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  • Oxford Univ. Press  (229)
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  • 1
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    PalVol v1: a proxy-based semi-stochastic ensemble reconstruction of volcanic stratospheric sulfur injection for the last glacial cycle (140 000–50 BP) (2024)
    Copernicus
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    Publikationsdatum: 2024-04-04
    Beschreibung: Perturbations in stratospheric aerosol due to explosive volcanic eruptions are a primary contributor to natural climate variability. Observations of stratospheric aerosol are available for the past decades, and information from ice cores has been used to derive estimates of stratospheric sulfur injections and aerosol optical depth over the Holocene (approximately 10 000 BP to present) and into the last glacial period, extending back to 60 000 BP. Tephra records of past volcanism, compared to ice cores, are less complete but extend much further into the past. To support model studies of the potential impacts of explosive volcanism on climate variability across timescales, we present here an ensemble reconstruction of volcanic stratospheric sulfur injection (VSSI) over the last 140 000 years that is based primarily on terrestrial and marine tephra records. VSSI values are computed as a simple function of eruption magnitude based on VSSI estimates from ice cores and satellite observations for identified eruptions. To correct for the incompleteness of the tephra record, we include stochastically generated synthetic eruptions assuming a constant background eruption frequency from the ice core Holocene record. While the reconstruction often differs from ice core estimates for specific eruptions due to uncertainties in the data used and reconstruction method, it shows good agreement with an ice-core-based VSSI reconstruction in terms of millennial-scale cumulative VSSI variations over the Holocene. The PalVol reconstruction provides a new basis to test the contributions of forced vs. unforced natural variability to the spectrum of climate and the mechanisms leading to abrupt transitions in the palaeoclimate record with low- to high-complexity climate models. The PalVol volcanic forcing reconstruction is available at https://doi.org/10.26050/WDCC/PalVolv1 (Toohey and Schindlbeck-Belo, 2023).
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  • 2
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    Body condition of larval roundherring, Gilchristella aestuaria (family Clupeidae), in relation to harmful algal blooms in a warm-temperate estuary (2023)
    Oxford Univ. Press
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    Publikationsdatum: 2024-02-07
    Beschreibung: Eutrophication-driven harmful algal blooms (HABs) can have secondary effects on larval fishes that rely on estuaries as nurseries. However, few studies worldwide have quantified these effects despite the global rise in eutrophication. This study presents a novel approach using biochemical body condition analyses to evaluate the impact of HABs on the growth and body condition of the larvae of an estuarine resident fish. Recurrent phytoplankton blooms of Heterosigma akashiwo occur in the warm-temperate Sundays Estuary on the southeast coast of South Africa. The response in body condition and assemblage structure on larval estuarine roundherring (Gilchristella aestuaria) was measured in conjunction with bloom conditions, water quality and zooplanktonic prey and predators. Larvae and early juveniles were sampled during varying intensity levels, duration and frequency of hypereutrophic blooms. This study demonstrated that extensive HABs could significantly impact larval roundherring, G. aestuaria, by decreasing larval nutritional condition and limiting their growth, resulting in poor grow-out into the juvenile phase. Poor condition and growth may likely affect recruitment success to adult populations, and since G. aestuaria is an important forage fish and zooplanktivore, poor recruitment will hold consequences for estuarine food webs.
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  • 3
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    Developing an Observing Air–Sea Interactions Strategy (OASIS) for the global ocean (2023)
    Oxford Univ. Press
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    Publikationsdatum: 2024-04-08
    Beschreibung: The Observing Air–Sea Interactions Strategy (OASIS) is a new United Nations Decade of Ocean Science for Sustainable Development programme working to develop a practical, integrated approach for observing air–sea interactions globally for improved Earth system (including ecosystem) forecasts, CO2 uptake assessments called for by the Paris Agreement, and invaluable surface ocean information for decision makers. Our “Theory of Change” relies upon leveraged multi-disciplinary activities, partnerships, and capacity strengthening. Recommendations from 〉40 OceanObs’19 community papers and a series of workshops have been consolidated into three interlinked Grand Ideas for creating #1: a globally distributed network of mobile air–sea observing platforms built around an expanded array of long-term time-series stations; #2: a satellite network, with high spatial and temporal resolution, optimized for measuring air–sea fluxes; and #3: improved representation of air–sea coupling in a hierarchy of Earth system models. OASIS activities are organized across five Theme Teams: (1) Observing Network Design & Model Improvement; (2) Partnership & Capacity Strengthening; (3) UN Decade OASIS Actions; (4) Best Practices & Interoperability Experiments; and (5) Findable–Accessible–Interoperable–Reusable (FAIR) models, data, and OASIS products. Stakeholders, including researchers, are actively recruited to participate in Theme Teams to help promote a predicted, safe, clean, healthy, resilient, and productive ocean.
