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  • Springer  (45)
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  • 2020-2024  (50)
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  • 1
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    CERN / Zenodo
    Publication Date: 2023-01-03
    Description: PRIMAP2 is the next generation of the PRIMAP climate policy analysis suite.
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  • 2
    Publication Date: 2023-10-11
    Description: All relevant model outputs to reproduce main analyses and figures in Sakschewski et al. 2021: Variable tree rooting strategies are key to model distribution, productivity and evapotranspiration of tropical evergreen forests, Biogeosciences; https://doi.org/10.5194/bg-2020-97
    Language: English
    Type: info:eu-repo/semantics/workingPaper
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  • 3
    Publication Date: 2023-10-11
    Description: Model code of LPJmL4.0-VR as used in Sakschewski et al. 2021: Variable tree rooting strategies are key to model distribution, productivity and evapotranspiration of tropical evergreen forests, Biogeosciences; https://doi.org/10.5194/bg-2020-97
    Language: English
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  • 4
    Publication Date: 2023-10-11
    Description: This data archive contains model runs and data analysis files to the research article "Impact of declining renewable energy costs on electrification in low emission scenarios" by Gunnar Luderer, Silvia Madeddu, Leon Merfort, Falko Ueckerdt, Michaja Pehl, Robert Pietzcker, Marianna Rottoli, Felix Schreyer, Nico Bauer, Lavinia Baumstark, Christoph Bertram, Alois Dirnaichner, Florian Humpenöder, Antoine Levesque, Alexander Popp, Renato Rodrigues, Jessica Strefler, Elmar Kriegler
    Language: English
    Type: info:eu-repo/semantics/workingPaper
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  • 5
    Publication Date: 2023-11-23
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  • 6
    Publication Date: 2024-02-07
    Description: Desalination remains in Saudi Arabia the supreme viable alternative to boost the future water supply requirements. The present research is focused on the environmental issue observations and modeling based on dissolved trace metals, hydrographic parameters, and nutrients at the discharging plume and nearby locations of Rabig desalination plant (RDP) and Yanbu desalination plant (YDP) located at the north of Jeddah city (~ 150 and 400 km, respectively). A multi-effect distillation (MED) technology is used in RDP whereas, in YDP, a combination of multistage flashing (MSF), reverse osmosis (RO), and MED technologies is in use for the production of potable waters. The concentration of dissolved Cu, Ni, and Zn was assessed by using cathodic stripping voltammetry. The observed pattern was reflecting an average value of dissolved Cu, Ni, and Zn at RDP that was 8.24, 5.28, and 12.69 nM, respectively. The correspondent changes at YDP were 17.53, 18.06, and 71.19 nM of Cu, Ni, and Zn, respectively. The statistical validation shows a significant positive correlation between metals and temperature with salinity and a significant negative correlation of dissolved oxygen and pH. The background concentration of nearby YDP is comparatively higher and which is ascribed by the negative effects of nearby industries. Detailed investigation of circulation pattern and brine discharge analysis near the Yanbu desalination plant also carried out with the help of 3d hydrodynamical numerical model Delft3d.
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  • 7
    Publication Date: 2024-02-07
    Description: Observations of the diversity, distribution and abundance of pelagic fauna are absent for many ocean regions in the Atlantic, but baseline data are required to detect changes in communities as a result of climate change. Gelatinous fauna are increasingly recognized as vital players in oceanic food webs, but sampling these delicate organisms in nets is challenging. Underwater (in situ) observations have provided unprecedented insights into mesopelagic communities in particular for abundance and distribution of gelatinous fauna. In September 2018, we performed horizontal video transects (50-1200 m) using the pelagic in situ observation system during a research cruise in the southern Norwegian Sea. Annotation of the video recordings resulted in 12 abundant and 7 rare taxa. Chaetognaths, the trachymedusa Aglantha digitale and appendicularians were the three most abundant taxa. The high numbers of fishes and crustaceans in the upper 100 m was likely the result of vertical migration. Gelatinous zooplankton included ctenophores (lobate ctenophores, Beroe spp., Euplokamis sp., and an undescribed cydippid) as well as calycophoran and physonect siphonophores. We discuss the distributions of these fauna, some of which represent the first record for the Norwegian Sea.
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  • 8
    Publication Date: 2024-02-07
    Description: This study presents culture experiments of the cold water species Neogloboquadrina pachyderma (sinistral) and provides new insights into the incorporation of elements in foraminiferal calcite of common and newly established proxies for paleoenvironmental applications (shell Mg/Ca, Sr/Ca and Na/Ca). Specimens were collected from sea ice during the austral winter in the Antarctic Weddell Sea and subsequently cultured at different salinities and a constant temperature. Incorporation of the fluorescent dye calcein showed new chamber formation in the culture at salinities of 30, 31, and 69. Cultured foraminifers at salinities of 46 to 83 only revealed chamber wall thickening, indicated by the fluorescence of the whole shell. Signs of reproduction and the associated gametogenic calcite were not observed in any of the culture experiments. Trace element analyses were performed using an electron microprobe, which revealed increased shell Mg/Ca, Sr/Ca, and Na/Ca values at higher salinities, with Mg/Ca showing the lowest sensitivity to salinity changes. This study enhances the knowledge about unusually high element concentrations in foraminifera shells from high latitudes. Neogloboquadrina pachyderma appears to be able to calcify in the Antarctic sea ice within brine channels, which have low temperatures and exceptionally high salinities due to ongoing sea ice formation.
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  • 9
    Publication Date: 2024-02-07
    Description: This paper uses two subsets of ensemble historical-Nat simulations and pi-Control simulations from CMIP5 as well as observational/reanalysis datasets to investigate responses of the tropical Pacific to the 11-yr solar cycle. A statistically significant 11-yr solar signal is found in the upper-ocean layers above the thermocline and tropospheric circulations. A warming response initially appears in the upper layers of the central equatorial Pacific in the solar maximum years in observations, then increases and shifts into the eastern Pacific at lagged 1–3 yr. Meanwhile, an anomalous updraft arises over the western equatorial Pacific and shifts eastwards in the following years with anomalous subsidence over the Maritime Continent. These lagged responses are confirmed by the historical-Nat simulations, except that the initial signal is located more to the west and all the responses are weaker than the observed. A simplified mixed-layer heat budget analysis based on the historical-Nat simulations suggests that the atmospheric forcing, especially the shortwave radiation, is the major contributor to the initial warming response, and the ocean heat transport effect is responsible for the eastward displacement of the lagged warming responses. In the solar maximum years, the zonal ocean temperature gradient in the western-central Pacific is reduced by the initial warming, and anomalous westerly winds appear over the western equatorial Pacific and extend into the eastern Pacific during the lagged years. These anomalous westerly winds reduce the wind-driven ocean dynamical transport, resulting in the initial warming in the central equatorial Pacific being amplified and the surface warming shifting eastward during the lagged 1–3 yr
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  • 10
    Publication Date: 2024-02-07
    Description: Environmental factors shape the structure and functioning of benthic communities. In coastal zones of the southwestern Baltic Sea, boulder fields represent one of the most productive habitats, supporting diverse benthic communities that provide many ecosystem services. In this study, the influence of the geological characteristics of boulder fields on the biodiversity of associated hard-bottom communities was investigated at two different spatial scales (few kilometers and tens of kilometers). The analyses on overall richness (taxonomic and functional) and community composition revealed how: (i) locally the size of boulders and (ii) regionally site-specific factors like the boulder density distribution and the sediment distribution can act as environmental driving forces. The overall richness of assemblages was shown to increase with increasing surface area of boulders, by up to 60% for species and up to 40% for functional richness. At both investigated scales, differences in compositional variability (β diversity) of the communities were detected. Locally, smallest boulders hosted more variable communities (β diversity up to 2 times higher), while at the regional level, indications of a larger habitat heterogeneity featuring the highest β diversity were observed. This study exemplifies how geological habitat characteristics shape the biodiversity of boulder field communities. The obtained information could be considered in assessment strategies, in order to avoid misclassifications of habitats naturally limited in biodiversity, making a step forward to the desired objective of protecting, conserving, and managing boulder field communities in the study area and at other comparable sites.
