous estimated age for the base of the Rupelian stage (33.9 Ma) and estimates the base of the Priabonian stage in the MCA section to be at 37.4 Ma. Finally, calcareous nannofossils with known paleoenvironmental preferences suggest a gradual shift from oligotrophic to meso-eutrophic conditions with an abrupt change at ~36.8 Ma. Besides, nannofossil assemblages suggest that enhanced nutrient availability pre- ceded water cooling at the late Eocene. Altogether, this evidence points to a poorly developed water column stratification prior to the cooling trend.
    Description: Published
    Description: 110563
    Description: 1A. Geomagnetismo e Paleomagnetismo
    Description: 5A. Ricerche polari e paleoclima
    Description: JCR Journal
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  • 15
    Publication Date: 2023-11-16
    Description: The increasing dinosaur record from Italy questioned classic palaeogeographic scenarios for the Central Mediterranean area and suggest the proximity of landmass areas and a geographical connection between Gondwana and Laurasia during Cretaceous times. Besides several track-sites and exceptionally-preserved specimens (e.g. Scipionyx samniticus), the Italian dinosaur record also consists of isolated bones, among which the bone fragment of a theropod discovered in north-western Sicily. The bone occurs in a shallowwater carbonate succession (i.e. Pizzo Muletta, Palermo Mountains) pertaining to the Panormide Carbonate Platform (PCP). The bone was previously ascribed to the Cenomanian, strongly supporting the hypothesis of a land bridge connecting Gondwana and Adria via PCP. More recently, new sedimentological and biostratigraphic studies on the Pizzo Muletta succession have been carried out. The obtained results allow to predate the stratigraphic position of the dinosaur bone to the late Aptianeearly Albian and to assess a detailed AptianeCenomanian evolution of this sector of the PCP. In particular, the karstic overprint of Cenomanian rudist limestones indicate a subaerial exposure of the platform preceding its drowning during latest Cenomanian times. The new assumptions allow to extend the temporal duration of the intermittent land bridge between Gondwana and Laurasia at least from Aptian to Cenomanian times and to add further evidences of the dominant tectonic control affecting the Western Tethys during Cretaceous times.
    Description: Published
    Description: 104919
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 16
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    American Association for the Advancement of Science (AAAS)
    In:  EPIC3Science, American Association for the Advancement of Science (AAAS), 378(6617), pp. 230-230, ISSN: 0036-8075
    Publication Date: 2023-05-10
    Description: 〈jats:p〉 Next week, the Convention on the Conservation of Antarctic Marine Living Resources (CCAMLR) convenes in Hobart, Tasmania, to examine the state of marine life in the Southern Ocean. As part of the Antarctic Treaty System, this convention entered into force in 1982, and its focus on the region’s environmental integrity has never been more important, given the increasing effects of climate change and commercial fishing. An important focus over the past 40 years has been Antarctic krill, 〈jats:italic〉Euphausia superba〈/jats:italic〉 (hereafter krill), a keystone species that helps to hold this marine ecosystem together. Climate and fishing stresses should prompt the CCAMLR to address whether management of krill fishing is at a level that protects the Southern Ocean from losing its overall balance of marine life and the oceanic processes that regulate global climate. 〈/jats:p〉
    Repository Name: EPIC Alfred Wegener Institut
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  • 17
    Publication Date: 2023-05-10
    Description: The Antarctic krill (Euphausia superba Dana) is a keystone species in the Southern Ocean that uses an arsenal of hydrolases for biomacromolecule decomposition to effectively digest its omnivorous diet. The present study builds on a hybrid-assembled transcriptome (13,671 ORFs) combined with comprehensive proteome profiling. The analysis of individual krill compartments allowed detection of significantly more different proteins compared to that of the entire animal (1464 vs. 294 proteins). The nearby krill sampling stations in the Bransfield Strait (Antarctic Peninsula) yielded rather uniform proteome datasets. Proteins related to energy production and lipid degradation were particularly abundant in the abdomen, agreeing with the high energy demand of muscle tissue. A total of 378 different biomacromolecule hydrolysing enzymes were detected, including 250 proteases, 99 CAZymes, 14 nucleases and 15 lipases. The large repertoire in proteases is in accord with the protein-rich diet affiliatedwith E. superba’s omnivorous lifestyle and complex biology. The richness in chitin-degrading enzymes allows not only digestion of zooplankton diet, but also the utilisation of the discharged exoskeleton after moulting.
    Repository Name: EPIC Alfred Wegener Institut
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  • 18
    Publication Date: 2023-08-01
    Description: Autonomous and cabled platforms are revolutionizing our understanding of ocean systems by providing 4D monitoring of the water column, thus going beyond the reach of ship-based surveys and increasing the depth of remotely sensed observations. However, very few commercially available sensors for such platforms are capable of monitoring large particulate matter (100–2000 μm) and plankton despite their important roles in the biological carbon pump and as trophic links from phytoplankton to fish. Here, we provide details of a new, commercially available scientific camera-based particle counter, specifically designed to be deployed on autonomous and cabled platforms: the Underwater Vision Profiler 6 (UVP6). Indeed, the UVP6 camera-and-lighting and processing system, while small in size and requiring low power, provides data of quality comparable to that of previous much larger UVPs deployed from ships. We detail the UVP6 camera settings, its performance when acquiring data on aquatic particles and plankton, their quality control, analysis of its recordings, and streaming from in situ acquisition to users. In addition, we explain how the UVP6 has already been integrated into platforms such as BGC-Argo floats, gliders and long-term mooring systems (autonomous platforms). Finally, we use results from actual deployments to illustrate how UVP6 data can contribute to addressing longstanding questions in marine science, and also suggest new avenues that can be explored using UVP6-equipped autonomous platforms.
    Repository Name: EPIC Alfred Wegener Institut
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  • 19
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    Elsevier
    In:  EPIC3Progress in Oceanography, Elsevier, 206, pp. 102851, ISSN: 00796611
    Publication Date: 2023-08-01
    Description: Harmful Algae Blooms pose an increasing threat to the public health and economic stability of Southern Chile, particularly to the aquaculture industries. This fieldwork performed during the PROFAN expedition from 12th to 22nd November 2019 extends the knowledge on the distribution of marine toxin-producing species in the difficult to access Última Esperanza Province in the Magallanes Region. Paralytic Shellfish Poisoning toxins with high relative abundances of saxitoxin and lipophilic toxins dominated by yessotoxins, pectenotoxins and domoic acid were detected at nearly each sampling station. The respective toxin-producing organisms are mainly from the genus Alexandrium and Dinophysis. Furthermore, the first detection of pinnatoxin-G (PnTx-G) in Chilean waters strongly indicates the presence of the dinoflagellate Vulcanodinium rugosum.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed
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  • 20
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    Wiley
    In:  EPIC3Rapid Communications in Mass Spectrometry, Wiley, 36(23), pp. e9401-e9401, ISSN: 0951-4198
    Publication Date: 2023-01-17
    Description: Rationale More than half of surveyed microalgae and over 90% of harmful algae have an obligate requirement for vitamin B12, but methods for directly measuring dissolved B12 in seawater are scarce due to low concentrations and rapid light-induced hydrolysis. Methods We present a method to detect and measure the four main congeners of vitamin B12 dissolved in seawater. The method includes solid-phase extraction, separation by ultrahigh-performance liquid chromatography and detection by triple-quadrupole tandem mass spectrometry utilizing an electrospray ion source. This method was applied to coastal field samples collected in the German Bay, Baltic Sea and the Danish Limfjord system. Results The total dissolved B12 pool ranged between 0.5 and 2.1 pM. Under ambient conditions methyl-B12 and adenosyl-B12 were nearly fully hydrolyzed to hydroxy-B12 in less than 1 h. Hydroxy-B12 and a novel, corresponding isomer were the main forms of B12 found at all field sites. This isomer eluted well after the OH-B12 peak and was also detected in commercially available OH-B12. Both compounds showed very high similarity in their collision-induced dissociation spectra. Conclusions The high instability of the biologically active forms of Me-B12 and Ado-B12 towards hydrolysis was shown, highlighting the importance of reducing the duration of the extraction protocol. In addition, the vitamin B12 pool in the study area was mostly comprised of a previously undescribed isomer of OH-B12. Further studies into the structure of this isomer and its bioavailability are needed.
    Repository Name: EPIC Alfred Wegener Institut
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  • 21
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    Wiley
    In:  EPIC3Rapid Communications in Mass Spectrometry, Wiley, 36(23), pp. e9401-e9401, ISSN: 0951-4198
    Publication Date: 2023-01-17
    Description: Rationale More than half of surveyed microalgae and over 90% of harmful algae have an obligate requirement for vitamin B12, but methods for directly measuring dissolved B12 in seawater are scarce due to low concentrations and rapid light-induced hydrolysis. Methods We present a method to detect and measure the four main congeners of vitamin B12 dissolved in seawater. The method includes solid-phase extraction, separation by ultrahigh-performance liquid chromatography and detection by triple-quadrupole tandem mass spectrometry utilizing an electrospray ion source. This method was applied to coastal field samples collected in the German Bay, Baltic Sea and the Danish Limfjord system. Results The total dissolved B12 pool ranged between 0.5 and 2.1 pM. Under ambient conditions methyl-B12 and adenosyl-B12 were nearly fully hydrolyzed to hydroxy-B12 in less than 1 h. Hydroxy-B12 and a novel, corresponding isomer were the main forms of B12 found at all field sites. This isomer eluted well after the OH-B12 peak and was also detected in commercially available OH-B12. Both compounds showed very high similarity in their collision-induced dissociation spectra. Conclusions The high instability of the biologically active forms of Me-B12 and Ado-B12 towards hydrolysis was shown, highlighting the importance of reducing the duration of the extraction protocol. In addition, the vitamin B12 pool in the study area was mostly comprised of a previously undescribed isomer of OH-B12. Further studies into the structure of this isomer and its bioavailability are needed.
    Repository Name: EPIC Alfred Wegener Institut
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  • 22
    Publication Date: 2023-01-17
    Description: In this paper we present the ground response analyses (GRA) of a site where an industrial facility is planned. Because of its location on an active normal fault system known as a relevant seismic gap, the Mt. Morrone Fault system (MMF), and at the edge of a basin filled with slow velocity continental deposits, a inter-disciplinary and non-standard approach has been applied to assess the seismic input of the dynamic numerical analyses. It includes geological, seismological, geotechnical and engineering contributions. Two fault scenarios, MMF1 and MMF2, were considered and scenario-based (SSHA) and probabilistic (time-dependent, TD, and time-independent, TI) seismic hazard (PSHA) analyses were implemented. Comparison among the spectra corresponding to the 90th percentile of the SSHA statistical distribution and the PSHA average ones, shows that the MMF2 has values similar to the TD model. The SSHA 90th percentile distribution was selected as target spectra to retrieve the seismic input for GRA. Nonlinear numerical simulations of seismic wave propagation were implemented to derive surface ground motion parameters. GRA acceleration response spectra and their PGA are notably higher, and thus on the safety site, than those obtained following the Italian code approach for seismic resistant buildings. These results confirm that a scenario-based methodology can better capture the shaking effect in near-field conditions, avoiding possibly unconservative underestimations of the seismic actions and in view of a more robust performance-based approach used by engineers for either new design and/or assessment/retrofit purposes of the built environment.
    Description: Published
    Description: 106970
    Description: 5T. Sismologia, geofisica e geologia per l'ingegneria sismica
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 23
    Publication Date: 2023-06-21
    Description: The copepod Calanus finmarchicus (Crustacea, Copepoda) is a key zooplanktonic spe-cies with a crucial position in the North Atlantic food web and significant contributor to ocean carbon flux. Like many other high latitude animals, it has evolved a programmed arrested development called diapause to cope with long periods of limited food sup-ply, while growth and reproduction are timed to take advantage of seasonal peaks in primary production. However, anthropogenic warming is inducing changes in the expected timing of phytoplankton blooms, suggesting phenological mismatches with negative consequences for the N. Atlantic ecosystem. While diapause mechanisms are mainly studied in terrestrial arthropods, specifically on laboratory model species, such as the fruit fly Drosophila, the molecular investigations of annual rhythms in wild marine species remain fragmentary. Here we performed a rigorous year-l ong monthly sampling campaign of C. finmarchicus in a Scottish Loch (UK; 56.45°N, 5.18°W) to generate an annual transcriptome. The mRNA of 36 samples (monthly triplicate of 25 individuals) have been deeply sequenced with an average depth of 137 ± 4 million reads (mean ± SE) per sample, aligned to the reference transcriptome, and filtered. We detail the quality assessment of the datasets and provide a high- quality resource for the investigation of wild annual transcriptomic rhythms (35,357 components) in a key diapausing zooplanktonic species.
    Repository Name: EPIC Alfred Wegener Institut
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  • 24
    Publication Date: 2023-06-21
    Description: Dissolved organic matter (DOM) is the largest organic carbon reservoir in the ocean and an integral component of biogeochemical cycles. The role of free-living microbes in DOM transformation has been studied thoroughly, whereas little attention has been directed towards the influence of benthic organisms. Sponges are efficient filter feeders and common inhabitants of many benthic communities circumglobally. Here, we investigated how two tropical coral reef sponges shape marine DOM. We compared bacterial abundance, inorganic and organic nutrients in off reef, sponge inhalant, and sponge exhalant water of Melophlus sarasinorum and Rhabdastrella globostellata. DOM and bacterial cells were taken up, and dissolved inorganic nitrogen was released by the two Indo-Pacific sponges. Both sponge species utilized a common set of 142 of a total of 3040 compounds detected in DOM on a molecular formula level via ultrahigh-resolution mass spectrometry. In addition, species-specific uptake was observed, likely due to differences in their associated microbial communities. Overall, the sponges removed presumably semi-labile and semi-refractory compounds from the water column, thereby competing with pelagic bacteria. Within minutes, sponge holobionts altered the molecular composition of surface water DOM (inhalant) into a composition similar to deep-sea DOM (exhalent). The apparent radiocarbon age of DOM increased consistently from off reef and inhalant to exhalant by about 900 14C years for M. sarasinorum. In the pelagic, similar transformations require decades to centuries. Our results stress the dependence of DOM lability definition on the respective environment and illustrate that sponges are hotspots of DOM transformation in the ocean.
    Repository Name: EPIC Alfred Wegener Institut
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  • 25
    Publication Date: 2023-06-21
    Description: In light of ongoing climate change, it is increasingly important to know how nutritional requirements of ectotherms are affected by changing temperatures. Here, we analyse the wide thermal response of phosphorus (P) requirements via elemental gross growth efficiencies of Carbon (C) and P, and the Threshold Elemental Ratios in different aquatic invertebrate ectotherms: the freshwater model species Daphnia magna, the marine copepod Acartia tonsa, the marine heterotrophic dinoflagellate Oxyrrhis marina, and larvae of two populations of the marine crab Carcinus maenas. We show that they all share a non-linear cubic thermal response of nutrient requirements. Phosphorus requirements decrease from low to intermediate temperatures, increase at higher temperatures and decrease again when temperature is excessive. This common thermal response of nutrient requirements is of great importance if we aim to understand or even predict how ectotherm communities will react to global warming and nutrient-driven eutrophication.
