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  • Nature Publishing Group
  • 2010-2014  (29)
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  • 2011  (29)
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  • 1
    Publication Date: 2017-04-04
    Description: The MW 8.8 mega-thrust earthquake and tsunami that occurred on February 27, 2010, offshore Maule region, Chile, was not unexpected. A clearly identified seismic gap existed in an area where tectonic loading has been accumulating since the great 1835 earthquake experienced and described by Darwin during the voyage of the Beagle. Here we jointly invert tsunami and geodetic data (InSAR, GPS, land-level changes), to derive a robust model for the co-seismic slip distribution and induced co-seismic stress changes, and compare them to past earthquakes and the pre-seismic locking distribution. We aim to assess if the Maule earthquake has filled the Darwin gap, decreasing the probability of a future shock . We find that the main slip patch is located to the north of the gap, overlapping the rupture zone of the MW 8.0 1928 earthquake, and that a secondary concentration of slip occurred to the south; the Darwin gap was only partially filled and a zone of high pre-seismic locking remains unbroken. This observation is not consistent with the assumption that distributions of seismic rupture might be correlated with pre-seismic locking, potentially allowing the anticipation of slip distributions in seismic gaps. Moreover, increased stress on this unbroken patch might have increased the probability of another major to great earthquake there in the near future.
    Description: Published
    Description: 173-177
    Description: 3.1. Fisica dei terremoti
    Description: 4.2. TTC - Modelli per la stima della pericolosità sismica a scala nazionale
    Description: JCR Journal
    Description: restricted
    Keywords: Source process ; Chile ; Tsunami ; Joint Inversion ; Seismic Gap ; 04. Solid Earth::04.06. Seismology::04.06.99. General or miscellaneous ; 04. Solid Earth::04.07. Tectonophysics::04.07.05. Stress ; 04. Solid Earth::04.07. Tectonophysics::04.07.06. Subduction related processes ; 05. General::05.01. Computational geophysics::05.01.03. Inverse methods
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
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  • 2
    Publication Date: 2022-05-25
    Description: © Macmillan Publishers Limited, 2011. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Nature Communications 2 (2011): 293, doi:10.1038/ncomms1297.
    Description: The relative importance of north–south migrations of the intertropical convergence zone (ITCZ) versus El Niño-Southern Oscillation and its associated Pacific Walker Circulation (PWC) variability for past hydrological change in the western tropical Pacific is unclear. Here we show that north–south ITCZ migration was not the only mechanism of tropical Pacific hydrologic variability during the last millennium, and that PWC variability profoundly influenced tropical Pacific hydrology. We present hydrological reconstructions from Cattle Pond, Dongdao Island of the South China Sea, where multi-decadal rainfall and downcore grain size variations are correlated to the Southern Oscillation Index during the instrumental era. Our downcore grain size reconstructions indicate that this site received less precipitation during relatively warm periods, AD 1000–1400 and AD 1850–2000, compared with the cool period (AD 1400–1850). Including our new reconstructions in a synthesis of tropical Pacific records results in a spatial pattern of hydrologic variability that implicates the PWC.
    Description: This work was supported by the Natural Science Foundation of China (NSFC) (40730107) and the Major State Basic Research Development Program of China (973 Program) (No.2010CB428902). DWO acknowledges support from the US NSF.
    Repository Name: Woods Hole Open Access Server
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  • 3
    Publication Date: 2022-05-25
    Description: © International Society for Microbial Ecology, 2011. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in The ISME Journal 5 (2011): 1565–1567, doi:10.1038/ismej.2011.39.
    Description: Interest in sampling of diverse environments, combined with advances in high-throughput sequencing, vastly accelerates the pace at which new genomes and metagenomes are generated. For example, as of January 2011, 12 500 user-generated metagenomes have been submitted to the public MG-RAST Annotation server (http://metagenomics. nmpdr.org; Meyer et al., 2008), 490% of which were produced using high-throughput sequencing methodologies. We have entered into an era of ‘mega-sequencing projects’ that include the Genomic Encyclopaedia of Bacteria and Archaea project (http://www.jgi.doe.gov/programs/GEBA), the Microbial Earth Project (http://genome.jgi-psf. org/programs/bacteria-archaea/MEP/index.jsf), the Human Microbiome Project (http://nihroadmap.nih. gov/hmp), the Metagenomics of the Human Intestinal Tract consortium (http://www.metahit.eu), the Terragenome Initiative (http://www.terragenome. org), the Tara Oceans Expedition (http://oceans. taraexpeditions.org), the National Ecological Observatory Network (NEON-http://www.neoninc.org), the International Census of Marine Microbes (ICoMM-http://icomm.mbl.edu), Microbial Inventory Research Across Diverse Aquatic Long-Term Ecological Research Sites (http://amarallab.mbl. edu/mirada/mirada.html), the Earth Microbiome Project (http://www.earthmicrobiome.org) and other funded and unfunded projects, with many more visionary projects on the horizon.
