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  • Journals
  • Other Sources  (121)
  • Taylor & Francis  (95)
  • American Chemical Society (ACS)
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  • 2015-2019  (121)
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  • 1
    Publication Date: 2021-04-23
    Description: Climate change has significant implications for biodiversity and ecosystems. With slow progress towards reducing greenhouse gas emissions, climate engineering (or ‘geoengineering’) is receiving increasing attention for its potential to limit anthropogenic climate change and its damaging effects. Proposed techniques, such as ocean fertilization for carbon dioxide removal or stratospheric sulfate injections to reduce incoming solar radiation, would significantly alter atmospheric, terrestrial and marine environments, yet potential side-effects of their implementation for ecosystems and biodiversity have received little attention. A literature review was carried out to identify details of the potential ecological effects of climate engineering techniques. A group of biodiversity and environmental change researchers then employed a modified Delphi expert consultation technique to evaluate this evidence and prioritize the effects based on the relative importance of, and scientific understanding about, their biodiversity and ecosystem consequences. The key issues and knowledge gaps are used to shape a discussion of the biodiversity and ecosystem implications of climate engineering, including novel climatic conditions, alterations to marine systems and substantial terrestrial habitat change. This review highlights several current research priorities in which the climate engineering context is crucial to consider, as well as identifying some novel topics for ecological investigation.
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  • 2
    Publication Date: 2019-02-01
    Description: The surface chemistry of aquatic organisms determines their biotic interactions. Metabolites in the spatially limited laminar boundary layer mediate processes, such as antifouling, allelopathy and chemical defense against herbivores. However, very few methods are available for the investigation of such surface metabolites. An approach is described in which surfaces are extracted by means of C18 solid phase material. By powdering wet algal surfaces with this material, organic compounds are adsorbed and can be easily recovered for subsequent liquid chromatography/mass spectrometry (LC/MS) and gas chromatography/mass spectrometry (GC/MS) investigations. The method is robust, picks up metabolites of a broad polarity range and is easy to handle. It is more universal compared to established solvent dipping protocols and it does not cause damage to the test organisms. A protocol is introduced for the macroalgae Fucus vesiculosus, Caulerpa taxifolia and Gracilaria vermiculophylla, but it can be easily transferred to other aquatic organisms.
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  • 3
    Publication Date: 2020-01-02
    Description: Different studies on the position of the non-indigenous species Neogobius melanostomus within the coastal food web of the Pomeranian Bay (western Baltic) were performed, resulting in a quantitative and qualitative species list of prey organisms found in the stomachs of the invader and an estimation concerning the importance of round goby as prey for different resident predators. It seems that the colonization process is not fully completed yet, but the results reveal that the species is already established in the food web 16 years after the first observation within the study area. The results show that N. melanostomus feed upon a wide range of different resident organisms. While a direct predation effect on native fish species appears rather unlikely, indirect effects such as competition cannot yet be excluded. In addition, our results reveal an ontogenetic diet shift and that the round goby itself already serves as an important prey for piscivorous fish and seabirds. Finally, we formulate different hypotheses based on our results which will require further research.
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  • 4
    Publication Date: 2020-02-06
    Description: International Ocean Discovery Program (IODP) Expedition 352 recovered a high-fidelity record of volcanism related to subduction initiation in the Bonin fore-arc. Two sites (U1440 and U1441) located in deep water nearer to the trench recovered basalts and related rocks; two sites (U1439 and U1442) located in shallower water further from the trench recovered boninites and related rocks. Drilling in both areas ended in dolerites inferred to be sheeted intrusive rocks. The basalts apparently erupted immediately after subduction initiation and have compositions similar to those of the most depleted basalts generated by rapid sea-floor spreading at mid-ocean ridges, with little or no slab input. Subsequent melting to generate boninites involved more depleted mantle and hotter and deeper subducted components as subduction progressed and volcanism migrated away from the trench. This volcanic sequence is akin to that recorded by many ophiolites, supporting a direct link between subduction initiation, fore-arc spreading, and ophiolite genesis.
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  • 5
    Publication Date: 2020-02-06
    Description: The production of shiga toxin (Stx) is a critical step in the establishment and progress of enterohemorrhagic Escherichia coli (EHEC) infections. The possible release of Stx from dead and dying bacteria, and the risk of resistance development have restricted the usage of antibiotics against EHEC. The chlorinated quaternary ammonium compound, strepthonium A, was isolated from the culture of Streptomyces sp. SBT345 that was cultivated from the Mediterranean sponge Agelas oroides. The structure was elucidated and confirmed by spectroscopic analyses including 1D and 2D NMR, ESI-HRMS, as well as ESI-HRMS2. Strepthonium A follows Lipinski's rule of five with respect to its molecular weight, CLogP values and the number of hydrogen acceptors and donors. Verotoxin ELISA assay demonstrated that Strepthonium A reduced the Stx production in EHEC strain EDL933 at 80 μM concentration without growth inhibition. This study demonstrates the potential of strepthonium A in restraining the production of Stx in EHEC infections.
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  • 6
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    Taylor & Francis
    In:  Journal of Maps, 13 (1). pp. 24-30.
    Publication Date: 2020-02-06
    Description: Land-use dynamic is a major challenge for town and country planners especially in developing countries such as Iran. Iran has been under rapid urban expansion and population growth for past three decades which led to lack of resources, environmental deterioration and haphazard landscape development. In this paper, an attempt has been made to map the urbanization dynamics of Tehran in 40 years based on remote sensing imagery and by means of artificial neural networks. The presented scheme could be taken into consideration when planning initiatives aimed at surveying, monitoring, managing and sustainable development of the territory. Moreover, it can serve the experts in the fields of geography, urban studies and planning as a background for number of geographical analyses.
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  • 7
    Publication Date: 2020-02-06
    Description: Current antifouling (AF) technologies are based on the continuous release of biocides into the water, and consequently discharge into the environment. Major efforts to develop more environmentally friendly coatings require efficient testing in laboratory assays, followed by field studies. Barnacles are important fouling organisms worldwide, increasing hydrodynamic drag on ships and damaging coatings on underwater surfaces, and thus are extensively used as models in AF research, mostly in static, laboratory-based systems. Reliable flow-through test assays for the screening of biocide-containing AF paints, however, are rare. Herein, a flow-through bioassay was developed to screen for diverse low-release biocide paints, and to evaluate their effects on pre- and post-settlement traits in barnacles. The assay distinguishes between the effects from direct surface contact and bulk-water effects, which are crucial when developing low-emission AF coatings. This flow-through bioassay adds a new tool for rapid laboratory-based first-stage screening of candidate compounds and novel AF formulations.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 8
    Publication Date: 2019-02-01
    Description: One new diterpene, trichocitrin (1), and four known secondary metabolites, nafuredin (2), 5-hydroxy-2,3-dimethyl-7-methoxychromone (3), 24-methylenecycloartanol (4) and citrostadienol (5), were isolated from the culture of marine brown alga-endophytic Trichoderma citrinoviride cf-27. Trichocitrin (1) represents the first Trichoderma-derived and furan-bearing fusicoccane diterpene, and its structure and relative configuration were identified by analysis of 1D/2D NMR and mass spectroscopic data. Compounds 1 and 2 exhibited 8.0- and 9.5-mm inhibition zones, respectively, against Escherichia coli at 20 μg/disc and 54.1 and 36.7% growth inhibition, respectively, of Prorocentrum donghaiense at 80 μg/mL.
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  • 9
    Publication Date: 2021-02-08
    Description: New biostratigraphical, geochemical, and magnetic evidence is synthesized with IODP Expedition 352 shipboard results to understand the sedimentary and tectono-magmatic development of the Izu–Bonin outer forearc region. The oceanic basement of the Izu–Bonin forearc was created by supra-subduction zone seafloor spreading during early Eocene (c. 50–51 Ma). Seafloor spreading created an irregular seafloor topography on which talus locally accumulated. Oxide-rich sediments accumulated above the igneous basement by mixing of hydrothermal and pelagic sediment. Basaltic volcanism was followed by a hiatus of up to 15 million years as a result of topographic isolation or sediment bypassing. Variably tuffaceous deep-sea sediments were deposited during Oligocene to early Miocene and from mid-Miocene to Pleistocene. The sediments ponded into extensional fault-controlled basins, whereas condensed sediments accumulated on a local basement high. Oligocene nannofossil ooze accumulated together with felsic tuff that was mainly derived from the nearby Izu–Bonin arc. Accumulation of radiolarian-bearing mud, silty clay, and hydrogenous metal oxides beneath the carbonate compensation depth (CCD) characterized the early Miocene, followed by middle Miocene–Pleistocene increased carbonate preservation, deepened CCD and tephra input from both the oceanic Izu–Bonin arc and the continental margin Honshu arc. The Izu–Bonin forearc basement formed in a near-equatorial setting, with late Mesozoic arc remnants to the west. Subduction-initiation magmatism is likely to have taken place near a pre-existing continent–oceanic crust boundary. The Izu–Bonin arc migrated northward and clockwise to collide with Honshu by early Miocene, strongly influencing regional sedimentation.
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  • 10
    Publication Date: 2021-02-08
    Description: To enable quality control of measurement procedures for determinations of Mg isotope amount ratios, expressed as δ26Mg and δ25Mg values, in Earth-surface studies, the δ26Mg and δ25Mg values of eight reference materials (RMs) were determined by inter-laboratory comparison between five laboratories and considering published data, if available. These matrix RMs, including river water SLRS-5, spring water NIST SRM 1640a, Dead Sea brine DSW-1, dolomites JDo-1 and CRM 512, limestone CRM 513, soil NIST SRM 2709a and vegetation NIST SRM 1515 apple leaves, are representative for a wide range of Earth-surface materials from low-temperature environments. The inter-laboratory variability, 2s (twice the standard deviation), of all eight RMs ranges from 0.05 to 0.17‰ in δ26Mg. Thus, it is suggested that all these materials are suitable for validation of δ26Mg and δ25Mg determinations of Earth-surface geochemical studies.
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  • 11
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    Taylor & Francis
    In:  Biodiversity, 17 (1-2). pp. 5-11.
    Publication Date: 2017-03-31
    Description: Antarctica is a still unexplored area in many respects, among which biological diversity and, even more so, chemical diversity are important challenges. Over recent years, our research group has been studying marine benthic ecosystems in different Antarctic areas. These studies yielded several interesting discoveries, including species new to science, as well as new natural products never seen before. Overall, we have been trying to unravel the complex network of interactions that exist between marine benthic organisms in these cold and hardly accessible ecosystems. We present here an overview of our recent results regarding the biological and the chemical diversity of these organisms. In fact, these ecosystems are as complex as many other marine environments on the planet, and indeed, many questions remain yet to be answered.
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  • 12
    Publication Date: 2020-02-06
    Description: IODP Expedition 350 was the first to be drilled in the rear part of the Izu-Bonin, although several sites had been drilled in the arc axis to fore-arc region; the scientific objective was to understand the evolution of the Izu rear arc, by drilling a deep-water volcaniclastic section with a long temporal record (Site U1437). The Izu rear arc is dominated by a series of basaltic to dacitic seamount chains up to ~100-km long roughly perpendicular to the arc front. Dredge samples from these are geochemically distinct from arc front rocks, and drilling was undertaken to understand this arc asymmetry. Site U1437 lies in an ~20-km-wide basin between two rear arc seamount chains, ~90-km west of the arc front, and was drilled to 1804 m below the sea floor (mbsf) with excellent recovery. We expected to drill a volcaniclastic apron, but the section is much more mud-rich than expected (~60%), and the remaining fraction of the section is much finer-grained than predicted from its position within the Izu arc, composed half of ashes/tuffs, and half of lapilli tuffs of fine grain size (clasts 〈3 cm). Volcanic blocks (〉6.4 cm) are only sparsely scattered through the lowermost 25% of the section, and only one igneous unit was encountered, a rhyolite peperite intrusion at ~1390 mbsf. The lowest biostratigaphic datum is at 867 mbsf (~6.5 Ma), the lowest palaeomagnetic datum is at ~1300 mbsf (~9 Ma), and the rhyolite peperite at ~1390 mbsf has yielded a U–Pb zircon concordia intercept age of (13.6 + 1.6/−1.7) Ma. Both arc front and rear arc sources contributed to the fine-grained (distal) tephras of the upper 1320 m, but the coarse-grained (proximal) volcaniclastics in the lowest 25% of the section are geochemically similar to the arc front, suggesting arc asymmetry is not recorded in rocks older than ~13 Ma.
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  • 13
    Publication Date: 2020-02-06
    Description: In this opinion paper, we, a group of scientists from environmental-, geo-, ocean- and information science, argue visual data exploration should become a common analytics approach in Earth system science due to its potential for analysis and interpretation of large and complex spatio-temporal data. We discuss the challenges that appear such as synthesis of heterogeneous data from various sources, reducing the amount of information and facilitating multidisciplinary, collaborative research. We argue that to fully exploit the potential of visual data exploration, several bottlenecks and challenges have to be addressed: providing an efficient data management and an integrated modular workflow, developing and applying suitable visual exploration concepts and methods with the help of effective and tailored tools as well as generating and raising the awareness of visual data exploration and education. We are convinced visual data exploration is worth the effort since it significantly facilitates insight into environmental data and derivation of knowledge from it.
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  • 14
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    Wiley-Blackwell
    In:  Fish and Fisheries, 18 (4). pp. 656-667.
    Publication Date: 2019-02-01
    Description: Fisheries advice is based on demographic calculations, which assume that density-dependent processes regulating recruitment occur only in early life. This assumption is challenged by laboratory and lake studies and some recent indications from marine systems that demonstrate density-dependent regulation late in life. By accounting for spatial dynamics of a population, something that has previously been ignored in models of fish, we show that density-dependent regulation is determined by the size of the habitat: in small habitats, for example small lakes, regulation occurs late in life, while it can occur early in large habitats. When regulation happens late in life, fisheries yield is maximized by exploitation of mainly juvenile fish, while exploiting mature fish maximizes yield if regulation happens early. We review and interpret observations of density dependence in the light of the theory. Our results challenge the current assumption that density dependence always occurs early in life and highlights the need for an increased understanding of density-dependent processes. This can only come about by a change of focus from determining stock-recruitment relationships towards understanding when and how density-dependent regulation occurs in nature.
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  • 15
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    Taylor & Francis
    In:  Marine Georesources & Geotechnology, 34 (5). pp. 465-473.