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  • 4
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    Anisotropic velocity models for (3D) seismic imaging ofthe Lower Seve Nappe in Jämtland, Sweden (2022)
    Oxford Univ. Press
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    Publikationsdatum: 2024-02-07
    Beschreibung: Strong anisotropy of seismic velocity in the Earth’scrust poses serious challenges for seismic imaging. Where in situ seismic properties are not available the anisotropy can be determined from velocity analysis of surface and borehole seismic profiles. This is well established for dense, long-offset reflection seismic data. However, it is unknown how applicable this approach is for sparse seismic reflection data with low fold and short offsets in anisotropic metamorphic rocks. Here we show that anisotropy parameters can be determined from a sparse 3D data set at the COSC-1 borehole site in the Swedish Caledonides and that the results agree well with the seismic anisotropy parameters determined from seismic laboratory measurements on core samples. Applying these anisotropy parameters during 3D seismic imaging improves the seismic image of the high amplitude reflections especially in the vicinity of the lower part of the borehole. Strong reflections in the resulting seismic data show good correlation with the borehole-derived lithology. Our results aid the interpretation and extrapolation of the seismic stratigraphy of the Lower Seve Nappe in Jämtland and other parts in the Caledonides.
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    GLODAPv2.2022: the latest version of the global interior ocean biogeochemical data product (2022)
    Copernicus
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    Publikationsdatum: 2024-02-07
    Beschreibung: The Global Ocean Data Analysis Project (GLODAP) is a synthesis effort providing regular compilations of surface-to-bottom ocean biogeochemical bottle data, with an emphasis on seawater inorganic carbon chemistry and related variables determined through chemical analysis of seawater samples. GLODAPv2.2022 is an update of the previous version, GLODAPv2.2021 (Lauvset et al., 2021). The major changes are as follows: data from 96 new cruises were added, data coverage was extended until 2021, and for the first time we performed secondary quality control on all sulphur hexafluoride (SF6) data. In addition, a number of changes were made to data included in GLODAPv2.2021. These changes affect specifically the SF6 data, which are now subjected to secondary quality control, and carbon data measured onboard the RV Knorr in the Indian Ocean in 1994–1995 which are now adjusted using CRM measurements made at the time. GLODAPv2.2022 includes measurements from almost 1.4 million water samples from the global oceans collected on 1085 cruises. The data for the now 13 GLODAP core variables (salinity, oxygen, nitrate, silicate, phosphate, dissolved inorganic carbon, total alkalinity, pH, CFC-11, CFC-12, CFC-113, CCl4, and SF6) have undergone extensive quality control with a focus on systematic evaluation of bias. The data are available in two formats: (i) as submitted by the data originator but converted to World Ocean Circulation Experiment (WOCE) exchange format and (ii) as a merged data product with adjustments applied to minimize bias. For the present annual update, adjustments for the 96 new cruises were derived by comparing those data with the data from the 989 quality controlled cruises in the GLODAPv2.2021 data product using crossover analysis. SF6 data from all cruises were evaluated by comparison with CFC-12 data measured on the same cruises. For nutrients and ocean carbon dioxide (CO2) chemistry comparisons to estimates based on empirical algorithms provided additional context for adjustment decisions. The adjustments that we applied are intended to remove potential biases from errors related to measurement, calibration, and data handling practices without removing known or likely time trends or variations in the variables evaluated. The compiled and adjusted data product is believed to be consistent to better than 0.005 in salinity, 1 % in oxygen, 2 % in nitrate, 2 % in silicate, 2 % in phosphate, 4 μmol kg-1 in dissolved inorganic carbon, 4 μmol kg-1 in total alkalinity, 0.01–0.02 in pH (depending on region), and 5 % in the halogenated transient tracers. The other variables included in the compilation, such as isotopic tracers and discrete CO2 fugacity (fCO2), were not subjected to bias comparison or adjustments.