    Repository Name: Woods Hole Open Access Server
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  • 4
    Publication Date: 2017-03-27
    Description: An influence of solar irradiance variations on Earth’s surface climate has been repeatedly suggested, based on correlations between solar variability and meteorological variables1. Specifically, weaker westerly winds have been observed in winters with a less active sun, for example at the minimum phase of the 11-year sunspot cycle2, 3, 4. With some possible exceptions5, 6, it has proved difficult for climate models to consistently reproduce this signal7, 8. Spectral Irradiance Monitor satellite measurements indicate that variations in solar ultraviolet irradiance may be larger than previously thought9. Here we drive an ocean–atmosphere climate model with ultraviolet irradiance variations based on these observations. We find that the model responds to the solar minimum with patterns in surface pressure and temperature that resemble the negative phase of the North Atlantic or Arctic Oscillation, of similar magnitude to observations. In our model, the anomalies descend through the depth of the extratropical winter atmosphere. If the updated measurements of solar ultraviolet irradiance are correct, low solar activity, as observed during recent years, drives cold winters in northern Europe and the United States, and mild winters over southern Europe and Canada, with little direct change in globally averaged temperature. Given the quasiregularity of the 11-year solar cycle, our findings may help improve decadal climate predictions for highly populated extratropical regions
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  • 5
    Publication Date: 2017-06-20
    Description: The anaerobic oxidation of methane (AOM) with sulphate, an area currently generating great interest in microbiology, is accomplished by consortia of methanotrophic archaea (ANME) and sulphate-reducing bacteria1, 2. The enzyme activating methane in methanotrophic archaea has tentatively been identified as a homologue of methyl-coenzyme M reductase (MCR) that catalyses the methane-forming step in methanogenic archaea3, 4. Here we report an X-ray structure of the 280 kDa heterohexameric ANME-1 MCR complex. It was crystallized uniquely from a protein ensemble purified from consortia of microorganisms collected with a submersible from a Black Sea mat catalysing AOM with sulphate4. Crystals grown from the heterogeneous sample diffract to 2.1 Å resolution and consist of a single ANME-1 MCR population, demonstrating the strong selective power of crystallization. The structure revealed ANME-1 MCR in complex with coenzyme M and coenzyme B, indicating the same substrates for MCR from methanotrophic and methanogenic archaea. Differences between the highly similar structures of ANME-1 MCR and methanogenic MCR include a F430 modification, a cysteine-rich patch and an altered post-translational amino acid modification pattern, which may tune the enzymes for their functions in different biological contexts.
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  • 6
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    Nature Publishing Group
    In:  Nature Reviews Microbiology, 9 (7). pp. 499-508.
    Publication Date: 2020-06-23
    Description: Biological N2 fixation is an important part of the marine nitrogen cycle as it provides a source of new nitrogen that can support biological carbon export and sequestration. Research in the past decade has focused on determining the patterns of distribution and abundance of diazotrophs, defining the environmental features leading to these patterns and characterizing the factors that constrain marine N2 fixation overall. In this Review, we describe how variations in the deposition of iron from dust to different ocean basins affects the limiting nutrient for N2 fixation and the distribution of different diazotrophic species. However, many questions remain about marine N2 fixation, including the role of temperature, fixed nitrogen species, CO2 and physical forcing in controlling N2 fixation, as well as the potential for heterotrophic N2 fixation.
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  • 7
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    Nature Publishing Group
    In:  Nature Geoscience, 4 (6). pp. 398-403.