    Publication Date: 2019-02-01
    Description: In this study, Lade's double-surface work-hardening constitutive model was adopted which uses the elasto-plasticity model as a basic conceptual framework. The model can analyze work hardening and work softening of nonlinear stress-strain behavior, and is regarded as superior to other elasto-plasticity constitutive models in terms of estimation. In the double-surface work-hardening constitutive model, 14 soil parameters are needed to estimate soil behaviors. To determine them, laboratory tests—isotropical consolidation test and conventional compression test—were conducted. Determining of soil parameters is highly complicated and time-consuming; randomness cannot be ruled out in determining parameters that are sensitive to stress-strain estimation, and error may occur. For this reason, a linear and nonlinear regression analysis was used to determine soil parameters. In estimation of undrained behavior, the estimated stress-strain behavior based on the two constitutive models largely overlapped with the test results. However, in estimating drained behavior, the outcome of the two models and the test results were mostly the same, but between the two models, the double-surface work-hardening constitutive model had a sharper slope in initial stress state, and a smaller maximum deviatoric stress.
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  • 16
    Publication Date: 2019-02-01
    Description: The spatial structure of species is important for their dynamics and evolution, but also for management and conservation. There are numerous ways of inferring spatial structures, and information from multiple methods is becoming more common to examine how different processes shape the spatial structures of species to improve fish management. Here, we investigate the spatial structure of a suite of Baltic Sea fish species based on the following: (i) spatial (presumably neutral) genetic differentiation, reviewed from the literature, and (ii) spatial synchrony in abundance changes from time series of fishery‐independent surveys, which we currently find to be underused given the amount of data available. For each of these two methods, species were classified as having a distinct, continuous or no/weak spatial structure. In addition, based on each source of information, we estimated the spatial scale of management units for species. The results show that only among species confined to the coastal zone the two sources of information yielded a congruence of the spatial structure (displaying a continuous spatial structure). In contrast, offshore species show weak spatial genetic structure but stronger spatial structure of synchrony in abundance. Based on this, we suggest that population genetic structure and synchrony in abundance should be used as complementary information as they reflect different spatial processes and suggest that management actions should differ with respect to scale depending on the management targets applied. We propose similar analysis should be applied to areas outside the Baltic Sea, and other stock identification methods, to improve management of fish resources.
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  • 17
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    Wiley-Blackwell
    In:  Journal of Metamorphic Geology .
    Publication Date: 2020-07-23
    Description: We report U–Pb zircon ages of c. 700–550 Ma, 262–220 Ma, 47–38 Ma and 15–14 Ma from amphibolites on Naxos Island in the Aegean extensional province of Greece. The zircon has complex internal structures. Based on cathodoluminescence response, zoning and crosscutting relationships a minimum of four zircon growth stages are identified: inherited core, magmatic core, inner metamorphic (?) rim and an outer metamorphic rim. Trace element compositions of the amphibolites suggest igneous differentiation and crustal assimilation. Zircon solubility as a function of saturation temperatures, Zr content and melt composition indicates that the zircon did not originally crystallize in the mafic bodies but was inherited from felsic precursor rocks, and subsequently assimilated into the mafic intrusives during emplacement. Zircon inheritance is corroborated by the complex, xenocrystic nature of the zircon in one sample. Ages of c. 700–550 Ma and 262–220 Ma are assigned to inherited zircon. Available geochemical data suggest that the 15–14 Ma metamorphic rims grew in situ in the amphibolites, corresponding to a high-grade metamorphic event at this time. However, the geochemical data cannot conclusively establish if the c. 40 Ma zircon rims also grew in situ, or whether they were inherited along with the xenocrystic cores. Two scenarios for emplacement of the mafic intrusives are discussed: (i) Intrusion during late-Triassic to Jurassic ocean basin development of the Aegean realm, in which case the 40 Ma zircon rims would have grown in situ, and (ii) emplacement in the Miocene as a result mafic underplating during large-scale extension. In this case, only the 15–14 Ma metamorphic outer rims would have formed in situ in the amphibolitic host rocks.
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  • 18
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    Taylor & Francis
    In:  Plant Biosystems - An International Journal Dealing with all Aspects of Plant Biology, 150 (1). pp. 152-160.
    Publication Date: 2019-02-01
    Description: The aim of this study was to test the effects of temperature on phenolic content of the brown seaweed Cystoseira amentacea. Phenolic compounds are secondary metabolites involved in different protection mechanisms as, for example, against grazers, epiphytes and UV radiation. Seasonal variations of phenolic content in C. amentacea were analysed and laboratory experiments, in which C. amentacea was exposed to an increase of temperature (25°C and 30°C), were performed. Total phenolic content (TPC) was determined colorimetrically with the Folin–Ciocalteu reagent. In C. amentacea, a seasonal pattern in TPC was observed, with a maximum value in winter-spring. C. amentacea responded significantly to the temperature treatments with a consistent decrease in TPC after 48 h.
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  • 19
    Publication Date: 2019-02-01
    Description: Fluorescent-amplified fragment length polymorphism (FAFLP) fingerprinting assay was used to compare the genetic diversity within and between tadpole shrimps (Notostraca) populations of Lepidurus apus (n=7) and Triops cancriformis (n=2) from rain pools in Israel. Each ephemeral water body has revealed a unique fingerprint pattern with an entailed genetic drift between nearby ponds. High similarity of genotypic diversity within each geographic area led to three clusters of water bodies, north, south and center of Israel. FAFLP assays on several newly hatched individuals of T. cancriformis revealed high identity amongst kin, as compared to L. apus where newly hatched from the same maternal source showed high diversity. Results indicate that T. cancriformis populations from Israel are probably parthenogenetic as indicated by clonal structures. The higher genetic variability in the L. apus populations and in laboratory-hatched specimens indicates the existence of sexual reproduction.
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  • 20
    Publication Date: 2020-07-09
    Description: Gammarids from the Caspian complex have invaded many European waters along the rivers and canals of the inland migration corridors. The species examined in this work are well known as invaders of European freshwater environments, so the colonization of brackish habitats is a phenomenon inviting more detailed investigation. The aim of this study was to determine the condition of the Ponto-Caspian gammarids Pontogammarus robustoides (G.O. Sars, 1894), Obesogammarus crassus (G.O. Sars, 1894), Dikerogammarus haemobaphes (Eichwald, 1841) and Dikerogammarus villosus (Sowinsky, 1894) as expressed by the relationship between total length and the wet weight of specimens in the brackish waters of the Gulf of Gdansk (Poland). The relationships can be regarded as responses to a newly expanded habitat after they overcome the salinity barrier of the southern Baltic Sea coastal waters. All these Ponto-Caspian gammarids demonstrated an increase in weight with increasing total length: P. robustoides (b = 2.852), O. crassus (b = 3.3477), D. haemobaphes (b = 3.7855) and D. villosus (b = 2.6917). The results are an indicator of the relatively good condition of the organisms and indicate that the brackish environment of the Gulf of Gdansk affords them excellent possibilities for growth.
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  • 21
    Publication Date: 2020-02-06
    Description: A bioassay-guided approach was used to identify defense compounds that are present on the surface of Zostera marina and which inhibit settlement of microfoulers at natural concentrations. Moderately polar eelgrass surface extracts inhibited the settlement of seven marine bacteria and one yeast that originated from non-living substrata. In contrast, five other bacterial strains that had been directly isolated from eelgrass surfaces were all insensitive, which suggested a selective effect of surface metabolites on the microbial communities present on eelgrass. Bioassay-guided isolation of active compounds from the extracts in combination with UPLC-MS and 1H-NMR spectroscopy resulted in the identification of rosmarinic acid, luteolin-7-sulfate and diosmetin-7-sulfate or its isomer chrysoeriol-7-sulfate. All three compounds are nontoxic repellents, as they did not inhibit bacterial growth, but prevented bacterial settlement in a dose-dependent manner. Between 15.6 and 106.8 μg ml−1 of rosmarinic acid were present on the eelgrass surface, enough for half maximal settlement inhibition of bacteria.
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  • 22
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    American Chemical Society (ACS)
    In:  Industrial & Engineering Chemistry Research, 56 (44). pp. 12755-12762.
    Publication Date: 2020-02-06
    Description: The discharges from industrial processes constitute the main source of copper contamination in aqueous ecosystems. In this study we investigated the capacity of different types of biochar (derived from chicken manure, eucalyptus, corncob, olive mill and pine sawdust) to remove copper from aqueous solution in a continuous-flow system. The flow rate of the system strongly influenced the amount of copper retained. The adsorption to the corncob biochar varied from 5.51 to 3.48 mg Cu g-1 as the flux decreased from 13 to 2.5 mL min-1. The physicochemical characteristics of biochar determine the copper retention capacity and the underlying immobilization mechanisms. Biochars with high inorganic contents retain the largest amounts of copper and may be suitable for using in water treatment systems to remove heavy metals. The copper retention capacity of the biochars ranged between ~1.3 and 26 mg g-1 and varied in the following order: chicken manure 〉 olive mill 〉〉 corncob 〉 eucalyptus 〉 sawdust pine.
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  • 23
    Publication Date: 2019-02-01
    Description: For the environmental monitoring of coral, mucus appears to be an appropriate biological matrix due to its array of functions in coral biology and the non-intrusive manner in which it can be collected. The aim of the present study was to evaluate the feasibility of using mucus of the stony coral Lophelia pertusa (L. pertusa) as an analytical matrix for discovery of biomarkers used for environmental monitoring. More specifically, to assess whether a mass-spectrometry-based proteomic approach can be applied to characterize the protein composition of coral mucus and changes related to petroleum discharges at the seafloor. Surface-enhanced laser desorption/ionization–time of flight mass spectrometry (SELDI-TOF MS) screening analyses of orange and white L. pertusa showed that the mucosal protein composition varies significantly with color phenotype, a pattern not reported prior to this study. Hence, to reduce variability from phenotype difference, L. pertusa white individuals only were selected to characterize in more detail the basal protein composition in mucus using liquid chromatography, mass spectrometry, mass spectrometry (LC-MS/MS). In total, 297 proteins were identified in L. pertusa mucus of unexposed coral individuals. Individuals exposed to drill cuttings in the range 2 to 12 mg/L showed modifications in coral mucus protein composition compared to unexposed corals. Although the results were somewhat inconsistent between individuals and require further validation in both the lab and the field, this study demonstrated preliminary encouraging results for discovery of protein markers in coral mucus that might provide more comprehensive insight into potential consequences attributed to anthropogenic stressors and may be used in future monitoring of coral health.
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  • 24
    Publication Date: 2021-02-08
    Description: Populations of fishes provide valuable services for billions of people, but face diverse and interacting threats that jeopardize their sustainability. Human population growth and intensifying resource use for food, water, energy and goods are compromising fish populations through a variety of mechanisms, including overfishing, habitat degradation and declines in water quality. The important challenges raised by these issues have been recognized and have led to considerable advances over past decades in managing and mitigating threats to fishes worldwide. In this review, we identify the major threats faced by fish populations alongside recent advances that are helping to address these issues. There are very significant efforts worldwide directed towards ensuring a sustainable future for the world's fishes and fisheries and those who rely on them. Although considerable challenges remain, by drawing attention to successful mitigation of threats to fish and fisheries we hope to provide the encouragement and direction that will allow these challenges to be overcome in the future.
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  • 25
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    Taylor & Francis
    In:  Geomechanics and Geoengineering, 12 (4). pp. 221-233.
    Publication Date: 2018-12-17
    Description: The progressive bond breakage of artificially cemented sands induced by shear straining was investigated through conventional isotropically consolidated drained triaxial compression tests. Sand specimens were prepared with a low degree of cementation by adopting a chemical grout. Test results were interpreted in terms of two stress–dilatancy theories for cohesive-frictional materials proposed in literature. The influence of debonding on the stress–dilatancy behaviour of cemented sands was analysed with particular emphasis on the ‘delayed dilatancy’ phenomenon. A bonding degradation curve was determined for each test relating the interparticle cohesion (c) to the magnitude of the total plastic strain vector (εd) and a bond degradation rate factor (Dc) was assessed from each curve. The maximum value of interparticle cohesion (c0) before the onset of bond degradation under shearing was found to correspond with a sharp decrease in the soil stiffness of the specimens. The influence of the effective confining stress (p′c)on both c0 and Dc parameters gathered from each test was also ascertained.
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  • 26
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    Taylor & Francis
    In:  In: Energy Geotechnics. , ed. by Wuttke, F., Bauer, S. and Sanchez, M. Taylor & Francis, London, pp. 437-443. ISBN 978-1-138-03299-6
    Publication Date: 2020-07-27
    Description: Results from two recent field trials, onshore in the Alaska permafrost and in the Nankai Trough offshore Japan, suggest that natural gas could be produced from marine gas hydrate reservoirs at compatible yields and rates. However, both field trials were accompanied by different technical issues, the most striking problems resulting from un-predicted geomechanical behaviour, sediment destabilization and catastrophic sand production. So far, there is a lack of experimental data which could help to understand relevant mechanisms and triggers for potential soil failure in gas hydrate production, to guide model development for simulation of soil behaviour in large-scale production, and to identify processes which drive or, further, mitigate sand production. We use high-pressure flow-through systems in combination with different online and in situ monitoring tools (e.g. Raman microscopy, MRI) to simulate relevant gas hydrate production scenarios. Key components for soil mechanical studies are triaxial systems with ERT (Electric resistivity tomography) and high-resolution localstrain analysis. Sand production control and management is studied in a novel hollow-cylinder-type triaxial setup with a miniaturized borehole which allows fluid and particle transport at different fluid injection and flow conditions. We further apply a novel large-scale high-pressure flow-through triaxial test system equipped with μ-CT to evaluate soil failure modes and triggers relevant to gas hydrate production and slope stability. The presentation will emphasize an in-depth evaluation of our experimental approach, and it is our concern to discuss important issues of translating laboratory results to gas hydrate reservoirs in nature. We will present results from high-pressure flow-through experiments which are designed to systematically compare soil mechanical behaviour of gas hydrate-bearing sediments in relevant production scenarios focusing on depressurization and CO2 injection. Experimental datasets are analyzed based on numerical models which are able to simulate coupled process dynamics during gas hydrate formation and gas production.
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  • 27
    Publication Date: 2017-01-19
    Description: Manganese nodule coverage is estimated based on multi-beam and deep-towed video nodule survey profiles of about 1,700 km in the China Pioneer Area of Eastern Pacific. Two statistical equations for estimating nodule coverage are derived separately from the multi-beam normal incidence amplitude data and angular amplitude data based on theoretical analysis of influence factors on multi-beam amplitude data. Predictions generated by the normal incidence amplitude model fall within 5% of real nodule coverage, and theoretically calculated angular amplitude data fits well with the original multi-beam amplitudes at incident angles larger than 20° according to nodule coverage estimated from the deep-towed video data.