    Repository Name: EPIC Alfred Wegener Institut
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  • 26
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    Elsevier
    In:  EPIC3Automatica, Elsevier, 144, pp. 110487-110487, ISSN: 0005-1098
    Publication Date: 2023-10-23
    Description: The presence of tipping points in ecological systems implies abrupt changes in the dynamics of the ecosystem. In these piecewise-smooth dynamical systems sliding dynamics, i.e., dynamics on the switching boundary, have been reported for population models. However, the question whether or not, and if so under which conditions, sliding dynamics may occur in an optimally controlled system have not yet been studied. We explore this issue in a simple harvesting model with two regimes, and find that optimal sliding may occur if regular steady states do not exist. Hence, sliding dynamics may be part of an optimal policy.
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  • 27
    Publication Date: 2023-10-18
    Description: We propose a procedure based on remote sensing Sentinel-1 InSAR data aiming at evaluating the variability of the moment tensor solutions provided by different agencies in case of light-to-moderate earthquake. We model the expected coseismic ground deformations from the available moment tensor solutions and compare them with the real ones retrieved with the InSAR data. Any differences between location and intensity of simulated and estimated seismic-induced deformation fields allow indirectly evaluating the variability of the solutions in terms of epicenter locations and kinematics of the causative faults. We applied this investigation method to several light (4〈Mw 〈 4.9) to moderate (5〈Mw 〈 5.9) earthquakes occurred along the Mediterranean area since the launch of the Sentinel-1A mission in 2014. The selected seismic events cover all the faulting mechanisms and are characterized by different estimated magnitudes and depths thus offering a synoptic view of the performance of the procedure in several cases. Thanks to the global coverage and the unprecedented revisit time of Sentinel-1 acquisitions, the proposed procedure can be easily extended to any seismic event occurred inland worldwide.
    Description: Published
    Description: 100057
    Description: 3T. Fisica dei terremoti e Sorgente Sismica
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 28
    Publication Date: 2023-06-21
    Description: Phytoplanktonic organisms are particularly sensitive to environmental change, and, as they represent a direct link between abiotic and biotic compartments within the marine food web, changes in the functional structure of phytoplankton communities can result in profound impacts on ecosystem functioning. Using a trait-based approach, we examined changes in the functional structure of the southern North Sea phytoplankton over the past five decades in relation to environmental conditions. We identified a shift in functional structure between 1998 and 2004 which coincides with a pronounced increase in diatom and decrease in dinoflagellate abundances, and we provide a mechanistic explanation for this taxonomic change. Early in the 2000s, the phytoplankton functional structure shifted from slow growing, autumn blooming, mixotrophic organisms, towards earlier blooming and faster-growing microalgae. Warming and decreasing dissolved phosphorus concentrations were linked to this rapid reorganization of the functional structure. We identified a potential link between this shift and dissolved nutrient concentrations, and we hypothesise that organisms blooming early and displaying high growth rates efficiently take up nutrients which then are no longer available to late bloomers. Moreover, we identified that the above-mentioned functional change may have bottom-up consequences, through a food quality-driven negative influence on copepod abundances. Overall, our study highlights that, by altering the phytoplankton functional composition, global and regional changes may have profound long-term impacts on coastal ecosystems, impacting both food-web structure and biogeochemical cycles.
    Repository Name: EPIC Alfred Wegener Institut
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  • 29
    Publication Date: 2023-09-27
    Description: Cell size is a master trait in the functional ecology of phytoplankton correlating with numerous morphological, physiological, and life-cycle characteristics of species that constrain their nutrient use, growth, and edibility. In contrast to well-known spatial patterns in cell size at macroecological scales or temporal changes in experimental contexts, few data sets allow testing temporal changes in cell sizes within ecosystems. To analyze the temporal changes of intraspecific and community-wide cell size, we use the phytoplankton data derived from the Lower Saxony Wadden Sea monitoring program, which comprises sample- and species-specific measurements of cell volume from 1710 samples collected over 14 yr. We find significant reductions in both the cell volume of most species and the weighted mean cell size of communities. Mainly diatoms showed this decline, whereas the size of dinoflagellates seemed to be less responsive. The magnitude of the trend indicates that cell volumes are about 30% smaller now than a decade ago. This interannual trend is overlayed by seasonal cycles with smaller cells typically observed in summer. In the subset of samples including environmental conditions, small community cell size was strongly related to high temperatures and low total phosphorus concentration. We conclude that cell size captures ongoing changes in phytoplankton communities beyond the changes in species composition. In addition, based on the changes in species biovolumes revealed by our analysis, we warn that using standard cell size values in phytoplankton assessment will not only miss temporal changes in size, but also lead to systematic errors in biomass estimates over time.
    Repository Name: EPIC Alfred Wegener Institut
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  • 30
    Publication Date: 2023-09-27
    Description: 〈jats:p〉Anthropogenic climate change is altering global biogeographical patterns. However, it remains difficult to quantify how bioregions are changing because pre‐industrial records of species distributions are rare. Marine microfossils, such as planktonic foraminifera, are preserved in seafloor sediments and allow the quantification of bioregions in the past. Using a recently compiled data set of pre‐industrial species composition of planktonic foraminifera in 3802 worldwide seafloor sediments, we employed multivariate and statistical model‐based approaches to study spatial turnover in order to 1) quantify planktonic foraminifera bioregions and 2) understand the environmental drivers of species turnover. Four latitudinally banded bioregions emerge from the global assemblage data. The polar and temperate bioregions are bi‐hemispheric, supporting the idea that planktonic foraminifera species are not limited by dispersal. The equatorial bioregion shows complex longitudinal patterns and overlaps in sea surface temperature (SST) range with the tropical bioregion. Compositional‐turnover models (Bayesian bootstrap generalised dissimilarity models) identify SST as the strongest driver of species turnover. The turnover rate is constant across most of the SST gradient, showing no SST threshold values with rapid shifts in species composition, but decelerates above 25°C, suggesting SST is less predictive of species composition in warmer waters. Other environmental predictors affect species turnover non‐linearly, and their importance differs across regions. In the Pacific ocean, net primary productivity below 500 mgC m〈jats:sup〉−2〈/jats:sup〉 day〈jats:sup〉−1〈/jats:sup〉 drives fast compositional change. Water depth values below 3000 m (which affect calcareous microfossil preservation) increasingly drive changes in species composition among death assemblages in the Pacific and Indian oceans. Together, our results suggest that the dynamics of planktonic foraminifera bioregions are expected to be highly responsive to climate change; however, at lower latitudes, environmental drivers other than SST may affect these dynamics.〈/jats:p〉
    Repository Name: EPIC Alfred Wegener Institut
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  • 31
    Publication Date: 2023-09-27
    Description: While environmental science, and ecology in particular, is working to provide better understanding to base sustainable decisions on, the way scientific understanding is developed can at times be detrimental to this cause. Locked-in debates are often unnecessarily polarised and can compromise any common goals of the opposing camps. The present paper is inspired by a resolved debate from an unrelated field of psychology where Nobel laureate David Kahneman and Garry Klein turned what seemed to be a locked-in debate into a constructive process for their fields. The present paper is also motivated by previous discourses regarding the role of thresholds in natural systems for management and governance, but its scope of analysis targets the scientific process within complex social-ecological systems in general. We identified four features of environmental science that appear to predispose for locked-in debates: (1) The strongly context-dependent behaviour of ecological systems. (2) The dominant role of single hypothesis testing. (3) The high prominence given to theory demonstration compared investigation. (4) The effect of urgent demands to inform and steer policy. This fertile ground is further cultivated by human psychological aspects as well as the structure of funding and publication systems.
    Repository Name: EPIC Alfred Wegener Institut
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  • 32
    Publication Date: 2023-09-27
    Description: Field studies are essential to reliably quantify ecological responses to global change because they are exposed to realistic climate manipulations. Yet such studies are limited in replicates, resulting in less power and, therefore, potentially unreliable effect estimates. Furthermore, while manipulative field experiments are assumed to be more powerful than non-manipulative observations, it has rarely been scrutinized using extensive data. Here, using 3847 field experiments that were designed to estimate the effect of environmental stressors on ecosystems, we systematically quantified their statistical power and magnitude (Type M) and sign (Type S) errors. Our investigations focused upon the reliability of field experiments to assess the effect of stressors on both ecosystem's response magnitude and variability. When controlling for publication bias, single experiments were underpowered to detect response magnitude (median power: 18%–38% depending on effect sizes). Single experiments also had much lower power to detect response variability (6%–12% depending on effect sizes) than response magnitude. Such underpowered studies could exaggerate estimates of response magnitude by 2–3 times (Type M errors) and variability by 4–10 times. Type S errors were comparatively rare. These observations indicate that low power, coupled with publication bias, inflates the estimates of anthropogenic impacts. Importantly, we found that meta-analyses largely mitigated the issues of low power and exaggerated effect size estimates. Rather surprisingly, manipulative experiments and non-manipulative observations had very similar results in terms of their power, Type M and S errors. Therefore, the previous assumption about the superiority of manipulative experiments in terms of power is overstated. These results call for highly powered field studies to reliably inform theory building and policymaking, via more collaboration and team science, and large-scale ecosystem facilities. Future studies also require transparent reporting and open science practices to approach reproducible and reliable empirical work and evidence synthesis.
    Repository Name: EPIC Alfred Wegener Institut
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  • 33
    Publication Date: 2023-09-27
    Description: Body size is a decisive functional trait in many organisms, especially for phytoplankton, which span several orders of magnitude in cell volume. Therefore, the analysis of size as a functional trait driving species’ performance has received wide attention in aquatic ecology, amended in recent decades by studies documenting changes in phytoplankton size in response to abiotic or biotic factors in the environment. We performed a systematic literature review to provide an overarching, partially quantitative synthesis of cell size as a driver and sentinel of phytoplankton ecology. We found consistent and significant allometric relationships between cell sizes and the functional performance of phytoplankton species (cellular rates of carbon fixation, respiration and exudation as well as resource affinities, uptake and content). Size scaling became weaker, absent or even negative when addressing C- or volume-specific rates or growth. C-specific photosynthesis and population growth rate peaked at intermediate cell sizes around 100 µm3. Additionally, we found a rich literature on sizes changing in response to warming, nutrients and pollutants. Whereas small cells tended to dominate under oligotrophic and warm conditions, there are a few notable exceptions, which indicates that other environmental or biotic constraints alter this general trend. Grazing seems a likely explanation, which we reviewed to understand both how size affects edibility and how size structure changes in response to grazing. Cell size also predisposes the strength and outcome of competitive interactions between algal species. Finally, we address size in a community context, where size-abundance scaling describes community composition and thereby the biodiversity in phytoplankton assemblages. We conclude that (a) size is a highly predictive trait for phytoplankton metabolism at the cellular scale, with less strong and nonlinear implications for growth and specific metabolism and (b) size structure is a highly suitable sentinel of phytoplankton responses to changing environments. A free Plain Language Summary can be found within the Supporting Information of this article.
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  • 34
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    Elsevier
    In:  EPIC3Remote Sensing of Environment, Elsevier, 268, pp. 112752-112752, ISSN: 0034-4257
    Publication Date: 2024-01-30
    Description: Permafrost is warming globally which leads to widespread permafrost thaw. Particularly ice-rich permafrost is vulnerable to rapid thaw and erosion, impacting whole landscapes and ecosystems. Retrogressive thaw slumps (RTS) are abrupt permafrost disturbances that expand by several meters each year and lead to an increased soil organic carbon release. Local Remote Sensing studies identified increasing RTS activity in the last two decades by increasing number of RTS or heightened RTS growth rates. However, a large-scale assessment across diverse permafrost regions and at high temporal resolution allowing to further determine RTS thaw dynamics and its main drivers is still lacking. In this study we apply the disturbance detection algorithm LandTrendr for automated large-scale RTS mapping and high temporal thaw dynamic assessment to North Siberia (8.1×106km2). We adapted and parametrised the temporal segmentation algorithm for abrupt disturbance detection to incorporate Landsat+Sentinel-2 mosaics, conducted spectral filtering, spatial masking and filtering, and a binary machine-learning object classification of the disturbance output to separate between RTS and false positives (F1 score: 0.609). Ground truth data for calibration and validation of the workflow was collected from 9 known RTS cluster sites using very high-resolution RapidEye and PlanetScope imagery. Our study presents the first automated detection and assessment of RTS and their temporal dynamics at large-scale for 2001–2019. We identified 50,895 RTS and a steady increase in RTS-affected area from 2001 to 2019 across North Siberia, with a more abrupt increase from 2016 onward. Overall the RTS-affected area increased by 331 compared to 2000 (2000: 20,158ha, 2001–2019: 66,699ha). Contrary to this, 5 focus sites show spatio-temporal variability in their annual RTS dynamics, with alternating periods of increased and decreased RTS development, indicating a close relationship to thaw drivers. The majority of identified RTS was active from 2000 onward and only a small proportion initiated during the assessment period, indicating that the increase in RTS-affected area was mainly caused by enlarging existing RTS and not by new RTS. The detected increase in RTS dynamics suggests advancing permafrost thaw and underlines the importance of assessing abrupt permafrost disturbances with high spatial and temporal resolution at large-scales. Obtaining such consistent disturbance products will help to parametrise regional and global climate change models.
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  • 35
    Publication Date: 2024-01-31
    Description: Arctic river deltas and deltaic near-shore zones represent important land–ocean transition zones influencing sediment dynamics and nutrient fluxes from permafrost-affected terrestrial ecosystems into the coastal Arctic Ocean. To accurately model fluvial carbon and freshwater export from rapidly changing river catchments as well as assess impacts of future change on the Arctic shelf and coastal ecosystems, we need to understand the sea floor characteristics and topographic variety of the coastal zones. To date, digital bathymetrical data from the poorly accessible, shallow, and large areas of the eastern Siberian Arctic shelves are sparse. We have digitized bathymetrical information for nearly 75 000 locations from large-scale (1:25 000–1:500 000) current and historical nautical maps of the Lena Delta and the Kolyma Gulf region in northeastern Siberia. We present the first detailed and seamless digital models of coastal zone bathymetry for both delta and gulf regions in 50 and 200 m spatial resolution. We validated the resulting bathymetry layers using a combination of our own water depth measurements and a collection of available depth measurements, which showed a strong correlation (r〉0.9). Our bathymetrical models will serve as an input for a high-resolution coupled hydrodynamic–ecosystem model to better quantify fluvial and coastal carbon fluxes to the Arctic Ocean, but they may be useful for a range of other studies related to Arctic delta and near-shore dynamics such as modeling of submarine permafrost, near-shore sea ice, or shelf sediment transport. The new digital high-resolution bathymetry products are available on the PANGAEA data set repository for the Lena Delta (https://doi.org/10.1594/PANGAEA.934045; Fuchs et al., 2021a) and Kolyma Gulf region (https://doi.org/10.1594/PANGAEA.934049; Fuchs et al., 2021b), respectively. Likewise, the depth validation data are available on PANGAEA as well (https://doi.org/10.1594/PANGAEA.933187; Fuchs et al., 2021c).
