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  • 1
    Publication Date: 2019-10-18
    Description: Plastic has become indispensable for human life. When plastic debris is discarded into waterways, these items can interact with organisms. Of particular concern are microscopic plastic particles (microplastics) which are subject to ingestion by several taxa. This review summarizes the results of cutting-edge research about the interactions between a range of aquatic species and microplastics, including effects on biota physiology and secondary ingestion. Uptake pathways via digestive or ventilatory systems are discussed, including (1) the physical penetration of microplastic particles into cellular structures, (2) leaching of chemical additives or adsorbed persistent organic pollutants (POPs), and (3) consequences of bacterial or viral microbiota contamination associated with microplastic ingestion. Following uptake, a number of individual-level effects have been observed, including reduction of feeding activities, reduced growth and reproduction through cellular modifications, and oxidative stress. Microplastic-associated effects on marine biota have become increasingly investigated with growing concerns regarding human health through trophic transfer. We argue that research on the cellular interactions with microplastics provide an understanding of their impact to the organisms’ fitness and, therefore, its ability to sustain their functional role in the ecosystem. The review summarizes information from 236 scientific publications. Of those, only 4.6% extrapolate their research of microplastic intake on individual species to the impact on ecosystem functioning. We emphasize the need for risk evaluation from organismal effects to an ecosystem level to effectively evaluate the effect of microplastic pollution on marine environments. Further studies are encouraged to investigate sublethal effects in the context of environmentally relevant microplastic pollution conditions.
    Repository Name: EPIC Alfred Wegener Institut
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  • 2
    Publication Date: 2019-03-28
    Description: Beside its global effects, climate change is manifested in many regionally pronounced features mainly resulting from changes in the oceanic and atmospheric circulation. Here we investigate the influence of the North Atlantic SST on shaping the winter-time response to global warming. Our results are based on a long-term climate projection with the Max Planck Institute Earth System Model (MPI-ESM) to investigate the influence of North Atlantic sea surface temperature pattern changes on shaping the atmospheric climate change signal. In sensitivity experiments with the model’s atmospheric component we decompose the response into components controlled by the local SST structure and components controlled by global/remote changes. MPI-ESM simulates a global warming response in SST similar to other climate models: there is a warming minimum—or ”warming hole”—in the subpolar North Atlantic, and the sharp SST gradients associated with the Gulf Stream and the North Atlantic Current shift northward by a few a degrees. Over the warming hole, global warming causes a relatively weak increase in rainfall. Beyond this, our experiments show more localized effects, likely resulting from future SST gradient changes in the North Atlantic. This includes a significant precipitation decrease to the south of the Gulf Stream despite increased underlying SSTs. Since this region is characterised by a strong band of precipitation in the current climate, this is contrary to the usual case that wet regions become wetter and dry regions become drier in a warmer climate. A moisture budget analysis identifies a complex interplay of various processes in the region of modified SST gradients: reduced surface winds cause a decrease in evaporation; and thermodynamic, modified atmospheric eddy transports, and coastal processes cause a change in the moisture convergence. The changes in the the North Atlantic storm track are mainly controlled by the non-regional changes in the forcing. The impact of the local SST pattern changes on regions outside the North Atlantic is small in our setup.
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  • 3
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    In:  In: Oceanographic and Biological Aspects of the Red Sea. , ed. by Rasul, N. M. A. and Stewart, I. C. F. Springer, Cham, Switzerland, pp. 401-418. ISBN 978-3-319-99416-1
    Publication Date: 2018-12-14
    Description: Coral reefs in the Red Sea belong to the most diverse and productive reef ecosystems worldwide, although they are exposed to strong seasonal variability, high temperature, and high salinity. These factors are considered stressful for coral reef biota and challenge reef growth in other oceans, but coral reefs in the Red Sea thrive despite these challenges. In the central Red Sea high temperatures, high salinities, and low dissolved oxygen on the one hand reflect conditions that are predicted for ‘future oceans’ under global warming. On the other hand, alkalinity and other carbonate chemistry parameters are considered favourable for coral growth. In coral reefs of the central Red Sea, temperature and salinity follow a seasonal cycle, while chlorophyll and inorganic nutrients mostly vary spatially, and dissolved oxygen and pH fluctuate on the scale of hours to days. Within these strong environmental gradients micro- and macroscopic reef communities are dynamic and demonstrate plasticity and acclimatisation potential. Epilithic biofilm communities of bacteria and algae, crucial for the recruitment of reef-builders, undergo seasonal community shifts that are mainly driven by changes in temperature, salinity, and dissolved oxygen. These variables are predicted to change with the progression of global environmental change and suggest an immediate effect of climate change on the microbial community composition of biofilms. Corals are so-called holobionts and associate with a variety of microbial organisms that fulfill important functions in coral health and productivity. For instance, coral-associated bacterial communities are more specific and less diverse than those of marine biofilms, and in many coral species in the central Red Sea they are dominated by bacteria from the genus Endozoicomonas. Generally, coral microbiomes align with ecological differences between reef sites. They are similar at sites where these corals are abundant and successful. Coral microbiomes reveal a measurable footprint of anthropogenic influence at polluted sites. Coral-associated communities of endosymbiotic dinoflagellates in central Red Sea corals are dominated by Symbiodinium from clade C. Some corals harbour the same specific symbiont with a high physiological plasticity throughout their distribution range, while others maintain a more flexible association with varying symbionts of high physiological specificity over depths, seasons, or reef locations. The coral-Symbiodinium endosymbiosis drives calcification of the coral skeleton, which is a key process that provides maintenance and formation of the reef framework. Calcification rates and reef growth are not higher than in other coral reef regions, despite the beneficial carbonate chemistry in the central Red Sea. This may be related to the comparatively high temperatures, as indicated by reduced summer calcification and long-term slowing of growth rates that correlate with ocean warming trends. Indeed, thermal limits of abundant coral species in the central Red Sea may have been exceeded, as evidenced by repeated mass bleaching events during previous years. Recent comprehensive baseline data from central Red Sea reefs allow for insight into coral reef functioning and for quantification of the impacts of environmental change in the region.
    Type: Book chapter , NonPeerReviewed
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  • 4
    Publication Date: 2019-02-22
    Description: Dosidicus gigas (the Humboldt squid) is a widely distributed and ecologically important predator in the eastern Pacific Ocean, but its mating behaviour is poorly understood. Individuals of this species have undergone a drastic change in size at maturity in the last years. We investigated mating activity of Humboldt squid in the Gulf of California in 2013, 2014, and 2015 by quantifying spermatangia deposited in the tissue of the buccal area. In 2015, we encountered the smallest mean mantle length of mature specimens recorded to date in the Gulf of California. In all years, numerous males were encountered that had been mated by other males. Spermatangia in males were deposited on the tissue in similar numbers and in the same location as normally occurs in females (the buccal area), suggesting that male-to-male mating behaviour is similar to male-to-female. This behaviour is referred to as same-sex sexual behaviour and has been described for various taxa, including other cephalopods. Overall similarity in mating frequency between males and females and in body size of mated individuals (in 2015) suggests non-discriminative and brief encounters with body size being a cue for mating. This mating strategy may be beneficial for males, as Humboldt squid live in groups where competition for mates is likely high. The energetic costs of male-to-male mating events may be counterbalanced by the fitness profits of indiscriminate mating behaviour.
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  • 5
    Publication Date: 2019-04-26
    Description: An interactive (multi-access) global identification key (OncIdent) has been developed for the pelagic marine microcopepod family Oncaeidae and made accessible online. Details of the general approach and development of the key are given in Bottger-Schnack and Schnack (J Nat Hist 49:2727-2741, 2015). After beta-testing, new additions include illustrations for all species and feature attributes considered, plus a textual summary of each species' feature states in the key. Additional taxonomic notes are given where required, highlighting morphological or molecular genetic peculiarities or problems, with links to large data bases leading directly to more comprehensive information about each species. The present paper briefly reviews the taxonomic background for key construction, summarizes the opportunities and limitations of the current online version OncIdent2.0, and provides guidance for its practical use.
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  • 6
    Publication Date: 2019-04-10
    Description: Our knowledge on distribution, habitats and behavior of Southern Ocean fishes living at water depths beyond scuba-diving limits is still sparse, as it is difficult to obtain quantitative data on these aspects of their biology. Here, we report the results of an analysis of seabed images to investigate species composition, behavior, spatial distribution and preferred habitats of demersal fish assemblages in the southern Weddell Sea. Our study was based on a total of 2736 high-resolution images, covering a total seabed area of 11,317 m2, which were taken at 13 stations at water depths between 200 and 750 m. Fish were found in 380 images. A total of 379 notothenioid specimens were recorded, representing four families (Nototheniidae, Artedidraconidae, Bathydraconidae, Channichthyidae), 17 genera and 25 species. Nototheniidae was the most speciose fam- ily, including benthic species (Trematomus spp.) and the pelagic species Pleuragramma antarctica, which was occasionally recorded in dense shoals. Bathydraconids ranked second with six species, followed by artedidraconids and channichthyids, both with five species. Most abundant species were Trematomus scotti and T. lepidorhinus among nototheniids, and Dol- loidraco longedorsalis and Pagetopsis maculatus among artedidraconids and channichthyids, respectively. Both T. lepi- dorhinus and P. maculatus preferred seabed habitats characterized by biogenous debris and rich epibenthic fauna, whereas T. scotti and D. longedorsalis were frequently seen resting on fine sediments and scattered gravel. Several fish species were recorded to make use of the three-dimensional structure formed by epibenthic foundation species, like sponges, for perching or hiding inside. Nesting behavior was observed, frequently in association with dropstones, in species from various families, including Channichthyidae (Chaenodraco wilsoni and Pagetopsis macropterus) and Bathydraconidae (Cygnodraco mawsoni).
    Repository Name: EPIC Alfred Wegener Institut
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  • 7
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    In:  In: Oceanographic and Biological Aspects of the Red Sea. , ed. by Rasul, N. M. A. and Stewart, I. C. F. Springer Oceanography Series . Springer, Cham, pp. 185-194.
    Publication Date: 2018-12-11
    Description: The deep-sea brines of the Red Sea are unusual extreme environments and form characteristically steep gradients across the brine-seawater interfaces. Due to their unusual nature and unique combination of physical-chemical conditions these interfaces provide an interesting source of new findings in the fields of geochemistry, geology, microbiology, biotechnology, virology, and general biology. The current chapter summarizes recent and new results in the study of geochemistry and life at the interfaces of brine-filled deeps of the Red Sea.
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  • 8
  • 9
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    In:  A Mathematical Modeling Approach from Nonlinear Dynamics to Complex Systems
    Publication Date: 2018-03-05
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  • 10
  • 11
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    In:  In: Geological Setting, Palaeoenvironment and Archaeology of the Red Sea. , ed. by Rasul, N. M. A. and Stewart, I. C. F. Springer, Cham, Switzerland, pp. 221-232.
    Publication Date: 2019-04-16
    Description: Hydrothermal circulation at mid-ocean ridges and assimilation of hydrothermally altered crust or hydrothermal fluids by rising magma can be traced by measuring chlorine (Cl) excess in erupted lavas. The Red Sea Rift provides a unique opportunity to study assimilation of hydrothermally altered crust at an ultra-slow spreading ridge (maximum 1.6 cm yr−1 full spreading rate) by Cl, due to its saline seawater (40–42‰, cf. 35‰ in open ocean water), the presence of (hot) brine pools (up to 270‰ salinity and 68 °C) and the thick evaporite sequences that flank the young rift. Absolute chlorine concentrations (up to 1300 ppm) and Cl concentrations relative to minor or trace elements of similar mantle incompatibility (e.g., K, Nb) are much higher in Red Sea basalts than in basalts from average slow spreading ridges. Mantle Cl/Nb concentrations can be used to calculate the Cl-excess, above the magmatic Cl, that is present in the samples. Homogeneous within-sample Cl concentrations, high Cl/H2O, the decoupling of Cl-excess from other trace elements and its independence of the presence of highly saline seafloor brines at the site of eruption indicate that Cl is not enriched at the seafloor. Instead we find basaltic Cl-excess to be spatially closely correlated with evidence of hydrothermal activity, suggesting that deeper assimilation of hydrothermal Cl is the dominant Cl-enrichment process. A proximity of samples to both evaporite outcrops and bathymetric signs of volcanism on the seafloor enhance Cl-excess in basalts. The basaltic Cl-excess can be used as a tracer together with new bathymetric maps as well as indications of hydrothermal venting (hot brine pools, metalliferous Hydrothermal circulation at mid-ocean ridges and assimilation of hydrothermally altered crust or hydrothermal fluids by rising magma can be traced by measuring chlorine (Cl) excess in erupted lavas. The Red Sea Rift provides a unique opportunity to study assimilation of hydrothermally altered crust at an ultra-slow spreading ridge (maximum 1.6 cm yr−1 full spreading rate) by Cl, due to its saline seawater (40–42‰, cf. 35‰ in open ocean water), the presence of (hot) brine pools (up to 270‰ salinity and 68 °C) and the thick evaporite sequences that flank the young rift. Absolute chlorine concentrations (up to 1300 ppm) and Cl concentrations relative to minor or trace elements of similar mantle incompatibility (e.g., K, Nb) are much higher in Red Sea basalts than in basalts from average slow spreading ridges. Mantle Cl/Nb concentrations can be used to calculate the Cl-excess, above the magmatic Cl, that is present in the samples. Homogeneous within-sample Cl concentrations, high Cl/H2O, the decoupling of Cl-excess from other trace elements and its independence of the presence of highly saline seafloor brines at the site of eruption indicate that Cl is not enriched at the seafloor. Instead we find basaltic Cl-excess to be spatially closely correlated with evidence of hydrothermal activity, suggesting that deeper assimilation of hydrothermal Cl is the dominant Cl-enrichment process. A proximity of samples to both evaporite outcrops and bathymetric signs of volcanism on the seafloor enhance Cl-excess in basalts. The basaltic Cl-excess can be used as a tracer together with new bathymetric maps as well as indications of hydrothermal venting (hot brine pools, metalliferous sediments) to predict where hydrothermal venting or now inactive hydrothermal vent fields can be expected. Sites of particular interest for future hydrothermal research are the Mabahiss Deep, the Thetis-HadarbaHatiba Deeps and Shagara-Aswad-Erba Deeps (especially their large axial domes), and Poseidon Deep. Older hydrothermal vent fields may be present at the Nereus and Suakin Deeps. These sites significantly increase the potential of hydrothermal vent field prospection in the Red Sea.