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  • 28
    Publication Date: 2019-02-01
    Description: Suspended particulate matter (SPM) causes most of the scattering in natural waters and thus has a strong influence on the underwater light field, and consequently on the whole ecosystem. Turbidity is related to the concentration of SPM which usually is measured gravimetrically, a rather time-consuming method. Measuring turbidity is quick and easy, and therefore also more cost-effective. When derived from remote sensing data the method becomes even more cost-effective because of the good spatial resolution of satellite data and the synoptic capability of the method. Turbidity is also listed in the European Union’s Marine Strategy Framework Directive as a supporting monitoring parameter, especially in the coastal zone. In this study, we aim to provide a new Baltic Sea algorithm to retrieve SPM concentration from in situ turbidity and investigate how this can be applied to satellite data. An in situ dataset was collected in Swedish coastal waters to develop a new SPM model. The model was then tested against independent datasets from both Swedish and Lithuanian coastal waters. Despite the optical variability in the datasets, SPM and turbidity were strongly correlated (r = 0.97). The developed model predicts SPM reliably from in situ turbidity (R2 = 0.93) with a mean normalized bias (MNB) of 2.4% for the Swedish and 14.0% for the Lithuanian datasets, and a relative error (RMS) of 25.3% and 37.3%, respectively. In the validation dataset, turbidity ranged from 0.3 to 49.8 FNU (Formazin Nephelometric Unit) and correspondingly, SPM concentration ranged from 0.3 to 34.0 g m–3 which covers the ranges typical for Baltic Sea waters. Next, the medium-resolution imaging spectrometer (MERIS) standard SPM product MERIS Ground Segment (MEGS) was tested on all available match-up data (n = 67). The correlation between SPM retrieved from MERIS and in situ SPM was strong for the Swedish dataset with r = 0.74 (RMS = 47.4 and MNB = 11.3%; n = 32) and very strong for the Lithuanian dataset with r = 0.94 (RMS = 29.5% and MNB = −1.5%; n = 35). Then, the turbidity was derived from the MERIS standard SPM product using the new in situ SPM model, but retrieving turbidity from SPM instead. The derived image was then compared to existing in situ data and showed to be in the right range of values for each sub-area. The new SPM model provides a robust and cost-efficient method to determine SPM from in situ turbidity measurements (or vice versa). The developed SPM model predicts SPM concentration with high quality despite the high coloured dissolved organic matter (CDOM) range in the Baltic Sea. By applying the developed SPM model to already existing remote sensing data (MERIS/Envisat) and most importantly to a new generation of satellite sensors (in particular OLCI on board the Sentinel-3), it is possible to derive turbidity for the Baltic Sea.
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  • 29
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    In:  Journal of the World Aquaculture Society, 48 (2). pp. 353-359.
    Publication Date: 2020-07-16
    Description: Japanese flounder, Paralichthys olivaceus, is an economically important marine fish species in Asia. A suite of 18 microsatellite markers chosen from published genetic linkage maps was used to carry out parentage assignments of 188 hatchery-reared juveniles from a small number of breeders. The probabilities of exclusion for the 18 microsatellite markers were 0.604–0.913, and the effectiveness of combined probability of exclusion reached 100% when using the eight microsatellite markers with higher Excl 1 probabilities. The cultured and wild stocks (WSs) were differentiated in a release-recapture population based on these markers. Of the 321 recaptured offspring, 28.34% were assigned to their parental pairs in our broodstock, whereas the remaining offspring could not be traced back to a possible sire or dam. Significant reduction in genetic diversity of the cultured stock (CS) had not been found compared with that of the WS. The results suggest that CSs released into the wild will not adversely affect the genetic structure of natural populations. Our results demonstrate that these markers provide an efficient tool for parentage assignments and genetic analysis of Japanese flounder.
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  • 30
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    In:  Isotopes in Environmental and Health Studies, 53 (6). pp. 563-579.
    Publication Date: 2020-01-02
    Description: The spatial variations in the elemental and stable carbon, nitrogen, and sulphur isotope composition of bladder wrack (Fucus vesiculosus) growing along the shore line of the semi-enclosed urbanized Kiel Fjord (western Baltic Sea) was investigated at more than 60 sites. The analyses of the carbon-nitrogen-sulphur (CNS) stoichiometry and C and N stable isotope signature of F. vesiculosus displayed substantial differences between the north-western and the south-eastern parts of the Kiel Fjord. Different size classes displayed in part differences in C:N and C:S ratios, and the carbon isotope composition, reflecting the impact of the boundary conditions during growth. Whereas the sulphur isotope composition was controlled by the assimilation of seawater sulphate, the carbon isotope composition reflected the difference in the composition of surface waters. The δ15N values of the organic tissue tend to be an integrated monitor of anthropogenic impacts on the fjord. Results are compared to the composition of surface waters.
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  • 31
    Publication Date: 2021-02-08
    Description: The fluttering shearwater (Puffinus gavia) is an abundant seabird endemic to breeding colonies in northern and central New Zealand. The species remains poorly studied, and here we present the first study to examine its breeding biology in detail. Fluttering shearwater nests were monitored daily from laying in September 2015 to fledging in January 2016 on Burgess Island (Mokohinau Islands group) in the outer Hauraki Gulf, northern New Zealand. Burrows were generally simple and non-branched. Eggs were laid over a period of 39 days with laying peaking 12th September. Incubation was 50 ± 3.7 days and chicks fledged after an average of 74 ± 4.3 days, from late December to the end of January. Chick development corresponds to the pattern observed for other Procellariiformes, gaining body mass rapidly to a maximum of 115% of adult mass, and then losing weight until fledging. Chicks were fed most nights throughout chick-rearing, indicating adult birds have access to a stable food supply close to the colony. Breeding success was 63.8% and similar to other Puffinus species. This study provides baseline biological data for a poorly studied, yet common, New Zealand endemics seabird. The obtained new information will allow for further ecological investigations and improved conservation management for the species
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  • 32
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    In:  Journal of Asian Natural Products Research, 17 (5). pp. 468-474.
    Publication Date: 2017-10-04
    Description: Chemical examination of the fermentation broth of a sponge-associated fungus Trichoderma harzinum HMS-15-3 led to the isolation of four pairs of new C13 lipid enantiomers namely harzianumols A–H (1a–4b). Their structures were elucidated on the basis of extensive spectroscopic (IR, MS, 1D, and 2D NMR) data analysis, including the modified Mosher's method for the assignment of their absolute configurations. The new compounds were evaluated for antihyperlipidemic effects in HepG2 cells.
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  • 33
    Publication Date: 2020-02-06
    Description: This study aimed to differentiate local and migratory spawning groups of the shortfin squid Illex argentinus caught in Brazilian waters using geometric and traditional morphometric methods and size-selective processes. The back-calculated length distributions reconstructed from daily growth increments deposited in the gladius allowed the identification of size-selective processes that may be related to different life history strategies. Landmark analysis on body shape (geometric morphometric) revealed that spawning groups presented significant ontogenetic variations in terms of body outline. In addition, traditional morphometric methods, based on multivariate analysis, associated juveniles of the expected migratory group (large size) and differentiated them from the local group individuals (small size). The changes in form, probably linked to the environmental gradients experienced by individuals throughout ontogeny, were interpreted as adaptations to improve swimming capacity. Migrant individuals have being differentiated from the smaller sizes group by body characteristics (broad fins, elongated and thicker mantle), which may increase the ability to perform long migrations.
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  • 34
    Publication Date: 2020-07-30
    Description: We investigated the biogeochemical constituents, microbial communities and functional genes (mcr and dsr) associated with anaerobic methane oxidation and sulfate reduction, and metabolic activities by sulfate reduction in the sulfate–methane transition zone (SMTZ) of gas-hydrate-bearing sediment of the Ulleung Basin in the East Sea. Maxima in the sulfate reduction rate (12.6 nmol cm¡3 d¡1), CO concentration (83 mM), and gene abundances of dsrA (9.1 £ 106 copies cm¡3) and mcrA (11.6 £ 106 copies cm¡3) occurred in the SMTZ. The peaks of CO consistently found in the SMTZ suggested that CO is an intermediate metabolic product related to methane oxidation. Candidate division JS1, the predominant bacterial group that comprised 59.0–63.7% of the 16S rRNA gene sequences, was recognized as an important organic carbon oxidizer. Both Marine Benthic Group D (MBGD) and Marine Benthic Group B (MBGB), which constituted 40.8–52.9 and 10.3–43.9% of the 16S rRNA gene sequences, respectively, were the dominant archaeal groups. Analysis of functional gene diversity revealed that anaerobic methanotroph-1-related phylotypes appeared to be the major CH4 oxidizer, whereas Firmicutes-like group was a predominant sulfate reducer in the 0.8 mbsf in SMTZ with low SO42¡ concentration. Overall results indicated that JS1 and two archaeal groups (MBGB and MBGD) seem to play a significant role in carbon and elements cycles in the gas-hydrate-bearing subsurface sediment of the Ulleung Basin.
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  • 35
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    In:  Fish and Fisheries, 18 (2). pp. 199-211.
    Publication Date: 2019-02-01
    Description: Managing fisheries presents trade-offs between objectives, for example yields, profits, minimizing ecosystem impact, that have to be weighed against one another. These trade-offs are compounded by interacting species and fisheries at the ecosystem level. Weighing objectives becomes increasingly challenging when managers have to consider opposing objectives from different stakeholders. An alternative to weighing incomparable and conflicting objectives is to focus on win–wins until Pareto efficiency is achieved: a state from which it is impossible to improve with respect to any objective without regressing at least one other. We investigate the ecosystem-level efficiency of fisheries in five large marine ecosystems (LMEs) with respect to yield and an aggregate measure of ecosystem impact using a novel calibration of size-based ecosystem models. We estimate that fishing patterns in three LMEs (North Sea, Barents Sea and Benguela Current) are nearly efficient with respect to long-term yield and ecosystem impact and that efficiency has improved over the last 30 years. In two LMEs (Baltic Sea and North East US Continental Shelf), fishing is inefficient and win–wins remain available. We additionally examine the efficiency of North Sea and Baltic Sea fisheries with respect to economic rent and ecosystem impact, finding both to be inefficient but steadily improving. Our results suggest the following: (i) a broad and encouraging trend towards ecosystem-level efficiency of fisheries; (ii) that ecosystem-scale win–wins, especially with respect to conservation and profits, may still be common; and (iii) single-species assessment approaches may overestimate the availability of win–wins by failing to account for trade-offs across interacting species.
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  • 36
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    In:  Expert Review of Anti-infective Therapy, 15 (5). pp. 425-433.
    Publication Date: 2018-12-17
    Description: Introduction: The combination of growing antimicrobial resistance with a dry pipeline has resulted in infections that can no longer be treated. Specific reasons have led to companies’ exit from the antibacterial space, however recent incentives are spurring interest to reinvigorate the pipeline. Areas covered: This article summarizes the available information on the discovery, developmental, and regulatory challenges in antibacterial development that have led to disinterest in the space, as well as ongoing incentives such as public-private partnerships and streamlined pathways to mend these challenges and bring new antibiotics to patients in need. Expert commentary: Clinicians should not only understand the reasons for the decline in antibiotic development that have resulted in the dry pipeline, but also the ongoing initiatives in place to build an appropriate supply. Doing so will result in greater appreciation and prudent use of these life-saving drugs when they become available.
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  • 37
    Publication Date: 2021-02-08
    Description: Mass fractions of Sn and In were determined in sixteen geological reference materials including basaltic/mafic (BCR‐2, BE‐N, BHVO‐1, BHVO‐2, BIR‐1, OKUM, W‐2, WS‐E), ultramafic (DTS‐2b, MUH‐1, PCC‐1, UB‐N) and felsic/sedimentary reference materials (AGV‐2, JA‐1, SdAR‐M2, SdAR‐H1). Extensive digestion and ion exchange separation tests were carried out in order to provide high yields (〉 90% for Sn, 〉 85% for In), low total procedural blanks (~ 1 ng for Sn, 〈 3 pg for In) and low analytical uncertainties for the elements of interest in a variety of silicate sample matrices. Replicate analyses (n = 2–13) of Sn‐In mass fractions give a combined measurement uncertainty of 2u that are generally 〈 3% and in agreement with literature data, where available. We present the first high precision In data for reference materials OKUM (32.1 ± 1.5 ng g−1), DTS‐2b (2.03 ± 0.25 ng g−1), MUH‐1 (6.44 ± 0.30 ng g−1), and PCC‐1 (3.55 ± 0.35 ng g−1) as well as the first Sn data for MUH‐1 (0.057 ± 0.010 μg g−1) and DTS‐2b (0.623 ± 0.018 μg g−1).
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  • 38
    Publication Date: 2020-10-26
    Description: Ecological studies based on time-series often investigate community changes centered on species abundance or biomass but rarely expose the consequential functional aspects underlying such changes. Functional diversity measures have proven to be more accurate predictors for ecosystem functioning than traditional taxonomic approaches and hence gained much attention. There are only limited studies available that analyse the functional implications behind decadal changes of entire communities. We studied zoobenthic communities of two habitats, sheltered and exposed, of a coastal system subject to contrasting changes in community composition over the past four decades. Besides eutrophication and climate-related impacts, the system has been invaded by a non-native polycheate Marenzelleria spp., adding altered functional properties to the communities. The functional dispersion (FDis) metric was used as a measure for comparing the functional diversity of the contrasting habitats, with special focus on the role of Marenzelleria for the entire communities. We highlight changes in the functional identity of the communities, expressed as community-weighted means of trait expression (CWM), using multivariate techniques, and investigate the relationship between taxonomic and functional changes. Despite contrasting community developments in the two habitats, with characteristics traditionally suggesting different environmental quality, we found that the FDis in both habitats remained similar and increased with the introduction of Marenzelleria. Although showing maintained functional diversity across time and space, the functional identity (CWM) of communities changed irrespective of taxonomical differences. Examples include inter alia alterations in palatability proxies, feeding position and sediment transportation types, indicating changed functionality of zoobenthos in coastal systems. We show, when focussing on qualitative functional changes of communities, it is important to evaluate the underlying functional identity, and not only rely on measures of the diversity of functions per se, as the quality indication of expressed functional traits can be concealed when using multi-functionality approaches.
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  • 39
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    In:  Journal of Natural History, 49 (45-48). pp. 2891-2903.