    Repository Name: EPIC Alfred Wegener Institut
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  • 36
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    Wiley
    In:  EPIC3Limnology and Oceanography Methods, Wiley, 20(9), pp. 568-580, ISSN: 1541-5856
    Publication Date: 2024-04-03
    Description: The fluorophore [2-(4-pyridyl)-5{[4-dimethylaminoethyl-aminocarbamoyl-methoxy]phenyl}oxazole], in short PDMPO, is incorporated in newly polymerized silica in diatom frustules and thereby provides a tool to estimate Si uptake, study diatom cell cycles but also determine mortality-independent abundance-based species specific-growth rates in cultures and natural assemblages. In this study, the theoretical framework and applicability of the PDMPO staining technique to estimate diatom species specific-growth rates were investigated. Three common polar diatom species, Pseudo-nitzschia subcurvata, Chaetoceros simplex, and Thalassiosira sp., chosen in order to cover a broad range of species specific frustule and life-cycle characteristics, were incubated over 24 h in control (no PDMPO) and with 0.125 and 0.6 μM PDMPO addition, respectively. Results indicate that specific-growth rates of the species tested were not affected in both treatments with PDMPO addition. The specific-growth rate estimates based on the PDMPO staining patterns (μPDMPO) were comparable and more robust than growth rates estimated from the changes in cell concentrations (μcc). This technique also allowed to investigate and highlight the importance of the illumination cycle (light and dark phases) on cell division in diatoms.
    Repository Name: EPIC Alfred Wegener Institut
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  • 37
    Publication Date: 2024-04-03
    Description: The redox speciation of iron was determined during the iron fertilization LOHAFEX and for the first time, the chemiluminescence assay of filtered and unfiltered samples was systematically compared. We hypothesize that higher chemiluminescence in unfiltered samples was caused by Fe(II) adsorbed onto biological particles. Dissolved and particulate Fe(II) increased in the mixed layer steadily 6-fold during the first two weeks and decreased back to initial levels by the end of LOHAFEX. Both Fe(II) forms did not show diel cycles downplaying the role of photoreduction. The chemiluminescence of unfiltered samples across the patch boundaries showed strong gradients, correlated significantly to biomass and the photosynthetic efficiency and were higher at night, indicative of a biological control. At 150 m deep, a secondary maximum of dissolved Fe(II) was associated with maxima of nitrite and ammonium despite high oxygen concentrations. We hypothesize that during LOHAFEX, iron redox speciation was mostly regulated by trophic interactions.
    Repository Name: EPIC Alfred Wegener Institut
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  • 38
    Publication Date: 2024-04-03
    Description: Marine planktonic eukaryotes play critical roles in global biogeochemical cycles and climate. However, their poor representation in culture collections limits our understanding of the evolutionary history and genomic underpinnings of planktonic ecosystems. Here, we used 280 billion Tara Oceans metagenomic reads from polar, temperate, and tropical sunlit oceans to reconstruct and manually curate more than 700 abundant and widespread eukaryotic environmental genomes ranging from 10 Mbp to 1.3 Gbp. This genomic resource covers a wide range of poorly characterized eukaryotic lineages that complement long-standing contributions from culture collections while better representing plankton in the upper layer of the oceans. We performed the first, to our knowledge, comprehensive genome-wide functional classification of abundant unicellular eukaryotic plankton, revealing four major groups connecting distantly related lineages. Neither trophic modes of plankton nor its vertical evolutionary history could completely explain the functional repertoire convergence of major eukaryotic lineages that coexisted within oceanic currents for millions of years.
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  • 39
    Publication Date: 2024-04-17
    Description: The term ‘destructive fishing’ appears in multiple international policy instruments intended to improve outcomes for marine biodiversity, coastal communities and sustainable fisheries. However, the meaning of ‘destructive fishing’ is often vague, limiting effectiveness in policy. Therefore, in this study, we systematically reviewed the use of ‘destructive fishing’ in three record types: academic literature, media articles and policy documents between 1976 and 2020. A more detailed analysis was performed on subsets of these records, considering the extent to which the term is characterised, geographic distribution of use, and specific impacts and practices associated with the term. We found that use of ‘destructive fishing’ relative to the generic term ‘fisheries’ has increased since the 1990s. Records focussed predominantly on fishing practices in South-eastern Asia, followed by Southern Asia and Europe. The term was characterised in detail in only 15% of records. Habitat damage and blast/poison fishing were the most associated ecological impacts and gear/practices, respectively. Bottom trawling and unspecified net fishing were regularly linked to destructive fishing. Importantly, the three record types use the term differently. Academic literature tends to specifically articulate the negative impacts, while media articles focus generally on associated gears/practices. Significant regional variation also exists in how the term is used and what phenomena it is applied to. This study provides evidence and recommendations to inform stakeholders in any future pursuit of a unified definition of ‘destructive fishing’ to support more meaningful implementation of global sustainability goals.
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  • 40
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    Wiley
    In:  EPIC3Multi‐Scale Biogeochemical Processes in Soil Ecosystems, Multi‐Scale Biogeochemical Processes in Soil Ecosystems, Hoboken, NJ, Wiley, pp. 157-181, ISBN: 9781119480471
    Publication Date: 2024-04-22
    Description: Tundra is experiencing more intense warming than any other ecosystem on earth. While warming is the most direct effect of climate change on tundra, warming leads to a cascade of environmental changes such as permafrost thaw, altered precipitation regimes, and increased wildfires. This chapter will first focus on how climate change is changing the environment of Arctic and subarctic tundra and then focus on how climate change is altering tundra's carbon, nitrogen, and phosphorus cycles with a focus on soils. Overall, tundra soils are shifting from being a carbon sink into a carbon source as rising temperatures increase microbial activity—a positive feedback to climate change. However, those rising temperatures are also increasing nutrient mineralization rates, which could increase ecosystem carbon storage via enhanced plant productivity as well as increase emissions of nitrous oxide, a powerful greenhouse gas. There is currently a disconnect between the large soil carbon losses measured in many in situ experiments and the strong plant carbon gains predicted by models. Ultimately, more research is needed on the interplay between tundra soils, nutrients, and plants to determine the magnitude of tundra's feedback to climate change.
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  • 41
    Publication Date: 2024-04-23
    Description: Boreal forests cover over half of the global permafrost area and protect underlying permafrost. Boreal forest development, therefore, has an impact on permafrost evolution, especially under a warming climate. Forest disturbances and changing climate conditions cause vegetation shifts and potentially destabilize the carbon stored within the vegetation and permafrost. Disturbed permafrost-forest ecosystems can develop into a dry or swampy bush- or grasslands, shift toward broadleaf- or evergreen needleleaf-dominated forests, or recover to the pre-disturbance state. An increase in the number and intensity of fires, as well as intensified logging activities, could lead to a partial or complete ecosystem and permafrost degradation. We study the impact of forest disturbances (logging, surface, and canopy fires) on the thermal and hydrological permafrost conditions and ecosystem resilience. We use a dynamic multilayer canopy-permafrost model to simulate different scenarios at a study site in eastern Siberia. We implement expected mortality, defoliation, and ground surface changes and analyze the interplay between forest recovery and permafrost. We find that forest loss induces soil drying of up to 44%, leading to lower active layer thicknesses and abrupt or steady decline of a larch forest, depending on disturbance intensity. Only after surface fires, the most common disturbances, inducing low mortality rates, forests can recover and overpass pre-disturbance leaf area index values. We find that the trajectory of larch forests after surface fires is dependent on the precipitation conditions in the years after the disturbance. Dryer years can drastically change the direction of the larch forest development within the studied period.
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  • 42
    Publication Date: 2024-04-19
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  • 43
    Publication Date: 2024-02-07
    Description: Responding to societal challenges requires an understanding of how institutional change happens or does not happen. In the context of flood risk reduction, a central impediment of transformational change is a struggle over how public participation is understood and practiced. Risk institutions are often portrayed as resistant to change, which overlooks the individuals within institutions who struggle to implement innovative power-sharing approaches/arrangements. Using two rounds of qualitative interviews spread over 5 years, this research identifies factions within the risk sector—those who view participation as awareness raising and those who are struggling to make participation part of a wider commitment to power-sharing: a group that, for the purpose of this analysis, we call “mavericks.” Through focus on how mavericks struggle for change, this analysis uncovers tensions that arise as individuals attempt to alter prevailing knowledge-practices. The findings highlight the importance of experiential learning, active listening, and the alteration of space. By applying a relational conceptualisation, we explore how mavericks advocate for relationship building, which alters spaces of public participation and, in that way, lays the foundation for transformational social innovations. The conclusions offer flood risk researchers perspective on the institutional struggles that preconfigure how frontrunner projects are or are not able to facilitate the community participation needed to successfully implement societal transformations.
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  • 44
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    Elsevier
    In:  EPIC3International Journal of Disaster Risk Reduction, Elsevier, 68, pp. 102699-102699, ISSN: 2212-4209
    Publication Date: 2024-02-07
    Description: Community engagement for disaster risk reduction has become central to participatory emergency management. In neoliberal contexts, publics are increasingly portrayed as responsible for preparing and responding to disasters, while at the same time and contradictorily, they are engaged by the state to encourage compliance with top-down policies and directives. This is happening while incremental budget cuts reinforce the operationalisation of community engagement as information dissemination and service delivery. In this paper we scrutinize the ways in which community engagement for disaster risk reduction has been governed and translated into practice in Australia, focusing on the experiences of the practitioners and community representatives doing community engagement in a peri-urban and multi-hazard area of Victoria. We identify and discuss the role of connectors—individuals fostering connections within and among state-led emergency services, local government, and publics—in negotiating change and building relationships. Our analysis shows how the political economy of state-led emergency management hinders the efforts of connectors, contributing to disconnection between publics, community representatives, and emergency agencies. In navigating the bureaucratic, temporal, and financial constraints of state-led community engagement, the emergency sector is missing opportunities to listen, learn, and work with connectors. The result is missed opportunities to build meaningful connections with publics for disaster risk reduction.
    Repository Name: EPIC Alfred Wegener Institut
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  • 45
    Publication Date: 2024-04-09
    Description: Epibenthic dinoflagellates occur globally and include many toxin-producing species of concern to human health and benthic ecosystem function. Such benthic harmful algal blooms (BHABs) have been well described from tropical and sub-tropical coastal environments, but assessments from north temperate waters, e.g., northern Europe, and polar regions are scarce. The present study addressed the biodiversity and distribution of potentially toxic epibenthic dinoflagellate populations along the west coast of Sweden (Kattegat-Skagerrak) by morphological and molecular criteria. Morphological analysis conducted by light- and electron-microscopy was then linked by DNA barcoding of the V4 region of 18S rRNA gene sequences to interpret taxonomic and phylogenetic relationships. The presence of two potentially toxigenic epibenthic dinoflagellates, Prorocentrum lima (Ehrenberg) F.Stein and Coolia monotis Meunier was confirmed, along with a description of their spatial and temporal distribution. For P. lima, one third of the cell abundance values exceeded official alarm thresholds for potentially toxic BHAB events (〉1000 cells gr–1 of macroalgae fresh weight). The same species were recorded consecutively for two summers, but without significant temporal variation in cell densities. SEM analyses confirmed the presence of other benthic Prorocentrum species: P. fukuyoi complex, P. cf. foraminosum and P. cf. hoffmannianum. Analyses of the V4 region of the 18S rRNA gene also indicated the presence P. compressum, P. hoffmannianum, P. foraminosum, P. fukuyoi, and P. nanum. These findings provide the first biogeographical evidence of toxigenic benthic dinoflagellates along the west coast of Sweden, in the absence of ongoing monitoring to include epibenthic dinoflagellates. Harmful events due to the presence of Coolia at shellfish aquaculture sites along the Kattegat-Skagerrak are likely to be rather marginal because C. monotis is not known to be toxigenic. In any case, as a preliminary assessment, the results highlight the risk of diarrhetic shellfish poisoning (DSP) events caused by P. lima, which may affect the development and sustainability of shellfish aquaculture in the region.
    Repository Name: EPIC Alfred Wegener Institut
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  • 46
    Publication Date: 2024-04-09
    Description: The marine dinoflagellate Alexandrium Halim represents perhaps the most significant and intensively studied genus with respect to species diversity, life history strategies, toxigenicity, biogeographical distribution, and global magnitude and consequences harmful algal blooms (HABs). The socioeconomic impacts, environmental and human health risks, and mitigation strategies for toxigenic Alexandrium blooms have also been explored in recent years. Human adaptive actions based on future scenarios of bloom dynamics and shifts in biogeographical distribution under climate-change parameters remain under development and not yet implemented on a regional scale. In the CoCliME (Co-development of climate services for adaptation to changing marine ecosystems) project these issues were addressed with respect to past, current and anticipated future status of key HAB genera and expected benefits of enhanced monitoring. Data on the distribution and frequency of Alexandrium blooms related to paralytic shellfish toxin (PST) events from key CoCliME Case Study areas, comprising the North Sea and adjacent Kattegat-Skagerrak, Norwegian Sea, and Baltic Sea, and eastern North Atlantic marginal seas, were evaluated in a contemporary and historical context over the past several decades. The first evidence of possible biogeographical expansion of Alexandrium taxa into eastern Arctic gateways was provided from DNA barcoding signatures. Various key climate change indicators, such as salinity, temperature, and water-column stratification, relevant to Alexandrium bloom initiation and development were identified. The possible influence of changing variables on bloom dynamics, magnitude, frequency and spatial and temporal distribution were interpreted in the context of regional ocean climate models. These climate change impact indicators may play key roles in selecting for the occurrence and diversity of Alexandrium species within the broader microeukaryote communities. For example, shifts to higher temperature and lower salinity regimes predicted for the southern North Sea indicate the potential for increased Alexandrium blooms, currently absent from this area. Ecological and socioeconomic impacts of Alexandrium blooms and effects on fisheries and aquaculture resources and coastal ecosystem function are evaluated, and, where feasible, effective adaptation strategies are proposed herein as emerging climate services.