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  • 11
    Publication Date: 2024-02-07
    Description: Invasive alien species impacts might be mediated by environmental factors such as climatic warming. For invasive predators, multiple predator interactions could also exacerbate or dampen ecological impacts. These effects may be especially pronounced in highly diverse coastal ecosystems that are prone to profound and rapid regime shifts. We examine emergent effects of warming on the strength of intraspecific multiple predator effects from a highly successful invasive gammarid Gammarus tigrinus, using a functional response approach towards larval chironomids (feeding rates under different prey densities). Single predator maximum feeding rates were three-times higher at 24 °C compared to 18 °C overall, with potentially prey destabilising type II functional responses exhibited. However, pairs of gammarids exhibited intraspecific multiple predator effects that were in turn mediated by temperature regime, whereby synergisms were found at the lower temperature (i.e. positive non-trophic interactions) and antagonisms detected at the higher temperature (i.e. negative non-trophic interactions) under high prey densities. Accordingly, warming scenarios may worsen the impact of this invasive alien species, yet implications of temperature change are dependent on predator–predator interactions. Emergent effects between abiotic and biotic factors should be considered in ecological impact predictions across habitat types for invasive alien species.
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  • 12
    Publication Date: 2024-02-07
    Description: Background Edema is commonly seen after surgical fixation of ankle fractures. Rest, ice, compression, and elevation (RICE) is an established combination to prevent swelling but hardly able to stimulate lymphatic resorption. Recently, an epicutaneously applied negative pressure suction apparatus (LymphaTouch®) has been introduced to stimulate lymphatic flow. While postoperative recovery, soft tissue, and osseous healing as well as functional outcome are probably linked to the amount of postoperative swelling, estimates on this relative to prevention (RICE) or prevention + stimulated resorption (RICE + ) of fluid are scarce. Methods and analysis This is a single-center, evaluator-blinded randomized pilot trial to investigate postoperative swelling in adults requiring surgical fixation of a closed unilateral ankle fracture. A total of 50 patients will be recruited and randomly assigned to RICE or RICE + prior to surgery. All patients will undergo evaluator-blinded measurements of the ankle volume the day before surgery and subsequently from the evening of the 2nd postoperative day every 24 h until discharge. RICE will be initiated right after surgery and continued until discharge from the hospital in all patients. Additional application of negative pressure therapy (RICE + ) will be initiated on the morning of the 2nd postoperative day and repeated every 24 h until the time of discharge from the hospital. Outcome measures are (i) the relative amount and the time course of the postoperative swelling, (ii) the demand for analgesic therapy (type and amount) together with the perception of pain, (iii) the rate of complications, and (iv) mobility of the ankle joint and the recovery of walking abilities during a 12-weeks follow-up period. Serum and urine samples taken prior to sugery and during postoperative recovery will allow to evaluate the ratio of naturally occurring stable calcium isotopes (δ 44/42 Ca) as a marker of skeletal calcium accrual.
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  • 13
    Publication Date: 2024-02-07
    Description: The influence of climate change on the ecological impacts of invasive alien species (IAS) remains understudied, with deoxygenation of aquatic environments often-overlooked as a consequence of climate change. Here, we therefore assessed how oxygen saturation affects the ecological impact of a predatory invasive fish, the Ponto-Caspian round goby (Neogobius melanostomus), relative to a co-occurring endangered European native analogue, the bullhead (Cottus gobio) experiencing decline in the presence of the IAS. In individual trials and mesocosms, we assessed the effect of high, medium and low (90%, 60% and 30%) oxygen saturation on: (1) functional responses (FRs) of the IAS and native, i.e. per capita feeding rates; (2) the impact on prey populations exerted; and (3) how combined impacts of both fishes change over invasion stages (Pre-invasion, Arrival, Replacement, Proliferation). Both species showed Type II potentially destabilising FRs, but at low oxygen saturation, the invader had a significantly higher feeding rate than the native. Relative Impact Potential, combining fish per capita effects and population abundances, revealed that low oxygen saturation exacerbates the high relative impact of the invader. The Relative Total Impact Potential (RTIP), modelling both consumer species’ impacts on prey populations in a system, was consistently higher at low oxygen saturation and especially high during invader Proliferation. In the mesocosm experiment, low oxygen lowered RTIP where both species were present, but again the IAS retained high relative impact during Replacement and Proliferation stages at low oxygen. We also found evidence of multiple predator effects, principally antagonism. We highlight the threat posed to native communities by IAS alongside climate-related stressors, but note that solutions may be available to remedy hypoxia and potentially mitigate impacts across invasion stages.
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  • 14
    Publication Date: 2024-02-07
    Description: Information on the feeding habits of species is essential to develop appropriate conservation actions. This study aimed to assess spatial and temporal variation in the diet of the Eurasian otter, Lutra lutra in the Anzali Wetland, through fecal and stable isotope analysis. Seven main prey items were observed in the analysis of 300 fresh spraints. The highest feeding index was observed for fish, followed by snakes. Among the fish species consumed, the index of preponderance of Prussian carp (Carassius gibelio) was the highest followed by pike (Esox lucius) and white bream (Blicca bjoerkna). Results of Shannon diversity index suggest spatial variation of species diversity within and between feeding items (p 〈 0.05); snakes, frogs, and oriental river prawn (Macrobrachium nipponense) showed a seasonal variation. The otter’s trophic level (TL) (3.79) was higher than the TLs of other Anzali Wetland predators, such as pike. Bayesian mixing model showed source proportion contributions of fish 49.5%, reptiles 16.7%, insects 14.8%, crustacean 10.5%, amphibians 4.3%, birds 4.1%, and mollusks 0.1%. When considering only fish species in the Bayesian mixing model, Prussian carp was the main fish prey in the otters’ diet accounting for 47%. Based on the results of this study, the Eurasian otter plays an important role in the ecology of the Anzali Wetland ecosystem even though it preys on exotic species, such as the Prussian carp and the oriental river prawn.
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  • 15
    Publication Date: 2024-02-07
    Description: Cristamonadea is a large class of parabasalian protists that reside in the hindguts of wood-feeding insects, where they play an essential role in the digestion of lignocellulose. This group of symbionts boasts an impressive array of complex morphological characteristics, many of which have evolved multiple times independently. However, their diversity is understudied and molecular data remain scarce. Here we describe seven new species of cristamonad symbionts from Comatermes, Calcaritermes, and Rugitermes termites from Peru and Ecuador. To classify these new species, we examined cells by light and scanning electron microscopy, sequenced the symbiont small subunit ribosomal RNA (rRNA) genes, and carried out barcoding of the mitochondrial large subunit rRNA gene of the hosts to confirm host identification. Based on these data, five of the symbionts characterized here represent new species within described genera: Devescovina sapara n. sp., Devescovina aymara n. sp., Macrotrichomonas ashaninka n. sp., Macrotrichomonas secoya n. sp., and Macrotrichomonas yanesha n. sp. Additionally, two symbionts with overall morphological characteristics similar to the poorly-studied and probably polyphyletic ‘joeniid’ Parabasalia are classified in a new genus Runanympha n. gen.: Runanympha illapa n. sp., and Runanympha pacha n. sp.