    Publication Date: 2016-02-23
    Description: This paper reviews aspects of the biology of copepods infecting marine fish commercially cultured at fish farms or held as broodstock at governmental hatcheries in Japan. In total, 20 species of parasitic copepods have been reported from these fish: they are mostly caligids (12 spp.), followed by lernaeopodids (4 spp.), pennellid (1 sp.), chondracanthid (1 sp.), taeniacanthid (1 sp.), and unidentified species (1 sp.). The identified copepods are: Caligus fugu, C. lagocephalus, C. lalandei, C. latigenitalis, C. longipedis, C. macarovi, C. orientalis, C. sclerotinosus, C. spinosus, Lepeophtheirus longiventralis, L. paralichthydis, L. salmonis (Caligidae); Alella macrotrachelus, Clavella parva, Parabrachiella hugu, P. seriolae (Lernaeopodidae); Peniculus minuticaudae (Pennellidae); Acanthochondria priacanthi (Chondracanthidae); and Biacanthus pleuronichthydis (Taeniacanthidae). The fish recorded as hosts include carangids (4 spp.), sparids (2 spp.), monacanthids (2 spp.), salmonids (2 spp.), scombrid (1 sp.), tetraodontid (1 sp.), pleuronectid (1 sp.), paralichthyid (1 sp.), and trichodontid (1 sp.). Only five species (C. orientalis, L. longiventralis, L. salmonis, C. parva and A. priacanthi) parasitize farmed fish in subarctic waters, while all other species (15 spp.) infect farmed fish in temperate waters. No information is yet available on copepods from fish farmed in subtropical waters. Three species of Caligus (C. fugu, C. sclerotinosus and C. longipedis) are serious pests in aquaculture of Japanese pufferfish (Takifugu rubripes), red seabream (Pagrus major), and striped jaw (Pseudocaranx dentex), respectively. Due to its one-host life cycle that is unique among pennellids, P. minuticaudae is considered as a potentially serious pest with further development of aquaculture of its filefish hosts, threadsail filefish (Stephanolepis cirrhifer) and black scraper (Thamnaconus modestus). Infection of farmed salmonids by L. salmonis is not a serious problem in Japan
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  • 40
    Publication Date: 2015-08-03
    Description: The Soil Moisture and Ocean Salinity (SMOS) mission observes brightness temperatures at a low microwave frequency of 1.4 GHz (L-band) with a daily coverage of the polar regions. L-band radiometry has been shown to provide information on the thickness of thin sea ice. Here, we apply a new emission model that has previously been used to investigate the impact of snow on thick Arctic sea ice. The model has not yet been used to retrieve ice thickness. In contrast to previous SMOS ice thickness retrievals, the new model allows us to include a snow layer in the brightness temperature simulations. Using ice thickness estimations from satellite thermal imagery, we simulate brightness temperatures during the ice growth season 2011 in the northern Baltic Sea. In both the simulations and the SMOS observations, brightness temperatures increase by more than 20 K, most likely due to an increase of ice thickness. Only if we include the snow in the model, the absolute values of the simulations and the observations agree well (mean deviations below 3.5 K). In a second comparison, we use high-resolution measurements of total ice thickness (sum of ice and snow thickness) from an electromagnetic (EM) sounding system to simulate brightness temperatures for 12 circular areas. While the SMOS observations and the simulations that use the EM modal ice thickness are highly correlated (r2=0.95), the simulated brightness temperatures are on average 12 K higher than observed by SMOS. This would correspond to an 8-cm overestimation of the modal ice thickness by the SMOS retrieval. In contrast, if the simulations take into account the shape of the EM ice thickness distributions (r2=0.87), the mean deviation between simulated and observed brightness temperatures is below 0.1 K.
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  • 41
    Publication Date: 2019-08-19
    Description: Marine calcifiers as a plankton functional type (PFT) are a crucial part of the global carbon cycle, being responsible for much of the carbon export to the deep ocean entering via biological pathways. Deep ocean carbon export through calcifiers is controlled by physiological, ecological, and biogeochemical factors. This paper describes the implementation of a calcifying phytoplankton PFT in the University of Victoria Earth System Climate Model, version 2.9 (UVic ESCM), and mechanistic improvements to the representation of model carbon export (a full calcite tracer, carbonate chemistry dependent calcite dissolution rates, and a ballasting scheme). An iterative method for stabilizing and tuning the biogeochemistry is furthermore described. The UVic ESCM now fills a niche in Earth system modelling that was previously unoccupied in that it is relatively inexpensive to run, yet resolves the complete Earth system carbon cycle including prognostic calcium carbonate and a separate phytoplankton calcifier PFT. The model is now well suited to testing feedbacks between the carbonate and carbon cycles and the climate system as transient simulations. The modifications described improve the UVic ESCM's mechanistic realism without compromising performance with respect to observed carbon and nutrient fluxes. Primary production, export production, particulate organic carbon, and calcite fluxes all fall within independently observed estimates.
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  • 42
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    In:  Journal of Natural History, 49 (45-48). pp. 2727-2741.
    Publication Date: 2017-04-11
    Description: The current state of development of an interactive electronic identification key for females of the marine pelagic microcopepod family Oncaeidae is presented. To date, 112 species have been described, allocated to seven genera (Archioncaea, Conaea, Epicalymma, Monothula, Oncaea s.str., Spinoncaea, and Triconia) and 16 species groups within the speciose paraphyletic taxon Oncaea s.l. Only two species of Oncaea s.l. show an uncertain group status. Of all described oncaeids, seven species are not yet included in the key due to inadequacies in morphological description and/or lack of type material for re-examination. In addition, seven morphologically distinct species and two new species groups are considered that have not yet been formally described. The key uses easily distinguishable morphological characters as far as possible (e.g. body size, proportional lengths of urosomites, length of P5 exopod) and includes more difficult characters (e.g. spine counts on swimming legs, proportional spine lengths) where required for unequivocal identification. The characters used in the key allow the identification of genera and species groups by investigators with limited taxonomic experience; species separation in most cases requires some advanced dissection skills. Potential identification problems caused by difficulties discerning minute morphological features or intraspecific morphometric variability are discussed. The present version of the identification key still requires complementary illustrations of character states and inclusion of fact sheets summarizing the characteristics of each species with notes on taxonomic uncertainties and links to databases providing zoogeographical and genetic information.
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  • 43
    Publication Date: 2020-07-30
    Description: The advent of genomic-, transcriptomic- and proteomic-based approaches has revolutionized our ability to describe marine microbial communities, including biogeography, metabolic potential and diversity, mechanisms of adaptation, and phylogeny and evolutionary history. New interdisciplinary approaches are needed to move from this descriptive level to improved quantitative, process-level understanding of the roles of marine microbes in biogeochemical cycles and of the impact of environmental change on the marine microbial ecosystem. Linking studies at levels from the genome to the organism, to ecological strategies and organism and ecosystem response, requires new modelling approaches. Key to this will be a fundamental shift in modelling scale that represents micro-organisms from the level of their macromolecular components. This will enable contact with omics data sets and allow acclimation and adaptive response at the phenotype level (i.e. traits) to be simulated as a combination of fitness maximization and evolutionary constraints. This way forward will build on ecological approaches that identify key organism traits and systems biology approaches that integrate traditional physiological measurements with new insights from omics. It will rely on developing an improved understanding of ecophysiology to understand quantitatively environmental controls on microbial growth strategies. It will also incorporate results from experimental evolution studies in the representation of adaptation. The resulting ecosystem-level models can then evaluate our level of understanding of controls on ecosystem structure and function, highlight major gaps in understanding and help prioritize areas for future research programs. Ultimately, this grand synthesis should improve predictive capability of the ecosystem response to multiple environmental drivers.
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  • 44
    Publication Date: 2019-01-23
    Description: Some 290 species of squids comprise the order Teuthida that belongs to the molluscan Class Cephalopoda. Of these, about 30-40 squid species have substantial commercial importance around the world. Squid fisheries make a rather small contribution to world landings from capture fisheries relative to that of fish, but the proportion has increased steadily over the last decade, with some signs of recent leveling off. The present overview describes all substantial squid fisheries around the globe. The main ecological and biological features of exploited stocks, and key aspects of fisheries management are presented for each commercial species of squid worldwide. The history and fishing methods used in squid fisheries are also described. Special attention has been paid to interactions between squid fisheries and marine ecosystems including the effects of fishing gear, the role of squid in ecosystem change induced by overfishing on groundfish, and ecosystem-based fishery management.
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  • 45
    Publication Date: 2016-02-23
    Description: Sea ice leads play an essential role in ocean-ice-atmosphere exchange, in ocean circulation, geochemistry and in ice dynamics. Their precise detection is crucial for altimetric estimations of sea ice thickness and volume. This study evaluates the performance of the SARAL/AltiKa altimeter to detect leads and to monitor their spatio-temporal dynamics. We show that a pulse peakiness parameter (PP) used to detect leads by Envisat RA-2 and ERS-1,-2 altimeters is not suitable because of saturation of AltiKa return echoes over the leads. The signal saturation results in loss of 6–10% of PP data over sea ice. We propose a different parameter: maximal power of waveform, and define the threshold to discriminate the leads. Our algorithm can be applied from December until May. It detects well the leads of small and medium size: from 200 m to 3–4 km. So, the combination of the high-resolution altimetric estimates with low-resolution thermal infra-red or radiometric lead fraction products could enhance the capability of remote sensing to monitor sea ice fracturing.
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  • 46
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    In:  Hydrological Sciences Journal - Journal Des Sciences Hydrologiques, 60 (7-8). pp. 1225-1241.
    Publication Date: 2017-01-24
    Description: The impact of fire on daily discharges from two mountainous basins located in the permafrost region of Eastern Siberia; the Vitimkan (969 km2) and Vitim rivers (18 200 km2), affected by fire over 78% and 49% of their areas, respectively, in 2003 was investigated. The results of hydrological and meteorological data analysis suggested that the Vitimkan River basin had a rapid and profound hydrological response to wildfire in 2003 expressed through an increased summer flow of 41% (133 mm). Conversely, the larger Vitim River basin showed no significant changes in discharges after the fire. The parameters of the process-based hydrological model Hydrograph were estimated for pre-fire conditions. The results of runoff simulations conducted for continuous pre-fire periods of 1966–2002 and 1970–2002 for the Vitimkan and Vitim River basins respectively on a daily time step showed satisfactory agreement with the observed flow series of both basins. Significant underestimation of precipitation and its poor representativeness for mountainous watersheds was revealed as the main cause of observed and simulated flow discrepancies, especially for high flood events. The set of dynamic parameters was developed based on data analysis and post-fire landscape changes as derived from a literature review. The model was applied to investigate the processes in the soil column and their effect on runoff formation during the post-fire period. The new set of model parameters implied intensification of soil thaw, reduction of infiltration rate and evapotranspiration, and increase of upper subsurface flow fraction in summer flood events following the fire. According to modelling results, the post-fire thaw depth exceeded the pre-fire thaw depth by 0.4–0.7 m. Total evapotranspiration reduced by 40% in summer months, while surface flow increased almost 2.5 times during maximum flood events.
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  • 47
    Publication Date: 2019-09-23
    Description: Macroalgae, especially perennial species, are exposed to a seasonally variable fouling pressure. It was hypothesized that macroalgae regulate their antifouling defense to fouling pressure. Over one year, the macrofouling pressure and the chemical anti-macrofouling defense strength of the brown algae Fucus vesiculosus and Fucus serratus were assessed with monthly evaluation. The anti-macrofouling defense was assessed by means of surface-extracted Fucus metabolites tested at near-natural concentrations in a novel in situ bioassay. Additionally, the mannitol content of both Fucus species was determined to assess resource availability for defense production. The surface chemistry of both Fucus species exhibited seasonal variability in attractiveness to Amphibalanus improvisus and Mytilus edulis. Of this variability, 50–60% is explained by a sinusoidal model. Only F. vesiculosus extracts originating from the spring and summer significantly deterred settlement of A. improvisus. The strength of macroalgal antifouling defense did not correlate either with in situ macrofouling pressure or with measured mannitol content, which, however, were never depleted.
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  • 48
    Publication Date: 2019-01-21
    Description: We used our novel and programmable Porpoise Alarm (PAL, patd.) to synthesize life-like, electronic harbour porpoise communication signals based on those described for captive animals. In the Little Belt, Denmark, we employed PAL (source level 158 ± 1 dB p–p re 1 μPa@1 m; centroid frequency 133 ± 8.5 kHz) to synthesize three aggressive click train types termed “A”, “F3” and “M1” to naive, free-living harbour porpoises. Via theodolite tracking (372 h of total visual effort spread over 10 expeditions) we found that, depending on signal type, porpoises either avoid or become attracted to PAL: Signal types “A” and “F3” are slight deterrents, porpoises increasing minimum range (+23 to 32 m, respectively), whereas “M1” attracts porpoises, reducing range (by − 29 m). As determined via archival acoustic detectors (AADs), both signals “F3” and “M1” led the animals to significantly intensify their click rate (by +10% and 68%, respectively) while signal “A” led to a significant reduction ( − 59%). We propose that equipping fishing gear with PAL emitting signal “F3” could potentially reduce porpoise by-catch by increasing (1) awareness through enhanced echolocation and (2) distance to the nets. Detection probability and radius of PAL/AAD tandems could be improved by emitting signal “M1” to focus porpoise echolocation signals on the AAD. The signal may also be useful in luring animals away from hazards, which may be helpful for conservation measures prior to the onset of harmful acoustic activities such as pile-driving, seismic exploration or ammunition clearance.
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  • 49
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    Taylor & Francis
    In:  Israel Journal of Ecology & Evolution, 61 (2). pp. 77-89.
    Publication Date: 2017-04-13
    Description: Rarity of species is often considered to set priorities for biodiversity conservation. Less abundant species are expected to be at higher risk of extinction and make significant contribution to food web functioning. However, the relationship between species abundance and position in food webs is still unclear. Here we tested possible correlations between species abundance and structural position in Prince William Sound food web. Species abundance was inferred from biomass data and structural position was characterized by 13 centrality indices. We found that less abundant species have higher trophic positions and display more generalist feeding strategies. However, positive correlations link most of the centrality indices to population size. Thus, being locally rare translates into more peripheral food web positions and implies marginal roles in the spread of indirect effects. Species characterized by largest population size are responsible for the transfer of largest amounts of biomass and regulate the transmission of indirect effects. Less abundant species are of marginal structural importance and are exposed to impacts mediated by larger populations. In Prince William Sound ecosystem, rarity is associated with critical food web positions and does not simply reflect a marginal contribution to biodiversity. We suggest that knowing the food web position of rare species might help to formulate more effective, system-level solutions for their conservation, rather than simply focusing on the direct treatment of symptoms.