    Repository Name: EPIC Alfred Wegener Institut
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  • 47
    Publication Date: 2024-04-09
    Description: A bloom of the fish-killing haptophyte Chrysochromulina leadbeateri in northern Norway during May and June 2019 was the most harmful algal event ever recorded in the region, causing massive mortalities of farmed salmon. Accordingly, oceanographic and biodiversity aspects of the bloom were studied in unprecedented detail, based on metabarcoding and physico-chemical and biotic factors related with the dynamics and distribution of the bloom. Light- and electron-microscopical observations of nanoplankton samples from diverse locations confirmed that C. leadbeateri was dominant in the bloom and the primary cause of associated fish mortalities. Cell counts by light microscopy and flow cytometry were obtained throughout the regional bloom within and adjacent to five fjord systems. Metabarcoding sequences of the V4 region of the 18S rRNA gene from field material collected during the bloom and a cultured isolate from offshore of Tromsøy island confirmed the species identification. Sequences from three genetic markers (18S, 28S rRNA gene and ITS region) verified the close if not identical genetic similarity to C. leadbeateri from a previous massive fish-killing bloom in 1991 in northern Norway. The distribution and cell abundance of C. leadbeateri and related Chrysochromulina species in the recent incident were tracked by integrating observations from metabarcoding sequences of the V4 region of the 18S rRNA gene. Metabarcoding revealed at least 14 distinct Chrysochromulina variants, including putative cryptic species. C. leadbeateri was by far the most abundant of these species, but with high intraspecific genetic variability. Highest cell abundance of up to 2.7 × 107 cells L − 1 of C. leadbeateri was found in Balsfjorden; the high cell densities were associated with stratification near the pycnocline (at ca. 12 m depth) within the fjord. The cell abundance of C. leadbeateri showed positive correlations with temperature, negative correlation with salinity, and a slightly positive correlation with ambient phosphate and nitrate concentrations. The spatio-temporal succession of the C. leadbeateri bloom suggests independent initiation from existing pre-bloom populations in local zones, perhaps sustained and supplemented over time by northeastward advection of the bloom from the fjords.
    Repository Name: EPIC Alfred Wegener Institut
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  • 48
    Publication Date: 2024-05-03
    Description: Rapid changes of the biosphere observed in recent years are caused by both small and large scale drivers, like shifts in temperature, transformations in land-use, or changes in the energy budget of systems. While the latter processes are easily quantifiable, documentation of the loss of biodiversity and community structure is more difficult. Changes in organismal abundance and diversity are barely documented. Censuses of species are usually fragmentary and inferred by often spatially, temporally and ecologically unsatisfactory simple species lists for individual study sites. Thus, detrimental global processes and their drivers often remain unrevealed. A major impediment to monitoring species diversity is the lack of human taxonomic expertise that is implicitly required for large-scale and fine-grained assessments. Another is the large amount of personnel and associated costs needed to cover large scales, or the inaccessibility of remote but nonetheless affected areas. To overcome these limitations we propose a network of Automated Multisensor stations for Monitoring of species Diversity (AMMODs) to pave the way for a new generation of biodiversity assessment centers. This network combines cutting-edge technologies with biodiversity informatics and expert systems that conserve expert knowledge. Each AMMOD station combines autonomous samplers for insects, pollen and spores, audio recorders for vocalizing animals, sensors for volatile organic compounds emitted by plants (pVOCs) and camera traps for mammals and small invertebrates. AMMODs are largely self-containing and have the ability to pre-process data (e.g. for noise filtering) prior to transmission to receiver stations for storage, integration and analyses. Installation on sites that are difficult to access require a sophisticated and challenging system design with optimum balance between power requirements, bandwidth for data transmission, required service, and operation under all environmental conditions for years. An important prerequisite for automated species identification are databases of DNA barcodes, animal sounds, for pVOCs, and images used as training data for automated species identification. AMMOD stations thus become a key component to advance the field of biodiversity monitoring for research and policy by delivering biodiversity data at an unprecedented spatial and temporal resolution.
    Repository Name: EPIC Alfred Wegener Institut
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  • 49
    Publication Date: 2024-05-07
    Description: Previous field studies in the Southern Ocean (SO) indicated an increased occurrence and dominance of cryptophytes over diatoms due to climate change. To gain a better mechanistic understanding of how the two ecologically important SO phytoplankton groups cope with ocean acidification (OA) and iron (Fe) availability, we chose two common representatives of Antarctic waters, the cryptophyte Geminigera cryophila and the diatom Pseudo-nitzschia subcurvata. Both species were grown at 2°C under different pCO2 (400 vs. 900 μatm) and Fe (0.6 vs. 1.2 nM) conditions. For P. subcurvata, an additional high pCO2 level was applied (1400 μatm). At ambient pCO2 under low Fe supply, growth of G. cryophila almost stopped while it remained unaffected in P. subcurvata. Under high Fe conditions, OA was not beneficial for P. subcurvata, but stimulated growth and carbon production of G. cryophila. Under low Fe supply, P. subcurvata coped much better with OA than the cryptophyte, but invested more energy into photoacclimation. Our study reveals that Fe limitation was detrimental for the growth of G. cryophila and suppressed the positive OA effect. The diatom was efficient in coping with low Fe, but was stressed by OA while both factors together strongly impacted its growth. The distinct physiological response of both species to OA and Fe limitation explains their occurrence in the field. Based on our results, Fe availability is an important modulator of OA effects on SO phytoplankton, with different implications on the occurrence of cryptophytes and diatoms in the future.
    Repository Name: EPIC Alfred Wegener Institut
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  • 50
    Publication Date: 2024-05-29
    Description: Data from the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition allowed us to investigate the temporal dynamics of snowfall, snow accumulation and erosion in great detail for almost the whole accumulation season (November 2019 to May 2020). We computed cumulative snow water equivalent (SWE) over the sea ice based on snow depth and density retrievals from a SnowMicroPen and approximately weekly measured snow depths along fixed transect paths. We used the derived SWE from the snow cover to compare with precipitation sensors installed during MOSAiC. The data were also compared with ERA5 reanalysis snowfall rates for the drift track. We found an accumulated snow mass of 38 m SWE between the end of October 2019 and end of April 2020. The initial SWE over first-year ice relative to second-year ice increased from 50 % to 90 % by end of the investigation period. Further, we found that the Vaisala Present Weather Detector 22, an optical precipitation sensor, and installed on a railing on the top deck of research vessel Polarstern, was least affected by blowing snow and showed good agreements with SWE retrievals along the transect. On the contrary, the OTT Pluvio2 pluviometer and the OTT Parsivel2 laser disdrometer were largely affected by wind and blowing snow, leading to too high measured precipitation rates. These are largely reduced when eliminating drifting snow periods in the comparison. ERA5 reveals good timing of the snowfall events and good agreement with ground measurements with an overestimation tendency. Retrieved snowfall from the ship-based Ka-band ARM zenith radar shows good agreements with SWE of the snow cover and differences comparable to those of ERA5. Based on the results, we suggest the Ka-band radar-derived snowfall as an upper limit and the present weather detector on RV Polarstern as a lower limit of a cumulative snowfall range. Based on these findings, we suggest a cumulative snowfall of 72 to 107 m and a precipitation mass loss of the snow cover due to erosion and sublimation as between 47 % and 68 %, for the time period between 31 October 2019 and 26 April 2020. Extending this period beyond available snow cover measurements, we suggest a cumulative snowfall of 98-114 m.
    Repository Name: EPIC Alfred Wegener Institut
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  • 51
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    In:  Ecology and Evolution vol. 12 no. e9549 | H2020 European Institute of Innovation and Technology, Grant/Award Number: 813360; Nederlandse Organisatie voor Wetenschappelijk Onderzoek, Grant/ Award Number: 16.161.301
    Publication Date: 2024-06-13
    Description: Monitoring community composition of Foraminifera (single-celled marine protists) pro-vides valuable insights into environmental conditions in marine ecosystems. Despitethe efficiency of environmental DNA (eDNA) and bulk-sample DNA (bulk-DNA) me-tabarcoding to assess the presence of multiple taxa, this has not been straightforwardfor Foraminifera partially due to the high genetic variability in widely used ribosomalmarkers. Here, we test the correctness in retrieving foraminiferal communities by me-tabarcoding of mock communities, bulk-DNA from coral reef sediment samples, andeDNA from their associated ethanol preservative using the recently sequenced cy-tochrome c oxidase subunit 1 (COI) marker. To assess the detection success, we com-pared our results with large benthic foraminiferal communities previously reportedfrom the same sampling sites. Results from our mock communities demonstrate thatall species were detected in two mock communities and all but one in the remainingfour. Technical replicates were highly similar in number of reads for each assigned ASVin both the mock communities and bulk-DNA samples. Bulk-DNA showed a signifi-cantly higher species richness than their associated eDNA samples, and also detectedadditional species to what was already reported at the specific sites. Our study con-firms that metabarcoding using the foraminiferal COI marker adequately retrieves thediversity and community composition of both the mock communities and the bulk-DNA samples. With its decreased variability compared with the commonly used nu-clear 18 S rRNA, the COI marker renders bulk-DNA metabarcoding a powerful tool toassess foraminiferal community composition under the condition that the referencedatabase is adequate to the target taxa.
    Keywords: bulk-sample ; DNA ; community composition ; coral reef ; environmental DNA ; foraminifera ; metabarcoding
    Repository Name: National Museum of Natural History, Netherlands
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  • 52
    Publication Date: 2024-06-18
    Description: Pronounced glacial and interglacial climate cycles characterized northern ecosystems during the Pleistocene. Our understanding of the resultant community transformations and past ecological interactions strongly depends on the taxa found in fossil assemblages. Here, we present a shotgun metagenomic analysis of sedimentary ancient DNA (sedaDNA) to infer past ecosystem-wide biotic composition (from viruses to megaherbivores) from the Middle and Late Pleistocene at the Batagay megaslump, East Siberia. The shotgun DNA records of past vegetation composition largely agree with pollen and plant metabarcoding data from the same samples. Interglacial ecosystems at Batagay attributed to Marine Isotope Stage (MIS) 17 and MIS 7 were characterized by forested vegetation (Pinus, Betula, Alnus) and open grassland. The microbial and fungal communities indicate strong activity related to soil decomposition, especially during MIS17. The local landscape likely featured more open, herb-dominated areas, and the vegetation mosaic supported birds and small omnivorous mammals. Parts of the area were intermittently/partially flooded as suggested by the presence of water-dependent taxa. During MIS 3, the sampled ecosystems are identified as cold-temperate, periodically flooded grassland. Diverse megafauna (Mammuthus, Equus, Coelodonta) coexisted with small mammals (rodents). The MIS 2 ecosystems existed under harsher conditions, as suggested by the presence of cold-adapted herbaceous taxa. Typical Pleistocene megafauna still inhabited the area. The new approach, in which shotgun sequencing is supported by metabarcoding and pollen data, enables the investigation of community composition changes across a broad range of taxonomic groups and inferences about trophic interactions and aspects of soil microbial ecology.
    Repository Name: EPIC Alfred Wegener Institut
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  • 53
    Publication Date: 2024-06-20
    Description: Because continuous and high-resolution records are scarce in the polar Urals, a multiproxy study was carried out on a 54 m long sediment succession (Co1321) from Lake Bolshoye Shchuchye. The sedimentological, geochemical, pollen and chironomid data suggest that glaciers occupied the lake's catchment during the cold and dry MIS 2 and document a change in ice extent around 23.5–18 cal ka bp. Subsequently, meltwater input, sediment supply and erosional activity decreased as local glaciers progressively melted. The vegetation around the lake comprised open, herb and grass-dominated tundra-steppe until the Bølling-Allerød, but shows a distinct change to probably moister conditions around 17–16 cal ka bp. Local glaciers completely disappeared during the Bølling-Allerød, when summer air temperatures were similar to today and low shrub tundra became established. The Younger Dryas is confined by distinct shifts in the pollen and chironomid records pointing to drier conditions. The Holocene is characterised by a denser vegetation cover, stabilised soil conditions and decreased minerogenic input, especially during the local thermal maximum between c. 10 and 5 cal ka bp. Subsequently, present-day vegetation developed and summer air temperatures decreased to modern, except for two intervals, which may represent the Little Ice Age and Medieval Warm Period.
    Repository Name: EPIC Alfred Wegener Institut
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  • 54
    Publication Date: 2024-07-05
    Repository Name: EPIC Alfred Wegener Institut
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  • 55
    Publication Date: 2023-01-04
    Description: The ubiquitous use of microplastics and their release into the environment especially the water bodies by anthropogenic/industrial activities are the major resources for microplastic contamination. The widespread and often injudicious use of antimicrobial drugs or antibiotics in various sectors including human health and hygiene, agriculture, animal husbandry and food industries are leading to the release of antibiotics into the wastewater/sewage and other water bodies, particularly in urban setups and thus leads to the antimicrobial resistance (AMR) in the microbes. Microplastics are emerging as the hubs as well as effective carriers of these microbial pathogens beside their AMR-genes (ARGs) in marine, freshwater, sewage/wastewater, and urban river ecosystems. These drug resistant bacteria interact with microplastics forming synthetic plastispheres, the ideal niche for biofilm formations which in turn facilitates the transfer of ARGs via horizontal gene transfer and further escalates the occurrence and levels of AMR. Microplastic-associated AMR is an emerging threat for human health and healthcare besides being a challenge for the research community for effective management/address of this menace. In this review, we encompass the increasing prevalence of microplastics in environment, emphasizing mainly on water environments, how they act as centers and vectors of microbial pathogens with their associated bacterial assemblage compositions and ultimately lead to AMR. It further discusses the mechanistic insights on how microplastics act as hosts of biofilms (creating the plastisphere). We have also presented the modern toolbox used for microplastic-biofilm analyses. A review on potential strategies for addressing microplastic-associated AMR is given with recent success stories, challenges and future prospects.
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  • 56
    Publication Date: 2023-01-04
    Description: The European Union cap-and-trade emissions trading system (EU ETS) faces two challenges in the context of the European Green Deal. First, to meet the Paris temperature target, emissions in the energy and industrial sectors must fall to net-zero and then even become net-negative. Second, there is a concern that excessive CO2 price spikes and volatility on this path will jeopardize the political acceptance and support for emissions trading as a climate policy instrument. Conditional supply of carbon removal credits (CRCs) to support dynamic carbon price caps would make it possible to stabilize the market in the transition from positive to net-negative emissions trading while keeping the net-emissions path unchanged. CRCs would be assigned for carbon removal achieved for example with methods like Direct Air Carbon Capture and Storage or Bioenergy with Carbon Capture and Storage and would be used by companies under the EU ETS to compensate for their emissions. However, we suggest that there would be no direct exchange between emitting companies under the EU ETS and carbon removal companies, i.e., the demand and supply side of CRCs, during an initial phase. Instead, we suggest assigning an institutional mandate to for example a carbon central bank (CCB) to organize the supply of CRCs. Under this mandate, carbon removal would be procured, would be translated into a corresponding number of CRCs, and a fraction of it could be auctioned to the market at a later point in time, provided that market prices exceed a certain (dynamic) price cap.