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  • 16
    Publication Date: 2024-02-07
    Description: The Laptev Sea and the East Siberian Sea are remote areas of the Arctic region where detailed data on phytoplankton composition and spatial distribution remain limited. In the context of the ongoing environmental changes (increasing warming and ice melting) and prospective exploration activities (oil and gas production) on the Arctic shelves, understanding of the seasonal and interannual phytoplankton community dynamics is of critical importance. Our study provides new specifying data on species composition of phytoplankton over the vast area of the Laptev Sea shelf and the East Siberian Sea shelf. We found that the outer shelf of the Laptev and East Siberian seas was characterized by typical late spring diatom species (Chaetoceros furcellatus, Chaetoceros diadema, Chaetoceros debilis, Chaetoceros constrictus). On the inner shelf of the Laptev Sea, which is strongly affected by the Lena River water masses, the phytoplankton were characterized by the transition from the summer to an autumn stage of development. Local algal assemblages were composed by mixo- and heterotrophic dinoflagellates (Dinophysis and Protoperidinium genera) together with marine and brackish water-marine diatoms (Thalassiosira hyperborea, Thalassiosira baltica, Thalassiosira gravida, Thalassiosira nordenskioeldii) accompanied by sporadically occurring freshwater riverine planktonic diatom species (Aulacoseira granulata, Aulacoseira italica, Asterionella formosa). These variations in species composition over the Laptev Sea shelf were attributed to differences in the hydrography, marine chemical conditions, and the sea-ice regime.
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  • 17
    Publication Date: 2024-02-07
    Description: Supratidal sands are vitally important for coastal defence in the German Wadden Sea. They are less affected by human activities than other areas as they are located far off the mainland shore, touristical and commercial activities are generally prohibited. Therefore, supratidal sands are of high ecological interest. Nevertheless, the faunal inventory and distribution pattern of microorganisms on these sands were studied very little. The composition of living and dead foraminiferal assemblages was therefore investigated along a transect from the supratidal sand Japsand up to Hallig Hooge. Both assemblages were dominated by calcareous foraminifera of which Ammonia batava was the most abundant species. Elphidium selseyense and Elphidium williamsoni were also common in the living assemblage, but Elphidium williamsoni was comparably rare in the dead assemblage. The high proportions of Ammonia batava and Elphidium selseyense in the living assemblage arose from the reproduction season that differed between species. While Ammonia batava and Elphidium selseyense just finished their reproductive cycles, Elphidium williamsoni was just about to start. This was also confirmed by the size distribution patterns of the different species. The dead assemblage revealed 20 species that were not found in the living assemblage of which some were reworked from older sediments (e.g., Bucella frigida) and some were transported via tidal currents from other areas in the North Sea (e.g., Jadammina macrescens). The living foraminiferal faunas depicted close linkages between the open North Sea and the mainland. Key species revealing exchange between distant populations were Haynesina germanica, Ammonia batava and different Elphidium species. All these species share an opportunistic behaviour and are able to inhabit a variety of different environments; hence, they well may cope with changing environmental conditions. The benthic foraminiferal association from Japsand revealed that transport mechanisms via tides and currents play a major ecological role and strongly influence the faunal composition at this site.
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  • 18
    Publication Date: 2024-02-07
    Description: Nutrient depletion in the ecosystem mainly occurred via the base cations leach from the ecosystems. Isotope technology can provide new information on the nutrients’ behavior (cycle) in ecosystems. To better understand the strontium (Sr) biogeochemical cycle in the forest, radiogenic and stable Sr isotopes were determined in various environmental samples (rainwater, groundwater, calcareous soil, vegetation, and bedrocks) collected from a karst forest ecosystem, Southwest China. The Sr supplies are supported via the deposition of atmospheric materials and the weathering of carbonate rock in this area. These supplied sources observably influence the Sr isotope compositions (both stable and radiogenic isotope). Across the ecosystem, the varied ranges of 87Sr/86Sr ratios increased in the order: bedrock (0.708) ~ groundwater (0.708–0.709) ~ rainwater (0.709–0.711) ~ vegetation (0.709–0.710) 〈 surface calcareous soil (0.713–0.719) 〈 deep calcareous soil (0.714–0.724). Both rainwater and groundwater present similar 87Sr/86Sr ratios to the water-draining carbonate-dominated terrain. The 87Sr/86Sr ratios of vegetation are similar to that of rainwater but slightly heavier than groundwater. In contrast, the varied ranges of δ88/86Sr values followed a sequence of rainwater (0.08–0.21‰) 〈 groundwater (0.11–0.27‰) 〈 deep calcareous soil (0.02–0.29‰) 〈 tree leaves (0.12–0.17‰) 〈 surface calcareous soil (0.14–0.29‰) 〈 bedrock (0.40‰) 〈 shrub leaves (0.50‰). The δ88/86Sr values of tree leaves are between surface calcareous soil and deep calcareous soil, and the δ88/86Sr values of shrub leaves are higher than all of the compartments in the forest ecosystem, which indicated vegetation uptake might control the stable strontium fractionation. In combination with the radiogenic and stable Sr isotopes, our investigation presents that the 87Sr/86Sr provides sources’ information, whereas the δ88/86Sr records biogeochemical cycle information.
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  • 19
    Publication Date: 2024-02-07
    Description: This work introduces Waterburya agarophytonicola Bonthond and Shalygin gen. nov., sp. nov, a baeocyte producing cyanobacterium that was isolated from the rhodophyte Agarophyton vermiculophyllum (Ohmi) Gurgel et al., an invasive seaweed that has spread across the northern hemisphere. The new species genome reveals a diverse repertoire of chemotaxis and adhesion related genes, including genes coding for type IV pili assembly proteins and a high number of genes coding for filamentous hemagglutinin family (FHA) proteins. Among a genetic basis for the synthesis of siderophores, carotenoids and numerous vitamins, W. agarophytonicola is potentially capable of producing cobalamin (vitamin B-12), for which A. vermiculophyllum is an auxotroph. With a taxonomic description of the genus and species and a draft genome, this study provides as a basis for future research, to uncover the nature of this geographically independent association between seaweed and cyanobiont.
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  • 20
    Publication Date: 2024-02-07
    Description: We review the literature on the relationship between water temperature and size of freshwater phytoplankton, to examine the hypothesis that freshwater phytoplankton, like marine phytoplankton and many other groups of organisms, conform to Bergmann's Rule and become smaller with warming. We provide both experimental and field evidence in support of the above hypothesis, much of this evidence was hidden in studies focused on other issues, but presenting temperature and phytoplankton size data. Freshwater phytoplankton size shrinks with increasing temperature at both the species level (by cells or colonies becoming smaller) and at the community level (shift to smaller species). Exceptions to the Rule do occur but in most cases those exceptions can be explained by indirect effects of temperature on phytoplankton size, via processes such as grazing or nutrient availability. With global warming, freshwater phytoplankton are likely to be of smaller size. This article is dedicated to Colin S. Reynolds, who has had a leading role in our personal education and understanding of phytoplankton ecology.
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  • 21
    Publication Date: 2024-02-07
    Description: In aquatic systems, invasive submerged macrophytes considerably alter the structure and functioning of communities, thus potentially compromising ecosystem services. The prolific spread of invasive macrophytes is often aided by vegetative fragment propagation, yet the contributions of various commonly occurring invertebrates to such fragmentation are often unquantified. In the present study, we examine fragmentary spread of invasive macrophytes by a group of shredder-herbivores, larval caddisflies. Through novel application of the comparative functional response (FR; resource use as a function of density) approach to the native case-building species Limnephilus lunatus, we compared utilisation of non-native waterweeds Elodea canadensis and E. nuttallii in mono- and polycultures. Furthermore, we quantified de-cased and cased caddisfly-induced fragment production and length changes among non-native E. canadensis, E. nuttallii, Crassula helmsii and Lagarosiphon major under two different plant orientations: horizontal (floating) versus vertical (upright) growth forms. Larval caddisflies exhibited Type II (hyperbolic) FRs towards both Elodea species, and utilised each plant at similar rates when plants were provided separately. When plant species were presented in combination horizontally, E. canadensis was significantly less utilised compared to E. nuttallii, corroborating observations in the field. De-cased larvae produced new plant fragments for all four aquatic macrophytes, whereas cased larvae fragmented plants significantly less. Elodea nuttalii and C. helmsii were fragmented the most overall. Crassula helmsii was utilised to the greatest extent when plants were horizontally orientated, and Elodea species when vertically orientated. This study identifies and quantifies a mechanism from a novel species group that may contribute to the spread of invasive macrophytes in aquatic systems. Whilst exploititative interactions are thought to impede invasion success, here we demonstrate how resource utilisation by a resident species may exacerbate propagule pressure from an invasive species.