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  • 50
    Publication Date: 2019-02-01
    Description: Despite considerable progress in the production of alternative diets, small concentrations of antinutrients remain common in aquaculture nutrition, resulting in a perpetual limitation with regard to the inclusion of plant ingredients in aquafeeds. These compounds are known to impair the general performance of fish when fed for a prolonged period of time, potentially affecting the animal's susceptibility to stress, too. Therefore, a 12-week feeding trial was conducted to examine the chronic effects of purified rapeseed protein concentrate (RPC), containing low concentrations of glucosinolates and phytic acid, on the relative expression of multiple target genes in the liver of juvenile turbot (Psetta maxima, L.). Our results revealed divergent patterns of gene expression, suggesting different coping strategies dependent on the grade of RPC substitution. Data implies increased metabolic rate of turbot fed a 33% RPC-substituted diet due to an upregulation of cytochrome c oxidase mRNA, accompanied by minor adjustments in metabolic pathways. While no signs of reduced welfare were found, data adumbrate a beneficial hormetic reaction. In the highest treatment level (66% RPC), diminished fish condition and reduced growth performance coincided with a downregulation of insulin-like growth factor I, further indicating a potential impaired resistance to stress. An additional downregulation of transferrin hints towards an increased liability to bacterial infections.
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  • 51
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    Wiley-Blackwell
    In:  (In Press / Accepted) Zoological Journal of the Linnean Society .
    Publication Date: 2020-04-21
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  • 52
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    Wiley-Blackwell
    In:  Geology Today, 31 (4). pp. 153-159.
    Publication Date: 2020-07-30
    Description: The geological development of the Fogo island volcano commenced in the early Quaternary, and much later during the Last Glacial stage this involved a mega-scale lateral collapse of the former edifice. This later event created a large caldera-like landform open to the east, the floor of which is known as the Chã, and subsequently within this a strato-volcanic cone has grown. The last phase of volcanic activity started in late 2014 and persisted for 77 days. It had a devastating impact on the lives of the 1000 plus people who were living within the ‘caldera’, since two large villages and a smaller one were each totally destroyed in a matter of days by the advancing lavas. In addition, large areas of cultivated land, upon which the inhabitants were dependent for their livelihood, were enveloped by lava. The eruption proved to be of a greater magnitude than the immediately preceding one of 1995, when a mass evacuation was necessary but as only a few buildings were affected, resettlement followed. Unfortunately the much greater devastation to the human environment makes it doubtful whether any significant resettlement will be possible after the 2014–2015 event.
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  • 53
    Publication Date: 2020-06-19
    Description: This review covers 214 marine natural compounds and 23 of their synthetic analogs, which were discovered and/or synthesized from mid-2009 to August 2014. The antifouling (AF) compounds reported have medium to high bioactivity (with a threshold of EC(50) 〈 15.0 mg ml(-1)). Among these compounds, 82 natural compounds were identified as new structures. All the compounds are marine-derived, demonstrating that marine organisms are prolific and promising sources of natural products that may be developed as environmentally friendly antifoulants. However, this mini-review excludes more than 200 compounds that were also reported as AF compounds but with rather weak bioactivity during the same period. Also excluded are terrestrial-derived AF compounds reported during the last five years. A brief discussion on current challenges in AF compound research is also provided to reflect the authors' own views in terms of future research directions.
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  • 54
    Publication Date: 2020-07-09
    Description: The White Shrimp (Litopenaeus vannamei) is reared in several types of systems. Changes in pH in some can produce sub-lethal effects that result in poor growth and survival. The aim of the present study was to detennine the acidic and basic pH 50% lethal limits after 96 h exposure (pH50_96 h) and to evaluate the sub-lethal effects of pH on oxidative stress parameters in juvenile L. vannamei. The experimental design comprised nine treatments with three replications of each. The nine treatments consisted of pH 10.5, 10.0, 9.5, 9.0, 7.0, 5.0, 4.5, 4.0 and 3.5. The treatment at 7.0 was used as the control. The sub~lethal pH tests were: basic pH 9.5, neutral pH 7.0 (control) and acidio pH 4.5. For each experimental pH and sampling point, the hemolymph of six shrimp was collected to determine catalase and glutathione S-transferase's activities and total antioxidant capacity. The values of lethat pH50 at 24, 48, 72 and 96 h for juvenile L. vannamei had basic pH values equal to 9.82, 9.62, 9.59 and 9.58 and acidic pH values of 3.86, 3.92, 3.94 and 4.04, respectively. The shrimp exposed to basic and acidic pH levels showed antioxidant responses with changes in antioxidant activity.
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  • 55
    Publication Date: 2019-02-01
    Description: Abstract: Context: Some Ajuga L. (Lamiaceae) species are traditionally used for the treatment of malaria, as well as fever, which is a common symptom of many parasitic diseases. Objective: In the continuation of our studies on the identification of antiprotozoal secondary metabolites of Turkish Lamiaceae species, we have investigated the aerial parts of Ajuga laxmannii. Materials and methods: The aerial parts of A. laxmannii were extracted with MeOH. The H2O subextract was subjected to polyamide, C18-MPLC and SiO2 CCs to yield eight metabolites. The structures of the isolates were elucidated by NMR spectroscopy and MS analyses. The extract, subextracts as well as the isolates were tested for their in vitro antiprotozoal activities against Plasmodium falciparum, Trypanasoma brucei rhodesiense, T. cruzi and Leishmania donovani at concentrations of 90–0.123 μg/mL. Results: Two iridoid glycosides harpagide (1) and 8-O-acetylharpagide (2), three o-coumaric acid derivatives cis-melilotoside (3), trans-melilotoside (4) and dihydromelilotoside (5), two phenylethanoid glycosides verbascoside (6) and galactosylmartynoside (7) and a flavone-C-glycoside, isoorientin (8) were isolated. Many compounds showed moderate to good antiparasitic activity, with isoorientin (8) displaying the most significant antimalarial potential (an IC50 value of 9.7 μg/mL). Discussion and conclusion: This is the first report on the antiprotozoal evaluation of A. laxmannii extracts and isolates. Furthermore, isoorientin and dihydromelilotoside are being reported for the first time from the genus Ajuga.
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  • 56
    Publication Date: 2020-02-06
    Description: The Red Sea has been recognized as a unique region to study the effects of ecohydrographic gradients at a basin-wide scale. Its gradient of temperature and salinity relates to the Indian Ocean monsoon and associated wind-driven transport of fertile and plankton-rich water in winter from the Gulf of Aden into the Red Sea. Subsequent evaporation and thermohaline circulation increase the salinity and decrease water temperatures toward the North. Compared with other ocean systems, however, relatively little is known about the zooplankton biodiversity of the Red Sea and how this relates to Red Sea latitudinal gradients. Among the most abundant zooplankton taxa are Chaetognatha, which play an important role as secondary consumers in most marine food webs. Since Chaetognatha are sensitive to changes in temperature and salinity, we surmised latitudinal changes in their biodiversity, community structure and diel variability along the coast of Saudi Arabia. Samples were collected at nine coral reefs spanning approximately 1500 km, from the Gulf of Aqaba in the northern Red Sea to the Farasan Archipelago in the southern Red Sea. Thirteen Chaetognatha species belonging to two families (Sagittidae and Krohnittidae) were identified. Latitudinal environmental changes and availability of prey (i.e. Copepoda, Crustacea) altered Chaetognatha density and distribution. The cosmopolitan epiplanktonic Flaccisagitta enflata (38.1%) dominated the Chaetognatha community, and its abundance gradually decreased from South to North. Notable were two mesopelagic species (Decipisagitta decipiens and Caecosagitta macrocephala) in the near-reef surface mixed layers at some sites. This was related to wind-induced upwelling of deep water into the coral reefs providing evidence of trophic oceanic subsidies. Most Sagittidae occurred in higher abundances at night, whereas Krohnittidae were more present during the day. Chaetognatha with developing (stage II) or mature ovaries (stage III) were more active at night, demonstrating stage-specific diel vertical migration as a potential predator avoidance strategy.
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  • 57
    Publication Date: 2020-07-15
    Description: The herbal remedy, milk thistle (Silybum marianum), has been used in traditional medicine for various liver, kidney, and gall bladder ailments. For over a decade, our research group has been investigating the flavonolignans obtained from this medicinal herb for cancer chemoprevention and hepatoprotection.[1–6] Recently, we extended our studies toward examining the diversity as well as distribution patterns of fungal endophytes in leaves, stem, and roots of milk thistle.[7] These fungi inhabit the internal living tissues of the host plants asymptomatically, though they may also cause disease over time.[8] In addition to the phylogenetic profiling of these endophytes, a series of fungal extracts were also examined for chemical composition. Although the plant–endophyte relationship may ormay not be mutualistic, the compounds produced by some endophytes could play a role in the growth and survival of the host. In a previous study, Penicillium restrictum, isolated from milk thistle, yielded promising secondary metabolites.[9] Hence, in pursuit of interesting chemistry, a related monoverticillate endophytic Penicillium sp. was explored.
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  • 58
    Publication Date: 2020-06-19
    Description: This study aimed to improve understanding of the strategies developed by the Mediterranean seaweed Taonia atomaria to chemically control bacterial epibiosis. An experimental protocol was optimized to specifically extract algal surface-associated metabolites by a technique involving dipping in organic solvents whilst the integrity of algal cell membranes was assessed by fluorescent microscopy. This methodology was validated using mass spectrometry-based profiles of algal extracts and analysis of their principal components, which led to the selection of methanol as the extraction solvent with a maximum exposure time of 15 s. Six compounds (A–F) were identified in the resulting surface extracts. Two of these surface-associated compounds (B and C) showed selective anti-adhesion properties against reference bacterial strains isolated from artificial surfaces while remaining inactive against epibiotic bacteria of T. atomaria. Such specificity was not observed for commercial antifouling biocides and other molecules identified in the surface or whole-cell extracts of T. atomaria.
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  • 59
    Publication Date: 2017-05-02
    Description: Despite the importance of Ancistrocheirus lesueurii in the diet of a wide variety of oceanic predators, many aspects of its biology are unknown. We report new observations on the reproductive system of the species and provide age estimates of one normal and two intersexual males based on the number of increments in the statoliths. The age of the examined mature males was estimated to be more than 2 years, increasing the maximum age known for males of the species. Female A. lesueurii have specific modified areas for spermatangia reception in the nuchal region. The morphology of the right hectocotylized ventral arm and the relatively large spermatophore are also described.
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  • 60
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    Taylor & Francis
    In:  Journal of Biomolecular Structure and Dynamics, 36 (10). pp. 2699-2712.
    Publication Date: 2020-01-02
    Description: Glyoxalase is one of two enzymes of the glyoxalase detoxification system against methylglyoxal and other aldehydes, the metabolites derived from glycolysis. The glyoxalase system is found almost in all living organisms: bacteria, protozoa, plants, and animals, including humans, and is related to the class of ‘life essential proteins’. The enzyme belongs to the expanded Glyoxalase/Bleomycin resistance protein/Dioxygenase superfamily. At present the GenBank contains about 700 of amino acid sequences of this enzyme type, and the Protein Data Bank includes dozens of spatial structures. We have offered a novel approach for structural identification of glyoxalase I protein family, which is based on the selecting of basic representative proteins with known structures. On this basis, six new subfamilies of these enzymes have been derived. Most populated subfamilies A1 and A2 were based on representative human Homo sapiens and bacterial Escherichia coli enzymes. We have found that the principle feature, which defines the subfamilies’ structural differences, is conditioned by arrangement of N- and C-domains inside the protein monomer. Finely, we have deduced the structural classification for the glyoxalase I and assigned about 460 protein sequences distributed among six new subfamilies. Structural similarities and specific differences of all the subfamilies have been presented. This approach can be used for structural identification of thousands of the so-called hypothetical proteins with the known PDB structures allowing to identify many of already existing atomic coordinate entrees.
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  • 61
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    Taylor & Francis
    In:  Atmospheric and Oceanic Science Letters, 10 (4). pp. 325-328.
    Publication Date: 2020-01-02
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  • 62
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    American Chemical Society (ACS)
    In:  Environmental Science & Technolog, 51 (23). pp. 13733-13739.
    Publication Date: 2020-02-06
    Description: The majority of methane produced in many anoxic sediments is released via ebullition. These bubbles are subject to dissolution as they rise, and dissolution rates are strongly influenced by bubble size. Current understanding of natural methane bubble size distributions is limited by the difficulty in measuring bubble sizes over wide spatial or temporal scales. Our custom optical bubble size sensors recorded bubble sizes and release timing at 8 locations in Upper Mystic Lake, MA continuously for 3 months. Bubble size distributions were spatially heterogeneous even over relatively small areas experiencing similar flux, suggesting that localized sediment conditions are important to controlling bubble size. There was no change in bubble size distributions over the 3 month sampling period, but mean bubble size was positively correlated with daily ebullition flux. Bubble data was used to verify the performance of a widely used bubble dissolution model, and the model was then used to estimate that bubble dissolution accounts for approximately 10% of methane accumulated in the hypolimnion during summer stratification, and at most 15% of the diffusive air–water–methane flux from the epilimnion.
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  • 63
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    American Chemical Society (ACS)
    In:  Environmental Science & Technology, 49 (22). pp. 13121-13129.
    Publication Date: 2019-10-24
    Description: Laboratory sediment incubations and continuous ebullition monitoring over an annual cycle in the temperate Saar River, Germany confirm that impounded river zones can produce and emit methane at high rates (7 to 30 (g CH4 m–3 d–1) at 25 °C and 270 to 700 (g CH4 m–2 yr–1), respectively). Summer methane ebullition (ME) peaks were a factor of 4 to 10 times the winter minima, and sediment methane formation was dominated by the upper sediment (depths of 0.14 to 0.2 m). The key driver of the seasonal ME dynamics was temperature. An empirical model relating methane formation to temperature and sediment depth, derived from the laboratory incubations, reproduced the measured daily ebullition from winter to midsummer, although late summer and autumn simulated ME exceeded the observed ME. A possible explanation for this was substrate limitation. We recommend measurements of methanogenically available carbon sources to identify substrate limitation and help characterize variation in methane formation with depth and from site to site.
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  • 64
    Publication Date: 2020-01-02
    Description: Morphological variability in gorgonians is frequent and commonly associated with habitat variability, often resulting in segregated morphotypes. Paramuricea macrospina is an endemic Mediterranean gorgonian species found on rocky bottoms between 40 and 160 m depth and has recently been reported as one of the most abundant species in continental shelf and shelf edge environments. Three different chromatic forms of P. macrospina were observed in the Menorca Channel: a yellow form and a light purple form occurring on maërl beds of the continental shelf, and a dark purple form occurring on rocky substrates of the shelf edge. The objective of the present work is to verify if these P. macrospina forms may represent distinct taxonomic units by analysing differences in colony morphology and sclerite size and shape of the three chromatic forms. No significant differences were found in colony shape, suggesting that environmental variability between the continental shelf and the shelf edge is not influential enough to significantly alter colony morphology. Significant differences in sclerite size and shape were found amongst all forms, suggesting that sclerites may be influenced by environmental conditions. However, the co-occurrence of the yellow and light purple forms side by side on the continental shelf may indicate a certain degree of genetic differentiation.