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  • 57
    Publication Date: 2023-01-04
    Description: Algae synthesise structurally complex glycans to build a protective barrier, the extracellular matrix. One function of matrix glycans is to slow down microorganisms that try to enzymatically enter living algae and degrade and convert their organic carbon back to carbon dioxide. We propose that matrix glycans lock up carbon in the ocean by controlling degradation of organic carbon by bacteria and other microbes not only while algae are alive, but also after death. Data revised in this review shows accumulation of algal glycans in the ocean underscoring the challenge bacteria and other microbes face to breach the glycan barrier with carbohydrate active enzymes. Briefly we also update on methods required to certify the uncertain magnitude and unknown molecular causes of glycan-controlled carbon sequestration in a changing ocean.
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  • 58
    Publication Date: 2023-01-04
    Description: The depth of the Labrador Sea mixed layer during winter convection is a balance between atmospheric buoyancy loss and lateral buoyancy exchange, and is notoriously difficult to represent accurately in ocean and climate models. This study shows that lateral exchanges of heat and salt between the shelf and the interior are smaller in a regional coupled ocean–sea ice model at higher vertical resolution (75 levels compared with 50 levels), due in part to altered bathymetry along the Greenland shelf. Reduced lateral exchange results in a stronger stratification in the interior of the Labrador Sea, with stronger convection resistance which results in unrealistically shallow mixed layers. The westward fluxes of heat and salt associated with Irminger Water at Cape Farewell are 50 % and 33 % lower, respectively, with higher vertical resolution. Exchanges south of the Labrador Sea from the North Atlantic Current are also smaller, contributing to a reduction in salt and heat import into the Labrador Sea interior. When the high resolution model is forced with a stronger wintertime buoyancy loss at the ocean surface, this weakens the Labrador Sea stratification, allowing the forcing to break through the freshwater cap and increasing convection, bringing mixed layer depths back to observed values. A strong atmospheric forcing can therefore compensate for a reduction in lateral advection. The mixed layer depths, which are representative of convection and Labrador Sea water formation, will be the focus in this study. Therefore, this study suggests that convection and Labrador Sea Water formation is a complex interplay of surface and lateral fluxes, linked to stratification thresholds.
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  • 59
    Publication Date: 2023-01-04
    Description: Plankton is a massive and phylogenetically diverse group of thousands of prokaryotes, protists (unicellular eukaryotic organisms), and metazoans (multicellular eukaryotic organisms; Fig. 1). Plankton functional diversity is at the core of various ecological processes, including productivity, carbon cycling and sequestration, nutrient cycling (Falkowski 2012), interspecies interactions, and food web dynamics and structure (D'Alelio et al. 2016). Through these functions, plankton play a critical role in the health of the coastal and open ocean and provide essential ecosystem services. Yet, at present, our understanding of plankton dynamics is insufficient to project how climate change and other human-driven impacts affect the functional diversity of plankton. That limits our ability to predict how critical ecosystem services will change in the future and develop strategies to adapt to these changes.
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  • 60
    Publication Date: 2023-01-04
    Description: Mussel aquaculture is heavily reliant on wild mussel populations that supply juveniles (spat) for seeding farms. However, little is often known about parent populations, representing a risk for the sustainability of the industry. We used hydrodynamic back-tracking models to identify potential parental areas that provision green-lipped mussel (Perna canaliculus) spat across a range of settlement sites in New Zealand's largest aquaculture area. Median parental area varied considerably between 19 km2 for sites located in enclosed bays and a maximum of 〉1150 km2 for sites located in open bays. Median distance to parent populations ranged between 1.8 and 21.4 km, with a maximum larval dispersal estimated to be ca. 100 km. Small seasonal variations in parental area and dispersal distance were detected in some regions, whereas inter-annual variability was relatively minor. Regional connectivity between settlement and parental regions ranged between a minimum of 45% of larvae originating in the same parental region, to maximum retention rates of 99.9% for sites in enclosed bays, implying a considerable regional variation in the potential for self-seeding and exporting mussel larvae other areas. Our results also delineate areas that support spatfall by identifying likely locations for wild or farmed parental populations, and by establishing the spatial extent where mussel reproduction and larval development through to settlement take place. These dispersal and connectivity patterns are crucial to support management decisions for the conservation and restoration of parental populations, and other environmental constraints, such as water quality, which are necessary to ensure the sustainability of spat catching operations that enable shellfish farming.
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  • 61
    Publication Date: 2023-01-04
    Description: Varying culture methods are commonly used for eastern oyster, Crassostrea virginica, aquaculture in the Northeast United States. Vibrio vulnificus and V. parahaemolyticus, two human pathogenic bacteria species, accumulate in this edible, filter feeding shellfish. This study examined the use of two methods in an intertidal area (oysters cultured in trays and in bags on sediment) and two methods in a subtidal area (oysters cultured in trays and loose on the sediment) in Massachusetts over the growing season in 2015. Abundance of total V. vulnificus along with total and pathogenic (tdh+/trh+) V. parahaemolyticus were determined in oysters, sediment and water using real-time PCR. Temperature, salinity, turbidity and chlorophyll were continually measured every 15 min at each location. There were significantly higher abundances of total and pathogenic V. parahaemolyticus in on-bottom cultured oysters, while significantly higher abundances of V. vulnificus were identified in oysters from off-bottom culture in a subtidal location in Duxbury Bay, MA. In an intertidal location, Wellfleet Bay, MA, significantly higher abundances of total and tdh+ V. parahaemolyticus were found in off-bottom oysters, but significantly higher abundances of V. vulnificus and trh+ V. parahaemolyticus were found in on-bottom oysters. Spearman's correlation indicated that temperature is positively associated with concentrations of Vibrio spp. in oysters, water and sediment, but positive correlations between salinity and Vibrio spp. was also observed. Conversely, turbidity had a negative effect on Vibrio spp. concentrations in all sample types. There was no observed relationship inferred between chlorophyll and Vibrio spp. abundances in oysters, water or sediment.
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  • 62
    Publication Date: 2023-01-04
    Description: Saccharina japonica is a commercially farmed seaweed of global importance. However, disease occurrence during different stages of cultivation can result in substantial economic losses. Identification of the causative agents of disease remains a significant bottleneck to the large scale cultivation of S. japonica. In this study, an aerobic heterotrophic, flagellated, rod-shaped Gram-negative bacterial strain X-8 was isolated from the bleaching diseased S. japonica sporelings. Pathogenecity of strain X-8 was tested by re-infection assay. The ultrastructural changes of infected S. japonica cells by strain X-8 indicated that chloroplasts were the first organelle responding to X-8 infection with deformed structure and later followed by fragmented nucleus. However, the ultra-structure of mitochondria and cell wall remained intact during the re-infection. Based on 16S rRNA gene sequence, morphological and biochemical characteristics, strain X-8 was designated as Pseudoalteromonas piscicida X-8. The pathogenicity of P. piscicida X-8 was identified by Koch's Postulate under laboratory conditions. Our results will not only help to establish a stable experimental model between the pathogenic bacteria and the host S. japonica to further elucidate the virulence mechanisms, but will also provide information for disease management to effectively prevent and mitigate the occurrence of bleaching disease of S. japonica at nursery stage.
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  • 63
    Publication Date: 2023-01-04
    Description: How do people’s perceptions about when they work affect their intrinsic motivation? We find that working during non-standard work time (weekends/holidays) versus standard work time (Monday-Friday, 9-to-5) undermines people’s intrinsic motivation for their professional and academic pursuits. Working during non-standard work time decreases intrinsic motivation by causing people to consider better uses of their time. That is, people generate more upward counterfactual thoughts, which mediates the effect of work time on reduced intrinsic motivation. As a causal test of this process, increasing consideration of upward counterfactuals during standard work time reduces intrinsic motivation, whereas decreasing consideration of upward counterfactuals during non-standard work time helps employees and students maintain intrinsic motivation for their professional and academic pursuits. Overall, we identify a novel determinant of intrinsic motivation and address a real challenge many people face: How changing work schedules affect interest and enjoyment of work, with important consequences for work outcomes.
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  • 64
    Publication Date: 2023-01-04
    Description: Seagrasses are complex benthic coastal ecosystems that play a crucial role in organic matter cycling and carbon sequestration. However, little is known about how seagrasses influence the structure and carbon utilization potential of benthic bacterial communities. This study examined the bacterial communities in monospecific and mixed meadows of seagrasses and compared with bulk (unvegetated) sediments from Chilika, a brackish water coastal lagoon of India. High-throughput sequencing of 16S rRNA genes revealed a vegetation effect in terms of differences in benthic bacterial community diversity, composition, and abundances in comparison with bulk sediments. Desulfobacterales, Chromatiales, Enterobacteriales, Clostridiales, Vibrionales, and Acidimicrobiales were major taxa that contributed to differences between seagrass and bulk sediments. Seagrasses supported ∼5.94 fold higher bacterial abundances than the bulk due to rich organic carbon stock in their sediments. Co-occurrence network demonstrated much stronger potential interactions and connectedness in seagrass bacterial communities compared to bulk. Chromatiales and Acidimicrobiales were identified as the top two keystone taxa in seagrass bacterial communities, whereas, Dehalococcoidales and Rhizobiales were in bulk communities. Seagrasses and local environmental factors, namely, water depth, water pH, sediment salinity, redox potential, total organic carbon, available nitrogen, sediment texture, sediment pH, and sediment core depth were the major drivers of benthic bacterial community composition. Carbon metabolic profiling revealed that heterotrophic bacteria in seagrass sediments were much more metabolically diverse and active than bulk. The utilization of carbon substrate guilds, namely, amino acids, amines, carboxylic acids, carbohydrates, polymers, and phenolic compounds was enhanced in seagrass sediments. Metabolic mapping predicted higher prevalence of sulfate-reducer and N2 fixation metabolic functions in seagrass sediments. Overall, this study showed that seagrasses control benthic bacterial community composition and diversity, enhance heterotrophic carbon substrate utilization, and play crucial roles in organic matter cycling including degradation of hydrocarbon and xenobiotics in coastal sediments.
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  • 65
    Publication Date: 2023-01-04
    Description: Ringed seals (Pusa hispida) are slowly recovering in the eastern and northern parts of the Baltic Sea after years of hunting pressure and contaminant exposure. Still, consequences of anthropogenic activities such as contaminant exposure and increasing temperatures are stressors that continue to have deleterious effects on their habitat and health. Transcription profiles of seven health-related genes involved in xenobiotic metabolism, endocrine disruption and stress were evaluated in blood, blubber, and liver of Baltic ringed seals in a multi-tissue approach. Selected persistent organic pollutants and total mercury concentrations were measured in blubber and liver, and muscle and liver of these animals, respectively. Concentrations of contaminants varied across tissues on a lipid weight basis but not with sex. mRNA transcript levels for all seven target genes did not vary between sexes or age classes. Transcript levels of thyroid hormone receptor alpha (TRα), retinoic acid receptor alpha (RARα) and heat shock protein 70 (HSP70) correlated with levels of persistent organic pollutants. TRα transcript levels also correlated positively with mercury concentrations in the liver. Of the three tissues assessed in this multi-tissue approach, blubber showed highest transcription levels of aryl hydrocarbon receptor nuclear translocator (ARNT), thyroid stimulating hormone receptor beta (TSHβ), oestrogen receptor alpha (ESR1) and peroxisome proliferator activated receptor alpha (PPARα). The wide range of genes expressed highlights the value of minimally invasive sampling (e.g. biopsies) for assessing health endpoints in free-ranging marine wildlife and the importance of identifying optimal matrices for targeted gene expression studies. This gene transcript profile study has provided baseline information on transcript levels of biomarkers for early on-set health effects in ringed seals and will be a useful guide to assess the impacts of environmental change in Baltic pinnipeds for conservation and management.
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  • 66
    Publication Date: 2023-01-04
    Description: Highlights • Our data split method handles spatial autocorrelation and imposes prediction fairness. • The sets impose fair algorithms with similar difficulty in all machine learning steps. • Kriging variance is a surrogate of spatial prediction difficulty. • The resulting training and test sets are compatible with any machine learning model. Machine learning supports prediction and inference in multivariate and complex datasets where observations are spatially related to one another. Frequently, these datasets depict spatial autocorrelation that violates the assumption of identically and independently distributed data. Overlooking this correlation result in over-optimistic models that fail to account for the geographical configuration of data. Furthermore, although different data split methods account for spatial autocorrelation, these methods are inflexible, and the parameter training and hyperparameter tuning of the machine learning model is set with a different prediction difficulty than the planned real-world use of the model. In other words, it is an unfair training-testing process. We present a novel method that considers spatial autocorrelation and planned real-world use of the spatial prediction model to design a fair train-test split. Demonstrations include two examples of the planned real-world use of the model using a realistic multivariate synthetic dataset and the analysis of 148 wells from an undisclosed Equinor play. First, the workflow applies the semivariogram model of the target to compute the simple kriging variance as a proxy of spatial estimation difficulty based on the spatial data configuration. Second, the workflow employs a modified rejection sampling to generate a test set with similar prediction difficulty as the planned real-world use of the model. Third, we compare 100 test sets' realizations to the model's planned real-world use, using probability distributions and two divergence metrics: the Jensen-Shannon distance and the mean squared error. The analysis ranks the spatial fair train-test split method as the only one to replicate the difficulty (i.e., kriging variance) compared to the validation set approach and spatial cross-validation. Moreover, the proposed method outperforms the validation set approach, yielding a minor mean percentage error when predicting a target feature in an undisclosed Equinor play using a random forest model. The resulting outputs are training and test sets ready for model fit and assessment with any machine learning algorithm. Thus, the proposed workflow offers spatial aware sets ready for predictive machine learning problems with similar estimation difficulty as the planned real-world use of the model and compatible with any spatial data analysis task.
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  • 67
    Publication Date: 2023-01-04
    Description: Deep-sea polymetallic nodule mining is expected to start within the next decade. There is currently a pressing need to develop best practices to minimise the potential environmental impacts of this new industry. Project-specific environmental management processes, such as environmental impact assessment (EIA), and the associated environmental management and monitoring plan (EMMP), must be effective to sufficiently mitigate environmental impacts of deep-sea mining (DSM) projects. This paper identifies the key drivers, barriers, and enablers to polymetallic nodule mining from a review of recent literature and develops an environmental management framework prior to any exploitation licenses being approved. We explore how the drivers to polymetallic nodule mining are framed in a global context, including claims that it will facilitate clean energy transitions, increase mineral supply diversity, and improve life cycle sustainability. We highlight the key barriers to effective environmental management, including epistemic uncertainty about deep-sea ecosystems, assessment of harmful effects from mining activities, and stakeholder support for a social license. We identify three enablers, including the precautionary approach, the ecosystem approach, and adaptive management, all of which are highly interdependent and must be operationalised to address the identified barriers. The results of this analysis indicate a complex social-ecological narrative infused throughout recent literature, emphasising the need for systems-level thinking and broader stakeholder participation. We present an environmental management framework designed to support good industry practice and guide future research.