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    Active ocean–continent transform margins: seismic investigation of the Cayman Trough-Swan Island ridge-transform intersection (2022)
    Oxford Univ. Press
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    Publikationsdatum: 2024-02-07
    Beschreibung: The southern boundary of the Cayman Trough in the Caribbean is marked by the Swan Islands transform fault (SITF), which also represents the ocean-continent transition of the Honduras continental margin. This is one of the few places globally where a transform continental margin is currently active. The CAYSEIS experiment acquired an ∼165-km-long seismic refraction and gravity profile (P01) running across this transform margin, and along the ridge-axis of the Mid-Cayman Spreading Centre (MCSC) to the north. This profile reveals not only the crustal structure of an actively evolving transform continental margin, that juxtaposes Mesozoic-age continental crust to the south against zero-age ultraslow spread oceanic crust to the north, but also the nature of the crust and uppermost mantle beneath the ridge-transform intersection (RTI). The traveltimes of arrivals recorded by ocean-bottom seismographs (OBSs) deployed along-profile have been inverse and forward modelled, in combination with gravity modelling, to reveal an ∼25-km-thick continental crust that has been continuously thinned over a distance of ∼65 km to ∼10 km adjacent to the SITF, where it is juxtaposed against ∼3-4-km-thick oceanic crust. This thinning is primarily accommodated within the lower crust. Since Moho reflections are only sparsely observed, and, even then, only by a few OBSs located on the continental margin, the 7.5 km s-1 velocity contour is used as a proxy to locate the crust-mantle boundary along-profile. Along the MCSC, the crust-mantle boundary appears to be a transition zone, at least at the seismic wavelengths used for CAYSEIS data acquisition. Although the traveltime inversion only directly constrains the upper crust at the SITF, gravity modelling suggests that it is underlain by a higher density (〉3000 kg m-3) region spanning the width (∼15 km) of its bathymetric expression, that may reflect a broad region of metasomatism, mantle hydration or melt-depleted lithospheric mantle. At the MCSC ridge-axis to the north, the oceanic crust appears to be forming in zones, where each zone is defined by the volume of its magma supply. The ridge tip adjacent to the SITF is currently in a magma rich phase of accretion. However, there is no evidence for melt leakage into the transform zone. The width and crustal structure of the SITF suggests its motion is currently predominantly orthogonal to spreading. Comparison to CAYSEIS Profile P04, located to the west and running across-margin and through 10 Ma MCSC oceanic crust, suggests that, at about this time, motion along the SITF had a left-lateral transtensional component, that accounts for its apparently broad seabed appearance westwards.
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    Phytoplankton nutritional quality is altered by shifting Si:N ratios and selective grazing (2021)
    Oxford Univ. Press
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    Publikationsdatum: 2024-02-07
    Beschreibung: Diatoms often dominate phytoplankton in temperate, polar and upwelling regions. Decreases in silicate availability or silicon to nitrogen (Si:N) ratios may induce silicon limitation in diatoms and lower their proportion within phytoplankton communities. The effects of such changes on the nutritional quality of phytoplankton are not well understood. To examine how changing Si:N ratios affect plankton nutritional value, we applied a range of Si:N ratios on a natural plankton community and manipulated grazing pressure to assess top-down effects of copepod selective grazing. Diatom proportion in phytoplankton increased with increasing Si:N ratios and so did phytoplankton nutritional quality in terms of major fatty acid concentrations, such as polyunsaturated fatty acids, docosahexaenoic (DHA) and eicosapentaenoic (EPA) acids. However, stoichiometric quality (carbon to nitrogen and carbon to phosphorus ratios), DHA:EPA and omega 3:6 (omega 3:omega 6) ratios declined with increasing Si:N ratios, suggesting that proportions between essential compounds in copepod diet may be more favorable in lowered Si:N ratios. Copepods had a negative effect on DHA contents, DHA:EPA and omega 3:omega 6 ratios, indicating possible selective grazing on more nutritious plankton. Our findings show that declining silicate concentrations can affect stoichiometric and biochemical quality of phytoplankton, which copepods can also moderate by selective grazing.