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  • 22
    Publication Date: 2024-02-07
    Description: The Osborn Plateau is a large intraplate elevation in the eastern Indian Ocean, which has been poorly studied by geological and geophysical methods. On cruise SO258/1 aboard the R/V Sonne, new data were collected by Parasound seismic processing, multibeam survey, and, for the first time, dredging. Faults in the sedimentary cover, which extend to the seafloor surface, indicate high neotectonic activity in the area of the Osborn Plateau. It may have continued up to the present, as well as in the adjacent segment of the Ninetyeast Ridge, where strong earthquakes are recorded. Two reflectors A and C in the upper part of the sedimentary cover mark global regressive changes in the World Ocean level at the Pliocene–Pleistocene and Miocene–Pliocene and boundaries. Reflector B in sediments at the Lower–Upper Pliocene boundary is associated with a change in the regional hydrodynamic regime at the time in the eastern Indian Ocean. Reflector B at the Lower–Upper Pliocene boundary is associated with a change in the local hydrodynamic regime in the region of the plateau and was caused by uncompensated sedimentation. As a result of dredging, strongly altered vitroclastic tuffs were obtained, consisting of palagonized ash particles and lapilli. Analysis of geochemical data on the composition of palagonite made it possible to reconstruct the main geochemical features of the primary composition of glass in tuffs, in particular, high enrichment in incompatible elements (Nb, Zr, Ti, La, etc.). The results of studying the dredged rocks suggest that tuffs dredged on the Osborn Plateau were formed as a result of explosive volcanic eruptions of alkaline basalts under subaerial or relatively shallow conditions and represent the latest eruption products in the region.
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  • 23
    Publication Date: 2024-02-07
    Description: In a conserved culture of the purple sulfur bacterium Thiospirillum jenense DSM216T, cells of this species were easily recognized by cell morphology, large-size spirilla and visible flagellar tuft. The Tsp. jenense genome is 3.22 Mb in size and has a GC content of 48.7 mol%. It was readily identified as a member of the Chromatiaceae by the complement of proteins in its genome. A whole genome comparison clearly placed Tsp. jenense near Thiorhodovibrio and Rhabdochromatium species and somewhat more distant from Thiohalocapsa and Halochromatium species. This relationship was also found with the sequences of the photosynthetic reaction center protein PufM. The genome sequence supported important properties of this bacterium: the presence of ribulose-bisphosphate carboxylase and enzymes of the Calvin cycle of autotrophic carbon dioxide fixation but the absence of carboxysomes, an incomplete tricarboxylic acid cycle and the lack of malate dehydrogenase, the presence of a sulfur oxidation pathway including adenylylsulfate reductase (aprAB) but absence of assimilatory sulfate reduction, the presence of hydrogenase (hoxHMFYUFE), nitrogenase and a photosynthetic gene cluster (pufBALMC). The FixNOP type of cytochrome oxidase was notably lacking, which may be the reason that renders the cells highly sensitive to oxygen. Two minor phototrophic contaminants were found using metagenomic binning: one was identified as a strain of Rhodopseudomonas palustris and the second one has an average nucleotide identity of 82% to the nearest neighbor Rhodoferax antarcticus. It should be considered as a new species of this genus and Rhodoferax jenense is proposed as the name.
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  • 24
    Publication Date: 2024-02-07
    Description: For many coastal areas including the Baltic Sea, ambitious nutrient abatement goals have been set to curb eutrophication, but benefits of such measures were normally not studied in light of anticipated climate change. To project the likely responses of nutrient abatement on eelgrass (Zostera marina), we coupled a species distribution model with a biogeochemical model, obtaining future water turbidity, and a wave model for predicting the future hydrodynamics in the coastal area. Using this, eelgrass distribution was modeled for different combinations of nutrient scenarios and future wind fields. We are the first to demonstrate that while under a business as usual scenario overall eelgrass area will not recover, nutrient reductions that fulfill the Helsinki Commission’s Baltic Sea Action Plan (BSAP) are likely to lead to a substantial areal expansion of eelgrass coverage, primarily at the current distribution’s lower depth limits, thereby overcompensating losses in shallow areas caused by a stormier climate.
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  • 25
    Publication Date: 2024-02-07
    Description: Predicting the ecological impacts of invasive species is impeded by context-dependencies that can mediate the strength of trophic interactions. Reproductive status is a pervasive context across trophic and taxonomic groups, yet has mostly been neglected in studies of invader impact. The present study examines the influence of the reproductive cycle on predatory impacts of a known damaging invasive freshwater crustacean, Gammarus pulex (Amphipoda), using a comparative functional response approach. Across females that were non-ovigerous, or had immature- or mature-stage embryonic broods, all G. pulex exhibited potentially prey destabilising Type II functional responses towards chironomid larvae. Attack rates were highest by immature embryonic brood stages, and significantly lower by mature embryonic brood stages. Conversely, handling times were consistently lower, and hence maximum feeding rates higher, where broods were present as compared to absent. These predatory patterns may reflect changing resource demands for progeny development across the reproductive cycle, the influence of brood bulk, female moult stage and/or motivational aspects of feeding, such as avoidance of filial cannibalism. Accordingly, many aspects of reproduction may alter the intensity of predatory impacts by invasive species. Future studies considering invader impacts should consider the influence of sex and reproductive status to more holistically quantify and predict population-level invader impacts.
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  • 26
    Publication Date: 2024-02-07
    Description: Species invasions often occur on coasts and estuaries where abiotic conditions vary, e.g. salinity, temperature, runoff etc. Successful establishment and dispersal of non-indigenous species in many such systems are poorly understood, partially since the species tend to show genetic and ecological plasticity at population level towards many abiotic conditions, including salinity tolerance. Plasticity may be driven by shifting expression of heat shock proteins such as Hsp70, which is widely recognized as indicator of physical stress. In this study, we developed a qPCR assay for expression of the hsp70 gene in the invasive round goby (Neogobius melanostomus) and tested the expression response of fish collected from a brackish environment in the western Baltic Sea to three different salinities, 0, 10 and 30. hsp70 expression was highest in fresh water, indicating higher stress, and lower at brackish (ambient condition for the sampled population) and oceanic salinities, suggestive of low stress response to salinities above the population’s current distribution. The highest stress in fresh water was surprising since populations in fresh water exist, e.g. large European rivers and Laurentian Great Lakes. The results have implications to predictions for the species’ plasticity potential and possible range expansion of the species into other salinity regimes.
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  • 27
    Publication Date: 2024-02-07
    Description: Understanding mechanisms of tropical Pacific decadal variability (TPDV) is of high importance for differentiating between natural climate variability and human induced climate change as this region sustains strong global teleconnections. Here, we use an ocean general circulation model along with a Lagrangian tracer simulator to investigate the advection of density compensated temperature anomalies (“spiciness mechanism”) as a potential contributor to TPDV during the 1980–2016 period. Consistent with observations, we find the primary regions of spiciness generation in the eastern subtropics of each hemisphere. Our results indicate that 75% of the equatorial subsurface water originates in the subtropics, of which two thirds come from the Southern hemisphere. We further show two prominent cases where remotely generated spiciness anomalies are advected to the equatorial Pacific, impacting subsurface temperature. The relative contribution of Northern versus Southern Hemisphere prominence and/or interior versus western boundary pathways depends on the specific event. The anomalously warm case largely results from advection via the Southern hemisphere interior (65%), while the anomalously cold case largely results from advection via the Northern hemisphere western boundary (48%). The relatively slow travel times from the subtropics to the equator (〉 4 years) suggests that these spiciness anomalies underpin a potentially predictable contribution to TPDV. However, not all decadal peaks in equatorial spiciness can be explained by remotely generated spiciness anomalies. In those cases, we propose that spiciness anomalies are generated in the equatorial zone through changes in the proportion of Northern/Southern hemisphere source waters due to their different mean spiciness distribution.