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  • 12
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    In:  In: Geological Setting, Palaeoenvironment and Archaeology of the Red Sea. , ed. by Rasul, N. M. A. and Stewart, I. C. F. Springer, Cham, Switzerland, pp. 37-52. ISBN 978-3-319-99407-9
    Publication Date: 2019-04-16
    Description: Continental rifting and ocean basin formation can be observed at the present day in the Red Sea, which is used as the modern analogue for the formation of mid-ocean ridges. Competing theories for how spreading begins—either by quasi-instantaneous formation of a whole spreading segment or by initiation of spreading at multiple discrete “nodes” separated by thinned continental lithosphere—have been put forward based, until recently, on the observations that many seafloor features and geophysical anomalies (gravity, magnetics) along the axis of the Red Sea appeared anomalous compared to ancient and modern examples of ocean basins in other parts of the world. The latest research shows, however, that most of the differences between the Red Sea Rift (RSR) and other (ultra)slow-spreading mid-ocean ridges can be related to its relatively young age and the presence and movement of giant submarine salt flows that blanket large portions of the rift valley. In addition, the geophysical data that was previously used to support the presence of continental crust between the axial basins with outcropping oceanic crust (formerly named “spreading nodes”) can be equally well explained by processes related to the sedimentary blanketing and hydrothermal alteration. The observed spreading nodes are not separated from one another by tectonic boundaries but rather represent “windows” onto a continuous spreading axis which is locally inundated and masked by massive slumping of sediments or evaporites from the rift flanks. Volcanic and tectonic morphologies are comparable to those observed along slow and ultra-slow spreading ridges elsewhere and regional systematics of volcanic occurrences are related to variations in volcanic activity and mantle heat flow. Melt-salt interaction due to salt flows, that locally cover the active spreading segments, and the absence of large detachment faults as a result of the nearby Afar plume are unique features of the RSR. The differences and anomalies seen in the Red Sea still may be applicable to all young oceanic rifts, associated with plumes and/or evaporites, which makes the Red Sea a unique but highly relevant type example for the initiation of slow rifting and seafloor spreading and one of the most interesting targets for future ocean research.
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  • 13
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    In:  Springer Oceanography Book series . Springer, Cham, Switzerland, 550 pp. ISBN 978-3-319-99417-8
    Publication Date: 2018-12-14
    Description: This book includes invited contributions presenting the latest research on the oceanography and environment of the Red Sea. In addition to covering topics relevant to research in the region and providing insights into marine science for non-experts, it is also of interest to those involved in the management of coastal zones and encourages further research on the Red Sea
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  • 14
    Publication Date: 2019-02-11
    Description: The present study details the effects of basin-scale hydrographic characteristics of the Red Sea on the macroecology of Chaetognatha, a major plankton component in the pelagic realm. The hydrographic attributes and circulation of the Red Sea as a result of its limited connection with the northern Indian Ocean make it a unique ecohydrographic region in the world ocean. Here, we aimed to identify the prime determinants governing the community structure and vertical distribution of the Cheatognatha in this ecologically significant world ocean basin. The intrusion of Gulf of Aden Water influenced the Chaetognatha community composition in the south, whereas the overturning circulation altered their vertical distribution in the north. The existence of hypoxic waters (〈 100 µmol kg−1) at mid-depth also influenced their vertical distribution. The detailed evaluation of the responses of the different life stages of Chaetognatha revealed an increased susceptibility of adult individuals to hypoxic waters compared to immature stages. Higher oxygen demands of the adults for the egg and sperm production might have prevented them from inhabiting the oxygen-deficient mid-depth zones. The carbon and nitrogen content of the Copepoda and Chaetognatha communities and the quantification of the predation impact of Chaetognatha on Copepoda based on the feeding rate helped in corroborating the significant trophic link between these two prey–predator taxa. The observed influences of physical and chemical attributes on the distribution of Chaetognatha can be used as a model example for the role of the hydrography on the zooplankton community of the Red Sea.
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  • 15
    Publication Date: 2019-03-20
    Description: Climate model components involve both high-dimensional input and output fields. It is desirable to efficiently generate spatio-temporal outputs of these models for applications in integrated assessment modelling or to assess the statistical relationship between such sets of inputs and outputs, for example, uncertainty analysis. However, the need for efficiency often compromises the fidelity of output through the use of low complexity models. Here, we develop a technique which combines statistical emulation with a dimensionality reduction technique to emulate a wide range of outputs from an atmospheric general circulation model, PLASIM, as functions of the boundary forcing prescribed by the ocean component of a lower complexity climate model, GENIE-1. Although accurate and detailed spatial information on atmospheric variables such as precipitation and wind speed is well beyond the capability of GENIE-1’s energy-moisture balance model of the atmosphere, this study demonstrates that the output of this model is useful in predicting PLASIM’s spatio-temporal fields through multi-level emulation. Meaningful information from the fast model, GENIE-1 was extracted by utilising the correlation between variables of the same type in the two models and between variables of different types in PLASIM. We present here the construction and validation of several PLASIM variable emulators and discuss their potential use in developing a hybrid model with statistical components.
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  • 16
    Publication Date: 2019-03-04
    Description: Climate engineering (CE) deployment would alter prevailing relationships between Earth system variables, making indicators and metrics used so far in the climate change assessment context less appropriate to assess CE measures. Achieving a comprehensive CE assessment requires a systematic and transparent reevaluation of the indicator selection process from Earth system variables. Here, we provide a first step towards such a systematic assessment of changes in correlations between Earth system variables following simulated deployment of different CE methods. We therefore analyze changes in the correlation structure of a broad set of Earth system variables for two conventional climate change scenarios without CE and with three idealized CE model experiments: (i) solar radiation management, (ii) large-scale afforestation, and (iii) ocean alkalinity enhancement. First, we investigate how the three CE scenarios alter prevailing correlations between Earth system variables when compared to an intermediate-high and a business-as-usual future climate change scenario. Second, we contrast the indicators identified for the non-CE climate change scenarios and the indicators identified when all five scenarios are considered. Finally, we use the identified indicator sets for an evaluation of the five climate change scenarios. We find that the additional indicators provide valuable information for the assessment of the CE measures, and their application hence allows for a more comprehensive and a comparative assessment of the mitigation and CE deployment scenarios.
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  • 17
    Publication Date: 2019-03-04
    Description: Many marine gastropods show species-specific behavioral responses to different predators, but less is known about the mechanisms influencing differences or similarities in specific responses. Herein, we examined whether two limpet species, Scurria viridula (Lamarck, 1819) and Fissurella latimarginata (Sowerby, 1835), show species- and size-specific similarities or differences in their reaction to predatory seastars and crabs. Both S. viridula and F. latimarginata reacted to their main seastar predators with escape responses. In contrast, both limpets did not flee from common crab predators, but, instead, fastened to the rock. All tested size classes of both limpet species reacted in a similar way, escaping from seastars, but clamping onto the rock in response to crabs. Limpets could reach velocities sufficient to outrun their specific seastar predators, but they were not fast enough to escape crabs. Experiments with limpets of different shell conditions (with and without shell damage) indicated that F. latimarginata with a damaged shell showed “accommodation movements” (slow movements away from stimulus) in response to predatory crabs. In contrast, intact F. latimarginata and all S. viridula (intact and damaged) clamped the shell down to the substratum. The response details suggest that the keyhole limpet F. latimarginata is more sensitive to predators (faster reaction time, longer escape distances, and higher proportion of reacting individuals) than S. viridula, possibly because the morphology of F. latimarginata (the relationship of its shell size and structure to its total body size) makes this species more vulnerable to predation. Our study suggests that chemically mediated effects of seastar and crab predators result in contrasting behavioral responses of both limpet species, independent of their habitat and morphology. Despite the different characteristics of the limpet species and the identity of predators, the limpets react in comparable ways to similar predator types.
    Repository Name: EPIC Alfred Wegener Institut
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  • 18
    Publication Date: 2019-05-16
    Description: Climate engineering (CE) deployment would alter prevailing relationships between Earth system variables, making indicators and metrics used so far in the climate change assessment context less appropriate to assess CE measures. Achieving a comprehensive CE assessment requires a systematic and transparent reevaluation of the indicator selection process from Earth system variables. Here, we provide a first step towards such a systematic assessment of changes in correlations between Earth system variables following simulated deployment of different CE methods. We therefore analyze changes in the correlation structure of a broad set of Earth system variables for two conventional climate change scenarios without CE and with three idealized CE model experiments: (i) solar radiation management, (ii) large-scale afforestation, and (iii) ocean alkalinity enhancement. First, we investigate how the three CE scenarios alter prevailing correlations between Earth system variables when compared to an intermediate-high and a business-as-usual future climate change scenario. Second, we contrast the indicators identified for the non-CE climate change scenarios and the indicators identified when all five scenarios are considered. Finally, we use the identified indicator sets for an evaluation of the five climate change scenarios. We find that the additional indicators provide valuable information for the assessment of the CE measures, and their application hence allows for a more comprehensive and a comparative assessment of the mitigation and CE deployment scenarios.
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  • 19
    Publication Date: 2019-04-23
    Description: Author Posting. © The Author(s), 2019. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in , Zakroff, C., Mooney, T.A. & Berumen, M.L. Dose-dependence and small-scale variability in responses to ocean acidification during squid, Doryteuthis pealeii, development. Marine Biology, (2019), 166: 62. doi:10.1007/s00227-019-3510-8.
    Description: Coastal squids lay their eggs on the benthos, leaving them to develop in a dynamic system that is undergoing rapid acidification due to human influence. Prior studies have broadly investigated the impacts of ocean acidification on embryonic squid, but have not addressed the thresholds at which these responses occur or their potential variability. We raised squid, Doryteuthis pealeii (captured in Vineyard Sound, Massachusetts, USA: 41° 23.370N 70° 46.418´W), eggs in three trials across the breeding season (May - September, 2013) in a total of six chronic pCO2 exposures (400, 550, 850, 1300, 1900, and 2200 ppm). Hatchlings were counted and subsampled for mantle length, yolk volume, hatching time, hatching success, and statolith morphology. New methods for analysis of statolith shape, rugosity, and surface degradation were developed and are presented (with code). Responses to acidification (e.g., reduced mantle lengths, delayed hatching, and smaller, more degraded statoliths) were evident at ~ 1300 ppm CO2. However, patterns of physiological response and energy management, based on comparisons of yolk consumption and growth, varied among trials. Interactions between pCO2 and hatching day indicated a potential influence of exposure time on responses, while interactions with culture vessel highlighted the substantive natural variability within a clutch of eggs. While this study is consistent with, and expands upon, previous findings of sensitivity of the early life stages to acidification, it also highlights the plasticity and potential for resilience in this population of squid.
    Description: This material was based upon work supported by the National Science Foundation Graduate Research Fellowship under Grant No. 1122374 to CZ. This project was funded by National Science Foundation Grant No. 1220034 to TAM.
    Description: 2020-04-19
    Keywords: cephalopod ; embryo ; hypercapnia ; paralarvae ; statolith ; stress
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
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  • 20
    Publication Date: 2019-06-06
    Description: Differences in habitat and diet between species are often associated with morphological differences. Habitat and trophic adaptation have therefore been proposed as important drivers of speciation and adaptive radiation. Importantly, habitat and diet shifts likely impose changes in exposure to different parasites and infection risk. As strong selective agents influencing survival and mate choice, parasites might play an important role in host diversification. We explore this possibility for the adaptive radiation of Lake Tanganyika (LT) cichlids. We first compare metazoan macroparasites infection levels between cichlid tribes. We then describe the cichlids’ genetic diversity at the major histocompatibility complex (MHC), which plays a key role in vertebrate immunity. Finally, we evaluate to what extent trophic ecology and morphology explain variation in infection levels and MHC, accounting for phylogenetic relationships. We show that different cichlid tribes in LT feature partially non-overlapping parasite communities and partially non-overlapping MHC diversity. While morphology explained 15% of the variation in mean parasite abundance, trophic ecology accounted for 16% and 22% of the MHC variation at the nucleotide and at the amino acid level, respectively. Parasitism and immunogenetic adaptation may thus add additional dimensions to the LT cichlid radiation.