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  • 68
    Publication Date: 2023-01-04
    Description: Northern peatlands store 300–600 Pg C, of which approximately half are underlain by permafrost. Climate warming and, in some regions, soil drying from enhanced evaporation are progressively threatening this large carbon stock. Here, we assess future CO2 and CH4 fluxes from northern peatlands using five land surface models that explicitly include representation of peatland processes. Under Representative Concentration Pathways (RCP) 2.6, northern peatlands are projected to remain a net sink of CO2 and climate neutral for the next three centuries. A shift to a net CO2 source and a substantial increase in CH4 emissions are projected under RCP8.5, which could exacerbate global warming by 0.21°C (range, 0.09–0.49°C) by the year 2300. The true warming impact of peatlands might be higher owing to processes not simulated by the models and direct anthropogenic disturbance. Our study highlights the importance of understanding how future warming might trigger high carbon losses from northern peatlands.
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  • 69
    Publication Date: 2023-01-04
    Description: Increased water temperature is considered an important cause of the loss of seagrass beds. This paper quantified the interactive influence of different combinations of water temperature and duration on the responses of Zostera marina plants in terms of survivorship, morphology, growth and physiology. The LT50 (lethal temperature that caused an increase in mortality to 50% of that of the control) and ET50 (effect time that caused a decrease in growth to 50% of that of the control) were calculated to reveal the quantitative relationship between temperature and duration that resulted in limiting effects on the survival and growth of Z. marina plants. Z. marina plants were exposed to different combinations of water temperature [23 (control), 25, 27, 29, and 31 °C] and duration (5, 10, 15 and 20 days), and then the plants were transferred to the control condition for over 30 days under laboratory conditions. The results showed that the survival rate of plants at the end of recovery were significantly lower than those of plants at the end of direct impact under the temperature levels of 29 and 31 °C in each duration, indicating that short-term periods of obviously increased water temperature would lead to long-term effects on the survival of Z. marina plants. Regression analysis revealed that the relationship between water temperature and duration that resulted in limiting effects on the survival and growth of Z. marina could be described as a strong power function. Pearson correlation analysis showed that the survival and growth of Z. marina plants exposed to different temperature levels were significantly correlated with leaf soluble sugar contents. This study will further develop our understanding of the degradation and disappearance of seagrass beds induced by increased temperature.
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  • 70
    Publication Date: 2023-01-04
    Description: This study investigates the mesoscale dynamics involved in the 8–11 October 2008 unseasonably strong African dust episode, during which dust was transported to the Iberian Peninsula (IP). We employ observational datasets and a high-resolution Weather Research and Forecasting model coupled with Chemistry simulations. The analysis shows that during 0900–1200 UTC 9 October, a mesoscale convective system developed over the Atlas Mountains and resulted in a southwestward propagating convective cold pool outflow on the southern foothills of the Anti-Atlas, which lifted dust from the source region. Between 1200 and 1800 UTC 9 October, new moist convection was enhanced over the Atlas Mountains due to intensifying confluence among a heat low, moist southwesterly Atlantic sea-breeze front, and northeasterly flow associated with the convective cold pool near western Algeria. This new moist convection intensified the strength of the convective cold pool outflow and haboob, both of which continued propagating southwestward. At 1200 UTC 10 October, the low-pressure system migrated poleward on the southern slopes of the Anti-Atlas Mountains in association with a mountain-plains solenoidal circulation due to the daytime differential heating between the southern slopes of the Anti-Atlas and nearby atmosphere. The deepening low-pressure and strengthening Atlantic sea-breeze redirected an equatorward advancing dust plume into the poleward direction. The dust plume ultimately crossed the Saharan Atlas Mountains on 11 October and finally impacted the IP. Key Points: - WRF-Chem simulation of an unseasonably strong haboob on the southern slopes of the Atlas Mountains - The equatorward-advancing dust plume was recirculated in the poleward direction by an Atlantic sea-breeze front - The Atlantic sea-breeze front and an intensified upper-level cutoff vortex are instrumental for dust transport over the Iberian Peninsula
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  • 71
    Publication Date: 2023-01-04
    Description: Opportunities to include Cetancodontamorpha in the study of the evolution of the immune system in the clades of Artiodactylamorpha, Ruminantiamorpha, Suinamorpha, and Camelidamorpha have increased with the use of the bottlenose dolphin, Tursiops truncatus, as a sentinel species to study the effects of environmental pollutants on the health of marine mammals. Efforts are currently underway to increase the number reagents needed for detailed studies. Thus far, screening of monoclonal antibodies (mAbs) made to leukocyte differentiation molecules (LDM) and the major histocompatibility (MHC) class I and class II molecules in Ruminantiamorpha have yielded some mAbs that recognize conserved epitopes expressed on orthologues in the bottlenose dolphin. More direct approaches are in progress to identify additional mAbs to bottlenose LDM and cytokines. As reported here, both direct and indirect approaches were used to identify mAbs specific for cytokines useful in monitoring the effects of environmental pollutants on the immune system. Immunization of mice with expressed bottlenose dolphin cytokines yielded mAbs specific for IFN-γ, TNF-α, IL-6, IL-8, IL-10, and IL-17A. Screening of previously developed mAbs used in livestock immunology research revealed mAbs developed against ovine IFN-γ and bovine IL-17 and IL-1β recognize conserved epitopes in bottlenose dolphin orthologues. The mAbs identified in the present study expand the reagents available to study the function of the immune system in bottlenose dolphins and cattle.
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  • 72
    Publication Date: 2023-01-24
    Description: Knowledge of the spatial distribution of dust aerosols and their effects on crops is important for policy formulation and food security. This study aims to investigate the impact of dust source susceptibility areas (DSSA) on the loss of agricultural crop and corresponding water consumption in terms of Water Footprint in the Great Salt Desert, Iran. To this goal, MODIS satellite images during the 2005–2020 period were used to identify dust sources and 135 dust source zones were identified. Machine learning algorithm viz. Random Forest (RF), generalized linear model (GLM), and Artificial neural network (ANN) were tested to reproduce DSSA. The best method was RF and applied to calculate and classify DSSA in five risk levels from very low to very high. The amount of wheat production under high risk of DSSA was estimated using the average crop yield from recent years using agriculture statistics. We calculated the loss of crops and corresponding water consumption for three scenarios, assuming a typical loss of 20, 40, and 60% of the wheat production for better crop loss estimation. Finally, the spatial relationships between wheat farmland and high-risk DSSA were assessed using ordinary least squares regression (OLS) and geographically weighted regression (GWR) at sub-watershed scale. The area of wheat cultivation in high and very high risk of DSSA is 10188.04 km2, which is 36% of all agricultural land for wheat in the region. Loss of wheat crop to DSSA meant that 1270.58 to 3811 million m3 water used for the production of wheat were lost, corresponding to 2%, to 7% of lost water compared to the total water consumption for wheat production in the study area.
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  • 73
    Publication Date: 2023-01-24
    Description: Despite the implication of aerosols for the radiation budget, there are persistent differences in data for the aerosol optical depth (τ) for 1998–2019. This study presents a comprehensive evaluation of the large-scale spatio-temporal patterns of mid-visible τ from modern data sets. In total, we assessed 94 different global data sets from eight satellite retrievals, four aerosol-climate model ensembles, one operational ensemble product, two reanalyses, one climatology and one merged satellite product. We include the new satellite data SLSTR and aerosol-climate simulations from the Coupled Model Intercomparison Project Phase 6 (CMIP6) and the Aerosol Comparisons between Observations and Models Phase 3 (AeroCom-III). Our intercomparison highlights model differences and observational uncertainty. Spatial mean τ for 60°N – 60°S ranges from 0.124 to 0.164 for individual satellites, with a mean of 0.14. Averaged τ from aerosol-climate model ensembles fall within this satellite range, but individual models do not. Our assessment suggests no systematic improvement compared to CMIP5 and AeroCom-I. Although some regional biases have been reduced, τ from both CMIP6 and AeroCom-III are for instance substantially larger along extra-tropical storm tracks compared to the satellite products. The considerable uncertainty in observed τ implies that a model evaluation based on a single satellite product might draw biased conclusions. This underlines the need for continued efforts to improve both model and satellite estimates of τ, for example, through measurement campaigns in areas of particularly uncertain satellite estimates identified in this study, to facilitate a better understanding of aerosol effects in the Earth system. Key Points: - Present-day patterns in aerosol optical depth differ substantially between 94 modern global data sets - The range in spatial means from individual satellites is −11% to +17% of the multi-satellite mean - Spatial means from climate model intercomparison projects fall within the satellite range but strong regional differences are identified
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  • 74
    Publication Date: 2023-01-24
    Description: Pseudomonas is one the best studied bacterial genera, and it is the genus with the highest number of species among the gram-negative bacteria. Pseudomonas spp. are widely distributed and play relevant ecological roles; several species are commensal or pathogenic to humans, animals and plants. The main aim of the present minireview is the discussion of how the Pseudomonas taxonomy has evolved with the development of bacterial taxonomy since the first description of the genus in 1894. We discuss how the successive implementation of novel methodologies has influenced the taxonomy of the genus and, vice versa, how the taxonomic studies developed in Pseudomonas have introduced novel tools and concepts to bacterial taxonomy. Current phylogenomic analyses of the family Pseudomonadaceae demonstrate that a considerable number of named Pseudomonas spp. are not monophyletic with P. aeruginosa, the type species of the genus, and that a reorganization of several genera can be foreseen. Phylogenomics of Pseudomonas, Azomonas and Azotobacter within the Pseudomonadaceae is presented as a case study. Five new genus names are delineated to accommodate five well-defined phylogenetic branches that are supported by the shared genes in each group, and two of them can be differentiated by physiological and ecological properties: the recently described genus Halopseudomonas and the genus Stutzerimonas proposed in the present study. Five former Pseudomonas species are transferred to Halopseudomonas and 10 species to Stutzerimonas.
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  • 75
    Publication Date: 2023-01-24
    Description: Solar radiation received at the Earth's surface (Rs) is comprised of two components, the direct radiation (Rd) and the diffuse radiation (Rf). Rd, the direct beam from the sun, is essential for concentrated solar power generation. Rf, scattered by atmospheric molecules, aerosols, or cloud droplets, has a fertilization effect on plant photosynthesis. But how Rd and Rf change diurnally is largely unknown owing to the lack of long-term measurements. Taking advantage of 22 years of homogeneous hourly surface observations over China, this study documents the climatological means and evolutions in the diurnal cycles of Rd and Rf since 1993, with an emphasis on their implications for solar power and agricultural production. Over the solar energy resource region, we observe a loss of Rd which is relatively large near sunrise and sunset at low solar elevation angles when the sunrays pass through the atmosphere on a longer pathway. However, the concentrated Rd energy covering an average 10-hr period around noon during a day is relatively unaffected. Over the agricultural crop resource region, the large amounts of clouds and aerosols scattering more of the incoming light result in Rf taking the main proportion of Rs during the whole day. Rf resources and their fertilization effect in the main crop region of China further enhances since 1993 over almost all hours of the day. Key Points: - The loss of direct radiation over China since 1993 is relatively large at sunrise and sunset with little effect on solar power generation - The diffuse component dominates solar radiation normally near sunrise and sunset, but for the whole day over the main sown area of China - The diffuse fraction is further enhanced in the main sown area of China over almost all hours of the day since 1993
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  • 76
    Publication Date: 2023-01-24
    Description: Highlights • Broad analysis of bias propagation with seven irradiance data sets in PV model. • We identify seasonal and regional biases in irradiance and PV power. • There is no single data set performing best in all metrics for means and variability. Abstract Model estimates of expected photovoltaic (PV) power production rely on accurate irradiance data. Reanalysis and satellite products freely provide irradiance data with a high temporal and spatial resolution including locations for which no ground-based measurements are available. We assess differences in such gridded irradiance data and quantify the subsequent bias propagation from individual radiation components to capacity factors in a contemporary PV model. PV power production is simulated based on four reanalysis (ERA5, COSMO-REA6, COSMO-REA6pp, COSMO-REA2) and three satellite products (CAMS, SARAH-2, CERES Syn1Deg). The results are compared against simulations using measurements from 30 weather stations of the German Weather Service. We compute metrics characterizing biases in seasonal and annual means, day-to-day variability and extremes in PV power. Our results highlight a bias of −1.4% (COSMO-REA6) to +8.2% (ERA5) in annual and spatial means of PV power production for Germany. No single data set is best in all metrics, although SARAH-2 and the postprocessed COSMO-REA6 data (COSMO-REA6pp) outperform the other products for many metrics. SARAH-2 yields good results in summer, but overestimates PV output in winter by 16% averaged across all stations. COSMO-REA6pp represents day-to-day variability in the PV power production of a simulated PV fleet best and has a particularly small bias of 0.5% in annual means. This is at least in parts due to compensating biases in local and seasonal means. Our results imply that gridded irradiance data should be used with caution for site assessments and ideally be complemented by local measurements.
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  • 77
    Publication Date: 2023-01-24
    Description: Submarine geomorphology, the study of landforms and processes within the submarine domain, is a young discipline that owes its birth to technological achievements that made it possible to explore the underwater sphere of our Earth system. Submarine domains represent over 70% of Earth's surface, i.e. the largest geomorphic system on our planet (more than twice the size of what we can observe on Earth's land surface). From the middle of the last century onwards, technological advances have led to more and more high-performance acoustic equipment and robotic underwater systems, enabling us to depict and investigate, in ever greater detail, parts of the ocean floor long thought to be unfathomable. The present chapter gives an overview of the extent to which technological progress has strongly determined the way in which the study of landscapes and landforms within the submarine domain is approached, creating substantial differences to approaches used in classical studies of geomorphology. Main drivers of seafloor geomorphic changes are introduced to provide a representative summary of the variety of landforms generated by the action of a range of tectonic, sedimentary, and bio-geochemical processes, including the impact of human activity. The chapter concludes with a brief discussion on the relevance of the applied value of submarine geomorphological research, its new trends, and the key contribution it is providing to confirming the importance of geomorphology to the full range of Earth system sciences and environment-related topics.