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  • 28
    Publication Date: 2024-02-07
    Description: Numerical models have become indispensable tools for investigating submarine hydrothermal systems and for relating seafloor observations to physicochemical processes at depth. Particularly useful are multiphase models that account for phase separation phenomena, so that model predictions can be compared to observed variations in vent fluid salinity. Yet, the numerics of multiphase flow remain a challenge. Here we present a novel hydrothermal flow model for the system H 2 O–NaCl able to resolve multiphase flow over the full range of pressure, temperature, and salinity variations that are relevant to submarine hydrothermal systems. The method is based on a 2-D finite volume scheme that uses a Newton–Raphson algorithm to couple the governing conservation equations and to treat the non-linearity of the fluid properties. The method uses pressure, specific fluid enthalpy, and bulk fluid salt content as primary variables, is not bounded to the Courant time step size, and allows for a direct control of how accurately mass and energy conservation is ensured. In a first application of this new model, we investigate brine formation and mobilization in hydrothermal systems driven by a transient basal temperature boundary condition—analogue to seawater circulation systems found at mid-ocean ridges. We find that basal heating results in the rapid formation of a stable brine layer that thermally insulates the driving heat source. While this brine layer is stable under steady-state conditions, it can be mobilized as a consequence of variations in heat input leading to brine entrainment and the venting of highly saline fluids.
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  • 29
    Publication Date: 2024-02-07
    Description: The growth of El Niño/Southern Oscillation (ENSO) events is determined by the balance between ocean dynamics and thermodynamics. Here we quantify the contribution of the thermodynamic feedbacks to the sea surface temperature (SST) change during ENSO growth phase by integrating the atmospheric heat fluxes over the temporarily and spatially varying mixed layer to derive an offline “slab ocean” SST. The SST change due to ocean dynamics is estimated as the residual with respect to the total SST change. In observations, 1 K SST change in the Niño3.4 region is composed of an ocean dynamical SST forcing of + 2.6 K and a thermodynamic damping of − 1.6 K, the latter mainly by the shortwave-SST (− 0.9 K) and latent heat flux-SST feedback (− 0.7 K). Most climate models from the Coupled Model Intercomparison Project phase 5 (CMIP5) underestimate the SST change due to both ocean dynamics and net surface heat fluxes, revealing an error compensation between a too weak forcing by ocean dynamics and a too weak damping by atmospheric heat fluxes. In half of the CMIP5 models investigated in this study, the shortwave-SST feedback erroneously acts as an amplifying feedback over the eastern equatorial Pacific, resulting in a hybrid of ocean-driven and shortwave-driven ENSO dynamics. Further, the phase locking and asymmetry of ENSO is investigated in the CMIP5 model ensemble. The climate models with stronger atmospheric feedbacks tend to simulate a more realistic seasonality and asymmetry of the heat flux feedbacks, and they exhibit more realistic phase locking and asymmetry of ENSO. Moreover, the almost linear latent heat flux feedback contributes to ENSO asymmetry in the far eastern equatorial Pacific through an asymmetry in the mixed layer depth. This study suggests that the dynamic and thermodynamic ENSO feedbacks and their seasonality and asymmetries are important metrics to consider for improving ENSO representation in climate models.
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  • 30
    Publication Date: 2024-02-07
    Description: In the Comechingones pegmatitic field, central Argentina, leucogranite and pegmatite bodies crop out in a relatively narrow (25 × 10 km) belt, and were emplaced synkinematically with the main deformational event of the crustal-scale Guacha Corral shear zone during the Early Ordovician (~ 475 Ma). These leucogranites and pegmatites are geochemically evolved rocks with high silica and alkalis, low Fe2O3, MgO, TiO2 and CaO, and high ASI values. The leucogranites display quite variable Sr and Nd isotope compositions (initial 87Sr/86Sr ratios from 0.7048 to 0.7170, and εNd values from + 2.0 to − 3.1), some of which do not overlap with almost any other pre-Famatinian rock from the Sierras de Córdoba. The major and trace element geochemistry and the particular Sr and Nd isotope compositions of the leucogranites are here explained by the following processes: (1) water-fluxed partial melting of amphibolites at relatively low P–T conditions generating currently unexposed granodioritic melts with unradiogenic 87Sr/86Sr ratios and radiogenic εNd values; (2) fractionation of mostly plagioclase and monazite leading to compositions close to the leucogranite melts; and (3) assimilation of metasedimentary rocks with crustal isotopic signatures, modelled by assimilation and fractional crystallization processes. The major, trace and isotope compositions of the pegmatites suggest a derivation from partial melting of the same metasedimentary protoliths of the Sierras de Córdoba that were assimilated by leucogranite melts. We propose a feedback relationship among deformation, anatexis, magma evolution and mass transfer in the context of such a crustal-scale shear zone in the foreland of the Famatinian orogen.
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  • 31
    Publication Date: 2024-02-07
    Description: Ocean warming is affecting marine ectothermic herbivores as well as the macroalgal species they consume and this has the potential to alter their trophic interaction. However, it is currently still unknown how these two important components of benthic food webs will react to a warming environment. Consumption rates of grazers change with increasing temperatures, but it is unclear whether this is also true for feeding preferences. In this study, multiple-choice feeding assays with the tropical abalone Haliotis squamata from Western Indonesia were conducted in August 2018. After brief acclimation of either the grazer or the macroalgae to moderately elevated water temperatures (maximum 2 °C above the long-term average) in the laboratory, three species of living macroalgae were simultaneously offered to the abalone in feeding assays. Consumption rates of H. squamata were lower under elevated water temperatures, while its feeding preference switched: At 27 °C (2 °C below long-term average), abalone preferred non-acclimated Gracilaria salicornia, but switched to non-acclimated Amphiroa spp. at 31 °C. Interestingly, no such switch in preference occurred when the macroalgae, but not the grazers were acclimated. This indicates that the grazer will presumably be the driver of this potential change in interactions between H. squamata and its macroalgal food. Ocean warming may result in changes in the structure of benthic communities, mediated by changes in the feeding behaviour of herbivorous invertebrates.
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  • 32
    Publication Date: 2024-02-07
    Description: In 2019 the RV Meteor cruised from Guadalupe in April/May to Cape Verde in June/July and to Namibia in August/September. The distance is about 10,000 km. The ship has a moon pool for installation of instruments. In Cape Verde we had a first glimpse of the already sparsely populated moon pool. We reached Namibian waters in mid-August. In mid-September, 47 days later and 6000 km south, the ship's moon pool was sampled in the port of Walvis Bay. 13 different taxa could be identified belonging to two phyla, four classes, six orders and 10 families. Most of these species have not yet been observed in the port or in the adjacent areas and are new records for the entire Namibian coast. The goose barnacles Conchoderma auritum (Linnaeus, 1767), Conchoderma virgatum Spengler, 1789 and Lepas anatifera Linnaeus, 1758 were particularly noticeable. They were only surpassed by the large number of amphipods. The species Ericthonius brasiliensis (Dana, 1853), Jassa marmorata Holmes, 1905, Stenothoe senegalensis Krapp-Schickel, 2015 and Paracaprella pusilla Mayer, 1890 are particularly noteworthy here. In addition, the pycnogonid species Endeis straughani Clark, 1970 and the titan acorn barnacle Megabalanus coccopoma (Darwin, 1854) should be mentioned, which occurred very frequently as well. The present study shows, on the one hand, an example of the transatlantic spread of bioinvasive species by ships as vectors and, on the other hand, a convenient method for sampling ship hulls.