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  • 21
    Publication Date: 2019-05-28
    Description: The spatial pattern of the first mode of interannual variability associated with the East Asian summer monsoon (EASM), obtained from a multivariate Empirical Orthogonal Functions (MV-EOF) analysis, corresponds to the Pacific–Japan (PJ) pattern and is referred to as the PJ-mode. The present study investigates the interannual variation of the PJ-mode from the perspective of the intraseasonal timescale. In particular, the impact of the Madden–Julian oscillation (MJO) on the interannual variation of the PJ-mode is investigated. The results show that the MJO has a significant influence on the interannual variation of the PJ-mode mainly in the lower troposphere (850 hPa) and that the former accounts for approximately 11% of the amplitude of the latter. The major part of the contribution comes from a change in frequency of the different phases of the MJO, especially that of MJO phase 6. This suggests that intraseasonal variation of the convection anomalies over the tropical eastern Indian and western Pacific Oceans plays an important role in the interannual variation of the PJ-mode. In addition, MJO phase 7 also contributes to the interannual variability of the PJ-mode, in this case induced by both the change in frequency and the change in circulation anomalies associated with MJO phase 7.
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  • 22
    Publication Date: 2019-05-28
    Description: Solar signals in the atmosphere and the ocean, especially in tropopause temperatures and lower stratospheric water vapour are investigated using recent observational and reanalyses data sets for the period from 1958 through 2013. Previous observational and modeling studies demonstrated solar influences in the lower stratosphere resembling a positive Northern Annular Mode due to the top-down mechanism involving enhanced solar UV radiation in the stratosphere during solar maxima and dynamical amplification mechanisms in the atmosphere. We found that these stratospheric changes might propagate down to the troposphere and become zonally asymmetric with characteristic pressure and wind pattern over the North Atlantic and North Pacific. Such changes in tropospheric circulation are related to anomalous positive SST anomalies in the central Pacific which resemble an El Niño Modoki event. We show for the first time with ocean reanalysis data that these SST anomalies are amplified by a positive feedback through oceanic subsurface currents and heat transport in the equatorial Pacific. Anomalous warm SSTs in the equatorial central Pacific change the zonal SST gradient and lead to anomalous westerly winds and currents in the western Pacific and easterly winds and currents in the eastern Pacific. This indicates a convergence and less upwelling and therefore enhances the positive SST anomalies in the equatorial central Pacific. Such a positive feedback results in a peak of El Niño Modoki events about 2 years after the solar maximum. These solar-induced signals in the ocean in turn modify the circulation and convection in the troposphere, resulting in lagged solar signals of anomalous high tropopause heights and negative anomalies in tropopause temperatures as well as in lower stratospheric water vapour over the equatorial Pacific which are in agreement with a time evolving solar-induced El Niño Modoki-like SST pattern. We demonstrate a solar modulation of intrinsic decadal climate variability over the Pacific which is amplified by positive feedbacks between the ocean and the atmosphere.
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  • 23
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    In:  Natural Gas Engines: For Transportation and Power Generation | Energy, Environment, and Sustainability
    Publication Date: 2019-06-14
    Description: Lean-burn natural gas engines can be used to reduce exhaust emissions significantly. However, as the mixture is leaned out, the occurrence of extinction and incomplete combustion increases, resulting in poor performance and stability, as well as elevated levels of unburned hydrocarbon (UHC) and nitrogen oxides (NOx) emissions. The partially stratified charge (PSC) method can be used to mitigate these issues, while extending the lean misfire limit (LML) beyond its equivalent, homogeneous level. In this chapter, the PSC ignition and combustion processes are examined following a comprehensive experimental and numerical approach. Experiments are conducted in an idealized PSC configuration, using a constant volume combustion chamber (CVCC), to identify the principle enabling mechanisms of the PSC methodology. Engine tests conducted in a single-cylinder research engine (SCRE) demonstrate the feasibility of various PSC implementations in improving performance and emission characteristics in real-world settings. Complementary numerical analyses for the CVCC are obtained through large eddy simulations (LES), while Reynolds-averaged Navier?Stokes (RANS) simulations are conducted for SCRE with reduced chemical kinetics. The corresponding simulated results provide additional insights in characterizing the effect of fuel stratification on flame kernel maturation and flame propagation, the interplay between chemistry and turbulence at different overall air?fuel ratios, as well as formation of major pollutant species.
    Language: English
    Type: http://purl.org/eprint/type/BookItem
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  • 24
    Publication Date: 2019-06-13
    Description: Diseases increasingly threaten aquaculture of kelps and other seaweeds. At the same time, protection concepts that are based upon application of biocides are usually not applicable, as such compounds would be rapidly diluted in the sea, causing ecological damage. An alternative concept could be the application of immune stimulants to prevent and control diseases in farmed seaweeds. We here present a pilot study that investigated the effects of oligoalginate elicitation on juvenile and adult sporophytes of Saccharina japonica cultivated in China and on adult sporophytes of Saccharina latissima cultivated in Germany. In two consecutive years, treatment with oligoalginate clearly reduced the detachment of S. japonica juveniles from their substrate curtains during the nursery stage in greenhouse ponds. Oligoalginate elicitation also decreased the density of endobionts and the number of bacterial cells on sporophytes of S. latissima that were cultivated on sea-based rafts. However, the treatment increased the susceptibility of kelp adults to settlement of epibionts (barnacles in Germany and filamentous algal epiphytes in China). In addition, oligoalginate elicitation accelerated the aging of S. japonica adults. Based upon these findings, oligoalginate elicitation could be a feasible way to provide “environmentally friendly” protection of kelp juveniles in nurseries. The same treatment causes not only beneficial, but also unwanted effects in adult kelp sporophytes. Therefore, it is not recommended as a treatment after the juvenile stage is completed. Future tests with other elicitors and other cultivated seaweed species may allow for the development of more feasible applications of targeted defense elicitation in seaweed aquaculture.
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  • 25
    Publication Date: 2019-06-14
    Description: Methane gas hydrates have increasingly become a topic of interest because of their potential as a future energy resource. There are significant economical and environmental risks associated with extraction from hydrate reservoirs, so a variety of multiphysics models have been developed to analyze prospective risks and benefits. These models generally have a large number of empirical parameters which are not known a priori. Traditional optimization-based parameter estimation frameworks may be ill-posed or computationally prohibitive. Bayesian inference methods have increasingly been found effective for estimating parameters in complex geophysical systems. These methods often are not viable in cases of computationally expensive models and high-dimensional parameter spaces. Recently, methods have been developed to effectively reduce the dimension of Bayesian inverse problems by identifying low-dimensional structures that are most informed by data. Active subspaces is one of the most generally applicable methods of performing this dimension reduction. In this paper, Bayesian inference of the parameters of a state-of-the-art mathematical model for methane hydrates based on experimental data from a triaxial compression test with gas hydrate-bearing sand is performed in an efficient way by utilizing active subspaces. Active subspaces are used to identify low-dimensional structure in the parameter space which is exploited by generating a cheap regression-based surrogate model and implementing a modified Markov chain Monte Carlo algorithm. Posterior densities having means that match the experimental data are approximated in a computationally efficient way.
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  • 26
    Publication Date: 2019-06-21
    Description: Reproductive systems of rare adult specimens of the deep-sea squid genera Chiroteuthis, Mastigoteuthis, Liocranchia, and Bathoteuthis were collected in 2006 and 2015 in the different research surveys in the Atlantic Ocean between 46 degrees 40'S and 17 degrees 11'N. Whole squids were preserved in 4% buffered formaldehyde solution, subsequently transferred into 70% ethanol and studied in laboratory condition providing initial observations on spawning pattern in these animals. The potential fecundity of Ch. cf. joubini was similar to 45,000-50,000, the maximum egg size was 1.6-1.7 mm, while those of M. agassizii were similar to 8000-16,000 and 1.7-1.9 mm respectively. A maturing female of B. skolops had similar to 4800 eggs of which some similar to 1200 were atretic. The ovary of a spent L. reinhardti contained similar to 116,500 post-ovulatory follicles and no residual egg. Mature females of Chiroteuthis and Mastigoteuthis had spematangia implanted externally in the mantle, whereas Liocranchia had a specialised spermatangia receptacle on the inside of the mantle. Reproductive adaptations of these genera are discussed in relation to spawning habits of other deep-sea squids. Synchronous ovulation was found to be a prevailing type of the gonad development with all eggs being spawned as a single batch, with ot without brooding. In some species, this single batch is not released at once but in several consequent portions exhibiting 'extended synchronous' spawning.
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  • 27
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    In:  Climate Dynamics, 53 (1-2). pp. 1111-1124.
    Publication Date: 2019-06-27
    Description: There is a controversy about the origin of the recent decadal Atlantic Meridional Overturning Circulation (AMOC) slowing observed at 26.5°N and concurrent sea surface temperature cooling in the central and eastern mid-latitude North Atlantic. We investigate decadal AMOC slowing events simulated in a multi-millennial preindustrial control integration of the Kiel Climate Model (KCM), providing an estimate of internal AMOC variability. Preindustrial control integrations of 15 models participating in the Coupled Model Intercomparison Project phase 5 also are investigated, as well as historical simulations with them providing estimates of AMOC variability during 1856–2005. It is shown that the recent decadal AMOC decline is still within the range of the models’ internal AMOC variability and thus could be of natural origin. In this case, the decline would represent an extreme realization of internal variability provided the climate models yield realistic levels of AMOC variability. The model results suggest that internal decadal AMOC variability is large, requiring multi-decadal observational records to detect an anthropogenic AMOC signal with high confidence. When analyzing the strongest decadal AMOC slowing events in the KCM, which have amplitudes similar to or larger than the recently observed decadal AMOC decline, the following composite picture emerges: a very strong decadal AMOC decline is preceded by a decadal rise in atmospheric surface pressure over large parts of the mid-latitude North Atlantic. The change in low-level atmospheric circulation drives reduced oceanic heat loss over and diminished upper-ocean salt content in the Labrador Sea. In response, oceanic deep convection and subsequently the AMOC and northward oceanic heat transport weaken, and anomalously cold sea surface temperatures develop in the central and eastern mid-latitude North Atlantic
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  • 28
    Publication Date: 2019-06-27
    Description: Biodiversity is generally believed to be a main determinant of ecosystem functioning. This principle also applies to the microbiome and could consequently contribute to host health. According to ecological theory, communities are shaped by top predators whose direct and indirect interactions with community members cause stability and diversity. Bdellovibrio and like organisms (BALOs) are a neglected group of predatory bacteria that feed on Gram-negative bacteria and can thereby influence microbiome composition. We asked whether BALOs can predict biodiversity levels in microbiomes from distinct host groups and environments. We demonstrate that genetic signatures of BALOs are commonly found within the 16S rRNA reads from diverse host taxa. In many cases, their presence, abundance, and especially richness are positively correlated with overall microbiome diversity. Our findings suggest that BALOs can act as drivers of microbial alpha-diversity and should therefore be considered candidates for the restoration of microbiomes and the prevention of dysbiosis.
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  • 29
    Publication Date: 2019-07-10
    Description: High-resolution bathymetry collected with an autonomous underwater vehicle (AUV) along the flanks of three ridges of the accretionary prism offshore southwestern (SW) Taiwan revealed more than 650 elongated depressions in water depths ranging from 1155 to 1420 m. The depressions are between 12 and 129 m long, 5 to 70 m wide, and up 9 m deep at their center and shallowing downslope to about 1-m depth. Due to their shape in downslope cross section, they are termed comet-shaped depressions (CSD). The CSD occur in patches of more than 100 with densities of 53 to 98 CSD/km2. In addition, seven topographic mounds were mapped and interpreted as pingos, which remotely operate vehicle (ROV) observations and sampling show to be covered with authigenic carbonate. These features overlie areas where multichannel seismic reflection (MCS) profiles show bottom simulating reflectors (BSR) and dipping strata extending from below the BSR to near the seafloor. We consider comet-shaped depression, a new type of pockmark, forms on a sloping seafloor where fluids expulsion occurred. We also suggest that the two types of distinctive geomorphic features are attributed to fluid venting which occurs at different rates, with the mounds developing slowly over time, but the CSD forming in discrete events perhaps associated with large earthquakes.