    Type: Book chapter , PeerReviewed
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  • 78
    Publication Date: 2023-02-13
    Description: Hydrothermal vent areas are unique ecosystems with high productivity and high biodiversity that are subject to ongoing research. Hydrothermal vents form in areas with increased magmatic activity where superheated, mineral rich water leaks from the seafloor. Due to the rapid cooling of the water the metal sulfides precipitate and form a black or white plume that can be sensed several hundred meters away from the vent source. Finding and reliably following such plumes with autonomous underwater vehicles (AUVs) is a challenging task since the plume does not have a smooth concentration gradient but lots of local patches due to the turbulent particle flow. This paper presents an algorithm that combines biology inspired chemotaxis with Unscented Kalman filter (UKF) based extremum seeking control (ESC). The effectiveness is demonstrated by a simulation of a physics-based AUV model in a turbulent 3D Plume model.
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  • 79
    Publication Date: 2023-06-06
    Description: We review the current knowledge of the biodiversity of the ocean as well as the levels of decline and threat for species and habitats. The lack of understanding of the distribution of life in the ocean is identified as a significant barrier to restoring its biodiversity and health. We explore why the science of taxonomy has failed to deliver knowledge of what species are present in the ocean, how they are distributed and how they are responding to global and regional to local anthropogenic pressures. This failure prevents nations from meeting their international commitments to conserve marine biodiversity with the results that investment in taxonomy has declined in many countries. We explore a range of new technologies and approaches for discovery of marine species and their detection and monitoring. These include: imaging methods, molecular approaches, active and passive acoustics, the use of interconnected databases and citizen science. Whilst no one method is suitable for discovering or detecting all groups of organisms many are complementary and have been combined to give a more complete picture of biodiversity in marine ecosystems. We conclude that integrated approaches represent the best way forwards for accelerating species discovery, description and biodiversity assessment. Examples of integrated taxonomic approaches are identified from terrestrial ecosystems. Such integrated taxonomic approaches require the adoption of cybertaxonomy approaches and will be boosted by new autonomous sampling platforms and development of machine-speed exchange of digital information between databases.
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  • 80
    Publication Date: 2023-11-20
    Description: Key Points High-resolution reflection seismic data reveals that the internal architecture of the Kolumbo Volcanic Chain The Kolumbo Volcanic Chain evolved during two episodes along NE-SW striking normal faults A prominent volcanic ridge connects the Kolumbo Volcanic Chain with Santorini highlighting a former connection between both systems Abstract The Christiana-Santorini-Kolumbo volcanic field in the southern Aegean Sea is one of the most hazardous volcanic regions in the world. Forming the northeastern part of this volcanic field, the Kolumbo Volcanic Chain (KVC) comprises more than submarine volcanic cones. However, due to their inaccessibility, little is known about the spatio-temporal evolution and tectonic control of these submarine volcanoes and their link to the volcanic plumbing system of Santorini. In this study, we use multichannel reflection seismic imaging to study the internal architecture of the KVC and its link to Santorini. We show that the KVC evolved during two episodes, which initiated at ~1 Ma with the formation of mainly effusive volcanic edifices along a NE-SW trending zone. The cones of the second episode were formed mainly by submarine explosive eruptions between 0.7 and 0.3 Ma and partly developed on top of volcanic edifices from the first episode. We identify two prominent normal faults that underlie and continue the two main trends of the KVC, indicating a direct link between tectonics and volcanism. In addition, we reveal several buried volcanic centers and a distinct volcanic ridge connecting the KVC with Santorini, suggesting a connection between the two volcanic centers in the past. This connection was interrupted by a major tectonic event and, as a result, the two volcanic systems now have separate, largely independent plumbing systems despite their proximity
    Type: Article , NonPeerReviewed , info:eu-repo/semantics/article
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  • 81
    Publication Date: 2023-12-21
    Description: To limit global warming to 1.5 °C, vast amounts of CO2 will have to be removed from the atmosphere via Carbon Dioxide Removal (CDR). Enhancing the CO2 sequestration of ecosystems will require not just one approach but a portfolio of CDR options, including so-called nature-based approaches alongside CDR options that are perceived as more technical. Creating a CDR “supply curve” would however imply that all carbon removals are considered to be perfect substitutes. The various co-benefits of nature-based CDR approaches militate against this. We discuss this aspect of nature-based solutions in connection with the enhancement of blue carbon ecosystems (BCE) such as mangrove or seagrass habitats. Enhancing BCEs can indeed contribute to CO2 sequestration, but the value of their carbon storage is low compared to the overall contribution of their ecosystem services to wealth. Furthermore, their property rights are often unclear, i.e. not comprehensively defined or not enforced. Hence, payment schemes that only compensate BCE carbon sequestration could create tradeoffs at the expense of other important, often local, ecosystem services and might not result in socially optimal outcomes. Accordingly, one chance for preserving and restoring BCEs lies in the consideration of all services in potential compensation schemes for local communities. Also, local contexts, management structures, and benefit-sharing rules are crucial factors to be taken into account when setting up international payment schemes to support the use of BCEs and other nature- or ecosystem-based CDR. However, regarding these options as the only hope of achieving more CDR will very probably not bring about the desired outcome, either for climate mitigation or for ecosystem preservation. Unhalted degradation, in turn, will make matters worse due to the large amounts of stored carbon that would be released. Hence, countries committed to climate mitigation in line with the Paris targets should not hide behind vague pledges to enhance natural sinks for removing atmospheric CO2 but commit to scaling up engineered CDR.
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  • 82
    Publication Date: 2024-01-08
    Description: Omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) are essential fatty acids for the growth, development and survival of virtually all organisms. There is increasing evidence that anthropogenic climate change has a direct and indirect impact on the availability of natural n-3 LC-PUFA. However, this information is fragmented and not well organized. Therefore, this article reviewed published data from laboratory experiments, field experiments and model simulations to reveal the impact of climate change on the global supply of natural n-3 LC-PUFA and how this will limit the availability of n-3 LC-PUFA in the future food web. In general, climate change can significantly reduce the availability of natural n-3 LC-PUFA in grazing food webs in the following ways: 1) decrease the total biomass of phytoplankton and shift the plankton community structure to a smaller size, which also reduce the biomass of animals in higher trophics; 2) reduce the n-3 LC-PUFA content and/or quality (n-3: n-6 ratio) of all marine organisms; 3) reduce the transfer efficiency of n-3 LC-PUFA in grazing food web. In addition, as an anthropogenic climate adaptation measure, this review also proposed some alternative sources of n-3 LC-PUFA and determined the direction of future research. The information in this article is very useful for providing a critical analysis of the impact of climate change on the supply of natural n-3 LC-PUFA. Such information will aid to establish climate adaptation or management measures, and determine the direction of future research.
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  • 83
    Publication Date: 2024-01-08
    Description: In recent years, deep learning methods have shown great promise in the field of geophysics, especially for seismic interpretation. However, there is very little information with regard to its application in the field of magnetic methods. Our research introduces the use of convolutional neural networks for the characterization of magnetic anomalies. The models developed allow the localization of magnetic dipoles, including counting the number of dipoles, their geographical position, and the prediction of their parameters (magnetic moment, depth, and declination). To go even further, we applied visualization tools to understand our model's predictions and its working principle. The Grad-CAM tool improved prediction performance by identifying several layers that had no influence on the prediction and the t-SNE tool confirmed the strong capacity of our model to differentiate between different parameter combinations. Then, we tested our model with real data to establish its limitations and application domain. Results demonstrate that our model detects dipolar anomalies in a real magnetic map even after learning from a synthetic database with a lower complexity, which indicates a significant generalization capability. We also noticed that it is unable to identify dipole anomalies of shapes and sizes different from those considered for the creation of the synthetic database. Finally, the perspectives for this work consist of creating a more complex database to approach the complexity traditionally observed in magnetic maps, using real data from multiple acquisition campaigns, and other applications with alternative geophysical methods.
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  • 84
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    Elsevier
    Publication Date: 2024-01-08
    Description: As environmental DNA (eDNA) approaches gain momentum for biodiversity analysis, validation becomes a key consideration. I focus on four facets of eDNA validation. Validation through technical processes, legal use, official statements, and ‘good enough’ scenarios can advance the field to aid societal issues such as climate emergency and biodiversity crisis.
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  • 85
    Publication Date: 2024-01-08
    Description: Metabolic interactions between auxotrophs and prototrophs in microbial communities are understudied. Yu et al. showed how intracellular as well as intercellular metabolism affects community fitness in the absence and presence of abiotic stress, that is, drugs.
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  • 86
    Publication Date: 2024-01-08
    Description: Seagrasses are capable of sanitizing coastal seawaters polluted by fecal bacteria. In this work, the reduction of Enterococci concentration in the presence of a seagrasses’ assemblage (Pacific Ocean) was related to the decrease in the probability of gastroenteritis. A linear model fitted to data extracted from the literature showed a 20% reduction of this probability in the presence of these plants. Seagrass sanitation effect was estimated to allow avoiding ca. 24 million gastroenteritis cases/year, globally. Considering a global cost of gastroenteritis of ca. US$ 372 million/year, the global avoided cost, assuming that the sanitation service was always effective, was estimated to be ca. US$ 74 million/year (2020 US$). The seagrass sanitation effect appears genera/geographic dependent, and the targeted pathogen may change as well. Thus, the global estimates were roughly adjusted, obtaining conservative figures of ca. 8 million avoided cases/year and ca. US$ 24 million/year of avoided cost. Considering the importance of this Ecosystem Service (ES) for public health and the potential global spreading of diseases driven by climate change, further research is needed to ascertain the scope of this seagrass ES worldwide.
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  • 87
    Publication Date: 2024-01-08
    Description: The aim of the study is to evaluate the 3D dynamic response of a finite geological region containing two structures and rested on a semi-infinite elastic layered half-space with a dynamic source radiating transient waves. The hybrid modelling approach is applied. It is based on the decomposition of the whole domain under consideration into two sub-regions: a finite-sized near-field elastic isotropic zone with two containment structures and the open semi-infinite far-field layered region. The far-field zone is a semi-infinite elastic isotropic arbitrary layered medium where the near-field finite geological region is located on. The 3D hybrid computational tool is based on the boundary element method (BEM) for the far-field layered zone and the finite element method (FEM) for the finite near-field domain. The model for the semi-infinite layered zone is further extended by the incorporation of a new condensation algorithm which makes it possible to handle 3D wave propagation through arbitrary layered half-space. The condensation algorithm is developed to avoid high computational memory cost while retaining the compatibility with the hybrid FEM-hosted procedure which facilitates the useful solution for the practical three-dimensional engineering problems. The BEM model of the dynamically active far-field zone is inserted as a macro-finite element (MFE) in the FEM commercial program ABAQUS. The accuracy and convergence study of the hybrid numerical scheme is presented. Numerical simulations convincingly illustrate that the dynamic response of structure-soil-structure system depends on different key factors and their mutual interplay. These factors are arbitrary layering of the far-field geological zone, the characteristics of the dynamic source, the site effects phenomena, the structure-soil-structure dynamic interaction, the type and geometrical disposition of foundations and structures and the 3D features of the dynamic motion.
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  • 88
    Publication Date: 2024-01-08
    Description: Gas production from hydrates induced by depressurization is a complex thermal-hydrodynamic-mechanical–chemical (THMC) coupled process. In this paper, we present a THMC coupled model to simulate the fluid flow in hydrate-bearing sediments (HBS) and the geomechanical behavior of HBS. The model is made of two subsystems, which are the fluid part of non-isothermal multi-phase flow with hydrate kinetic and solid part of geomechanical deformation. It accounts for two-way coupling effects between these two subsystems, i.e. the effect of pore pressure and hydrate dissociation on the solid mechanical behavior and the effect of stress on the hydraulic behavior. A new numerical method based on the hybrid control volume finite element method (CVFEM)-finite element method (FEM) is developed to solve the mathematical models. The local conservative CVFEM is used for the fluid part, and the standard FEM for the solid part. In the framework of hybrid CVFEM-FEM, the local conservation is reserved and the primary variables for the two subsystem are co-located. A multi-point flux approximation (MPFA) is adopted without orthogonal meshes so that it is very flexible to build complex geometrical models. The accuracy and reliability of the newly developed simulator QIMGHyd-THMC are tested by comparing with two experimental examples and a large-scale benchmark problem of other popular simulators.
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  • 89
    Publication Date: 2024-02-07
    Description: Single-crystal (U-Th)/He dating of 32 apatite and zircon crystals from an impact breccia yielded a weighted mean age of 663 ± 28 ka (n = 3; 4.2 % 2σ uncertainties) for the Monturaqui impact structure, Chile. This ∼350 m diameter simple crater preserves a small volume of impactite consisting of polymict breccias that are dominated by reworked target rock clasts. The small size, young age and limited availability of melt material for traditional geochronological techniques made Monturaqui a good test to define the lower limits of the (U-Th)/He system to successfully date impact events. Numerical modelling of 4He loss in apatite and zircon crystals shows that, for even small craters such as Monturaqui, the short-lived compressional stage and shock metamorphic stage can account for the observed partial to full resetting of (U-Th)/He ages in accessory minerals. Despite the distinctly different 4He diffusion parameters of apatite and zircon, the 2σ-overlapping youngest ages are recorded in both populations of minerals, which supports the inference that the weighted mean of the youngest (U-Th)/He population is the age of formation of this impact structure.
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  • 90
    Publication Date: 2024-02-07
    Description: Highlights: • From 1960 to 2020 reported costs of US biological invasions were at least $1.22 tril. • Annual invasion costs increased from $2 bil in 1960–69 to $21 bil in 2010–20. • Most costs were damages ($896 bil), with lower management investments ($47 bil). • Agriculture sector ($510 bil) and terrestrial habitat ($644 bil) were impacted most. • Knowledge gaps in reporting make these monetary costs severely underestimated. Abstract: The United States has thousands of invasive species, representing a sizable, but unknown burden to the national economy. Given the potential economic repercussions of invasive species, quantifying these costs is of paramount importance both for national economies and invasion management. Here, we used a novel global database of invasion costs (InvaCost) to quantify the overall costs of invasive species in the United States across spatiotemporal, taxonomic, and socioeconomic scales. From 1960 to 2020, reported invasion costs totaled $4.52 trillion (USD 2017). Considering only observed, highly reliable costs, this total cost reached $1.22 trillion with an average annual cost of $19.94 billion/year. These costs increased from $2.00 billion annually between 1960 and 1969 to $21.08 billion annually between 2010 and 2020. Most costs (73%) were related to resource damages and losses ($896.22 billion), as opposed to management expenditures ($46.54 billion). Moreover, the majority of costs were reported from invaders from terrestrial habitats ($643.51 billion, 53%) and agriculture was the most impacted sector ($509.55 billion). From a taxonomic perspective, mammals ($234.71 billion) and insects ($126.42 billion) were the taxonomic groups responsible for the greatest costs. Considering the apparent rising costs of invasions, coupled with increasing numbers of invasive species and the current lack of cost information for most known invaders, our findings provide critical information for policymakers and managers.