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  • 33
    Publication Date: 2024-02-07
    Description: The extensive use of silver nanoparticles (AgNPs) in consumer products, medicine, and industry leads to their release into the environment. Thus, a characterization of the concentration, size, fate, and toxicity of AgNPs under environmental conditions is required. In this study, we present the characterization and optimization of an asymmetric flow field-flow fractionation (AF4) system coupled with UV/Vis spectrophotometer and dynamic light scattering (DLS) detector as a powerful tool for the size separation and multi-parameter characterization of AgNPs in complex matrices. The hyphenated AF4-UV/Vis-DLS system was first characterized using individual injections of the different size fractions. We used electrostatically stabilized AgNPs of 20-, 50-, and 80-nm nominal diameters coated with lipoic acid. We investigated the effect of applied cross-flows, carrier solutions, focus times, and quantity of injected particles on the nature of the AF4 fractograms and on the integrity of the AgNPs. Best size separation of a 1:1 mixture of 20- and 80-nm AgNPs was achieved using cross-flows of 0.5 and 0.7 mL/min with 1 mM NaCl and 0.05% v/v Mucasol as carrier solutions. We also researched the behavior of AgNPs in natural waters using the hyphenated AF4-UV/Vis-DLS system, under determined optimal conditions.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 34
    Publication Date: 2024-02-07
    Description: This encyclopedia is a reference for aquatic physical, biological and biogeochemical sciences, collecting and connecting a number of topics, concepts and facts about aquatic systems and their scientific investigation. The scope of the book comprises the aquatic physiosphere-biosphere transition zone, an entity that encompasses both inanimate matter and collectives (the physiosphere) as well as living organisms and collectives (the biosphere). This combined approach is meaningful because both realms are intimately linked and because available methods of investigation are often similar. Much can be gained from considering both spheres at and across their interface jointly, and while there is a strong focus on marine systems, most concepts presented are also applicable to freshwater systems. This presented snapshot of knowledge of the transition zone between the aquatic physiosphere and biosphere is taken from a very specific angle: the point of view of a modeler. Modeling is not only a state-of-the-art mode of scientific investigation, but also requires the explicit specification of all assumptions (helping to avoid fallacies), and offers the advantage of being quantitative and allows for theoretical "what if" scenarios. As in any reference work, equal emphasis is given to fundamental facts, the definition of terms and the explanation of concepts, in an attempt to establish a joint language for physicists, biologists and biogeochemists. Although originating from a modeler's approach to nature, the resulting suite of compatible concepts may also be useful beyond modeling purposes. Furthermore, the material is presented in a condensed, straightforward way. Hence, the length of each entry is limited to one (occasionally two) pages, thus offering a quick introductory overview. This excludes lengthy derivations and very specialized details. The book is geared towards researchers, teachers and advanced students in the field of aquatic (marine and limnic) sciences, in particular those interested or involved in interdisciplinary work.
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  • 35
    Publication Date: 2024-02-07
    Description: There is a long-standing debate on how the El Niño/Southern Oscillation (ENSO) amplitude may change during the twenty-first century in response to global warming. Here we identify the sources of uncertainty in the ENSO amplitude projections in models participating in the Coupled Model Intercomparison Phase 5 (CMIP5) and Phase 6 (CMIP6), and quantify scenario uncertainty, model uncertainty and uncertainty due to internal variability. The model projections exhibit a large spread, ranging from increasing standard deviation of up to 0.6 °C to diminishing standard deviation of up to − 0.4 °C by the end of the twenty-first century. The ensemble-mean ENSO amplitude change is close to zero. Internal variability is the main contributor to the uncertainty during the first three decades; model uncertainty dominates thereafter, while scenario uncertainty is relatively small throughout the twenty-first century. The total uncertainty increases from CMIP5 to CMIP6: while model uncertainty is reduced, scenario uncertainty is considerably increased. The models with “realistic” ENSO dynamics have been analyzed separately and categorized into models with too small, moderate and too large ENSO amplitude in comparison to instrumental observations. The smallest uncertainties are observed in the sub-ensemble exhibiting realistic ENSO dynamics and moderate ENSO amplitude. However, the global warming signal in ENSO-amplitude change is undetectable in all sub-ensembles. The zonal wind-SST feedback is identified as an important factor determining ENSO amplitude change: global warming signal in ENSO amplitude and zonal wind-SST feedback strength are highly correlated across the CMIP5 and CMIP6 models.
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  • 36
    Publication Date: 2024-02-07
    Description: Biodiversity is declining on a global scale and the spread of invasive alien species (IAS) is a major driver, particularly through predatory impacts. Thus, effective means of assessing and predicting the consequences of IAS predation on native prey population stability remains a vital goal for conservation. Here, we applied two classic ecological concepts, consumer functional response (FR) and prey switching, to predict and understand the ecological impacts of juveniles of the lionfish (Pterois volitans), a notorious and widespread marine invader. Functional responses and prey switching propensities were quantified towards three representative prey species: Artemia salina, Palaemonetes varians, and Gammarus oceanicus. Lionfish exhibited potentially destabilising Type II FRs towards individual prey species, owing to high consumption rates at low prey densities, whilst FR magnitudes differed among prey species. Functional response attack rates (a) were highest, and handling times (h) lowest, towards A. salina, followed by P. varians and then G. oceanicus. Maximum feeding rates (1/h) and functional response ratios (FRR; a/h) also followed this impact gradient for the three prey species. Lionfish, however, displayed a potentially population stabilising prey switching propensity (i.e. frequency-dependent predation) when multiple prey species were presented simultaneously, where disproportionately less of rare prey, and more of abundant prey, were consumed. Whilst FR and FRR magnitudes indicate marked per capita lionfish predatory impacts towards prey species, a strong prey switching propensity may reduce in-field impacts by offering low density prey refuge in biodiverse communities. Our results thus corroborate field patterns documenting variable impacts of lionfish, with prey extirpations less likely in diverse communities owing to frequency-dependent predation.
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  • 37
    Publication Date: 2024-02-07
    Description: Global freshwaters are increasingly threatened by pollutants emanating from human activities around watersheds. Microplastic pollution is an increasing problem for rivers worldwide, potentially threatening ecological integrity, ecosystem services and human health. We present quantifications and characterisations of sediment microplastic pollution in a subtropical river system in southern Africa, and relate distributions to wastewater treatment works, abiotic variables and urban environments. We additionally apply several diversity indices to decipher how microplastic types differ across the river system seasonally. Over two thousand microplastic particles were found across five sites and three seasons in the river system, comprising microbeads of various colours and microfibres. Microplastic concentrations were highest and most diverse in the hot–wet (mean range 76.0 ± 10.0–285.5 ± 44.5 microplastic kg−1) season as compared to the cool–dry (16.5 ± 4.5–27.0 ± 5.0 microplastic kg−1) and hot–dry (13.0 ± 4.0–29.0 ± 10.0 microplastic kg−1) seasons, and were mostly dominated by microfibres. However, no clear patterns were found in relation to wastewater treatment operations spatially, or in relation to abiotic variables in the river system. This study therefore finds a diverse range of microplastic types widely distributed in the river system that differ across seasons. Our results provide important, novel insights into plastic pollution in an understudied area of the Global South, and point to extensive pollution from sources outside of wastewater treatment works.
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  • 38
    Publication Date: 2024-02-07
    Description: A novel Actinobacterium strain YIM 131861 T, was isolated from lichen collected from the South Bank Forest of the Baltic Sea, Germany. It was Gram-stain-positive, strictly aerobic, catalase positive and oxidase negative, yellow pigmented. Cells were motile with a polar flagellum, irregular rod shaped and did not display spore formation. The strain grew at 15 − 30 °C (optimum 25 °C), at pH 6.0 − 10.0 (optimum pH 7.0) and in the presence of 0 − 1.5% (w/v) NaCl (optimum 1%). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain YIM 131861 T belonged to the genus Glaciibacter, and exhibited a high sequence similarity (96.4%) with Glaciibacter superstes NBRC 104264 T. The genomic DNA G + C content of strain YIM 131861 T was 68.2 mol%. The average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values between strain YIM 131861 T and Glaciibacter superstes NBRC 104264 T were 73.2 and 19.9% based on the draft genome sequence. The cell-wall peptidoglycan type was B2γ and contained the 2, 4-diaminobutyric acid as the diagnostic amino acid. Whole cell sugars were galactose, rhamnose, ribose and glucose. It contained MK-12 and MK-13 as the predominant menaquinones. The major cellular fatty acids (〉 10%) were identified as anteiso-C15:0, iso-C16:0 and anteiso-C17:0. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol and two unknown glycolipids. Based on the results of phenotypic, chemotaxonomic and phylogenetic analyses, strain YIM 131861 T should belong to the genus Glaciibacter and represents a novel species of the genus Glaciibacter, for which the name Glaciibacter flavus sp. nov. is proposed. The type strain is YIM 131861 T (= CGMCC 1.16588 T = NBRC 113572 T).