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  • 30
    Publication Date: 2019-07-08
    Description: Gelatinous zooplankton (GZ) such as medusae, ctenophores, siphonophores, pyrosomes and salps are important components of oceanic pelagic communities and small calycophoran siphonophores (CS) are typically abundant at shallow depths. The Sargasso Sea spawning area of the Atlantic catadromous freshwater eels has a regular pattern of shallow autumn to spring temperature fronts. There is limited information about the southern Sargasso Sea GZ fauna, and it is not known which species are distributed across these frontal zones. Plankton samples from a survey of larval European eel (Anguilla anguilla) abundance in March and April 2017 using an Isaacs-Kidd Midwater Trawl (0–300 m, 35 stations, three transects) were used to examine the distribution and abundance of net-captured CS and other GZ species in relation to oceanographic characteristics. More than 2200 specimens of 15 taxa were sub-sampled, with five CS (Abylopsis tetragona, A. eschscholtzii, Chelophyes appendiculata, Eudoxoides spiralis and E. mitra) dominating catches at every station. GZ were most abundant around the 22 and 24 °C isotherms, and higher abundances of CS in the north were correlated with lower water temperature. The widespread presence of CS across the European eel spawning area is consistent with a recent study detecting their DNA sequences in the gut contents of young eel larvae collected in the Sargasso Sea, suggesting CS material was either eaten directly or as part of ingested marine snow particles. The present study shows that both types of organisms occupy the southern Sargasso Sea during the European eel spawning season.
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  • 31
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    In:  Archaeological and Anthropological Sciences, 11 (4). pp. 1359-1371.
    Publication Date: 2019-07-08
    Description: Using a portable gas analyzer system, the geogenic gas regime below and around an ancient gate to hell at Hierapolis/Phrygia was characterized. The site was first described by Strabo and Plinius as a gate to the underworld. During centuries, it attracted even ancient tourists. In a grotto below the temple of Pluto, CO2 was found to be at deadly concentrations of up to 91%. Astonishingly, these vapors are still emitted in concentrations that nowadays kill insects, birds, and mammals. The concentrations of CO2 escaping from the mouth of the grotto to the outside atmosphere are still in the range of 4–53% CO2 depending on the height above ground level. They reach concentrations during the night that would easily kill even a human being within a minute. These emissions are thought to reflect the Hadean breath and/or the breath of the hellhound Kerberos guarding the entrance to hell. The origin of the geogenic CO2 is the still active seismic structure that crosses the old town of ancient Hierapolis as part of the Babadag fracture zone. Our measurements confirm the presence of geogenic CO2 in concentrations that explain ancient stories of killed bulls, rams, and songbirds during religious ceremonies. They also strongly corroborate that at least in the case of Hierapolis, ancient writers like Strabo or Plinius described a mystic phenomenon very exactly without much exaggeration. Two thousand years ago, only supernatural forces could explain these phenomena from Hadean depths whereas nowadays, modern techniques hint to the well-known phenomenon of geogenic CO2 degassing having mantle components with relatively higher helium and radon concentrations.
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  • 32
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    In:  Mineralium Deposita, 54 (6). pp. 789-820.
    Publication Date: 2019-07-17
    Description: Hydrothermal fluids on the modern seafloor are important carriers of base and precious metals in a wide range of volcanic and tectonic settings. The concentrations and distribution, especially of gold and silver, in associated seafloor massive sulfide (SMS) deposits are strongly influenced by variable source rocks, fluid chemistry, and precipitation mechanisms. Compositional data of 130 SMS deposits around the world show a large range of gold and silver grades, in part reflecting strong buffering of the hydrothermal fluids by their host rocks. Geochemical reaction-path modeling shows that in most cases the investigated hydrothermal fluids are undersaturated with gold and silver, and solubilities can be orders of magnitude higher than the Au and Ag concentrations measured in the corresponding fluids. Precipitation of gold during conductive cooling of mid-ocean ridge black smoker (MOR) fluids occurs at low temperatures but can be very rapid, with 〉 90% of the gold deposited in the first 25 °C of cooling below ~ 150 °C. The result is a Zn–Au polymetallic assemblage with Au and Ag deposited at the same time together with Pb and sulfosalts. In ultramafic-dominated (UM) systems, the strongly reduced hydrothermal fluids promote the deposition of gold at higher temperatures and explain the correlation between gold and copper in these deposits. In this case, the lower stability of the AuHS° complex at low ƒO2 (buffered by fayalite, magnetite, and quartz) results in gold deposition at 〉 250 °C with early bornite and chalcopyrite and before sphalerite and silver, producing a high-temperature Cu–Au assemblage. In sediment-hosted (SED) systems, the much higher pH stabilizes Au(HS)2− and keeps gold in solution to very low temperatures, after the precipitation of chalcopyrite, sphalerite, and galena, resulting in Au-poor polymetallic sulfides and very late-stage deposition of gold, commonly with amorphous silica. In arc-related (ARC) systems, gold deposition occurs at somewhat higher temperatures than in the MOR case, in part because the fluids start with higher gold concentrations. This can be explained by probable direct magmatic contributions, and the high ƒO2 of the fluids, which promotes the solubility of gold at the source. During cooling, gold precipitates at about 160 °C with sphalerite, tennantite, silver, and galena, resulting in an Au-rich polymetallic sulfide assemblage. The mixing of hydrothermal fluids with seawater generally causes oxidation and eventually a decrease in the pH at a mixing ratio of 1:1, causing an initial increase in the solubility of gold and silver. This can delay gold deposition from aqueous species to very low temperatures. These complex systematics make prediction of Au and Ag grades difficult. However, important new data are coming to light on the actual concentrations of the precious metals in hydrothermal fluids. In particular, the input of magmatic volatiles and leaching of pre-existing gold can lead to significant increases in the Au and Ag concentrations of the venting fluids and earlier deposition. In several cases, it appears that at least part of the gold load is present as nanoparticles in suspension, allowing bulk gold concentrations that may be far in excess of liquid saturation. Boiling at the seafloor is now widely observed, even at great water depths close to the critical point of seawater. Model calculations of phase separation during boiling show the competing effects on gold solubility of H2, H2S, and CO2 partitioning into the vapor, which can result in highly variable gold-to-base metal ratios in the deposits. Flashing of the vent fluids into steam at high temperatures is also commonly observed and can lead to spectacular Au grades, with a strong Cu–Au association in the deepest and hottest vents.
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  • 33
    Publication Date: 2019-07-15
    Description: Dramatic changes from a cold and dry last glacial to a warm and wet Holocene period intensified the Indian summer monsoon (ISM), resulting in vigorous hydrology and increased terrestrial erosion. Here we present seawater neodymium (Nd) data (expressed in εNd) from Andaman Sea sediments to assess past changes in the ISM and the related impact of Irrawaddy–Salween and Sittoung (ISS) river discharge into the Andaman Sea in the northeastern Indian Ocean. Four major isotopic changes were identified: (1) a gradual increase in εNd toward a more radiogenic signature during the Last Glacial Maximum (22–18 ka), suggesting a gradual decrease in the ISS discharge; (2) a relatively stable radiogenic seawater εNd between 17.2 and 8.8 ka, perhaps related to a stable reduced outflow; (3) a rapid transition to less radiogenic εNd signature after 8.8 ka, reflecting a very wet early–mid-Holocene with the highest discharge; and (4) a decrease in εNd signal stability in the mid–late Holocene. Taking into account the contribution of the ISS rivers to the Andaman Sea εNd signature that changes proportionally with the strengthening (less radiogenic εNd) or weakening (more radiogenic εNd) of the ISM, we propose a binary model mixing between the Salween and Irrawaddy rivers to explain the εNd variability in Andaman Sea sediments. We hypothesize that the Irrawaddy river mainly contributed detrital sediment to the northeastern Andaman Sea for the past 24 ka. Our εNd data shed new light on the regional changes in Indo-Asian monsoon systems when compared with the existing Indian and Chinese paleo-proxy records.
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  • 34
    Publication Date: 2019-07-31
    Description: As coastal areas become increasingly vulnerable to climate change, the study of nearshore sediment textures along the littoral cell of the Medjerda delta in the Gulf of Tunis, southern Mediterranean coast can provide valuable information (i) on the origin (continental or marine) of the sediment, (ii) its transport direction, and (iii) constitutes an important tool in the assessment of coastal sensitivity. A total of 120 sediments samples underwent grain size analysis and statistic parameters have been calculated. These allowed the identification of five different Sedimentary Types (ST). Accordingly, using grain size indexes (i.e. Mz, SKI and Ku), Sediment Trend Analysis (STA) modeling tools were applied to define the seasonal sediment transport pathways throughout the nearshore of the Medjerda sedimentary cell. Results show that grain size distribution (GSD) and STA model pathways are determined by cross-shore geomorphology, location of the sediment-cell, seasonal incident wave and local terrestrial supply. The appearance in an atypical seabed location of the finer (Mo = 0.1 mm) and the coarser STs (Mo = 0.8 mm) can be indicative of human influence since the coarser particles are usually retained by dam structures. Moreover, the bimodality and the increased distribution of mud are also related to the seasonal incident wave winnowing of the historic deltaic plain submerged by the relative rise in sea level. The evolution of the sediment pattern towards a greater proportion of very fine grains indicates a deficit of sediment supply, particularly of the coarser grains, and demonstrates the coastal vulnerability of the Gulf of Tunis due to anthropic effects.
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  • 35
    Publication Date: 2019-08-02
    Description: The genus Tabrizicola with its type species and strain Tabrizicola aquatica RCRI19T was previously described as a purely chemotrophic genus of Gram-negative, aerobic, non-motile and rod-shaped bacteria. With the present study, we expand the description of the metabolic capabilities of this genus and the T. aquatica type strain to include chlorophyll-dependent phototrophy. Our results confirmed that T. aquatica, does not grow under anaerobic photoautotrophic or photoheterotrophic conditions. However, the presence of the photosynthesis-related genes pufL and pufM could be demonstrated in the genomes of several Tabrizicola strains. Additionally, photosynthetic pigments (bacteriochlorophyll a) were formed under aerobic, heterotrophic and low light conditions in T. aquatica strain RCRI19T. Furthermore, all the genes necessary for a fully operational photosynthetic apparatus and bacteriochlorophyll a are present in the T. aquatica type strain genome. Therefore, we suggest categorising T. aquatica RCRI19T, isolated from freshwater environment of Qurugöl Lake, as an aerobic anoxygenic phototrophic (AAP) bacterium.
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  • 36
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    In:  In: Deep Oil Spills: Facts, Fate, and Effects. , ed. by Murawski, S. A., Ainsworth, C. H., Gilbert, S., Hollander, D. J., Paris, C. B., Schlüter, M. and Wetzel, D. L. Springer, Cham, Switzerland, pp. 139-154. ISBN 978-3-030-11604-0
    Publication Date: 2019-08-07
    Description: Deepwater spills pose a unique challenge for reliable predictions of oil transport and fate, since live oil spewing under very high hydrostatic pressure has characteristics remarkably distinct from oil spilling in shallow water. It is thus important to describe in detail the complex thermodynamic processes occurring in the near-field, meters above the wellhead, and the hydrodynamic processes in the far-field, up to kilometers away. However, these processes are typically modeled separately since they occur at different scales. Here we directly couple two oil prediction applications developed during the Deepwater Horizon blowout operating at different scales: the near-field Texas A&M Oilspill Calculator (TAMOC) and the far-field oil application of the Connectivity Modeling System (oil-CMS). To achieve this coupling, new oil-CMS modules were developed to read TAMOC output, which consists of the description of distinct oil droplet “types,” each of specific size and pseudo-component mixture that enters at a given mass flow rate, time, and position into the far field. These variables are transformed for use in the individual-based framework of CMS, where each droplet type fits into a droplet size distribution (DSD). Here we used 19 pseudo-components representing a large range of hydrocarbon compounds and their respective thermodynamic properties. Simulation results show that the dispersion pathway of the different droplet types varies significantly. Indeed, some droplet types remain suspended in the subsea over months, while others accumulate in the surface layers. In addition, the decay rate of oil pseudo-components significantly alters the dispersion, denoting the importance of more biodegradation and dissolution studies of chemically and naturally dispersed live oil at high pressure. This new modeling tool shows the potential for improved accuracy in predictions of oil partition in the water column and of advancing impact assessment and response during a deepwater spill.