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  • 91
    Publication Date: 2024-02-07
    Description: Highlights • AUV geophysical mapping reveals complex patterns of Mn nodule distribution. • Geophysical and image-based data suggest that Mn nodule occurence relates to sediment thickness. • The role of sediment thickness in nodule development requires detailed geochemical investigation. Abstract The relationship between polymetallic nodules (Mn nodules) and deep-sea stratigraphy is relatively poorly studied and the role of sediment thickness in determining nodule occurrence is an active field of research. This study utilizes geophysical observations from three types of autonomous underwater vehicle (AUV) data (multi-beam bathymetry, sub-bottom profiles and underwater photography) in order to assess this relationship. Multi-beam bathymetry was processed with a pattern recognition approach for producing objective geomorphometric classes of the seafloor for examining their relation to sediment thickness and nodule occurence. Sub-bottom profiles were used for extracting sediment thickness along a dense network of tracklines. Close-range AUV-photography data was used for automated counting of polymetallic nodules and their geometric features and it served as ground truth data. It was observed that higher nodule occurence were related to layers with increased sediment thickness. This evidence reveals the role of local seafloor heterogeneity in nodule formation and suggests that unique patterns of local stratigraphy may affect geochemical processes that promote polymetallic nodule development at local scales.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 92
    Publication Date: 2024-02-07
    Description: In the marine realm, microorganisms are responsible for the bulk of primary production, thereby sustaining marine life across all trophic levels. Longhurst provinces have distinct microbial fingerprints; however, little is known about how microbial diversity and primary productivity change at finer spatial scales. Here, we sampled the Atlantic Ocean from south to north (~50°S–50°N), every ~0.5° latitude. We conducted measurements of primary productivity, chlorophyll-a and relative abundance of 16S and 18S rRNA genes, alongside analyses of the physicochemical and hydrographic environment. We analysed the diversity of autotrophs, mixotrophs and heterotrophs, and noted distinct patterns among these guilds across provinces with high and low chlorophyll-a conditions. Eukaryotic autotrophs and prokaryotic heterotrophs showed a shared inter-province diversity pattern, distinct from the diversity pattern shared by mixotrophs, cyanobacteria and eukaryotic heterotrophs. Additionally, we calculated samplewise productivity-specific length scales, the potential horizontal displacement of microbial communities by surface currents to an intrinsic biological rate (here, specific primary productivity). This scale provides key context for our trophically disaggregated diversity analysis that we could relate to underlying oceanographic features. We integrate this element to provide more nuanced insights into the mosaic-like nature of microbial provincialism, linking diversity patterns to oceanographic transport through primary production.
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  • 93
    Publication Date: 2024-02-07
    Description: PUBLIC SUMMARY: Endothermy has evolved multiple times not only in mammals and birds but also in fishes (teleosts and chondrichthyans) A chromosome-level genome sequence of the whole-body endothermic opah was generated, explaining genetic changes in heat production, sensory, and adaptive immune system Convergent evolution in endothermic vertebrate lineages was investigated, and genes essential for heart function and metabolic heat production were screened Analyses of the unique pectoral muscle of opah revealed that numerous proteins were co-opted from dorsal swimming muscles for thermogenesis and oxidative phosphorylation ABSTRACT: Few fishes have evolved elevated body temperatures compared to ambient temperatures and only in opah (Lampris spp) is the entire body affected. To understand the molecular basis of endothermy, we analyzed the opah genome and identified 23 genes with convergent amino acid substitutions across fish, birds, and mammals, including slc8b1, which encodes the mitochondrial Na+/Ca2+ exchanger and is essential for heart function and metabolic heat production. Among endothermic fishes, 44 convergent genes with suggestive metabolic functions were identified, such as glrx3, encoding a crucial protein for hemoglobin maturation. Numerous genes involved in the production and retention of metabolic heat were also found to be under positive selection. Analyses of opah’s unique inner heat-producing pectoral muscle layer, an evolutionary key-innovation, revealed that many proteins were co-opted from dorsal swimming muscles for thermogenesis and oxidative phosphorylation. Thus, the opah genome provides valuable resources and opportunities to uncover the genetic basis of thermal adaptations in fish.
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  • 94
    Publication Date: 2024-02-07
    Description: Highlights: • First study to compare microplastic effects over a wide biogeographical range • Comparison between natural inorganic microparticles and plastic microparticles • Significant effects on byssus production, respiration and clearance rates, but small effect sizes • No ecologically relevant difference between impact of plastic and natural inorganic microparticles on Mytilidae Abstract: Microplastics are ubiquitous in the marine environment and studies on their effects on benthic filter feeders at least partly revealed a negative influence. However, it is still unclear whether the effects of microplastics differ from those of natural suspended microparticles, which constitute a common stressor in many coastal environments. We present a series of experiments that compared the effects of six-week exposures of marine mussels to two types of natural particles (red clay and diatom shells) to two types of plastic particles (Polymethyl Methacrylate and Polyvinyl Chloride). Mussels of the family Mytilidae from temperate regions (Japan, Chile, Tasmania) through subtropical (Israel) to tropical environments (Cabo Verde) were exposed to concentrations of 1.5 mg/L, 15 mg/L and 150 mg/L of the respective microparticles. At the end of this period, we found significant effects of suspended particles on respiration rate, byssus production and condition index of the animals. There was no significant effect on clearance rate and survival. Surprisingly, we observed only small differences between the effects of the different types of particles, which suggests that the mussels were generally equally robust towards exposure to variable concentrations of suspended solids regardless of whether they were natural or plastic. We conclude, that microplastics and suspended solids elicit similar effects on the tested response variables, and that both types of microparticles mainly cause acute responses rather than more persistent carry-over effects.
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  • 95
    Publication Date: 2024-02-07
    Description: Arctic sea ice cover has been steeply declining since the onset of satellite observations in the late 1970s. However, the available annually resolved sea ice data prior to this time are limited. Here, we evaluated the suitability of annual trace element (Mg/Ca) ratios and growth increments from the long-lived annual increment-forming benthic coralline red alga, Clathromorphum compactum, as high-resolution sea ice cover archive. It has previously been shown that growth of C. compactum is strongly light controlled and therefore greatly limited during polar night and underneath sea ice cover. We compare algal data from 11 sites collected throughout the Canadian Arctic, Greenland and Svalbard, with satellite sea ice data. Our results suggested that algal growth anomalies most often produced better correlations to sea ice concentration than Mg/Ca ratios or when averaging growth and Mg/Ca anomalies. High Arctic regions with persistently higher sea ice concentrations and shorter ice-free seasons showed strongest correlations between algal growth anomalies and satellite sea ice concentration over the study period (1979-2015). At sites where ice breakup took place prior to the return of sufficient solar irradiance, algal growth was most strongly tied to a combination of solar irradiance and other factors such as temperature, suspended sediments, phytoplankton blooms and cloud cover. These data are the only annually resolved in situ marine proxy data known to date and are of utmost importance to gain a better understanding of the sea ice system and to project future sea ice conditions.
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  • 96
    Publication Date: 2024-02-07
    Description: Ocean acidification (OA) is one of the most critical anthropogenic threats to marine ecosystems. While significant ecological responses of plankton communities to OA have been revealed mainly by small-scale laboratory approaches, the interactive effect of OA-related changes on zooplankton metabolism and their biogeochemical implications in the natural environment still remains less well understood. Here, we explore the responses of zooplankton respiration and ammonium excretion, two key processes in the nutrient cycling, to high pCO2 levels in a 9-week in situ mesocosm experiment conducted during the autumn oligotrophic season in the subtropical northeast Atlantic. By simulating an upwelling event halfway through the study, we further evaluated the combined effects of OA and nutrient availability on the physiology of micro-and mesozooplankton. OA conditions generally resulted in a reduction in the biomass-specific metabolic and enzymatic rates, particularly in the mesozooplankton community. The situation reversed after the nutrient-rich deep-water addition, which initially promoted a diatom bloom and increased heterotrophic activities in all mesocosms. Under high pCO2 conditions (〉800 μatm), however, the nutrient fertilization triggered the proliferation of the harmful alga Vicicitus globosus, with important consequences for the metabolic performance of the two zooplankton size classes. Here, the zooplankton contribution to the remineralization of organic matter and nitrogen regeneration dropped by 30% and 24%, respectively, during the oligotrophic period, and by 40% and 70% during simulated upwelling. Overall, our results indicate a potential reduction in the biogeochemical role of zooplankton under future ocean conditions, with more evident effects on the large mesozooplankton and during high productivity events
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 97
    Publication Date: 2024-02-07
    Description: When organic matter from thawed permafrost is released, the sources and sinks of greenhouse gases (GHGs), like carbon dioxide (CO2) and methane (CH4) in Arctic rivers will be influenced in the future. However, the temporal variation, environmental controls, and magnitude of the Arctic riverine GHGs are largely unknown. We measured in situ high temporal resolution concentrations of CO2, CH4, and oxygen (O2) in the Ambolikha River in northeast Siberia between late June and early August 2019. During this period, the largely supersaturated riverine CO2 and CH4 concentrations decreased steadily by 90% and 78%, respectively, while the O2 concentrations increased by 22% and were driven by the decreasing water temperature. Estimated gas fluxes indicate that during late June 2019, significant emissions of CO2 and CH4 were sustained, possibly by external terrestrial sources during flooding, or due to lateral exchange with gas-rich downstream-flowing water. In July and early August, the river reversed its flow constantly and limited the water exchange at the site. The composition of dissolved organic matter and microbial communities analyzed in discrete samples also revealed a temporal shift. Furthermore, the cumulative total riverine CO2 emissions (36.8 gC-CO2 m−2) were nearly five times lower than the CO2 uptake at the adjacent floodplain. Emissions of riverine CH4 (0.21 gC-CH4 m−2) were 16 times lower than the floodplain CH4 emissions. Our study revealed that the hydraulic connectivity with the land in the late freshet, and reversing flow directions in Arctic streams in summer, regulate riverine carbon replenishment and emissions.
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  • 98
    Publication Date: 2024-02-07
    Description: It is widely accepted that iron (Fe)-binding organic ligands play a crucial role in Fe distribution in the marine environment and thus in Fe biogeochemistry. Although Competitive Ligand Equilibration – Adsorptive Cathodic Stripping Voltammetry (CLE-AdCSV) is a well-established technique to investigate Fe chemical speciation in marine samples, several impediments still need to be addressed. These include the extrapolation of laboratory measurements to in-situ conditions, the harmonization of the analytical procedures used, and the applicability of the methods over salinity ranges wider than seawater (e.g., sea ice). This work focusses on the calibration of 2-(2-thiazolylazo)-p-cresol (TAC), salicylaldoxime (SA) and 1-nitroso-2-naphthol (NN), along the salinity range 1–90, and titration of natural samples at two different temperatures (4 °C and 20 °C). The artificial ligand concentration was 10 μM for TAC and 5 μM for SA and NN. Calibrations showed that increasing salinity caused a decrease in the conditional stability constants (logK'Fe’AL) for NN and SA (although different behaviours were noted for the two species FeSA and FeSA2). Less accuracy was noted using TAC, which behaved inconsistently outside the 21 〈 S 〈 35 range, and its use is therefore discouraged in fresh and highly saline waters. Titrations of natural samples showed that only SA covered the salinity range selected, up to 78, and its use is therefore recommended in sea-ice studies. The side reaction coefficient (logα'Fe’AL) of each artificial ligand was found to be influenced by temperature differently: logα'Fe’SA was higher at lower temperature (4 °C), whereas logα'Fe’SA2 and logα'Fe’NN3 increased with increasing temperature (to 20 °C). Although titrations performed at 4 °C highlighted that the uncomplexed Fe fraction was 14% lower than at 20 °C, with potential consequences on primary productivity, the percentage of natural Fe complexed was 〉99%. Future investigations should consider the analysis of the samples at a temperature as close as possible to in-situ conditions to reduce the potential temperature effects.
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  • 99
    Publication Date: 2024-02-07
    Description: Serpentinization and carbonation of ultramafic formations is a ubiquitous phenomenon, which deeply influences the biogeochemical cycles of water, hydrogen, carbon…while supporting the particular biosphere around the oceanic hydrothermal vents. Carbonation of peridotites and other mafic and ultramafic rocks is also a hot topic in the current energy landscape as the engineered sequestration of mineral CO2 in these formations could help reduce the atmospheric emissions and cope with climate change. In this study, we present two reactive percolation experiments performed on a natural serpentinite dredged from the ultraslow South-West Indian Oceanic Ridge. The serpentinite cores (length 3–4 cm and dia. 5.6 mm) were subjected for about 10 days to the continuous injection of a NaHCO3-saturated brine at respectively 160 °C and 280 °C. Petrographic and petrophysical results as well as outlet fluid compositions were compared to numerical batch simulations performed with the PHREEQC open software allowing to reconstruct the mineralogical evolution of both cores. The most striking observation is the fast and dramatic decrease of the permeability for both experiments principally due to the precipitation of carbonates. On the contrary, serpentine was found to be less impacting as it precipitates in low-flow zones, out of the main percolation paths. In total, about 5.6% of the total injected CO2 was retained in the core, at 280 °C. In the same time, hydrogen was consistently produced with a total recovered H2 corresponding to 0.8% of the maximum H2 possible. The global behavior of the cores is interpreted as the result from an interplay between interacting spatio-temporal lengthscales controlled by the Damköhler number.
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  • 100
    Publication Date: 2024-02-07
    Description: Although submarine landslides have been studied for decades, a persistent challenge is the integration of diverse geoscientific datasets to characterise failure processes. We present a core-log-seismic integration study of the Tuaheni Landslide Complex to investigate intact sediments beneath the undeformed seafloor as well as post-failure landslide deposits. Beneath the undeformed seafloor are coherent reflections underlain by a weakly-reflective and chaotic seismic unit. This chaotic unit is characterised by variable shear strength that correlates with density fluctuations. The basal shear zone of the Tuaheni landslide likely exploited one (or more) of the low shear strength intervals. Within landslide deposits is a widespread “Intra-debris Reflector”, previously interpreted as the landslide’s basal shear zone. This reflector is a subtle impedance drop around the boundary between upper and lower landslide units. However, there is no pronounced shear strength change across this horizon. Rather, there is a pronounced reduction in shear strength ∼10-15 m above the Intra-debris Reflector that presumably represents an induced weak layer that developed during failure. Free gas accumulates beneath some regions of the landslide and is widespread deeper in the sedimentary sequence, suggesting that free gas may have played a role in pre-conditioning the slope to failure. Additional pre-conditioning or failure triggers could have been seismic shaking and associated transient fluid pressure. Our study underscores the importance of detailed core-log-seismic integration approaches for investigating basal shear zone development in submarine landslides.
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