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  • 39
    Publication Date: 2024-02-07
    Description: The late-tectonic 511.4 ± 0.6 Ma-old Nomatsaus intrusion (Donkerhoek batholith, Damara orogen, Namibia) consists of moderately peraluminous, magnesian, calc-alkalic to calcic granites similar to I-type granites worldwide. Major and trace-element variations and LREE and HREE concentrations in evolved rocks imply that the fractionated mineral assemblage includes biotite, Fe–Ti oxides, zircon, plagioclase and monazite. Increasing K2O abundance with increasing SiO2 suggests accumulation of K-feldspar; compatible with a small positive Eu anomaly in the most evolved rocks. In comparison with experimental data, the Nomatsaus granite was likely generated from meta-igneous sources of possibly dacitic composition that melted under water-undersaturated conditions (X H2O: 0.25–0.50) and at temperatures between 800 and 850 °C, compatible with the zircon and monazite saturation temperatures of 812 and 852 °C, respectively. The Nomatsaus granite has moderately radiogenic initial 87Sr/86Sr ratios (0.7067–0.7082), relatively radiogenic initial εNd values (− 2.9 to − 4.8) and moderately evolved Pb isotope ratios. Although initial Sr and Nd isotopic compositions of the granite do not vary with SiO2 or MgO contents, fSm/Nd and initial εNd values are negatively correlated indicating limited assimilation of crustal components during monazite-dominated fractional crystallization. The preferred petrogenetic model for the generation of the Nomatsaus granite involves a continent–continent collisional setting with stacking of crustal slices that in combination with high radioactive heat production rates heated the thickened crust, leading to the medium-P/high-T environment characteristic of the southern Central Zone of the Damara orogen. Such a setting promoted partial melting of metasedimentary sources during the initial stages of crustal heating, followed by the partial melting of meta-igneous rocks at mid-crustal levels at higher P–T conditions and relatively late in the orogenic evolution.
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  • 40
    Publication Date: 2024-02-07
    Description: Seagrasses, a polyphyletic group of about 60 marine angiosperm species, are the foundation of diverse and functionally important marine habitats along sheltered sedimentary coasts. As a novel ecological function with high societal relevance, a role of the seagrass leaf canopy for reducing potentially harmful bacteria has recently been hypothesized in tropical regions, but data for temperate regions are lacking. Here, we tested whether or not the abundance of general bacteria and more specifically, those belonging to the genus Vibrio were reduced within temperate Zostera marina (eelgrass) meadows compared to adjacent sand flats and sampled 5 sites in the south-western Baltic Sea using SCUBA. Compared to non-vegetated area, we found an average reduction of 39% for all Vibrio and 63% for the potentially harmful V. vulnificus/cholerae subtype based on robust plate counting data on Vibrio selective agar. The underlying mechanism of the reduction in bacterial load is currently elusive and clearly merits further study. Our results underline the critical importance of seagrasses in maintaining shallow water ecosystem functioning including water quality and provide further motivation for their protection and restoration.
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  • 41
    Publication Date: 2024-02-07
    Description: The Sea of Marmara has been the focus of numerous marine geophysical studies during the last couple of decades. Determination of the interseismic slip distribution along the Main Marmara Fault (MMF) has observational difficulties due to the fact that the fault is under the sea. In addition to the onshore geodetic studies, two underwater geodetic studies were carried out recently and brought new clues about locked/creeping status of two different fault segments. In this study, we investigate the interseismic deformation of the Marmara region from a kinematic perspective using both block and continuum kinematic models. Block model inversion yields relative motion along the block boundaries as well as the distribution of slip deficit on the faults bounding the blocks. Calculated long term slip rates are 19–20 mm/yr for the MMF and 3–4 mm/yr for the Southern branch of the North Anatolian Fault (SNAF). In order to determine the sensitivity of the slip deficit solution to arbitrary spatial discretizations, we perform a series of checkerboard tests and optimize node distribution on the MMF accordingly. We also explore the sensitivity of inversion results on the MMF to assumptions regarding SNAF long term slip and interseismic locking. This study shows that the underwater geodetic data can be combined with the GPS data in a joint inversion, bringing a better constrained slip deficit distribution on the MMF. MMF has aseismic creep in the west of the Marmara Sea, with creep rates approaching long term slip rates in the Central Basin. On the other hand, the fault appears locked from ∼28.2°E eastward. In the best fitting model, the fault segment across Silivri is locked down to ∼10 km. The existence of a hazardous seismic gap in the Sea of Marmara, potentially yielding a magnitude 7.5 earthquake, is thus confirmed. The continuum approach is used to calculate strain rate fields from GPS data alone, from the output (slip rates and block average strain rates) of the best-fitting block model, and from the GPS residuals of this model. Our continuum models show that most of the accumulated strain in the Marmara region is indeed focused around the MMF, but also that strain distributed within the blocks cannot be neglected. On the other hand, the SNAF system differs from the MMF in that it appears as a 50 km wide zone of deformation with a patchy distribution of strain reflecting the activity of individual faults.
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  • 42
    Publication Date: 2024-02-07
    Description: Suppression of established populations of invasive alien species can be a complex and expensive process, which is frequently unsuccessful. The Asian clam, Corbicula fluminea (Müller, 1774), is considered a high impact invader that can adversely alter freshwater ecosystems and decrease their socioeconomic value. To date, C. fluminea continues to spread and persist within freshwater environments worldwide, despite repeated management attempts to prevent dispersal and suppress established populations. As extensive C. fluminea beds can often become exposed during low-water conditions, the direct application of hot or cold thermal shock treatments has been proposed as suitable mechanism for their control. Further, mechanical substrate disturbance may enhance the efficacy of thermal shock treatments by facilitating exposures to multiple layers of buried clams. In the present study, we advanced these methods by assessing combined applications of both hot and cold thermal shock treatments for control of C. fluminea, using steam spray (≥100 °C; 350 kPa), low- or high-intensity open-flame burns (~1000 °C) and dry ice (−78 °C). In a direct comparison of raking combined with hot thermal shock applications, both steam and high-intensity open-flame treatments tended to be most effective, especially following multiple applications. In addition, when hot thermal treatments are followed by a final cold shock (i.e. dry ice), steam treatments tended to be most effective. Further, when dry ice was applied either alone or prior to an application of a hot shock treatment, substantial if not complete C. fluminea mortality was observed. Overall, this study demonstrated that combined applications of hot and cold thermal shock treatments, applied following the disruption of the substrate, can substantially increase C. fluminea mortality compared to separate hot or cold treatments.
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  • 43
    Publication Date: 2024-02-07
    Description: The tropical Atlantic upper-ocean circulation experiences multiannual to decadal changes associated with different climate modes and is simultaneously adjusting to climate warming. The most energetic current in the tropical Atlantic is the Equatorial Undercurrent (EUC), which flows eastwards along the Equator. On the basis of long-term moored observations, we show that the EUC strengthened by more than 20% from 2008 to 2018. The intensification of the EUC is associated with increasing subsurface oxygen concentrations and a thickening of the upper-ocean oxygenated layer in the equatorial Atlantic. These changes counteract climate-warming-induced deoxygenation in the region. The EUC strengthening is found to be mainly forced by trade wind changes in the western tropical North Atlantic. A 60-yr dataset reveals that the recent oxygen increase in the upper equatorial Atlantic is associated with multidecadal variability. This variability is characterized by low oxygen concentrations in the 1990s and early 2000s, and high oxygen concentrations in the 1960s and 1970s. The observed oxygen variability seems to be linked to a compression and expansion of the habitat of tropical pelagic fish, and must be accounted for when evaluating the possible consequences of deoxygenation for marine ecosystems and fisheries.