    Type: Book chapter , NonPeerReviewed
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  • 37
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    In:  In: Deep Oil Spills: Facts, Fate, and Effects. , ed. by Murawski, S. A., Ainsworth, C. H., Gilbert, S., Hollander, D. J., Paris, C. B., Schlüter, M. and Wetzel, D. L. Springer, Cham, Switzerland, pp. 25-42. ISBN 978-3-030-11604-0
    Publication Date: 2019-08-07
    Description: Petroleum is one of the most complex naturally occurring organic mixtures. The physical and chemical properties of petroleum in a reservoir depend on its molecular composition and the reservoir conditions (temperature, pressure). The composition of petroleum varies greatly, ranging from the simplest gas (methane), condensates, conventional crude oil to heavy oil and oil sands bitumen with complex molecules having molecular weights in excess of 1000 daltons (Da). The distribution of petroleum constituents in a reservoir largely depends on source facies (original organic material buried), age (evolution of organisms), depositional environment (dysoxic versus anoxic), maturity of the source rock (kerogen) at time of expulsion, primary/secondary migration, and in-reservoir alteration such as biodegradation, gas washing, water washing, segregation, and/or mixing from different oil charges. These geochemical aspects define the physical characteristics of a petroleum in the reservoir, including its density and viscosity. When the petroleum is released from the reservoir through an oil exploration accident like in the case of the Deepwater Horizon event, several processes are affecting the physical and chemical properties of the petroleum from the well head into the deep sea. A better understanding of these properties is crucial for the development of near-field oil spill models, oil droplet and gas bubble calculations, and partitioning behavior of oil components in the water. Section 3.1 introduces general aspects of the origin of petroleum, the impact of geochemical processes on the composition of a petroleum, and some molecular compositional and physicochemical background information of the Macondo well oil. Section 3.2 gives an overview over experimental determination of all relevant physicochemical properties of petroleum, especially of petroleum under reservoir conditions. Based on the phase equilibrium modeling using equations of state (EOS), a number of these properties can be predicted which is presented in Sect. 3.3 along with a comparison to experimental data obtained with methods described in Sect. 3.2.
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  • 38
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    In:  Marine Biodiversity, 49 (1). pp. 131-146.
    Publication Date: 2019-08-06
    Description: Biodiversity is critical for maintaining and stabilizing ecosystem processes. There is a need for high-resolution biodiversity maps that cover large sea areas in order to address ecological questions related to biodiversity-ecosystem functioning relationships and to provide data for marine environmental protection and management decisions. However, traditional sampling-point-wise field work is not suitable for covering extensive areas in high detail. Spatial predictive modeling using biodiversity data from sampling points and georeferenced environmental data layers covering the whole study area is a potential way to create biodiversity maps for large spatial extents. Random forest (RF), generalized additive models (GAM), and boosted regression trees (BRT) were used in this study to produce benthic (macroinvertebrates, macrophytes) biodiversity maps in the northern Baltic Sea. Environmental raster layers (wave exposure, salinity, temperature, etc.) were used as independent variables in the models to predict the spatial distribution of species richness. A validation dataset containing data that was not included in model calibration was used to compare the prediction accuracy of the models. Each model was also evaluated visually to check for possible modeling artifacts that are not revealed by mathematical validation. All three models proved to have high predictive ability. RF and BRT predictions had higher correlations with validation data and lower mean absolute error than those of GAM. Both mathematically and visually, the predictions by RF and BRT were very similar. Depth and seabed sediments were the most influential abiotic variables in predicting the spatial patterns of biodiversity.
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  • 39
    Publication Date: 2019-08-20
    Description: The ecological approach to comparative cognition emphasizes that the ecological and social environment are important predictors of cognitive performance. We used this approach to test whether differences in habitat use and social behavior in the facultative Caribbean cleaning goby Elacatinus prochilos predict differences in learning performance in two discriminatory two-choice tasks. This species has two behavioral ecotypes: one that frequently engages in cleaning interactions and inhabits corals in male–female pairs (cleaning gobies) and another that rarely engages in cleaning interactions and inhabits barrel sponges in large groups (sponge-dwellers). We predicted that cleaning gobies would outperform sponge-dwellers in a pattern-cued task, which consisted of identifying the pattern on a plate that consistently provided food, while sponge-dwellers would outperform cleaning gobies in a spatial task, which consisted of identifying the location of the plate. Contrary to our predictions, there was no difference in performance between the two ecotypes. Most of the gobies performed poorly in the pattern-cued task and well in the spatial task. A possible explanation for these results is that the association of a pattern with positive and negative reinforcement may not be a pre-requisite for engaging in cleaning interactions, while spatial skills might be equally required in both ecotypes. Alternatively, the two ecotypes can flexibly adjust to new feeding conditions, which would explain their similar performance in the spatial task. Further research should investigate which aspects of E. prochilos’ social and ecological environment might impose challenges that require spatial cognition and whether individuals can flexibly adjust to new habitats and feeding conditions.
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  • 40
    Publication Date: 2019-08-21
    Description: A broad variety of materials of biological origin have been successfully used in recent decades for the removal of pollutants from waters. These biosorbents include natural polymers that play a key role for adsorption. It is therefore critical to understand the physicochemical properties of the chemical groups of these biopolymers. The acid–base properties of biomass are affected by pH, ionic strength and medium composition. Nevertheless, these parameters are not always considered during biosorption studies. According to the literature, less than 3% of biosorption reports include studies on proton binding. Moreover, in 60% of these papers, there is key experimental information missing such as the calibration of the electrodes employed for potentiometric titrations. We consider therefore that there is an important need for reviewing the role of proton binding in biosorption studies. This review outlines the major advances on data interpretation and modelling of proton binding on biosorbents. In addition, we discuss issues concerning the acid–base properties of biosorbents.
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  • 41
    Publication Date: 2019-08-29
    Description: © The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Mitchell, S. J., Houghton, B. F., Carey, R. J., Manga, M., Fauria, K. E., Jones, M. R., Soule, S. A., Conway, C. E., Wei, Z., & Giachetti, T. Submarine giant pumice: A window into the shallow conduit dynamics of a recent silicic eruption. Bulletin of Volcanology, 81(7), (2019): 42, doi:10.1007/s00445-019-1298-5.
    Description: Meter-scale vesicular blocks, termed “giant pumice,” are characteristic primary products of many subaqueous silicic eruptions. The size of giant pumices allows us to describe meter-scale variations in textures and geochemistry with implications for shearing processes, ascent dynamics, and thermal histories within submarine conduits prior to eruption. The submarine eruption of Havre volcano, Kermadec Arc, in 2012, produced at least 0.1 km3 of rhyolitic giant pumice from a single 900-m-deep vent, with blocks up to 10 m in size transported to at least 6 km from source. We sampled and analyzed 29 giant pumices from the 2012 Havre eruption. Geochemical analyses of whole rock and matrix glass show no evidence for geochemical heterogeneities in parental magma; any textural variations can be attributed to crystallization of phenocrysts and microlites, and degassing. Extensive growth of microlites occurred near conduit walls where magma was then mingled with ascending microlite-poor, low viscosity rhyolite. Meter- to micron-scale textural analyses of giant pumices identify diversity throughout an individual block and between the exteriors of individual blocks. We identify evidence for post-disruption vesicle growth during pumice ascent in the water column above the submarine vent. A 2D cumulative strain model with a flared, shallow conduit may explain observed vesicularity contrasts (elongate tube vesicles vs spherical vesicles). Low vesicle number densities in these pumices from this high-intensity silicic eruption demonstrate the effect of hydrostatic pressure above a deep submarine vent in suppressing rapid late-stage bubble nucleation and inhibiting explosive fragmentation in the shallow conduit.
    Description: This study was funded primarily through an NSF Ocean grant: OCE-1357443 (SJM, BFH and RJC). MM is supported by NSF EAR 1447559. The μXRT analysis was performed at the Lawrence Berkeley National Lab Advanced Light Source beamline 8.3.2 and the large CT scan by SAS at the University of Texas Austin micro-CT facility. Capillary flow porometry and He-pycnometry were assisted by TG and MRJ at the University of Oregon. Microprobe analysis was conducted at the University of Hawai’i at Mānoa. CEC was supported by post-doctoral research fellowship from the Japan Society for the Promotion of Science (JSPS16788). We would like to thank Kenichiro Tani, Takashi Sano, and Eric Hellebrand for their assistance with geochemical data acquisition, JoAnn Sinton and Wagner Petrographic for thin section preparation, Zachary Langdalen for binary processing of BSE images, Warren M. McKenzie for measuring clast densities, and Dula Parkinson for guidance with the μXRT imaging. We further acknowledge the full scientific team, crew and Jason ROV team (Woods Hole Oceanographic Institute) aboard the R/V Roger Revelle (Scripps Institute of Oceanography) during the MESH expedition in 2015, without whom, this study would not have been possible. Finally, we thank Andrew Harris, Katharine Cashman, Lucia Gurioli and an anonymous reviewer for their insightful and helpful reviews of the manuscript.
    Keywords: Giant pumice ; Submarine volcanism ; Banding ; Tube pumice ; Bubble deformation ; Conduit dynamics
    Repository Name: Woods Hole Open Access Server
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  • 42
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    Nature Publishing Group | Springer
    In:  Nature Communications, 10 (Article number: 4025 ).
    Publication Date: 2019-09-17
    Description: Export of warm and salty waters from the Caribbean to the North Atlantic is an essential component of the Atlantic Meridional Overturning Circulation (AMOC). However, there was also an active AMOC during the Miocene, despite evidence for an open Central American Seaway (CAS) that would have allowed low-salinity Pacific waters to enter the Caribbean. To address this apparent contradiction and to constrain the timing of CAS closure we present the first continuous Nd isotope record of intermediate waters in the Florida Strait over the past 12.5 million years. Our results indicate that there was no direct intermediate water mass export from the Caribbean to the Florida Strait between 11.5 and 9.5 Ma, at the same time as a strengthened AMOC. After 9 Ma a strong AMOC was maintained due to a major step in CAS closure and the consequent cessation of low-salinity Pacific waters entering the Caribbean.
    Type: Article , PeerReviewed
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  • 43
    Publication Date: 2019-09-23
    Description: A strong warm event occurred in the southeastern tropical Atlantic Ocean off Angola and Namibia in January and February 2016 with sea surface temperature anomalies reaching 3 °C. In contrast to classical Benguela Niño events, the analysis of various direct observations indicates that the warming was not predominantly forced by an equatorial Kelvin wave exciting a coastally trapped wave but instead resulted from a combination of local processes that are related to (1) a weakening of the alongshore, i.e. mainly southerly, winds and (2) enhanced freshwater input through local precipitation and river discharge. Consistent with the weakened winds, we find a reduction in latent heat loss from the ocean and a poleward surface current anomaly. The surface freshening, which is detected in satellite observations of sea surface salinity, caused a very shallow mixed layer and enhanced upper ocean stratification. This is supported by the analysis of the velocity structure of the Angola Current at 11°S, which shows that at the time of the event subsurface velocities were directed northward while surface velocities were directed southward. The shallow layer of warm and fresh surface water was thus advected poleward by the surface current. In addition, a reduction of the local upwelling and the formation of a barrier layer that inhibits the entrainment of cool subsurface waters into the surface mixed layer might have contributed to the warm surface anomaly. The sudden termination of the warm event was accompanied by a re-intensification of southerly winds in March
    Type: Article , PeerReviewed
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  • 44
    Publication Date: 2019-09-23
    Description: Common problems in state-of-the-art climate models are a cold sea surface temperature (SST) bias in the equatorial Pacific and the underestimation of the two most important atmospheric feedbacks operating in the El Niño/Southern Oscillation (ENSO): the positive, i.e. amplifying wind-SST feedback and the negative, i.e. damping heat flux-SST feedback. To a large extent, the underestimation of those feedbacks can be explained by the cold equatorial SST bias, which shifts the rising branch of the Pacific Walker Circulation (PWC) too far to the west by up to 30°, resulting in an erroneous convective response during ENSO events. Based on simulations from the Kiel Climate Model (KCM) and the 5th phase of Coupled Model Intercomparison Project (CMIP5), we investigate how well ENSO dynamics are simulated in case of underestimated ENSO atmospheric feedbacks (EAF), with a special focus on ocean–atmosphere coupling over the equatorial Pacific. While models featuring realistic atmospheric feedbacks simulate ENSO dynamics close to observations, models with underestimated EAF exhibit fundamental biases in ENSO dynamics. In models with too weak feedbacks, ENSO is not predominantly wind-driven as observed; instead ENSO is driven significantly by a positive shortwave radiation feedback. Thus, although these models simulate ENSO, which in terms of simple indices is consistent with observations, it originates from very different dynamics. A too weak oceanic forcing on the SST via the positive thermocline, the Ekman and the zonal advection feedback is compensated by weaker atmospheric heat flux damping. The latter is mainly caused by a biased shortwave-SST feedback that erroneously is positive in most climate models. In the most biased models, the shortwave-SST feedback contributes to the SST anomaly growth to a similar degree as the ocean circulation. Our results suggest that a broad continuum of ENSO dynamics can exist in climate models and explain why climate models with less than a half of the observed EAF strength can still depict realistic ENSO amplitude.
    Type: Article , PeerReviewed
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  • 45
    Publication Date: 2019-09-23
    Description: A long-standing difficulty of climate models is to capture the annual cycle (AC) of eastern equatorial Pacific (EEP) sea surface temperature (SST). In this study, we first examine the EEP SST AC in a set of integrations of the coupled Kiel Climate Model, in which only atmosphere model resolution differs. When employing coarse horizontal and vertical atmospheric resolution, significant biases in the EEP SST AC are observed. These are reflected in an erroneous timing of the cold tongue’s onset and termination as well as in an underestimation of the boreal spring warming amplitude. A large portion of these biases are linked to a wrong simulation of zonal surface winds, which can be traced back to precipitation biases on both sides of the equator and an erroneous low-level atmospheric circulation over land. Part of the SST biases also is related to shortwave radiation biases related to cloud cover biases. Both wind and cloud cover biases are inherent to the atmospheric component, as shown by companion uncoupled atmosphere model integrations forced by observed SSTs. Enhancing atmosphere model resolution, horizontal and vertical, markedly reduces zonal wind and cloud cover biases in coupled as well as uncoupled mode and generally improves simulation of the EEP SST AC. Enhanced atmospheric resolution reduces convection biases and improves simulation of surface winds over land. Analysis of a subset of models from the Coupled Model Intercomparison Project phase 5 (CMIP5) reveals that in these models, very similar mechanisms are at work in driving EEP SST AC biases.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 46
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    Springer
    In:  Climate Dynamics, 52 (5-6). pp. 3223-3239.