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  • 65
    Publication Date: 2019-11-19
    Description: The farming of the red seaweed Kappaphycus alvarezii and related species as raw material for the hydrocolloid carrageenan rapidly spread from the Philippines in the late 1960s to Indonesia, Tanzania, and other tropical countries around the world. Although numerous studies have documented positive socioeconomic impacts for seaweed farming, factors such as diseases and distance to export markets have led to an uneven development of the industry. Using standard budgeting techniques, this study adapted production and market data from a FAO-led global review of seaweed farming to develop comparative enterprise budgets for eight farming systems in six countries (Indonesia, the Philippines, Tanzania, India, Solomon Islands, and Mexico). Although the basic technology package is the same across countries, the study revealed large differences in the economic performance of systems due to wide variations in farm prices and the scale of operations. Although seaweed farming is a suitable activity for small-scale producers, a minimum of 2,000 m of cultures lines are still necessary to ensure adequate economic returns. Greater farming plots may be needed if farm prices are well below the average farm prices paid in Indonesia and the Philippines. Policy recommendations are made to improve the economic potential of underperforming systems.
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  • 66
    Publication Date: 2018-12-17
    Description: The feeding habits of two sympatric squid species, Uroteuthis (Photololigo) chinensis and Uroteuthis (Photololigo) duvaucelii from the southwestern Gulf of Thailand were studied. They fed on low numbers of food types (AF) and had a low diet breadth; 1.18 and 0.01 for U. (P.) chinensis and 1.49 and 0.05 for U. (P.) duvaucelii, respectively. Three major prey types (fishes, crustaceans and molluscs) were always detected and cannibalism was observed. Fish was the greatest contributor to the diet of both species, contributing 89.5% for U. (P.) chinensis and 69.9% for U. (P.) duvaucelii. Fish size significantly affected fullness index (FL) and AF for U. (P.) chinensis (P 〈 0.001) and U. (P.) duvaucelii (P 〈 0.001). Depth affected the FL of U. (P.) chinensis (P 〈 0.001) but not of U. (P.) duvaucelii (P 〉 0.05). Maturity stages of both male and female U. (P.) chinensis influenced FL (male: P 〈 0.001; female: P 〈 0.05) and AF (male: P 〈 0.05; female: P 〈 0.01). The FL of squid from cast nets was higher than those from trawls. The multivariate results showed dietary grouping between size classes of both species.
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  • 67
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    Wiley-Blackwell
    In:  Wiley Interdisciplinary Reviews: Climate Change, 8 (1). e441.
    Publication Date: 2019-02-01
    Description: To estimate the anthropogenic contribution to climate signals in the recent past and future decades implies a certain degree of confidence in both understanding and simulating natural internal variability at interdecadal time scales. If we are to embark on the challenge of decadal prediction, we must be able to mechanistically attribute events to known processes and phenomena, and reproduce their features and statistics within our models. To date, models have succeeded in reproducing only partially spatial patterns, statistics and climatic impacts of interdecadal modes of variability. Reasons for the partial success and agreement among models are to be attributed to the short observational record, the different and complex flavours of coupling between the many subcomponents of the climate system, and the present inability to resolve all climate processes. At an even more fundamental level, this difficulty is aggravated by the limited understanding of the physical mechanisms involved. Here, we review the proposed mechanisms giving rise to interdecadal climate variability, we discuss the hypotheses explaining the main interdecadal modes of variability, and present an overview on the ability and level of agreement in their simulation by the latest generation of coupled climate models. To achieve any progress, the modeling community should focus on both improving the representation and parameterization of key ocean physical processes and obtaining a firmer grasp on the physical mechanisms generating the variability. Both goals can benefit from process studies, intercomparisons with perturbation experiments to study model's sensitivities, and the use of a hierarchy of climate models.
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  • 68
    Publication Date: 2020-01-02
    Description: Indian squid, Uroteuthis (Photololigo) duvaucelii (Loliginidae) constitute an important component of the inshore cephalopod fisheries along the eastern Arabian Sea. Local environmental variation plays an important role in species–environment interactions in neritic squids, which inhabit nearshore/coastal waters. Such ‘active’ and ‘passive’ responses of squids to environmental changes is crucial in understanding their relationships and influence on the biological processes, distribution and abundance of the fast-growing short-lived coastal loliginids. The empirical relationship between squid abundance and the variability in rainfall and sea surface temperature (SST) were explored in a tropical monsoon fishery. Monthly catch rates (catch per fishing hour) of squids in commercial trawl during 1987–2009 were used as the abundance index. Linear regression models with ARIMA errors were fitted with catch per unit hour time series as dependent variable and rainfall and SST as exogenous variables. While rainfall was observed to have a negative effect on squid abundance, the SST recorded a positive impact. ARIMA models provided satisfactory fit to observed data and forecast of 22 months. Given that the squid life-cycle is a function of their environment, this result is relevant in forecasting squid biomass for the management of tropical monsoon fisheries.
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  • 69
    Publication Date: 2020-01-02
    Description: The distribution pattern of purpleback flying squid and the relationship between its abundance and environmental variables in the south-eastern Arabian Sea were analysed using a geographical information system (GIS) and a generalised additive model (GAM). Highest abundances were observed during December and January within 10 and 13°N and 71 and 72°E around the Lakshadweep Islands. The mean abundance in the area was 4.21 tonnes/km2 and the maximum sustainable yield (MSY) was estimated as 0.63 million tonnes. GAM indicated that very high squid abundance was associated with low values of dissolved oxygen (6.01–6.27 mg/L), sea surface temperature (28.03–28.62°C), pH (7.75–8.56), salinity (30.42–34.48 psu), chlorophyll-a (0.4–0.6 mg/m3), zooplankton biomass (0.23–0.64 mL/m3), and shallow 20°C isotherm (101.2–134.7 m) and mixed layer depth (17.8–29.8 m). As a carnivore from paralarval stages, S. oualaniensis depends on secondary and tertiary production to sustain its population for which primary production is used up. In the tropical Arabian Sea where temperature differences are not so pronounced, S. oualaniensis distribution was found to be related to a low but very narrow sea surface temperature (SST) band. There is sufficient fishable biomass in the area to possibly launch a new targeted oceanic squid fishery from the western seaboard of India.
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  • 70
    Publication Date: 2020-02-06
    Description: Many studies have shown that natural marine compounds can prevent biofouling by a broad spectrum of organisms without toxic effects, encouraging their use in antifouling (AF) coatings. Studies over the past 25 years of the natural product zosteric acid (ZA) are systematically organized in this review. ZA is a sulfated phenolic acid produced by the seagrass Zostera marina that has very promising AF potential against several micro- and macrofouling organisms. ZA was shown to have appropriate environmental fate parameters such as high water solubility, a low log P, low bioaccumulation, and no ecotoxicity, which demonstrated the potential of ZA as a safe AF agent. This review also highlights that ZA has been successfully incorporated into several types of coatings. The synthesis of analogs is also considered in this review, and it has allowed a better understanding of ZA structure–AF activity relationships and clarified the mechanism of action of ZA.
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  • 71
    Publication Date: 2021-02-08
    Description: The environmental system of the northern Nordic Seas is very sensitive to oceanographic and climatic changes at the contact of cold Arctic and warmer North Atlantic waters. These contrasts are reflected in the associations of marine microorganisms and archived in the bottom sediments. A microfossil study (diatoms, coccoliths) of late Holocene sediments in core MSM5/5-712-1 from the eastern Fram Strait provides a better understanding of marine ecosystems and palaeoenvironments during Arctic warming events of the last two millennia. Indicative diatom species and groups of species revealed a high variability of sea-surface conditions. Based on the diatom distribution, three warming periods could be detected, corresponding to the time intervals of 0 to 440 CE (the later part of the Roman Warm Period), 1200 to1420 CE (the final part of the Medieval Climate Anomaly) and 1730 CE to present (including the Recent Warming). The various micropalaeontological proxies used in this study and other publications describe the Roman Warm Period and, especially, the Recent Warming as the most pronounced warm events in the area during the last 2000 years. A comparison of data from the different microfossil groups, indicators of sea-surface and subsurface conditions, reveals variable, complicated and non-simultaneous palaeoenvironmental signals within the warm periods. This can potentially be explained by changes in the surface/subsurface water structure during the events (variations in the cold/warm water advection, stratification, availability of nutrients, seasonal succession of bioproductivity, etc.), which are reflected by changes in the microplankton communities.
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  • 72
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    In:  Atmospheric and Oceanic Science Letters, 9 (6). pp. 428-435.
    Publication Date: 2019-10-08
    Description: Recent SST and atmospheric circulation anomaly data suggest that the 2015/16 El Niño event is quickly decaying. Some researchers have predicted a forthcoming La Niña event in late summer or early fall 2016. From the perspective of the modulation of tropical SST by solar activity, the authors studied the evolution of the 2015/16 El Niño event, which occurred right after the 2014 solar peak year. Based on statistical and composite analysis, a significant positive correlation was found between sunspot number index and El Niño Modoki index, with a lag of two years. A clear evolution of El Niño Modoki events was found within 1–3 years following each solar peak year during the past 126 years, suggesting that anomalously strong solar activity during solar peak periods favors the triggering of an El Niño Modoki event. The patterns of seasonal mean SST and wind anomalies since 2014 are more like a mixture of two types of El Niño (i.e. eastern Pacific El Niño and El Niño Modoki), which is similar to the pattern modulated by solar activity during the years following a solar peak. Therefore, the El Niño Modoki component in the 2015/16 El Niño event may be a consequence of solar activity, which probably will not decay as quickly as the eastern Pacific El Niño component. The positive SST anomaly will probably sustain in the central equatorial Pacific (around the dateline) and the northeastern Pacific along the coast of North America, with a low-intensity level, during the second half of 2016.
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  • 73
    Publication Date: 2020-06-11
    Description: The farming of the red seaweed Kappaphycus alvarezii and related species as raw material for the hydrocolloid carrageenan rapidly spread from the Philippines in the late 1960s to Indonesia, Tanzania, and other tropical countries around the world. Although numerous studies have documented positive socioeconomic impacts for seaweed farming, factors such as diseases and distance to export markets have led to an uneven development of the industry. Using standard budgeting techniques, this study adapted production and market data from a FAO-led global review of seaweed farming to develop comparative enterprise budgets for eight farming systems in six countries (Indonesia, the Philippines, Tanzania, India, Solomon Islands, and Mexico). Although the basic technology package is the same across countries, the study revealed large differences in the economic performance of systems due to wide variations in farm prices and the scale of operations. Although seaweed farming is a suitable activity for small-scale producers, a minimum of 2,000 m of cultures lines are still necessary to ensure adequate economic returns. Greater farming plots may be needed if farm prices are well below the average farm prices paid in Indonesia and the Philippines. Policy recommendations are made to improve the economic potential of underperforming systems.
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  • 74
    Publication Date: 2020-01-02
    Description: Microplastics (MPs, 〈5 mm) have been reported as emerging environmental contaminants, but reliable data are still lacking. We compared the two most promising techniques for MP analysis, namely, Raman and Fourier transform infrared (FTIR) spectroscopy, by analyzing MPs extracted from North Sea surface waters. Microplastics 〉500 μm were visually sorted and manually analyzed by μ-Raman and attenuated total reflection (ATR)-FTIR spectroscopy. Microplastics ≤500 μm were concentrated on gold-coated filters and analyzed by automated single-particle exploration coupled to μ-Raman (ASPEx-μ-Raman) and FTIR imaging (reflection mode). The number of identified MPs 〉500 μm was slightly higher for μ-Raman (+23%) than ATR-FTIR analysis. Concerning MPs ≤500 μm, ASPEx-μ-Raman quantified two-times higher MP numbers but required a four-times higher analysis time compared to FTIR imaging. Because ASPEx-μ-Raman revealed far higher MP concentrations (38–2621 particles m–3) compared to the results of previous water studies (0–559 particles m–3), the environmental concentration of MPs ≤500 μm may have been underestimated until now. This may be attributed to the exceptional increase in concentration with decreasing MP size found in this work. Our results demonstrate the need for further research to enable time-efficient routine application of ASPEx-μ-Raman for reliable MP counting down to 1 μm.
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  • 75
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    In:  Environmental Politics, 28 (3). pp. 460-479.
    Publication Date: 2020-02-05
    Description: Geoengineering is regarded by advocates as a creative and responsible technological option in the face of a climate emergency. Critics often see it as a hubristic attempt to play God, with disastrous consequences for the planet and humanity. These antipodal perspectives are represented by the ideal types of Prometheans and Gaians. Prometheans and Gaians typically talk past each other. The geoengineering debate can be made more fruitful by well articulating their respective positions and subsequently situating them in the discourse of sustainability. A sustainability orientation does not answer the troubling question whether geoengineering should be developed and deployed. But it can foster a ‘fusion of horizons’ between Prometheans and Gaians, providing common ground in an otherwise polarized debate and making a more productive dialogue possible.
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  • 76
    Publication Date: 2019-01-02
    Description: Microplastic contamination of aquatic environments has become an increasingly alarming problem. These, defined as particles 〈5 mm, are mostly formed due to the cracking and embrittlement of larger plastic particles. Recent reports show that the increasing presence of microplastics in the environment could have significant deleterious consequences over the health of marine organisms, but also across the food chain. Herein, we have studied the effects of artificial seawater on polyethylene (PE)-based beads by exposing them up to eight weeks to saltwater in stirred batch reactors in the dark and examined the structural and morphological changes these endured. Electron microscopy observations showed that artificial seawater induces severe microcracking of the pellets' surfaces. Additionally, Fourier transform infrared spectroscopy (FTIR) analyses evidenced the formation of oxidized groups whenever these particles were exposed to water and an increase in organic matter content of the waters in which the pellets were kept was evidenced by Raman spectroscopy. There were also noticeable consequences in the thermal stability of the polyethylene pellets, as determined by thermogravimetric studies (TGA). Furthermore, the parallel exposure of polyethylene pellets to UV radiation yielded less pronounced effects, thus underscoring its lower preponderance in the degradation of this material. These results highlight the importance of determining the mechanisms of degradation of microplastics in marine settings and what the implications may be for the environment. Overall, the herein presented results show that a relatively short period of time of accelerated exposure can yield quantifiable chemical and physical impacts on the structural and morphological characteristics of PE pellets.