    Publication Date: 2017-05-11
    Description: The Pacific sector of Antarctica, including both the Antarctic Peninsula and continental West Antarctica, has experienced substantial warming in the past 30 years. An increase in the circumpolar westerlies, owing in part to the decline in stratospheric ozone concentrations since the late 1970s, may account for warming trends in the peninsula region in austral summer and autumn. The more widespread warming in continental West Antarctica (Ellsworth Land and Marie Byrd Land) occurs primarily in austral winter and spring, and remains unexplained. Here we use observations of Antarctic surface temperature and global sea surface temperature, and atmospheric circulation data to show that recent warming in continental West Antarctica is linked to sea surface temperature changes in the tropical Pacific. Over the past 30 years, anomalous sea surface temperatures in the central tropical Pacific have generated an atmospheric Rossby wave response that influences atmospheric circulation over the Amundsen Sea, causing increased advection of warm air to the Antarctic continent. General circulation model experiments show that the central tropical Pacific is a critical region for producing the observed high latitude response. We conclude that, by affecting the atmospheric circulation at high southern latitudes, increasing tropical sea surface temperatures may account for West Antarctic warming through most of the twentieth century.
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  • 8
    Publication Date: 2017-06-16
    Description: Climate warming at the end of the last glaciation caused ice caps on Icelandic volcanoes to retreat. Removal of surface ice load is thought to have decreased pressures in the underlying mantle, triggering decompression melting, enhanced magma generation and increased volcanic activity1–3. Present-day climate change could have the same effect, although there may be a time lag of hundreds of years between magma generation and eruption4,5. However, in addition to increased magma generation, pressure changes associated with ice retreat should also alter the capacity for storing magma within the crust. Here we use a numerical model to evaluate the effect of the current decrease in ice load on magma storage in the crust at the Kverkfjöll volcanic system, located partially beneath Iceland’s largest ice cap. We compare the model results with radar and global positioning system measurements of surface displacement and changes in crustal stress between 2007 and 2008, during the intrusion of a deep dyke at Upptyppingar. We find that although the main component of stress recorded during dyke intrusion relates to plate extension, another component of stress is consistent with the stress field caused by the retreating ice cap. We conclude that the retreating ice cap led to enhanced capture of magma within the crust. We suggest that ice-cap retreat can promote magma storage, rather than eruption, at least in the short term.
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  • 9
    Publication Date: 2018-01-05
    Description: There have been decades, such as 2000–2009, when the observed globally averaged surface-temperature time series shows little increase or even a slightly negative trend1 (a hiatus period). However, the observed energy imbalance at the top-of-atmosphere for this recent decade indicates that a net energy flux into the climate system of about 1 W m−2 (refs 2, 3) should be producing warming somewhere in the system4,5. Here we analyse twenty-first-century climate-model simulations that maintain a consistent radiative imbalance at the top-of-atmosphere of about 1 W m−2 as observed for the past decade. Eight decades with a slightly negative global mean surface-temperature trend show that the ocean above 300 m takes up significantly less heat whereas the ocean below 300 m takes up significantly more, compared with non-hiatus decades. The model provides a plausible depiction of processes in the climate system causing the hiatus periods, and indicates that a hiatus period is a relatively common climate phenomenon and may be linked to La Niña-like conditions.
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  • 10
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    Nature Publishing Group
    In:  Nature Immunology, 12 (1). pp. 5-9.
    Publication Date: 2020-06-25
    Description: The fields of immunology, microbiology, nutrition and metabolism are rapidly converging. Here we expand on a diet-microbiota model as the basis for the greater incidence of asthma and autoimmunity in developed countries.
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  • 11
    Publication Date: 2016-04-27
    Description: Hydrothermal vents emit sulphur and metals to the ocean1. Particular attention has been paid to hydrothermal fluxes of iron2–4, a limiting micronutrient of marine primary production5. Vent-derived ironwas previously thought to rapidly oxidize and precipitate around vents6. However, organic matter can bind to and stabilize dissolved and particulate iron in hydrothermal plumes7–9, facilitating its dispersion into the open ocean10. Here, we report measurements of the chemical speciation of sulphide and iron in high-temperature fluids emanating from vents in the East Pacific Rise and the Eastern Lau Spreading Center. We show that pyrite nanoparticles—composed of iron and sulphur—account for up to 10% of the filterable iron (less than 200nm in size) in these fluids. We suggest that these particles form before the discharge of the vent fluid. We estimate that pyrite nanoparticles sink more slowly than larger plume particles, and are more resistant to oxidation than dissolved Fe(II) and FeS.We suggest that the discharge of iron in the form of pyrite nanoparticles increases the probability that vent-derived iron will be transported over long distances in the deep ocean.