    Publication Date: 2019-09-23
    Description: The Earth will exhibit continued global surface warming in response to a sustained increase of atmospheric carbon dioxide (CO2) levels. Massive meltwater input from the Antarctic ice sheet into the Southern Ocean could be one consequence of this warming. Here we investigate the impacts which this meltwater input may have on Earth’s surface climate and ocean circulation in a warming world. To this end a set of ensemble experiments has been conducted with a global climate model forced by increasing atmospheric CO2-concentration and an idealized Antarctic meltwater input to the Southern Ocean with varying amplitude and spatial pattern. As long as the atmospheric CO2-concentration stays moderate, i.e. below approximately twice the preindustrial concentration, and if a strong meltwater forcing of either 0.05 or 0.1 Sv is applied, enhanced Antarctic sea–ice cover and surface air temperature cooling over most parts of the Southern Ocean is observed. When the atmospheric CO2-concentration becomes larger than twice the preindustrial concentration, the meltwater only plays a minor role. The Antarctic meltwater drives significant slowing of the Southern Ocean meridional overturning circulation (MOC). Again, the meltwater influence only is detectable as long as the CO2-forcing is moderate. Much larger MOC changes develop in response to highly elevated atmospheric CO2-levels independent of whether or not a meltwater forcing is applied. The response of the Antarctic circumpolar current (ACC) is nonlinear. Substantial and persistent ACC slowing is simulated when solely the meltwater forcing of 0.1 Sv is applied, which is due to the halt of Weddell Sea deep convection and subsequent collapse of the Southern Ocean MOC. When the increasing atmospheric CO2-concentration additionally drives the model the ACC partly recovers in the long run. The partial recovery is due to strengthening westerly wind stress over the Southern Ocean, which intensifies the Ekman Cell. This study suggests that Southern Hemisphere climate projections for the twenty-first century could benefit from incorporating interactive Antarctic ice sheet.
    Type: Article , PeerReviewed
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  • 47
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    Springer
    In:  International Journal of Earth Sciences, 108 . pp. 587-620.
    Publication Date: 2019-09-23
    Description: The nature of the warm climates of the Cretaceous has been enigmatic since the first numerical climate models were run in the late 1970s. Quantitative simulations of the paleoclimate have consistently failed to agree with information from plant and animal fossils and climate sensitive sediments. The ‘cold continental interior paradox’ (first described by DeConto et al. in Barrera E, Johnson C (eds) Evolution of the Cretaceous Ocean/climate system, vol 332. Geological Society of America Special Paper, Boulder, pp 391–406, 1999), has been an enigma, with extensive continental interiors, especially in northeast Asia, modeled as below freezing in spite of plant and other evidence to the contrary. We reconsider the paleoelevations of specific areas, particularly along the northeastern Siberian continental margin, where paleofloras indeed indicate higher temperatures than suggested by current climate models. Evidence for significant masses of ice on land during even the otherwise warmest times of the Cretaceous is solved by reinterpretation of the δ18O record of fossil plankton. The signal interpreted as an increase in ice volume on land is the same as the signal for an increase in the volume of groundwater reservoirs on land. The problem of a warm Arctic, where fossil floras indicate that they never experienced freezing conditions in winter, could not be solved by numerical simulations using higher CO2 equivalent greenhouse gas concentrations. We propose a solution by assuming that paleoelevations were less than today and that there were much more extensive wetlands (lakes, meandering rivers, swamps, bogs) on the continents than previously assumed. Using ~ 8 × CO2 equivalent greenhouse gas concentrations and assuming 50–75% water surfaces providing water vapor as a supplementary greenhouse gas on the continents reduces the meridional temperature gradients. Under these conditions the equatorial to polar region temperature gradients produce conditions compatible with fossil and sedimentological evidence.
    Type: Article , PeerReviewed
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  • 48
    Publication Date: 2019-09-23
    Description: Fluctuations in abundance of dominant species can cause competitive release of resources with consequences on community structure and functioning. In the present study, changes in the intertidal macroinfauna community of an exposed sandy beach were evaluated during two contrasting periods characterized by low and high densities of the yellow clam Amarilladesma mactroides. The increase in clam abundance and biomass was associated with a significant decrease in abundance of the rest of the community. In particular, a decline was observed for the pea crab Austinixa patagoniensis, a commensal species that lives in the burrows of the shrimp Sergio mirim. Our study demonstrates that fluctuations in clam abundance lead to long-term changes in community structure, suggesting the presence of competitive interactions. The environmental stability over the two periods strengthens the hypothesis that the competition between species is crucial for shaping the ecological community. Stable isotope analysis allows discarding trophic competition as mechanism of exclusion. Image maps reveal complementary distribution of species, showing the relevance of the spatial competition, which is mediated by changes in abundance of a third species. Indeed, high densities of A. mactroides reduce the available area for the establishment of the S. mirim burrows, limiting the foraging behavior of its commensal, the pea crab. Such an interaction drives density-dependent exclusion of the pea crab from the intertidal zone following the establishment of the yellow clam population. This study illustrates that spatial competition triggered by the increase of a bed-forming species can have community-wide consequences in exposed sandy beaches
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  • 49
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    Springer
    In:  In: Remote Sensing of the Asian Seas. , ed. by Barale, V. and Gade, M. Springer, Cham, pp. 123-138. ISBN 978-3-319-94065-6
    Publication Date: 2019-09-23
    Description: The Laptev and Eastern Siberian shelves are the world’s broadest shallow shelf systems. Large Siberian rivers and coastal erosion of up to meters per summer deliver large volumes of terrestrial matter into the Arctic shelf seas. In this chapter we investigate the applicability of Ocean Colour Remote Sensing during the ice-free summer season in the Siberian Laptev Sea region. We show that the early summer river peak discharge may be traced using remote sensing in years characterized by early sea-ice retreat. In the summer time after the peak discharge, the spreading of the main Lena River plume east and north-east of the Lena River Delta into the shelf system becomes hardly traceable using optical remote sensing methods. Measurements of suspended particulate matter (SPM) and coloured dissolved organic matter (cDOM) are of the same magnitude in the coastal waters of Buor Khaya Bay as in the Lena River. Match-up analyses of in situ chlorophyll-a (Chl-a) show that standard Medium Resolution Imaging Spectrometer (MERIS) and Moderate Resolution Imaging Spectroradiometer (MODIS) satellite-derived Chl-a is not a valid remote sensing product for the coastal waters and the inner shelf region of the Laptev Sea. All MERIS and MODIS-derived Chl-a products are overestimated by at least a factor of ten, probably due to absorption by the extraordinarily high amount of non-algal particles and cDOM in these coastal and inner-shelf waters. Instead, Ocean Colour remote sensing provides information on wide-spread resuspension over shallows and lateral advection visible in satellite-derived turbidity. Satellite Sea Surface Temperature (SST) data clearly show hydrodynamics and delineate the outflow of the Lena River for hundreds of kilometres out into the shelf seas.
    Type: Book chapter , NonPeerReviewed
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  • 50
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    Springer
    In:  In: Pattern Recognition - GCPR 2018. , ed. by Brox, T., Bruhn, A. and Fritz, M. Lecture Notes in Computer Science, 11269 . Springer, Cham, Switzerland, pp. 391-404. ISBN 978-3-030-12939-2
    Publication Date: 2019-09-23
    Description: The size of current plankton image datasets renders manual classification virtually infeasible. The training of models for machine classification is complicated by the fact that a large number of classes consist of only a few examples. We employ the recently introduced weight imprinting technique in order to use the available training data to train accurate classifiers in absence of enough examples for some classes. The model architecture used in this work succeeds in the identification of plankton using machine learning with its unique challenges, i.e. a limited number of training examples and a severely skewed class size distribution. Weight imprinting enables a neural network to recognize small classes immediately without re-training. This permits the mining of examples for novel classes.
    Type: Book chapter , PeerReviewed
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  • 51
    Publication Date: 2019
    Description: 〈h3〉Abstract〈/h3〉 〈p〉Advancement in research on dyes obtained from natural sources e.g., plants, animals, insects and micro-organisms is widening the application of natural dyes in various fields. The natural dyes substituted their synthetic analogs at the beginning of twentieth century due to their improved quality, value, ease of production, ease of dyeing and some other factors. This era of dominance ended soon when toxic effects of synthetic dyes were reported. In the last few decades, pigments from micro-organisms especially soil derived bacteria is replacing dyes from other natural sources because of the increasing demand for safe, non-toxic, and biodegradable natural product. Apart from application in agriculture practices, cosmetics, textile, food and paper industries, bacterial pigments have additional biological activities e.g., anti-tumor, anti-fungal, anti-bacterial, immunosuppressive anti-viral, and many more which make them a potential candidate for pharmaceutical industry. Optimization of culture conditions and fermentation medium is the key strategies for large scale production of these natural dyes. An effort has been done to give an overview of pigments obtained from bacteria of soil origin, their dominance over dyes from other sources (natural and synthetic) and applications in the medical world in the underlying study.〈/p〉 〈span〉 〈span〉 〈img alt="" src="https://static-content.springer.com/image/MediaObjects/284_2018_1557_Figa_HTML.png"〉 〈/span〉 〈/span〉
    Print ISSN: 0343-8651
    Electronic ISSN: 1432-0991
    Topics: Biology , Medicine
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  • 52
    Publication Date: 2019
    Description: 〈h3〉Abstract〈/h3〉 〈span〉 〈h3〉Purpose〈/h3〉 〈p〉This study aims to investigate the presence of aggregate hierarchy during the decomposition of rice straw in a subtropical soil (Ultisol) with large quantities of Fe and Al oxides and in two temperate soils with a large amount of montmorillonite (Vertisol) or with less organic matter but a large content of CaCO〈sub〉3〈/sub〉 (Inceptisol) and to explore the relationship between relative contributions of biotic and abiotic processes in soil aggregation and the presence of aggregate hierarchy.〈/p〉 〈/span〉 〈span〉 〈h3〉Materials and methods〈/h3〉 〈p〉A 120-day incubation experiment with or without 〈sup〉13〈/sup〉C-labeled straw was conducted in the above-mentioned three soils previously sieved at 〈 0.25 mm (i.e., without macroaggregates). During incubation, the aggregate size distribution, aggregate associated organic C (OC), straw-derived 〈sup〉13〈/sup〉C, soil respiration, soil microbial biomass C and N, and phospholipid fatty acids were measured several times.〈/p〉 〈/span〉 〈span〉 〈h3〉Results and discussion〈/h3〉 〈p〉At the end of each experiment, both macro- and microaggregates were present. Higher OC and 〈sup〉13〈/sup〉C concentrations in macroaggregates than in the fractions 〈 0.25 mm were observed within the first 15 days in all three soils. However, after 60 days, only the Vertisol could still show a slightly higher OC concentration in the macroaggregates. Same as the temperate Vertisol and Inceptisol, more macroaggregates could form by organic binding agents than by inorganic binding agents in the Ultisol at the early incubation stage. While similar to the subtropical Ultisol, macroaggregates could also mainly form by inorganic binding agents than by organic binging agents in the Vertisol and Inceptisol at the later stage. Despite the microbial community structure being different from each other, the macroaggregation was significantly related to the microbial biomass and activity in all three soils at the early incubation stage.〈/p〉 〈/span〉 〈span〉 〈h3〉Conclusions〈/h3〉 〈p〉A high degree of aggregate hierarchy can present in all three soils at the early decomposition stage of rice straw, while at the later stage, no aggregate hierarchy or only a small degree of aggregate hierarchy can present in the Ultisol and Inceptisol or in the Vertisol. Consequently, instead of soil type, the expression of aggregate hierarchy is essentially determined by the relative contributions of biotic and abiotic processes or of organic and inorganic binding agents in soil aggregation.〈/p〉 〈/span〉
    Print ISSN: 1439-0108
    Electronic ISSN: 1614-7480
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
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  • 53
    Publication Date: 2019