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  • 8
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    Water Balance and Desiccation Tolerance of the Invasive South American Tomato Pinworm (2021)
    Oxford Univ. Press
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    Publikationsdatum: 2024-02-07
    Beschreibung: Temperature and dehydration stress are two major co-occurring environmental stressors threatening the physiology, biochemistry, and ecology of insects. As such, understanding adaptive responses to desiccation stress is critical for predicting climate change impacts, particularly its influence on insect invasions. Here, we assessed water balance and desiccation resistance of the invasive Tuta absoluta (Meyrick, 1917) (Lepidoptera: Gelechiidae), and infer how eco-physiology shapes its niche. We measured basal body water and lipid content, water loss rates (WLRs), and desiccation resistance in larvae (second to fourth instars) and adults. Body -water, -lipid, and WLRs significantly varied across life stages. Second instars recorded the lowest while fourth instars exhibited the highest body water and lipid content. Adult body water and lipid content were higher than second and third instars and lower than fourth instars while proportion of body water and lipid contents were highest in adults and second larval instars respectively. Water loss rates were significantly highest in fourth-instar larvae compared to other life stages, but differences among stages were less apparent at longer exposure durations (48 h). Desiccation resistance assays showed that second instars had greatest mortality while fourth-instar larvae and adults were the most desiccation tolerant. Our results show that T. absoluta fourth-instar larvae and adults are the most resilient developmental stages and potentially contribute most to the invasion success of the pest in arid environments. Incorporation of these species-specific eco-physiological traits in predictive models can help refine invasive species potential spread under changing climates.
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  • 9
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    Five centuries of cod catches in Eastern Canada (2021)
    Oxford Univ. Press
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    Publikationsdatum: 2024-02-07
    Beschreibung: The fishery for Northern Atlantic cod (Gadus morhua) off Newfoundland and Labrador, Eastern Canada, presents the most spectacular case of an exploited stock crashed in a few decades by an industrial bottom trawl fishery under a seemingly sophisticated management regime after half a millennium of sustainable fishing. The fishery, which had generated annual catches of 100000 to 200000 tonnes from the beginning of the 16th century to the 1950s, peaked in 1968 at 810000 tonnes, followed by a devastating collapse and closure 24 years later. Since then, stock recovery may have been hindered by premature openings, with vessels targeting the remains of the cod population. Previous research paid little attention towards using multicentury time series to inform sustainable catches and recovery plans. Here, we show that a simple stock assessment model can be used to model the cod population trajectory for the entire period from 1508 to 2019 for which catch estimates are available. The model suggests that if fishing effort and mortality had been stabilized in the 1980s, precautionary annual yields of about 200000 tonnes could have been sustained. Our analysis demonstrates the value of incorporating prior knowledge to counteract shifting baseline effects on reference points and contemporary perceptions of historical stock status.
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  • 10
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    Establishment of Host–Algal Endosymbioses: Genetic Response to Symbiont Versus Prey in a Sponge Host (2021)
    Oxford Univ. Press
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    Publikationsdatum: 2024-02-07
    Beschreibung: The freshwater sponge Ephydatia muelleri and its Chlorella-like algal partner is an emerging model for studying animal: algal endosymbiosis. The sponge host is a tractable laboratory organism, and the symbiotic algae are easily cultured. We took advantage of these traits to interrogate questions about mechanisms that govern the establishment of durable intracellular partnerships between hosts and symbionts in facultative symbioses. We modified a classical experimental approach to discern the phagocytotic mechanisms that might be co-opted to permit persistent infections, and identified genes differentially expressed in sponges early in the establishment of endosymbiosis. We exposed algal-free E. muelleri to live native algal symbionts and potential food items (bacteria and native heat-killed algae), and performed RNA-Seq to compare patterns of gene expression among treatments. We found a relatively small but interesting suite of genes that are differentially expressed in the host exposed to live algal symbionts, and a larger number of genes triggered by host exposure to heat-killed algae. The upregulated genes in sponges exposed to live algal symbionts were mostly involved in endocytosis, ion transport, metabolic processes, vesicle-mediated transport, and oxidation–reduction. One of the host genes, an ATP-Binding Cassette transporter that is downregulated in response to live algal symbionts, was further evaluated for its possible role in the establishment of the symbiosis. We discuss the gene expression profiles associated with host responses to living algal cells in the context of conditions necessary for long-term residency within host cells by phototrophic symbionts as well as the genetic responses to sponge phagocytosis and immune-driven pathways.