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  • 12
    Publication Date: 2015-07-03
    Description: In this study, we present a single-cell genomics approach for the functional characterization of the candidate phylum Poribacteria, members of which are nearly exclusively found in marine sponges. The microbial consortia of the Mediterranean sponge Aplysina aerophoba were singularized by fluorescence-activated cell sorting, and individual microbial cells were subjected to phi29 polymerase-mediated 'whole-genome amplification'. Pyrosequencing of a single amplified genome (SAG) derived from a member of the Poribacteria resulted in nearly 1.6 Mb of genomic information distributed among 554 contigs analyzed in this study. Approximately two-third of the poribacterial genome was sequenced. Our findings shed light on the functional properties and lifestyle of a possibly ancient bacterial symbiont of marine sponges. The Poribacteria are mixotrophic bacteria with autotrophic CO(2)-fixation capacities through the Wood-Ljungdahl pathway. The cell wall is of Gram-negative origin. The Poribacteria produce at least two polyketide synthases (PKSs), one of which is the sponge-specific Sup-type PKS. Several putative symbiosis factors such as adhesins (bacterial Ig-like domains, lamininin G domain proteins), adhesin-related proteins (ankyrin, fibronectin type III) and tetratrico peptide repeat domain-encoding proteins were identified, which might be involved in mediating sponge-microbe interactions. The discovery of genes coding for 24-isopropyl steroids implies that certain fossil biomarkers used to date the origins of metazoan life on earth may possibly be of poribacterial origin. Single-cell genomic approaches, such as those shown herein, contribute to a better understanding of beneficial microbial consortia, of which most members are, because of the lack of cultivation, inaccessible by conventional techniques.
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  • 13
    Publication Date: 2016-05-25
    Description: Salinity is a major factor controlling the distribution of biota in aquatic systems, and most aquatic multicellular organisms are either adapted to life in saltwater or freshwater conditions. Consequently, the saltwater–freshwater mixing zones in coastal or estuarine areas are characterized by limited faunal and floral diversity. Although changes in diversity and decline in species richness in brackish waters is well documented in aquatic ecology, it is unknown to what extent this applies to bacterial communities. Here, we report a first detailed bacterial inventory from vertical profiles of 60 sampling stations distributed along the salinity gradient of the Baltic Sea, one of world's largest brackish water environments, generated using 454 pyrosequencing of partial (400 bp) 16S rRNA genes. Within the salinity gradient, bacterial community composition altered at broad and finer-scale phylogenetic levels. Analogous to faunal communities within brackish conditions, we identified a bacterial brackish water community comprising a diverse combination of freshwater and marine groups, along with populations unique to this environment. As water residence times in the Baltic Sea exceed 3 years, the observed bacterial community cannot be the result of mixing of fresh water and saltwater, but our study represents the first detailed description of an autochthonous brackish microbiome. In contrast to the decline in the diversity of multicellular organisms, reduced bacterial diversity at brackish conditions could not be established. It is possible that the rapid adaptation rate of bacteria has enabled a variety of lineages to fill what for higher organisms remains a challenging and relatively unoccupied ecological niche.
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  • 14
    Publication Date: 2015-09-23
    Description: The Denmark Strait overflow water is the largest dense water plume from the Nordic seas to feed the lower limb of the Atlantic Meridional Overturning Circulation. Its primary source is commonly thought to be the East Greenland Current. However, the recent discovery of the North Icelandic Jet—a deep-reaching current that flows along the continental slope of Iceland—has called this view into question. Here we present high-resolution measurements of hydrography and velocity north of Iceland, taken during two shipboard surveys in October 2008 and August 2009. We find that the North Icelandic Jet advects overflow water into the Denmark Strait and constitutes a pathway that is distinct from the East Greenland Current. We estimate that the jet supplies about half of the total overflow transport, and infer that it is the primary source of the densest overflow water. Simulations with an ocean general circulation model suggest that the import of warm, salty water from the North Icelandic Irminger Current and water-mass transformation in the interior Iceland Sea are critical to the formation of the jet. We surmise that the timescale for the renewal of the deepest water in the meridional overturning cell, and its sensitivity to changes in climate, could be different than presently envisaged.