    Description: 〈h3〉Abstract〈/h3〉 〈p〉The Joint Urban 2003 (JU 2003) experimental campaign took place in downtown Oklahoma City, Oklahoma, USA, comprising both continuous and puff releases of sulphur hexafluoride (SF〈sub〉6〈/sub〉) tracer gas. In the framework of the UDINEE project, intensive operation period 8 (IOP 8) conducted during the night is simulated using the Parallel-Micro-SWIFT-SPRAY (PMSS) three-dimensional modelling system. The PMSS modelling system is the assembly of a diagnostic or momentum flow solver (PSWIFT) and a Lagrangian particle dispersion model (PSPRAY) accounting for buildings and developed in parallel versions. A sensitivity study is performed regarding the flow modelling options, namely the meteorological data input, the characteristics of the turbulence, and the use of the diagnostic or momentum solver. Results shed light onto issues related to modelling puff releases in a built-up environment. Flow and concentration results are compared to measurements at the sample locations in IOP 8 and statistical metrics computed for all puffs released during IOP 8. These indicators illustrate satisfactory performance and robustness of the PMSS system with reference to the modelling options. Moreover, with moderate computational times and reliable predictions, the PMSS modelling system proves to be relevant for emergency response in cases of atmospheric release of hazardous materials.〈/p〉
    Print ISSN: 0006-8314
    Electronic ISSN: 1573-1472
    Topics: Geosciences , Physics
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  • 54
    Publication Date: 2019
    Description: 〈h3〉Abstract〈/h3〉 〈p〉 Environmental tobacco smoke is an important factor in indoor air quality and public health. In this study, the impacts of cigarette smoking on the characteristics of PM〈sub〉10〈/sub〉, PM〈sub〉2.5〈/sub〉, and PM〈sub〉1〈/sub〉 and their corresponding toxic metals in 50 indoor environments before and after smoking from 10 popular cigarette brands sold in Kuwait were investigated. Misleading advertisement branded ‘medium strong’ with less nicotine volume instigates the smokers use more cigarettes that may cause human health effects. Results showed high PM〈sub〉10〈/sub〉 level (range 150–1100 µg m〈sup〉−3〈/sup〉) followed by PM〈sub〉2.5〈/sub〉 (range 100–880 µg m〈sup〉−3〈/sup〉) and PM〈sub〉1〈/sub〉 (range 52–530 µg m〈sup〉−3〈/sup〉) after smoking. Establishment-wise, highest levels of particulate regardless the sizes were found in storehouse and lowest were observed in offices. The mean PM〈sub〉2.5〈/sub〉/PM〈sub〉10〈/sub〉 and PM〈sub〉1〈/sub〉/PM〈sub〉2.5〈/sub〉 ratios were in the range of 0.73–0.86 and 0.66–0.80, respectively, after smoking demonstrating that indoor PM〈sub〉10〈/sub〉 was mostly composed of fine particles, which confirms that cigarette smoke had a dominate impact on the presence of smaller particles. Toxic metals level exhibited similar patterns as those observed in particulate in the sequence of Pb 〉 Cd 〉 Sb 〉 Ba 〉 Hg. This study recommends the preventive measures and suggests policy makers to take stringent measures against cigarette smoking in Kuwait to protect public health.〈/p〉
    Print ISSN: 1735-1472
    Electronic ISSN: 1735-2630
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 55
    Publication Date: 2019
    Description: 〈h3〉Abstract〈/h3〉 〈p〉In the present study, air pollution monitoring was carried out in Chennai city continuously for more than 3 decades from 1978 to 2016 and air quality trends are established for planning mitigation measures. An extensive air pollution monitoring network consisting of 19 sampling locations covering traffic corridors and intersections, residential, commercial and industrial areas was operated to monitor dust and gaseous pollutants, toxic trace metals, polycyclic aromatic hydrocarbons (PAHs) and other criteria pollutants. Comprehensive emission inventory indicated contribution of pollution load is mainly from transport (80%) followed by domestic (13%), industry (4%), commercial activities (2%) and power back generators (1%). The air pollutant concentrations were high during day time in winter season at traffic corridors, intersections and industrial areas. The monitoring data indicated PM〈sub〉10〈/sub〉, PM〈sub〉2.5〈/sub〉 and PAHs concentrations were exceeding the limits due to vehicular emissions, road condition (paved and unpaved), construction, industrial and commercial activities. Carbon monoxide and hydrocarbon concentrations were high during traffic peak hours and near road corridors where traffic congestion is high. GM, ATDL and ISCST3 models were employed to assess the contribution of air pollutants from transport, domestic and industry sector, respectively. Performance evaluation of models was also carried out by comparing monitored and model-predicted concentration to assess model prediction accuracy.〈/p〉
    Print ISSN: 1735-1472
    Electronic ISSN: 1735-2630
    Topics: Energy, Environment Protection, Nuclear Power Engineering
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  • 56
    Publication Date: 2019
    Description: 〈h3〉Abstract〈/h3〉 〈p〉5-Hydroxymethylfurfural (HMF), which can be synthesized from hexose sugars without rearrangement of their carbon framework, is a key platform chemical that is readily convertible into fuels and chemicals that are now derived from petroleum. Methods to convert glucose, which is readily accessible from cellulose, to HMF typically rely on toxic heavy metals or harsh acidic conditions and often give low yields or low selectivity. Here, we report on a mild, efficient, and metal-free process that uses an organocatalyst, 2-carboxyphenylboronic acid, along with small amounts of chloride ion to effect the selective transformation of glucose to HMF.〈/p〉
    Print ISSN: 2190-6815
    Electronic ISSN: 2190-6823
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 57
    Publication Date: 2019
    Description: 〈h3〉Abstract〈/h3〉 〈p〉Duplication of the genome poses one of the most significant threats to genetic integrity, cellular fitness, and organismal health. Therefore, numerous mechanisms have evolved that maintain replication fork stability in the face of DNA damage and allow faithful genome duplication. The fission yeast BRCT-domain-containing protein Brc1, and its budding yeast orthologue Rtt107, has emerged as a “hub” factor that integrates multiple replication fork protection mechanisms. Notably, the cofactors and pathways through which Brc1, Rtt107, and their human orthologue (PTIP) act have appeared largely distinct. This either represents true evolutionary functional divergence, or perhaps an incomplete genetic and biochemical analysis of each protein. In this regard, we recently showed that like Rtt107, Brc1 supports key functions of the Smc5–Smc6 complex, including its recruitment into DNA repair foci, chromatin association, and SUMO ligase activity. Furthermore, fission yeast cells lacking the Nse5–Nse6 genome stability factor were found to exhibit defects in Smc5–Smc6 function, similar to but more severe than those in cells lacking Brc1. Here, we place these findings in context with the known functions of Brc1, Rtt107, and Smc5–Smc6, present data suggesting a role for acetylation in Smc5–Smc6 chromatin loading, and discuss wider implications for genome stability.〈/p〉
    Print ISSN: 0172-8083
    Electronic ISSN: 1432-0983
    Topics: Biology
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  • 58
    Publication Date: 2019
    Description: 〈h3〉Abstract〈/h3〉 〈p〉By borrowing theoretical insights from institutional theory and environmental and military sociology, the paper examines a relatively unobservable yet deep impact of Scott Pruitt’s tenure as the Environmental Protection Agency (EPA) administrator: changes in the institutional ethos of the EPA. Institutional ethos refers to the intangible and invisible fabric of the institution—its “spirit”—and implies the interconnection between moral priorities and emotions. The paper argues that Pruitt’s actions have been depleting the value dimension of the institutional ethos by 〈em〉devaluing〈/em〉 the EPA’s mission, and depleting the emotive dimension of the institutional ethos by 〈em〉demoralizing〈/em〉 EPA employees. The paper adds to the growing literature on the implications of the ongoing changes to US environmental policy and practice under the Trump Administration, and the counter-actions initiated by those opposing the current policy priorities. This paper serves as a call for further empirical research to uncover relatively intangible impacts of the Trump presidency on the EPA and other environmental institutions. More broadly, the paper intervenes in the scholarly discussion about the moral implications of institutional changes, especially ones exerted by political processes, and the impact of these changes on the character and integrity of institutions.〈/p〉
    Print ISSN: 2190-6483
    Electronic ISSN: 2190-6491
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Published by Springer
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  • 59
    Publication Date: 2019
    Description: 〈h3〉Abstract〈/h3〉 〈p〉In the present study, we start by formally deriving the simplified phenomenological models of long-crested shallow-water waves propagating in the equatorial ocean regions with the Coriolis effect due to the Earth’s rotation. These new model equations are analogous to the Green–Naghdi equations, the first-order approximations of the KdV-, or BBM type, respectively. We then justify rigorously that in the long-wave limit, unidirectional solutions of a class of KdV- or BBM type are well approximated by the solutions of the Camassa–Holm equation in a rotating setting. The modeling and analysis of those mathematical models then illustrate that the Coriolis forcing in the propagation of shallow-water waves can not be neglected. Indeed, the CH-approximation with the Coriolis effect captures stronger nonlinear effects than the nonlinear dispersive rotational KdV type. Furthermore, we demonstrate nonexistence of the Camassa–Holm-type peaked solution and classify various localized traveling wave solutions to the Camassa–Holm equation with the Coriolis effect depending on the range of the rotation parameter.〈/p〉
    Print ISSN: 0938-8974
    Electronic ISSN: 1432-1467
    Topics: Mathematics , Physics
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  • 60
    Publication Date: 2019
    Description: 〈h3〉Abstract〈/h3〉 〈p〉A very large floating structure (VLFS) may undergo buckling and yielding under rare and extreme waves. Then, the cross section of the VLFS collapses completely. The evaluation of the consequence of collapse is critical in view of the risk analysis. In this paper, the parametric dependencies of the collapse extent of a VLFS under extreme vertical bending moments are investigated. A mathematical equation to describe the collapse behavior of the VLFS is developed taking account of the hydroelastic deformation. The whole VLFS is modeled by a segmented beam on an elastic foundation with infinite length connected via a nonlinear rotational spring assuming that a plastic hinge is formed at the collapsing section of the VLFS under the extreme vertical bending moment. By solving the equation in an analytical manner, a simple formula to predict the extent of collapse of the VLFS is developed. The results by the formula are well correlated with those by numerical simulation that has been developed by the present authors. It is shown that the characteristic length defined for a VLFS plays a key role in the collapse behavior.〈/p〉
    Print ISSN: 0948-4280
    Electronic ISSN: 1437-8213
    Topics: Geosciences , Technology
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  • 61
    Publication Date: 2019
    Description: 〈h3〉Abstract〈/h3〉 〈p〉We consider the superposition of a symmetric simple exclusion dynamics, speeded-up in time, with a spin-flip dynamics in a one-dimensional interval with periodic boundary conditions. We prove the large deviations principle for the empirical measure under the stationary state. We deduce from this result that the stationary state is concentrated on the stationary solutions of the hydrodynamic equation which are stable.〈/p〉
    Print ISSN: 0178-8051
    Electronic ISSN: 1432-2064
    Topics: Mathematics
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  • 62
    Publication Date: 2019
    Description: 〈h3〉Abstract〈/h3〉 〈p〉Hard bottoms can negatively affect the surrounding infauna by hosting predatory fauna and modifying local hydrodynamics and sedimentation rates. Considering that these effects depend on the distance to the hard bottoms, we expected that the infaunal structure and recolonization would change accordingly. We assessed whether the distance from a rocky shore alters infaunal recolonization in a subtropical tidal flat. Sediment was defaunated on sites near and far from a rocky shore and the subsequent faunal recolonization was followed for 40 days. The sites near and far from the rocky shore displayed different assemblage structures, which we attributed to local variation in hydrodynamic conditions. Both the total infaunal abundance and the abundance of the dominant species recovered faster at the near site. We indicate that changes in infaunal recolonization at varying distances from natural rocky shores are primarily driven by the availability of adults. Infaunal recovery took less than 2 weeks, but recolonization rates increased near the rocky shore, as a function of its naturally variable assemblage structure and relatively lower species richness and abundances. We suggest that models of infaunal distribution and recolonization should incorporate landscape features such as the presence and distance from rocky bottoms.〈/p〉
    Print ISSN: 0018-8158
    Electronic ISSN: 1573-5117
    Topics: Biology
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  • 63
    Publication Date: 2019
    Description: 〈h3〉Abstract〈/h3〉 〈p〉The limited petroleum resources available for mankind have led to the exploration and development of oil fields in the offshore deep-sea regions, especially in light of the rising oil prices. Different studies and projects on the ocean thermal energy conversion (OTEC) technology, which operates the power generation facilities using the temperature difference between the deep-sea water and the sea surface water, are currently being undertaken. In this study, various methods of applying the OTEC technology to a floating production storage and offloading (FPSO) facility installed in a deep-sea area were simulated and analyzed. In the closed cycle, a 1595.5 kW net power generation capacity was obtained. In the open cycle, a 863.5 kW generating capacity and 54.4 m〈sup〉3〈/sup〉/h fresh water were obtained. In the hybrid cycle, a 643 kW generating capacity and 55.1 m〈sup〉3〈/sup〉/h fresh water were obtained. In addition, the cooling water of the heating, ventilation, and air-conditioning systems (HVACs) obtained using deep-sea water cooling was also investigated. Ultimately, a 100 MW OTEC power plant was designed, and the required seawater amount and operating fluid capacity were confirmed. Considering the similarity of OTEC power generation facilities and FPSOs, the conversion of an FPSO in the deep-sea region to an OTEC power generation facility after the end of the life of the FPSO was proposed. It will be an alternative way of addressing two important issues: the need for petroleum resource development considering the limited petroleum resources that are currently available, and the need to ensure the sustainable development of countries.〈/p〉