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    Marine sponges maintain stable bacterial communities between reef sites with different coral to algae cover ratios (2021)
    Oxford Univ. Press
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    Publikationsdatum: 2024-02-07
    Beschreibung: Marine sponges play a major ecological role in recycling resources on coral reef ecosystems. The cycling of resources may largely depend on the stability of the host-microbiome interactions and their susceptibility to altered environmental conditions. Given the current coral to algal phase shift on coral reefs, we investigated whether the sponge-associated bacterial communities of four sponge species, with either high or low microbial abundances (HMA and LMA), remain stable at two reefs sites with different coral to algae cover ratios. Additionally, we assessed the bacterial community composition of two of these sponge species before and after a reciprocal transplantation experiment between the sites. An overall stable bacterial community composition was maintained across the two sites in all sponge species, with a high degree of host-specificity. Furthermore, the core bacterial communities of the sponges remained stable also after a 21-day transplantation period, although a minor shift was observed in less abundant taxa (〈 1%). Our findings support the conclusion that host identity and HMA-LMA status are stronger traits in shaping bacterial community composition than habitat. Nevertheless, long-term microbial monitoring of sponges along with benthic biomass and water quality assessments are needed for identifying ecosystem tolerance ranges and tipping points in ongoing coral reef phase shifts.
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  • 12
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    MSY needs no epitaph—but it was abused (2021)
    Oxford Univ. Press
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    Publikationsdatum: 2024-02-07
    Beschreibung: The maximum sustainable yield (MSY) concept is widely considered to be outdated and misleading. In response, fisheries scientists have developed models that often diverge radically from the first operational version of the concept. We show that the original MSY concept was deeply rooted in ecology and that going back to that version would be beneficial for fisheries, not least because the various substitutes have not served us well.
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  • 13
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    Use of food web knowledge in environmental conservation and management of living resources in the Baltic Sea (2021)
    Oxford Univ. Press
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    Publikationsdatum: 2024-02-07
    Beschreibung: Food webs are central entities mediating processes and external pressures in marine ecosystems. They are essential to understand and predict ecosystem dynamics and provision of ecosystem services. Paradoxically, utilization of food web knowledge in marine environmental conservation and resource management is limited. To better understand the use of knowledge and barriers to incorporation in management, we assess its application related to the management of eutrophication, chemical contamination, fish stocks, and non-indigenous species. We focus on the Baltic, a severely impacted, but also intensely studied and actively managed semi-enclosed sea. Our assessment shows food web processes playing a central role in all four areas, but application varies strongly, from formalized integration in management decisions, to support in selecting indicators and setting threshold values, to informal knowledge explaining ecosystem dynamics and management performance. Barriers for integration are complexity of involved ecological processes and that management frameworks are not designed to handle such information. We provide a categorization of the multi-faceted uses of food web knowledge and benefits of future incorporation in management, especially moving towards ecosystem-based approaches as guiding principle in present marine policies and directives. We close with perspectives on research needs to support this move considering global and regional change.
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  • 14
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    Decrease in diatom dominance at lower Si:N ratios alters plankton food webs (2020)
    Oxford Univ. Press
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    Publikationsdatum: 2023-02-08
    Beschreibung: Many coastal oceans experience not only increased loads of nutrients but also changes in the stoichiometry of nutrient supply. Excess supply of nitrogen and stable or decreased supply of silicon lower silicon to nitrogen (Si:N) ratios, which may decrease diatom proportion in phytoplankton. To examine how Si:N ratios affect plankton community composition and food web structure, we performed a mesocosm experiment where we manipulated Si:N ratios and copepod abundance in a Baltic Sea plankton community. In high Si:N treatments, diatoms dominated. Some of them were likely spared from grazing unexpectedly resulting in higher diatom biomass under high copepod grazing. With declining Si:N ratios, dinoflagellates became more abundant under low and picoplankton under high copepod grazing. This altered plankton food web structure: under high Si:N ratios, edible diatoms were directly accessible food for copepods, while under low Si:N ratios, microzooplankton and phago-mixotrophs (mixoplankton) were a more important food source for mesograzers. The response of copepods to changes in the phytoplankton community was complex and copepod density-dependent. We suggest that declining Si:N ratios favor microzoo- and mixoplankton leading to increased complexity of planktonic food webs. Consequences on higher trophic levels will, however, likely be moderated by edibility, nutritional value or toxicity of dominant phytoplankton species.