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  • 44
    Publication Date: 2024-02-07
    Description: We assessed the abundance of microplastics (0.2–5 mm) in drift line sediments from three sites in Kiel Fjord, Western Baltic Sea. The first site is intensively used by beach visitors, the second is in close proximity to a sewage plant and the third is polluted with large-sized plastic litter. Samples were split into three grain size classes (0.2–0.5, 0.5–1, 1–5 mm), washed with calcium chloride solution, and filtered at 0.2 mm. Filters were then visually inspected, and a total of 180 fragments was classified as microplastics, of which 39% were analyzed using Raman spectroscopy. At the site that is close to a sewage plant as well as at the site with intense beach use, 1.8 and 4.5 particles (fibers plus fragments) per kg of dry sediment were found, respectively, while particle abundances reached 30.2 per kg of dry sediment at the site with high litter loads. Our data suggest that the fragmentation of large plastic debris at site seems to be a relevant source for microplastics in Western Baltic Sea beach sediments.
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  • 45
    Publication Date: 2024-02-07
    Description: Biological invasions via translocations are a textbook case of globalization’s impact on species distributions. Human-mediated transport helps species to overcome natural spatial boundaries and establish populations, often from a small number of individuals, in ecosystems previously unreachable through natural range expansion. The result is a discontinuous species distribution, with connectivity between the native and non-native range dependent on the recurrence of human-mediated species movement. The genetic diversity of introduced individuals represents a random fraction of the original diversity in the native range, but because connectivity is lost, non-native populations are bound to evolve independently. As a result, translocations can reshuffle genetic diversity in non-native populations, and thus, differentiation patterns arising after introduction may constitute the first step of novel evolutionary trajectories. By performing a meta-analysis on 5516 mitochondrial sequences of 20 different species, we explored whether life- and evolutionary history could explain differentiation among non-native populations of recently translocated organisms. We observed a general pattern consisting of reduced differentiation among non-native populations whose introduction derived from a single and intentional translocation, suggesting that these human actions play a role in reshaping genetic variance in non-native ranges. Additionally, we found geographic distance to be a poor predictor of population differentiation on the non-native range when compared to averaged evolutionary distances—the opposite being true for the native range—reinforcing connectivity break imposed by translocation events. Understanding the factors driving the distribution of genetic diversity upon translocations might not only facilitate the development of plans to mitigate the dispersal of invasive species but also to explore the emergence of novel evolutionary trajectories.
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  • 46
    Publication Date: 2024-02-07
    Description: The Arctic cryosphere is changing rapidly due to global warming. Northern Svalbard is a warming hotspot with a temperature rise of ~ 6 °C over the last three decades. Concurrently, modelled data suggest a marked increase in glacier runoff during recent decades in northern Svalbard, and runoff is projected to increase. However, observational data from before anthropogenic influence are sparse and the potential effects on the surface ocean are unclear. Here, we present a 200-year record of Ba/Ca ratios measured in annual increment-forming coralline algae from northern Spitsbergen as a proxy for past glacier-derived meltwater input. Our record shows a significant increasing trend in algal Ba/Ca ratios from the late-1980s onwards matching modelled regional runoff data, suggesting a drastic increase in land-based runoff. The rate of increase is unprecedented during the last two centuries and captures the impact of amplified warming on the coastal surface ocean in the high Arctic. The algal Ba/Ca runoff proxy offers an opportunity to reconstruct past land-based runoff variability in Arctic settings in high resolution, providing important data for validating and improving climate modelling studies.
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  • 47
    Publication Date: 2024-02-07
    Description: Global population projections foresee the biggest increase to occur in Africa with most of the available uncultivated land to ensure food security remaining on the continent. Simultaneously, greenhouse gas emissions are expected to rise due to ongoing land use change, industrialisation, and transport amongst other reasons with Africa becoming a major emitter of greenhouse gases globally. However, distinct knowledge on greenhouse gas emissions sources and sinks as well as their variability remains largely unknown caused by its vast size and diversity and an according lack of observations across the continent. Thus, an environmental research infrastructure-as being setup in other regions-is more needed than ever. Here, we present the results of a design study that developed a blueprint for establishing such an environmental research infrastructure in Africa. The blueprint comprises an inventory of already existing observations, the spatial disaggregation of locations that will enable to reduce the uncertainty in climate forcing's in Africa and globally as well as an overall estimated cost for such an endeavour of about 550 Meuro over the next 30 years. We further highlight the importance of the development of an e-infrastructure, the necessity for capacity development and the inclusion of all stakeholders to ensure African ownership.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 48
    Publication Date: 2024-02-07
    Description: To date the study of ocean acidification on fish otolith formation has been mainly focused on larval and juvenile stages. In the present pilot study, wild-captured adult Atlantic cod (Gadus morhua) were exposed to two different levels of pCO2, 422µatm (ambient, low pCO2) or 1091µatm (high pCO2), for a period of 30 weeks (from mid-October to early April 2014–2015) in order to study the effects on otolith size, shape and CaCO3 crystallization amongst other biological parameters. We found that otoliths from cod exposed to high pCO2 were slightly smaller (− 3.4% in length; − 3.3% in perimeter), rounder (− 2.9% circularity and + 4% roundness) but heavier (+ 5%) than the low pCO2 group. Interestingly, there were different effects in males and females; for instance, male cods exposed to high pCO2 exhibited significant changes in circularity (− 3%) and roundness (+ 4%) compared to the low pCO2 males, but without significant changes on otolith dimensions, while females exposed to high pCO2 had smaller otoliths as shown for length (− 5.6%), width (− 2%), perimeter (− 3.5%) and area (− 4.8%). Furthermore, while the majority of the otoliths analysed showed normal aragonite deposition, 10% of fish exposed to 1091µatm of pCO2 had an abnormal accretion of calcite, suggesting a shift on calcium carbonate polymorph crystallization in some individuals under high pCO2 conditions. Our preliminary results indicate that high levels of pCO2 in adult Atlantic cod might affect otolith growth in a gender-specific way. Our findings reveal that otoliths from adult cod are affected by ocean acidification, and we believe that the present study will prompt further research into this currently under-explored area.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 49
    Publication Date: 2024-02-07
    Description: This book is dedicated to the analysis of bottom waters flows through underwater channels of the Atlantic Ocean. The study is based on recent observations of the authors, analysis of historical data, numerical modeling, and literature review. For example, studying both the measurements from the World Ocean Circulation experiment in the 1990s and recent measurements reveals the decadal variations of water properties in the ocean. Seawater is cooled at high latitudes, descends to the ocean bottom, and slowly flows to the tropical latitudes and further. This current is slow in the deep basins, but intensifies in the abyssal channels connecting the basins. The current overflows submarine topographic structures and sometimes forms deep cataracts when water descends over slopes by several hundred meters. The flow of Antarctic Bottom Water (AABW) is studied on the basis of CTD sections combined with Lowered Acoustic Doppler Profiling (LADCP) carried out annually, and long-term moored measurements of currents. This book is a collection of oceanographic data, interpretation, and analysis, which can be used by field oceanographers, specialists in numerical modeling, and students who specialize in oceanography.
    Type: Book , NonPeerReviewed
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  • 50
    Publication Date: 2024-05-28
    Description: Until now, proxy records have been the primary tool for quantitative reconstructions of the physical world of the ancient and late antique Mediterranean. This chapter demonstrates the combined use of proxy datasets and the hitherto underutilized potential of earth system models in the scientific and historical study of past environmental variations and impacts on human societies. Results from model simulations are able to explain hydroclimatic anomalies observed in the proxy records and provide links to relevant mechanisms. The Late Roman Dry Period and the Late Roman Wet Period of the mid-fourth to early eighth centuries AD are each associated with the increase in the frequency of subsistence crises and with the accelerated infrastructural adaptations of communities and agricultural expansion, respectively. The chapter concludes with an examination of the historical and climatic contexts behind one such anomaly, a subsistence crisis in Cappadocia in the late 300s AD.
    Type: Book chapter , NonPeerReviewed
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