    Print ISSN: 0948-4280
    Electronic ISSN: 1437-8213
    Topics: Geosciences , Technology
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  • 64
    Publication Date: 2019
    Description: 〈h3〉Abstract〈/h3〉 〈p〉Cu-Bi alloy with high Bi content can be used for thermal surge protection and energy storage. For these applications, creep at high temperatures, including temperatures above the melting temperature of Bi, 〈em〉T〈/em〉〈sub〉m,Bi〈/sub〉, becomes important. Accordingly, the creep behavior of Cu-Bi alloys, comprising 30 and 40 vol pct Bi, was studied under compression at temperatures above and below 〈em〉T〈/em〉〈sub〉m,Bi〈/sub〉. At 200 °C, which is below 〈em〉T〈/em〉〈sub〉m,Bi〈/sub〉, Cu-Bi showed a stress exponent of ~ 4 at high stresses and ~ 1 at low stresses. Finite element analysis revealed that the creep behavior of Cu-Bi at 200 °C was predominantly governed by Bi. On the other hand, at temperatures higher than 〈em〉T〈/em〉〈sub〉m,Bi〈/sub〉, Cu-Bi showed a short transient stage at high stresses, followed by sudden failure of the material. However, at low stresses, the sample first continued to expand and then started to accumulate compressive strain. A qualitative model based on interaction between liquid Bi and Cu is developed to explain the observed creep behavior at temperatures higher than 〈em〉T〈/em〉〈sub〉m,Bi〈/sub〉. The results obtained here shed light on the creep behavior of alloys with constituents having significantly different creep behavior and containing a non-reacting liquid phase.〈/p〉
    Print ISSN: 1073-5623
    Electronic ISSN: 1543-1940
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 65
    Publication Date: 2019
    Description: 〈h3〉Abstract〈/h3〉 〈p〉This study describes the geoheritage sites in the Draa valley between Ouarzazate and M’Hamid in south-eastern Morocco. This area is remarkable for its diverse landscapes and very interesting geological, geomorphological, and archeological sites that could be used to explain the history of the earth as well as regional climate changes both to tourists and to the general public. The educational aspects of these sites are highlighted; in order to emphasize their magnificence and their scientific interest, the area includes many sites with the Ordovician Fezouata Biota. Information needs to be provided in various media, as geological and archeological booklets, guidebooks or interpretive panels at the geosites. The approach presented below can serve as a model for sustainable development of geotourism, for preservation of geological and archeological heritage, and also as a contribution toward establishing a geopark in the south-eastern provinces of Morocco.〈/p〉
    Print ISSN: 1867-2477
    Electronic ISSN: 1867-2485
    Topics: Geosciences
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  • 66
    Publication Date: 2019
    Description: 〈h3〉Abstract〈/h3〉 〈p〉The current fishing pressure in Lake Victoria, Tanzania indicates that the Nile perch (〈em〉Lates niloticus〈/em〉) is overfished and no regulations are enforced to maintain a sustainable fishery despite its significant contribution to the economy. This study examines the determinants of Nile perch overfishing and its intensity in Lake Victoria, Tanzania, using a double-hurdle model that is based on baseline survey data collected from 268 Nile perch fishers. The model analysed the data in two sequential hurdles, the first hurdle being whether or not a Nile perch fisher overfished (probability of overfishing), and the second hurdle being the difference between the actual average catch size and the minimum slot size of 50 cm total length (TL) (intensity of overfishing). The study revealed that different socio-economic, institutional and fishing effort influence Nile perch overfishing and its intensity in Lake Victoria, Tanzania. This, therefore, suggests that, to attain a balance between sustainable fishery management and the livelihood for Nile perch fishers in Lake Victoria, there is a need for the government to design policies that will consider the dynamics of the institutional setup and fishing effort in this lake.〈/p〉
    Print ISSN: 0018-8158
    Electronic ISSN: 1573-5117
    Topics: Biology
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  • 67
    Publication Date: 2019
    Description: 〈h3〉Abstract〈/h3〉 〈p〉〈em〉Gliricidia sepium〈/em〉 has the ability to recruit and release nutrients, increasing primary productivity of forest sites. There are no reports documenting intercroping of 〈em〉G. sepium〈/em〉 and 〈em〉Cedrela odorata〈/em〉 and few studies examining nutrient supply as strategies to decrease incidence of 〈em〉Hypsipyla grandella〈/em〉 in 〈em〉C. odorata〈/em〉 plantations. In this study, intercroping of 〈em〉G. sepium〈/em〉 and 〈em〉C. odorata〈/em〉 and fertilization with N and P was tested in order to examine the effects of such factors on growth, nutrient status, and incidence of 〈em〉H. grandella〈/em〉 on 〈em〉C. odorata〈/em〉 trees. Twelve treatments fourfold replicated and derived from a 3 × 2 × 2 set of factors were randomly established within the experimental site. During 12 months, growth and pest-incidence variables were measured quarterly and monthly, respectively. K and Mg were the most deficient nutrients in the experimental site. Interplanting three 〈em〉G. sepium〈/em〉 trees per plot increased K and Mg availability, thus improving 〈em〉C. odorata〈/em〉 nutrient status and minimizing incidence of the pest during the first year. N supply did not improve 〈em〉C. odorata〈/em〉 growth nor did it affect the incidence of 〈em〉H. grandella〈/em〉. P promoted tree height.〈/p〉
    Print ISSN: 0167-4366
    Electronic ISSN: 1572-9680
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
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  • 68
    Publication Date: 2019
    Description: 〈h3〉Abstract〈/h3〉 〈p〉This study addresses the multi-objective multi-mode resource-constrained project scheduling problem with payment planning where the activities can be done through one of the possible modes and the objectives are to maximize the net present value and minimize the completion time concurrently. Moreover, renewable resources including manpower, machinery, and equipment as well as non-renewable ones such as consumable resources and budget are considered to make the model closer to the real-world. To this end, a non-linear programming model is proposed to formulate the problem based on the suggested assumptions. To validate the model, several random instances are designed and solved by GAMS-BARON solver applying the ε-constraint method. For the high NP-hardness of the problem, we develop two metaheuristics of non-dominated sorting genetic algorithm II and multi-objective simulated annealing algorithm to solve the problem. Finally, the performances of the proposed solution techniques are evaluated using some well-known efficient criteria.〈/p〉
    Print ISSN: 0010-485X
    Electronic ISSN: 1436-5057
    Topics: Computer Science
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  • 69
    Publication Date: 2019
    Description: 〈h3〉Abstract〈/h3〉 〈p〉The spatial and temporal organization of genome duplication, also referred to as the replication program, is defined by the distribution and the activities of the sites of replication initiation across the genome. Alterations to the replication profile are associated with cell fate changes during development and in pathologies, but the importance of undergoing S phase with distinct and specific programs remains largely unexplored. We have recently addressed this question, focusing on the interplay between the replication program and genome maintenance. In particular, we demonstrated that when cells encounter challenges to DNA synthesis, the organization of DNA replication drives the response to replication stress that is mediated by the ATR/Rad3 checkpoint pathway, thus shaping the pattern of genome instability along the chromosomes. In this review, we present the major findings of our study and discuss how they may bring new perspectives to our understanding of the biological importance of the replication program.〈/p〉
    Print ISSN: 0172-8083
    Electronic ISSN: 1432-0983
    Topics: Biology
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  • 70
    Publication Date: 2019
    Description: 〈h3〉Abstract〈/h3〉 〈p〉A high-level radioactive waste repository requires a rock mass to have good retardation properties. However, because a fault zone can be a potential seepage conduit for nuclides, its influence on the hydraulic conductivity of that fault zone must be assessed. Key sets of fractures were found based on an assessment of the statistical characteristics of fracture orientations and the tectonic analysis of a representative north–east fault in the Jijicao rock block in the Beishan region of Gansu Province, China. The trace midpoint density of each set was calculated using ArcGIS, a geographic information system, and a model of the hydraulic conductivity in the fault zone was developed based on a water pressure test and calculations, such that the respect distance and margin for excavation of this fault could also be determined. The calculated results show that the fault core and host rock are less conductive when the damage zone is 10- to 100-fold more conductive due to its greater density of fractures. The density is stable at 100 m, while the key set is stable until 65 m, and the calculated hydraulic conductivity is stable until 25 m; these results are consistent with the results of water pressure analysis.〈/p〉
    Print ISSN: 1435-9529
    Electronic ISSN: 1435-9537
    Topics: Geosciences
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  • 71
    facet.materialart.
    Unknown
    Springer
    Publication Date: 2019
    Description: 〈h3〉Abstract〈/h3〉 〈p〉It would be of interest to formulate the general replacement models, combing the constant and random policies to satisfy the commonly planned and randomly needed replacement times. This paper takes up age and periodic replacement models again to formulate their general models when replacement actions are also conducted at random times 〈span〉 〈span〉\(Y_i~(i=1,2,\ldots ,n)\)〈/span〉 〈/span〉. The classic approach of whichever occurs first and the newly proposed approach of whichever occurs last are used for such general models, whose models are named as replacement first, modified replacement first, replacement last and modified replacement last, respectively. We compare all of the replacement models analytically and numerically to find which policy should be selected from the viewpoint of cost. It is shown that the modified replacement policies with combined approaches of whichever occurs first and last are more economical than others. In addition, the replacement models with different replacement costs are extended for further studies.〈/p〉
    Print ISSN: 0254-5330
    Electronic ISSN: 1572-9338
    Topics: Mathematics , Economics
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  • 72
    Publication Date: 2019
    Description: 〈h3〉Abstract〈/h3〉 〈p〉The spiny lobster 〈em〉Panulirus japonicus〈/em〉 (von Siebold, 1824) has a rather restricted distribution in the northwestern Pacific, ranging from Japan to Taiwan and southeastern China. It has been hypothesized that the Japanese populations of this species share a common pool of larvae for recruitment, and that these larvae are transported by the Kuroshio Subgyre. However, it remains unclear how the populations around western Taiwan and southeastern mainland China are maintained, as they are outside the Kuroshio Subgyre. In this work, a final-stage phyllosoma and a puerulus of this species were discovered for the first time in Taiwanese waters and off the southern coast. An extended genetic analysis of the Taiwanese and southeastern Chinese populations of 〈em〉P. japonicus〈/em〉 showed that they all share a common gene pool. The larval recruitment hypothesis for 〈em〉P. japonicus〈/em〉 was therefore modified by suggesting that its late-stage phyllosoma or puerulus may reach further south to southern Taiwan, with the branch of Kuroshio Current accounting for the larval recruitment of the populations around western Taiwan and southeastern China.〈/p〉
    Print ISSN: 0916-8370
    Electronic ISSN: 1573-868X
    Topics: Geosciences , Physics
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  • 73
    Publication Date: 2019
    Description: 〈h3〉Abstract〈/h3〉 〈p〉〈em〉Pseudomonas〈/em〉 sp. JY-Q was isolated from nicotine-rich environment and could degrade and tolerate high-content nicotine. Its specific genetic architecture comprised duplicated homologous nicotine-degrading clusters for different functional modules on the whole pathway. Its adaptive and genomic properties caused our concern whether the duplicated homologous gene clusters confer additive effects on nicotine degradation and result in strain JY-Q strong capability. After deletion of representative genes from duplicated homologous gene clusters of upstream module Nic1, midstream module Spm, and downstream module Nic2, the nicotine degradation efficiency of the wild type and mutant strains were examined. As the first genes of clusters Nic1-1 and Nic1-2, 〈em〉nicA2〈/em〉 and 〈em〉nox〈/em〉 are both involved in nicotine degradation, but 〈em〉nox〈/em〉 exhibited more contribution to nicotine metabolism due to the higher transcriptional amount of 〈em〉nox〈/em〉 than that of 〈em〉nicA2〈/em〉. Likewise, the sub-clusters 〈em〉spm1 and spm2〈/em〉 showed additive effect on nicotine metabolism. As two 〈em〉hpo〈/em〉-like genes of clusters Nic2-1 and Nic2-2, 〈em〉hpo1〈/em〉, and 〈em〉hpo2〈/em〉 also showed additive effect on the nicotine degrading, but 〈em〉hpo1〈/em〉 provided more contribution than 〈em〉hpo2〈/em〉. The third 〈em〉hpo〈/em〉-like gene in cluster NA (nicotinic acid degrading), 〈em〉nicX〈/em〉 is not necessary for 2,5-dihydroxypyridine transformation when 〈em〉hpo1〈/em〉 and 〈em〉hpo2〈/em〉 exist. A variety of transposases and integrases observed around Nic1 and Nic2 cluster genes suggests that the duplicated genes could evolve from horizontal gene transfer (HGT)-related dissemination. This study provide an insight into a novel adaptability mechanism of strains in extreme environment such as high nicotine concentration, and potential novel targets to enhance strain synthesis/degradation ability for future applications.〈/p〉
    Print ISSN: 0340-2118
    Electronic ISSN: 1432-0614
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
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