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  • 15
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    Nature Publishing Group
    In:  Nature, 470 (7332). pp. 31-33.
    Publication Date: 2016-10-28
    Description: Extracting minerals from sea-floor vents should not go ahead without a coherent conservation framework, argues Cindy Lee Van Dover.
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  • 16
    Publication Date: 2019-09-23
    Description: Fluids entering the subduction zone play a key role in the subduction process. They cause changes in the dynamics and thermal structure of the subduction zone1, and trigger earthquakes when released from the subducting plate during metamorphism. Fluids are delivered to the subduction zone by the oceanic crust and also enter as the oceanic plate bends downwards at the plate boundary. However, the amount of fluids entering subduction zones is not matched by that leaving through volcanic emissions4 or transfer to the deep mantle, implying possible storage of fluids in the crust. Here we use magnetotelluric data to map the entire hydration and dehydration cycle of the Costa Rican subduction zone to 120 km depth. Along the incoming plate bend, we detect a conductivity anomaly that we interpret as sea water penetrating down extensional faults and cracks into the upper mantle. Along the subducting plate interface we document the dehydration of sediments, the crust and mantle. We identify an accumulation of fluids at ~20–30 km depth at a distance of 30 km seaward from the volcanic arc. Comparison with other subduction zones5–14 indicates that such fluid accumulation is a global phenomenon. Although we are unable to test whether these fluid reservoirs grow with time, we suggest that they can account for some of the missing outflow of fluid at subduction zones.
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  • 17
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    Nature Publishing Group
    In:  Nature Geoscience, 4 . pp. 393-397.
    Publication Date: 2019-09-23
    Description: Lavas erupted within plate interiors above upwelling mantle plumes have chemical signatures that are distinct from midocean ridge lavas. When a plume interacts with a mid-ocean ridge, the compositions of both their lavas changes, but there is no consensus as to how this interaction occurs1–3. For the past 15 Myr, the Pacific–Antarctic mid-ocean ridge has been approaching the Foundation hotspot4 and erupted lavas have formed seamounts. Here we analyse the noble gas isotope and trace element signature of lava samples collected from the seamounts. We find that both intraplate and on-axis lavas have noble gas isotope signatures consistent with the contribution from a primitive plume source. In contrast, nearaxis lavas show no primitive noble gas isotope signatures, but are enriched in strontium and lead, indicative of subducted former oceanic lower crust melting within the plume source5–7. We propose that, in a near-ridge setting, primitive, plumesourced magmas formed deep in the plume are preferentially channelled to and erupted at the ridge-axis. The remaining residue continues to rise and melt, forming the near-axis seamounts. With the deep melts removed, the geochemical signature of subduction contained within the residue becomes apparent. Lavas with strontium and lead enrichments are found worldwide where plumes meet mid-ocean ridges6–8, suggesting that subducted lower crust is an important but previously unrecognised plume component.
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  • 18
    Publication Date: 2020-10-16
    Description: Experiments have shown that ocean acidification due to rising atmospheric carbon dioxide concentrations has deleterious effects on the performance of many marine organisms(1-4). However, few empirical or modelling studies have addressed the long-term consequences of ocean acidification for marine ecosystems(5-7). Here we show that as pH declines from 8.1 to 7.8 (the change expected if atmospheric carbon dioxide concentrations increase from 390 to 750 ppm, consistent with some scenarios for the end of this century) some organisms benefit, but many more lose out. We investigated coral reefs, seagrasses and sediments that are acclimatized to low pH at three cool and shallow volcanic carbon dioxide seeps in Papua New Guinea. At reduced pH, we observed reductions in coral diversity, recruitment and abundances of structurally complex framework builders, and shifts in competitive interactions between taxa. However, coral cover remained constant between pH 8.1 and similar to 7.8, because massive Porites corals established dominance over structural corals, despite low rates of calcification. Reef development ceased below pH 7.7. Our empirical data from this unique field setting confirm model predictions that ocean acidification, together with temperature stress, will probably lead to severely reduced diversity, structural complexity and resilience Of Indo-Pacific coral reefs within this century
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  • 19
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    Nature Publishing Group
    In:  Nature Geoscience, 4 (11). pp. 735-736.