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  • 77
    Publication Date: 2020-01-02
    Description: Hydroacoustic and optical remote sensing have been commonly used to map shallow nearshore benthic features. However, the number, type, scale, and accuracy of the mapping products that can be obtained from the two sensors differ; as such, there can be limited agreement between their mapping products. These differences can be further accentuated if the hydroacoustic data are interpolated to produce a map. Interpolation introduces spatial uncertainty and reduces map accuracy. Consequently, maps generated from the two sensors may provide dissimilar spatial and temporal representations of the same benthic features. We therefore compared the performance of a random forest regression (RFr) and a universal kriging (UK) interpolation method and a post-classification enhancement that can be used to increase the accuracy and complementarity of benthic habitat maps derived from hydroacoustic data. First, we used single beam echosounder (SBES) survey bathymetry data from the Bluefields Bay marine protected area (MPA) in western Jamaica (13.82 km2 in size), to create a bathymetric surface model (BSM), from which rugosity and bathymetric position index (BPI) maps were generated. Next, the RFr was used to create submerged aquatic vegetation (SAV) percentage cover maps from the SBES SAV cover data by predicting cover at un-sampled locations. Predictors included auxiliary data such as depth, BPI, survey points coordinates and radiometrically corrected, deglinted and water column corrected image reflectance index values from each of the following: WorldView-2, Geoeye-1 and Landsat 8. Additionally, a SAV map was created using the UK. The most accurate SAV cover thresholds were identified and were used to create binary maps from the RFr and UK maps. A rugosity derived coral reef map was then added to the binary maps. The resulting benthic habitat maps had comparable accuracies and class coverage to benthic maps classified from GeoEye-1 and WorldView-2 images using pixel and object-based classifiers. However, map accuracies were calculated using a suboptimal number of reference points (〈50) for two of the benthic map classes (SAV absent and coral reef). This was not considered to be problematic as the addition of the coral reef class to the binary maps resulted in a significant decrease in uncertainty (standard error and confidence interval width of the overall accuracy) and a significant increase in the user’s accuracy of the SAV absent map class. Also, the difference in uncertainty and accuracy between the map classes did not change. The methods used in this study can therefore be used to increase the accuracy (and to decrease the uncertainty) and the complementarity of maps derived from hydroacoustic data.
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  • 78
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    In:  Current Eye Research, 41 (10). pp. 1316-1325.
    Publication Date: 2019-08-30
    Description: Purpose: To compare keratocyte activation, cellular morphologic changes and wound healing after SMILE and PRK procedures using transmission electron microscope (TEM).Methods: In this study, 22 New Zealand white rabbits (10- to 15-week old) were used. The right eyes of all animals underwent SMILE procedure and the left eyes underwent PRK procedure. Cornea samples taken 1 day and 1 week postoperatively were examined using TEM.Results: Using TEM 1 day after SMILE procedure, the organization of collagen fibers seemed to have been preserved without thermal alterations. Keratocyte activation was observed in the anterior stroma. Disrupted collagen arrangement and debris of cells are visible in the area of damage, and some phagocytic cells and a large number of secondary lysosomes are visible in those cells. At the perimeter zone of the interface, many coenocytes and collagen fragments could be found within the phagocytic cell. One week after SMILE procedure, potential lacuna could be discerned. A large part of the interface of the lenticule extracted had an appearance of clearly being adhered to some mucus secretions. One day after PRK procedure, an irregular epithelial surface was visible using TEM. Keratocytes had been activated and the rough endoplasmic reticulum in those cells had expanded. One week after PRK procedure, the epithelial surface still was irregular and keratinization of the epithelium was still visible in some areas. Corneal endothelium cells were mildly damaged and some vacuoles within the cytoplasm could be discerned. In the anterior stroma, some unhealthy activated keratocytes could still be observed. New collagen fibrils were found present near the activated keratocytes.Conclusion: Using TEM, keratocyte activation could still be observed after SMILE compared to after PRK procedure. Fewer cellular ultrastructural changes were seen after SMILE procedure. Unlike in PRK procedure, no damaged epithelium and endothelium were found after SMILE.
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  • 79
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    In:  Atmospheric and Oceanic Science Letters, 10 (1). pp. 1-8.
    Publication Date: 2019-10-08
    Description: Solar radiation is a forcing of the climate system with a quasi-11-year period. As a quasi-period forcing, the influence of the phase of the solar cycle on the ocean system is an interesting topic of study. In this paper, the authors investigate a particular feature, the ocean heat content (OHC) anomaly, in different phases of the total solar irradiance (TSI) cycle. The results show that almostopposite spatial patterns appear in the tropical Pacific during the ascending and declining phases of the TSI cycle. Further analysis reveals the presence of the quasi-decadal (~11-year) solar signal in the SST, OHC and surface zonal wind anomaly field over the tropical Pacific with a high level of statistical confidence (〉95%). It is noted that the maximum centers of the ocean temperature anomaly are trapped in the upper ocean above the main pycnocline, in which the variations of OHC are related closely with zonal wind and ocean currents.
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  • 80
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    In:  European Journal of Environmental and Civil Engineering . pp. 1-25.
    Publication Date: 2021-01-08
    Description: A series of triaxial compression tests of frozen sandy soil are carried out under five confining pressures (1 MPa, 4 MPa, 6 MPa, 8 MPa and 10 MPa) at –6 °C. By comparing the grain size distribution curves of frozen sandy soil before and after shearing, it is found that significant particle breakage can occur during triaxial shearing. Particle breakage changes internal structure of geomaterials and has a significant effect on their stress–strain relationships. In order to accurately describe the effect of particle breakage of frozen sandy soil on the stress–strain relationships, an elastoplastic constitutive model for frozen sandy soil considering particle breakage is proposed. Based on the energy balance equation established by Indraratna and Salim, the constant critical state stress ratio (Mcr) in the energy balance equation is modified to the stress ratio (M) which changed with shear strain during the shearing process. A yield function, considering particle breakage, is proposed using the modified energy balance equation. The hardening law is determined based on the rebound test results of frozen sandy soil, and the associated flow rule is adopted in the model. Compared with experimental data, the model can well simulate the stress–strain relationships under different confining pressures for frozen sandy soil. • Highlights • The particle breakage characteristics of frozen sandy soil are studied. • The energy balance equation considering particle breakage is modified to calculate the energy dissipation of frozen sandy soil. • An elastoplastic constitutive model for frozen sandy soil considering particle breakage is proposed.
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  • 81
    Publication Date: 2021-01-08
    Description: Surfactant-mediated extraction (SME), pressurized liquid extraction (PLE), and enzyme-assisted extraction (EAE) have been compared to improve the isolation of phlorotannins from the brown algae Lobophora variegata. Enzymatic treatment with Alcalase 2.4 L FG, Carezyme 4500 L, protease from Streptomyces griseus, pectinase from Aspergillus niger, Celluclast 1.5 L, protease from Bacillus licheniformis; surfactant extraction with triacetin and guaiacol and PLE with ethanol:water as extracting solvent, have been studied in terms of total phenolic content by the Folin–Ciocalteu method and total phlorotannin content using the DMBA assay. The results showed that SME yields the highest amount of phenols and phlorotannins by using food grade guaiacol as the surfactant. An extraction protocol was developed to maximize the amount of extract obtained from L. variegata. The effects of various parameters such as the type of surfactant, efficacy of surfactant, and optimum pH, on the extraction efficiency of polyphenols were examined. The simultaneous use of the enzyme and surfactant was also investigated. However, a synergistic effect between the enzymes and the surfactant for the extraction of polyphenols has not been observed. Considering total phenols and total phlorotannins in the extract, the extraction yield were obtained for total phenols as SME 〉 EAE 〉 PLE and for total phlorotannins as SME 〉 PLE 〉 EAE.
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  • 82
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    In:  Critical Reviews in Microbiology, 42 (1). pp. 106-126.
    Publication Date: 2020-07-14
    Description: Bacterial collagenases are metalloproteinases involved in the degradation of the extracellular matrices of animal cells, due to their ability to digest native collagen. These enzymes are important virulence factors in a variety of pathogenic bacteria. Nonetheless, there is a lack of scientific consensus for a proper and well-defined classification of these enzymes and a vast controversy regarding the correct identification of collagenases. Clostridial collagenases were the first ones to be identified and characterized and are the reference enzymes for comparison of newly discovered collagenolytic enzymes. In this review we present the most recent data regarding bacterial collagenases and overview the functional and structural diversity of bacterial collagenases. An overall picture of the molecular diversity and distribution of these proteins in nature will also be given. Particular aspects of the different proteolytic activities will be contextualized within relevant areas of application, mainly biotechnological processes and therapeutic uses. At last, we will present a new classification guide for bacterial collagenases that will allow the correct and straightforward classification of these enzymes.
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  • 83
    Publication Date: 2020-07-14
    Description: Microbial production routes, notably whole-cell lipase-mediated biotransformation and fatty-acids-derived biosynthesis, offer new opportunities for synthesizing biodiesel. They compare favorably to immobilized lipase and chemically catalyzed processes. Genetically modified whole-cell lipase-mediated in vitro route, together with in vivo and ex vivo microbial biosynthesis routes, constitutes emerging and rapidly developing research areas for effective production of biodiesel. This review presents recent advances in customizing microorganisms for producing biodiesel, via genetic engineering of lipases and metabolic engineering (including system regulation) of fatty-acids-derived pathways. Microbial hosts used include Escherichia coli, Saccharomyces cerevisiae, Pichia pastoris and Aspergillus oryzae. These microbial cells can be genetically modified to produce lipases under different forms: intracellularly expressed, secreted or surface-displayed. They can be metabolically redesigned and systematically regulated to obtain balanced biodiesel-producing cells, as highlighted in this study. Such genetically or metabolically modified microbial cells can support not only in vitro biotransformation of various common oil feedstocks to biodiesel, but also de novo biosynthesis of biodiesel from glucose, glycerol or even cellulosic biomass. We believe that the genetically tractable oleaginous yeast Yarrowia lipolytica could be developed to an effective biodiesel-producing microbial cell factory. For this purpose, we propose several engineered pathways, based on lipase and wax ester synthase, in this promising oleaginous host.
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  • 84
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    In:  International Journal of Remote Sensing, 37 (24). pp. 6205-6215.
    Publication Date: 2019-02-01
    Description: In this article, a novel technique based on artificial neural networks (NN) is proposed for cloud coverage short-term forecasting (nowcasting). In particular, the capabilities of multi-layer perceptron NN and time series analysis with nonlinear autoregressive with exogenous input NN are explored and applied to the European meteorological system ‘Meteosat Second Generation’ with its payload Spinning Enhanced Visible and InfraRed Imager. The general neural architecture consists of a first stage addressing the prediction of the radiance images at six bands (0.6, 0.8, 1.6, 3.9, 6.2 and 10.8 μm). In a second stage a cloud masking algorithm, always based on NN, is applied to the predicted images for the cloud coverage nowcasting. The scheme was compared with the most basic forecast algorithm for the prediction: the persistent model. Two test areas characterized by different climatology have been considered for the performance analysis. The results show that about 85% of the changes occurring in the time window were recognized by the proposed technique.
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  • 85
    Publication Date: 2020-02-06
    Description: The spatial structure of species is important for their dynamics and evolution, but also for management and conservation. There are numerous ways of inferring spatial structures, and information from multiple methods is becoming more common to examine how different processes shape the spatial structures of species to improve fish management. Here, we investigate the spatial structure of a suite of Baltic Sea fish species based on the following: (i) spatial (presumably neutral) genetic differentiation, reviewed from the literature, and (ii) spatial synchrony in abundance changes from time series of fishery-independent surveys, which we currently find to be underused given the amount of data available. For each of these two methods, species were classified as having a distinct, continuous or no/weak spatial structure. In addition, based on each source of information, we estimated the spatial scale of management units for species. The results show that only among species confined to the coastal zone the two sources of information yielded a congruence of the spatial structure (displaying a continuous spatial structure). In contrast, offshore species show weak spatial genetic structure but stronger spatial structure of synchrony in abundance. Based on this, we suggest that population genetic structure and synchrony in abundance should be used as complementary information as they reflect different spatial processes and suggest that management actions should differ with respect to scale depending on the management targets applied. We propose similar analysis should be applied to areas outside the Baltic Sea, and other stock identification methods, to improve management of fish resources.
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  • 86
    Publication Date: 2019-02-01
    Description: This study focuses on the mechanism of density-dependent growth in a stream-dwelling landlocked population of brown trout Salmo trutta. Specifically, body growth estimated by scale reading was examined in relation to population density and recapture rate (approximation of persistence of individuals within a location associated with dispersal and mortality) across 7 years and two spatial scales – a reach and a whole stream. In concordance with previous studies, the whole-stream population density had a crucial effect on body growth in juveniles, but not in adult individuals. Furthermore, growth was negatively associated with the whole-stream population density in reaches with a low recapture rate, whereas no such relationship could be detected in reaches with a high recapture rate. Since persistence within a certain locality increases the familiarity of individuals with the habitat and with other conspecifics, we suggest that the negative effect of population density on growth might be relaxed in groups with a high recapture rate by positive influence of the familiarity both within the habitat but also towards other conspecifics, which decreases competition pressure.
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  • 87
    Publication Date: 2020-10-26
    Description: Climatic warming is a primary driver of change in ecosystems worldwide. Here, we synthesize responses of species richness and evenness from 187 experimental warming studies in a quantitative meta-analysis. We asked 1) whether effects of warming on diversity were detectable and consistent across terrestrial, freshwater and marine ecosystems, 2) if effects on diversity correlated with intensity, duration, and experimental unit size of temperature change manipulations, and 3) whether these experimental effects on diversity interacted with ecosystem types. Using multilevel mixed linear models and model averaging, we also tested the relative importance of variables that described uncontrolled environmental variation and attributes of experimental units. Overall, experimental warming reduced richness across ecosystems (mean log-response ratio = –0.091, 95% bootstrapped CI: –0.13, –0.05) representing an 8.9% decline relative to ambient temperature treatments. Richness did not change in response to warming in freshwater systems, but was more strongly negative in terrestrial (–11.8%) and marine (–10.5%) experiments. In contrast, warming impacts on evenness were neutral overall and in aquatic systems, but weakly negative on land (7.6%). Intensity and duration of experimental warming did not explain variation in diversity responses, but negative effects on richness were stronger in smaller experimental units, particularly in marine systems. Model-averaged parameter estimation confirmed these main effects while accounting for variation in latitude, ambient temperature at the sites of manipulations, venue (field versus lab), community trophic type, and whether experiments were open or closed to colonization. These analyses synthesize extensive experimental evidence showing declines in local richness with increased temperature, particularly in terrestrial and marine communities. However, the more variable effects of warming on evenness were better explained by the random effect of site identity, suggesting that effects on species’ relative abundances were contingent on local species composition.