    Publication Date: 2012-08-02
    Description: The impact of solar activity on climate has been debated heatedly. Simulations with a climate model using new observations of solar variability suggest a substantial influence of the Sun on the winter climate in the Northern Hemisphere.
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  • 20
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    Nature Publishing Group
    In:  Nature Geoscience, 4 (6). pp. 363-366.
    Publication Date: 2019-09-23
    Description: The Southern Ocean is thought to be one of the most energetic regions in the world’s oceans. As a result, it is a location of vigorous diapycnal mixing of heat, salt and biogeochemical properties1, 2, 3. At the same time, the Southern Ocean is poorly sampled, not least because of its harsh climate and remote location. Yet the spatial and temporal variation of diapycnal diffusivity in this region plays an important part in the large-scale ocean circulation and climate4, 5, 6. Here we use high-resolution hydrographic profiles from Argo floats in combination with the Iridium communications system to investigate diapycnal mixing in the Southern Ocean. We find that the spatial distribution of turbulent diapycnal mixing in the Southern Ocean at depths between 300 and 1,800 m is controlled by the topography, by means of its interaction with the Antarctic Circumpolar Current. The seasonal variation of this mixing can largely be attributed to the seasonal cycle of surface wind stress and is more pronounced in the upper ocean over flat topography. We suggest that additional high-resolution profiles from Argo floats will serve to advance our understanding of mixing processes in the global ocean interior.
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  • 21
    Publication Date: 2020-10-26
    Description: The origin of the Christmas Island Seamount Province in the northeast Indian Ocean is enigmatic. The seamounts do not form the narrow, linear and continuous trail of volcanoes that would be expected if they had formed above a mantle plume1, 2. Volcanism above a fracture in the lithosphere3 is also unlikely, because the fractures trend orthogonally with respect to the east–west trend of the Christmas Island chain. Here we combine 40Ar/39Ar age, Sr, Nd, Hf and high-precision Pb isotope analyses of volcanic rocks from the province with plate tectonic reconstructions. We find that the seamounts are 47–136 million years old, decrease in age from east to west and are consistently 0–25 million years younger than the underlying oceanic crust, consistent with formation near a mid-ocean ridge. The seamounts also exhibit an enriched geochemical signal, indicating that recycled continental lithosphere was present in their source. Plate tectonic reconstructions show that the seamount province formed at the position where West Burma began separating from Australia and India, forming a new mid-ocean ridge. We propose that the seamounts formed through shallow recycling of delaminated continental lithosphere entrained in mantle that was passively upwelling beneath the mid-ocean ridge. We conclude that shallow recycling of continental lithosphere at mid-ocean ridges could be an important mechanism for the formation of seamount provinces in young ocean basins.
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  • 22
    Publication Date: 2020-10-16
    Description: Three new 22-membered macrolactone antibiotics, atacamycins A-C, were produced by Streptomyces sp. C38, a strain isolated from a hyper-arid soil collected from the Atacama Desert in the north of Chile. The metabolites were discovered in our HPLC-diode array screening and isolated from the mycelium by extraction and chromatographic purification steps. The structures were determined by mass spectrometry and NMR experiments. Atacamycins A, B and C exhibited moderate inhibitory activities against the enzyme phosphodiesterase (PDE-4B2), whereas atacamycin A showed a moderate antiproliferative activity against adeno carcinoma and breast carcinoma cells
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  • 23
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    Nature Publishing Group
    In:  Nature, 475 (7354). p. 7.
    Publication Date: 2019-09-23
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  • 24
    Publication Date: 2019-03-05
    Description: Ostreococcus is a marine picophytoeukaryote for which culture studies indicate there are 'high-light' and 'low-light' adapted ecotypes. Representatives of these ecotypes fall within two to three 18S ribosomal DNA (rDNA) clades for the former and one for the latter. However, clade distributions and relationships to this form of niche partitioning are unknown in nature. We developed two quantitative PCR primer-probe sets and enumerated the proposed ecotypes in the Pacific Ocean as well as the subtropical and tropical North Atlantic. Statistical differences in factors such as salinity, temperature and NO 3 indicated the ecophysiological parameters behind clade distributions are more complex than irradiance alone. Clade OII, containing the putatively low-light adapted strains, was detected at warm oligotrophic sites. In contrast, Clade OI, containing high-light adapted strains, was present in cooler mesotrophic and coastal waters. Maximal OI abundance (19 555±37 18S rDNA copies per ml) was detected in mesotrophic waters at 40 m depth, approaching the nutricline. OII was often more abundant at the deep chlorophyll maximum, when nutrient concentrations were significantly higher than at the surface (stratified euphotic zone waters). However, in mixed euphotic-zone water columns, relatively high numbers (for example, 891±107 18S rDNA copies per ml, Sargasso Sea, springtime) were detected at the surface. Both Clades OI and OII were found at multiple euphotic zone depths, but co-occurrence at the same geographical location appeared rare and was detected only in continental slope waters. In situ growth rate estimates using these primer-probes and better comprehension of physiology will enhance ecological understanding of Ostreococcus Clades OII and OI which appear to be oceanic and coastal clades, respectively. © 2011 International Society for Microbial Ecology. All rights reserved.