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  • 88
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    In:  African Journal of Marine Science, 38 (sup1). S91-S104.
    Publication Date: 2020-06-03
    Description: The composition and distribution of macrobenthic communities was investigated in three areas in the KwaZulu- Natal Bight, a section of shelf off the east coast of South Africa. Areas were pre-selected on the basis of three known oceanographic features, posited to deliver land- or Agulhas Current-derived nutrients onto the shelf and to drive ecosystem functioning in this region. Replicate sediment samples were collected with a 0.2 m2 van Veen grab, during two surveys (A, B) corresponding with normal periods of high and low rainfall, respectively. A subset of the full station array was selected across the shelf in an arrangement of increasing depths (inner-, mid- and outer shelf) through each feature area to investigate the spatial distribution and feeding modes of macrobenthic taxa. The two periods showed some differences in abundance and numbers of macrobenthic taxa, but were not statistically different. Total macrobenthic abundance from Survey A was 20 215 individuals from 642 taxa, decreasing to 18 000 individuals from 503 taxa during Survey B. Polychaeta and Crustacea were the dominant taxa sampled; abundance of the latter was attributed largely to a proliferation of Paguristes sp.1 at inner-shelf samples in the midbight (Thukela) region during Survey B. Similarity classification distinguished seven sample groups reflecting differences in feature areas and shelf positions under investigation. The Thukela River midshelf community supported the highest macrobenthic abundance, while the midshelf off the southern bight (Durban region) was most species rich. Findings were attributed to the habitat complexity of the midshelf which includes a palaeo-dune cordon at the 60 m isobath. Functionally, the community was dominated by interface- and deposit-feeding fauna, emphasising the importance of trophic plasticity in an environmentally variable and heterogeneous shelf environment.
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  • 89
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    In:  African Journal of Marine Science, 38 (4). pp. 581-588.
    Publication Date: 2021-07-05
    Description: Bromoform released from phytoplankton and kelp in the ocean is the largest known carrier of bromine to the atmosphere. The photoproducts of atmospheric bromoform catalyse ozone depletion. Laboratory investigations were conducted into the link between nutrient limitation and bromoform production using axenic cultures of two warm-water diatoms (Chaetoceros neogracile and Phaeodactylum tricornutum). During exponential growth the bromoform production was 2 000–3 000 nmol bromoform (g Chl a)−1 h−1, i.e. 10–100 times higher than earlier values for temperate and cold-water diatoms. Bromoform production decreased down to zero under CO2 and nitrate limitation for both species. These results suggest that the bromoform production could be directly related to bromoperoxidase activity (and irradiance) only during exponential growth, whereas compounds other than bromoform might be formed under nutrient limitation.
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  • 90
    Publication Date: 2021-01-08
    Description: The Ponto-Caspian round goby (Neogobius melanostomus Pallas, 1814) is a prominent invasive species in many European waters. Eggs of the Western Baltic Spring Spawning Atlantic herring might be attractive prey for the invasive round goby during the spawning season. However, investigations of the small fish fauna in an important spawning area of herring, which was characterized by high densities of macrophytes, indicated a spatio-temporal mismatch of round goby and herring spawn in spring, at least on some of the known important spawning beds situated on vegetated sandy bottoms. In contrast, a spatio-temporal overlap between round gobies and herring spawn was observed in a more structured area, characterized with stones, where round gobies’ stomachs were sampled. Further field study results suggest that large round gobies (〉 10 cm) do not feed on herring eggs, while smaller round gobies (〈 10 cm) do so. To support these results, we conducted laboratory feeding experiments with round gobies. When C. crangon, M. edulis and herring eggs were offered simultaneously, round gobies preferred C. crangon. M. edulis was preferred over herring eggs when C. crangon was absent. The predatory impact of the round goby on herring eggs seems to be of minor importance compared to other species, such as three-spined stickleback or perch. Applying the same data, different food ‘preference indices’ revealed a discrepancy in preference between indices. Therefore, we propose a modified food preference index (mE), taking into account four important parameters and combining benefits of two commonly applied indices.
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  • 91
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    In:  Natural Product Research, 30 (15). pp. 1771-1775.
    Publication Date: 2020-04-24
    Description: The gut actinobacteria of marine-inhabited fish is one of the most important reservoirs of novel natural products. Currently, the Streptomyces sp. MNU FJ-36 was isolated from the intestinal fabric of Katsuwonus sp. and determined by 16S rRNA analysis. From the cultures of the S. sp. MNU FJ-36, three new 2,5-diketopiperazines (2,5-DKPs) were discovered and identified as 3-(3-hydroxy-4-methoxybenzyl)-6-isobutyl-2,5-diketopiperazine (1), 3-(1,3-benzodioxol-5-ylmethyl)-6-isobutyl-2,5-diketopiperazine (2) and 3-(1,3-benzodioxol-5-ylmethyl)-6-isopropyl-2,5-diketopiperazine (3). Their structures were elucidated on the basis of spectroscopic data analysis. All the compounds were also evaluated for their inhibitory activity against P388, A-549 and HCT-116 cell lines with the MTT assay.
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  • 92
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    In:  Molecular Physics, 117 (23-24). pp. 3556-3568.
    Publication Date: 2021-01-08
    Description: Gas hydrates continue to attract enormous attention throughout the energy industry, as both a hindrance in conventional production and a substantial unconventional resource. Scientists continue to be fascinated by the hydrates’ ability of sequestering large amounts of hydrophobic gases, unusual thermal transport properties and unique molecular structures. Technologically, clathrate hydrates promise advantages in applications as diverse as carbon sequestration and water desalination. The communities interested in hydrates span traditional academic disciplines, including earth science, physical chemistry and petroleum engineering. The studies on this field are equally diverse, including field expeditions to attempt the production of natural gas from hydrate deposits accumulated naturally on the seafloor, to lab-scale studies to exchange CO2 for CH4 in hydrates; from theoretical studies to understand the stability of hydrates depending on the guest molecules, to molecular simulations probing nucleation mechanisms. This review highlights a few fundamental questions, with focus on knowledge gaps representing some of the barriers that must be addressed to enable growth in the practical applications of hydrate technology, including natural gas storage, water desalination, CO2 – CH4 exchange in hydrate deposits and prevention of hydrate plugs in conventional energy transportation.
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  • 93
    Publication Date: 2021-01-08
    Description: The cage occupancy plays a crucial role in the thermodynamic stability of clathrate hydrates and is an important quantity for understanding the CO2–CH4 replacement phenomenon. In this work, the occupancy isotherms of pure CH4, pure CO2, and their mixture in sI and sII hydrates are studied by GCMC + MD simulations. The adsorption of CH4 and CO2 + CH4 in the sI and sII hydrates can be categorized as the one-site Langmuir type. The calculated occupancy ratio θL/θS and the abundance ratio of CO2 to CH4 vary with the temperature and pressure, which provide the prerequisite information for the prediction of CH4 recovery yield at different conditions in the CO2–CH4 gas exchange process. The phase equilibria of clathrate hydrates of pure gases and mixtures are explored and the corresponding heat of dissociation and hydration numbers are determined. The current investigation provides new perspectives to understand the mechanism behind the gas adsorption behavior of clathrate hydrates.
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  • 94
    Publication Date: 2020-07-08
    Description: The spread of aquatic invasive species through ballast water is a major ecological and economical threat. Because of this, the International Maritime Organization (IMO) set limits to the concentrations of organisms allowed in ballast water. To meet these limits, ballast water treatment systems (BWTSs) were developed. The main techniques used for ballast water treatment are ultraviolet (UV) radiation and electrochlorination (EC). In this study, phytoplankton regrowth after treatment was followed for six BWTSs. Natural plankton communities were treated and incubated for 20 days. Growth, photosystem II efficiency and species composition were followed. The three UV systems all showed similar patterns of decrease in phytoplankton concentrations followed by regrowth. The two EC and the chlorine dioxide systems showed comparable results. However, UV- and chlorine-based treatment systems showed significantly different responses. Overall, all BWTSs reduced phytoplankton concentrations to below the IMO limits, which represents a reduced risk of aquatic invasions through ballast water.
    Type: Article , PeerReviewed
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  • 95
    Publication Date: 2020-07-09
    Description: Species richness and species abundance (colonization pressure and propagule pressure, respectively) are commonly used to characterize invasion risk for ballast-water-mediated introductions, which can be high if either parameter is high. For practical reasons, the adopted IMO-D2 standard for organisms in discharged ballast water only considers total abundance of biological indicators, without consideration of species richness or source community. Here we explore the effect of ballast-water source, ballast water exchange, chlorination, or a combination of both (hybrid treatment) on both colonization pressure and propagule pressure for one IMO-D2 size class (≥10 µm and 〈50 µm; phytoplankton). A strong reduction of propagule pressure was observed in all experimental trials and taxonomic groups, probably owing to environment conditions inside ballast tanks and treatment effects. However, only the hybrid treatment met the IMO-D2 standard for propagule pressure, while also significantly reducing colonization pressure, from 25 initial groups to 16 final groups. In this treatment, dinoflagellates and diatoms dominated final composition. The impact of different treatments on colonization pressure and propagule pressure was always lower when the vessel was ballasted in a brackish than freshwater port. Our study demonstrates that even treated ballast water compliant with the IMO-D2 standard may still harbor a diverse phytoplankton community, albeit with low individual species abundances. These results might be similar even using a type approved ballast water management systems which usually includes a filter for 〉50 µm organisms as a pre-treatment.
    Type: Article , PeerReviewed
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  • 96
    Publication Date: 2020-08-03
    Description: Four quinolinones (1–4; 1 is a new compound) were isolated from the static fermentation culture of a shark gill-derived fungus Penicillium crustosum AP2T1. In addition, five new quinolinone derivatives (5–9) and also 1 were obtained in a trimethylsilyldiazomethane-induced methylation reaction of 4. Their structures were elucidated by spectroscopic analyses. In bioassays, compounds 7 and 5 with lactim structures moderately inhibited the proliferation of human cancer cell line HCT116 (wild-type) with IC50-24 h of 8.4 μg/mL and 30.7 μg/mL, respectively; the other compounds displayed weaker inhibition. The p53 gene may play some role in their action as suggested by their much weakened activity towards p53-knockout HCT116 cell line. Besides, 6 and 8 exhibited moderate or weak toxicity to brine shrimp larvae, and 3, 4, 8 and 9 showed weak inhibition against Staphylococcus aureus. It is the first report on elucidation of new compounds with origin of shark-derived fungi.
    Type: Article , PeerReviewed
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  • 97
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    Taylor & Francis
    In:  Geomicrobiology Journal, 36 (6). pp. 492-505.
    Publication Date: 2021-01-08
    Description: Fermentation plays a fundamental role in organic carbon degradation on a global scale. However, little is known about how environmental variables influence this process. In a step towards quantifying how temperature and composition influence fermentation, we have calculated the Gibbs energies of 47 fermentation reaction, ΔGr, from 0–150 °C for a broad range of compositions representing microbial habitats as variable as sediments, estuaries, soils, and crustal rocks. The organic compounds in these reactions include amino acids, nucleic acid bases, monosaccharides, carboxylates, methanogenic compounds and more. The amount of energy available varies considerably, from +54 kJ (mol C)−1 for palmitate fermentation, to −184 kJ (mol C)−1 for methylamine disproportionation. For some reactions, there is little difference in ΔGr between low and high energy systems (e.g., the monosaccharide reactions) while others span a much broader range (e.g., the nucleic acid bases). There is no clear-cut trend between exergonicity and temperature, and the values of standard state Gibbs energies of reactions, ΔG0r, for nearly half of the reactions lie outside the range of ΔGr values. To carry out some of these calculations, the thermodynamic properties for six organic compounds were estimated: dimethylamine, trimethylamine, resorcinol, phloroglucinol and cyclohexane carboxylate and its conjugate acid.
    Type: Article , PeerReviewed
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  • 98
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    Unknown
    Taylor & Francis
    In:  Journal of Asian Natural Products Research . pp. 1-22.
    Publication Date: 2018-12-17
    Description: A large number of remarkable studies on the secondary metabolites of fungi have been conducted in recent years. This review gives an overview of one hundred and sixty-seven molecules with novel skeletons and their bioactivities that have been reported in seventy-nine articles published from 2013 to 2017. Our statistical data showed that endophytic fungi and marine-derived fungi are the major sources of novel bioactive secondary metabolites.
    Type: Article , PeerReviewed
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  • 99
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    Taylor & Francis
    In:  Botany Letters . pp. 1-5.
    Publication Date: 2018-12-17
    Description: As an important DNA source, herbarium specimens have been widely used in plant phylogenetics due to their easy accessibility and richness. However, contamination is a constant risk owing to low quality and/or quantity of DNA extracted from old samples. The inclusion of contaminant sequences can mislead phylogenetic reconstruction, and thereby affect subsequent analyses, such as divergence time estimates and biogeographic inferences. To employ appropriately herbarium specimens in plant phylogenetics, we outline here several suggestions regarding DNA extraction, PCR amplification and sequencing. We hope that these suggestions will serve as a guide for researchers using herbarium specimens in plant phylogenetics and help them identify from the early steps potential contaminant sequences from other plants or other organisms.
    Type: Article , PeerReviewed
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  • 100
    Publication Date: 2021-02-08
    Description: Sediment core PS1904 reveals continuous records of planktic and benthic foraminiferal stable isotopes (δ18O/δ13C) from the north-eastern Greenland continental margin. The data show good comparability with other records from the Nordic Seas, allowing the stratigraphic range of PS1904 to be dated to Marine Isotope Stage (MIS) 6. Focusing on MIS 5 reveals light δ18O values during MIS 5a compared to the last interglacial peak (MIS 5e) which indicates that surface and bottom water layers were strongly affected by freshwater during the former event. We present two possible scenarios explaining the origin and routing of the freshwater: (i) drainage of a Eurasian proglacial lake coupled with the collapse of the Kara Sea Ice Sheet at the MIS 5b/a boundary, and (ii) destabilization and melting of the nearby Greenland Ice Sheet. Although both scenarios could have acted simultaneously, sediment records from the Eurasian sector of the Arctic Ocean hint at the proglacial lake system in north-western Siberia as the largest freshwater source. Regardless of the actual source, the freshwater lowered the surface ocean salinity causing water column stratification and sea ice expansion. Increased sea-ice abundance led to a higher albedo and probably contributed to the cooling and global ice sheet growth that occurred subsequently during MIS 4.
    Type: Article , PeerReviewed
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