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  • 25
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    Nature Publishing Group
    In:  Nature Geoscience, 4 . pp. 575-576.
    Publication Date: 2017-02-21
    Description: Reluctance to deposit data is rife among researchers, despite broad agreement on the principle of data sharing. More and better information will reach hitherto empty archives, if professional support is given during data creation, not in a project's final phase.
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  • 26
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    Nature Publishing Group
    In:  Nature Geoscience, 4 (4). pp. 220-221.
    Publication Date: 2019-09-23
    Description: How the chemical composition of sea water changes on its journey through the world’s oceans is poorly understood. Systematic measurements of dissolved trace metals across the Pacific Ocean suggest that these metals may help track sources and mixing of water masses.
    Type: Article , PeerReviewed
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  • 27
    Publication Date: 2022-02-18
    Description: The Atlantic Ocean receives warm, saline water from the Indo-Pacific Ocean through Agulhas leakage around the southern tip of Africa. Recent findings suggest that Agulhas leakage is a crucial component of the climate system and that ongoing increases in leakage under anthropogenic warming could strengthen the Atlantic overturning circulation at a time when warming and accelerated meltwater input in the North Atlantic is predicted to weaken it. Yet in comparison with processes in the North Atlantic, the overall Agulhas system is largely overlooked as a potential climate trigger or feedback mechanism. Detailed modelling experiments—backed by palaeoceanographic and sustained modern observations—are required to establish firmly the role of the Agulhas system in a warming climate.
    Type: Article , PeerReviewed
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  • 28
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    Nature Publishing Group
    In:  The science behind the Durban talks [Interview] | NATURE News: Q&A
    Publication Date: 2022-03-21
    Type: info:eu-repo/semantics/other
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  • 29
    Publication Date: 2023-11-08
    Description: Climate variability in the tropical Atlantic Ocean is determined by large-scale ocean–atmosphere interactions, which particularly affect deep atmospheric convection over the ocean and surrounding continents1. Apart from influences from the Pacific El Niño/Southern Oscillation2 and the North Atlantic Oscillation3, the tropical Atlantic variability is thought to be dominated by two distinct ocean–atmosphere coupled modes of variability that are characterized by meridional4, 5 and zonal6, 7 sea-surface-temperature gradients and are mainly active on decadal and interannual timescales, respectively8, 9. Here we report evidence that the intrinsic ocean dynamics of the deep equatorial Atlantic can also affect sea surface temperature, wind and rainfall in the tropical Atlantic region and constitutes a 4.5-yr climate cycle. Specifically, vertically alternating deep zonal jets of short vertical wavelength with a period of about 4.5 yr and amplitudes of more than 10 cm s−1 are observed, in the deep Atlantic, to propagate their energy upwards, towards the surface10, 11. They are linked, at the sea surface, to equatorial zonal current anomalies and eastern Atlantic temperature anomalies that have amplitudes of about 6 cm s−1 and 0.4 °C, respectively, and are associated with distinct wind and rainfall patterns. Although deep jets are also observed in the Pacific12 and Indian13 oceans, only the Atlantic deep jets seem to oscillate on interannual timescales. Our knowledge of the persistence and regularity of these jets is limited by the availability of high-quality data. Despite this caveat, the oscillatory behaviour can still be used to improve predictions of sea surface temperature in the tropical Atlantic. Deep-jet generation and upward energy transmission through the Equatorial Undercurrent warrant further theoretical study.
    Type: Article , PeerReviewed
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