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    Taxon-specific prey response to the invasion of a pelagic invertebrate predator, revealed by comparison of pre- and post-invasion time series (2020)
    Oxford Univ. Press
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    Publikationsdatum: 2023-02-08
    Beschreibung: Quantification and attribution of the food web changes associated with the invasion of non-indigenous species in the marine realm often remain a challenge. One of the pelagic non-indigenous species of concern in the recent history of aquatic bioinvasions is the predatory cladoceran Cercopagis pengoi, which invaded the Baltic Sea in the early 1990s. While several studies have reported immediate declines in abundances of its potential prey, the long-term effects of C. pengoi on the food webs remain to be examined. Based on the long-term time series (1968–2018) in the Gulf of Riga (Baltic Sea), we found significant declines in abundance of the cladoceran Pleopis spp. and copepod Eurytemora affinis by 90 and 80%, respectively, are associated with the invasion of C. pengoi as well as significant alterations in seasonal abundance patterns of Pleopis spp., E. affinis and cladoceran Bosmina spp. The invasion of the non-indigenous predator has led to the changed prey abundance–temperature relationships. Special caution was taken in data preprocessing, to minimize the likelihood that observed changes in the zooplankton prey could be associated with factors other than the invasion of C. pengoi, such as temperature and storminess.
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    Zooplankton growth and survival differentially respond to interactive warming and acidification effects (2020)
    Oxford Univ. Press
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    Publikationsdatum: 2023-02-08
    Beschreibung: The copepod Acartia tonsa is a key component of a wide range of marine ecosystems, linking energy transfer from phytoplankton to higher trophic levels, and has a central role in productivity and biogeochemistry. The interaction of end-of-century global warming and ocean acidification scenarios with testing moderate temperature effects on a seminatural copepod community is needed to understand future community functioning. Here, we deployed a mesocosm experimental set-up with a full factorial design using two temperatures (13°C and 19°C) crossed with a pCO2 gradient ranging from ambient (550 μatm) to 3000 μatm. We used the natural bacteria, phyto- and microzooplankton species composition and biomass of the Kiel Bight and tested the response of A. tonsa development, carbon growth, mortality, size and condition. The tested traits were differently affected by the interaction of temperature and acidification. Ocean acidification increased development, carbon growth, size and mortality under the warming scenario of 19°C. At 13°C mortality rates decreased, while carbon growth, size and condition increased with acidification. We conclude from our experimental approach that a single species shows a variety of responses depending on the focal functional trait. Trait-specific mesozooplankton responses need to be further investigated and compared between geographical regions, seasons and taxonomic groups.
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    Single-Cell Transcriptomics of Abedinium Reveals a New Early-Branching Dinoflagellate Lineage (2020)
    Oxford Univ. Press
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    Publikationsdatum: 2023-02-08
    Beschreibung: Dinoflagellates possess many cellular characteristics with unresolved evolutionary histories. These include nuclei with greatly expanded genomes and chromatin packaged using histone-like proteins and dinoflagellate-viral nucleoproteins instead of histones, highly reduced mitochondrial genomes with extensive RNA editing, a mix of photosynthetic and cryptic secondary plastids, and tertiary plastids. Resolving the evolutionary origin of these traits requires understanding their ancestral states and early intermediates. Several early-branching dinoflagellate lineages are good candidates for such reconstruction, however these cells tend to be delicate and environmentally sparse, complicating such analyses. Here, we employ transcriptome sequencing from manually isolated and microscopically documented cells to resolve the placement of two cells of one such genus, Abedinium, collected by remotely operated vehicle in deep waters off the coast of Monterey Bay, CA. One cell corresponds to the only described species, Abedinium dasypus, whereas the second cell is distinct and formally described as Abedinium folium, sp. nov. Abedinium has classically been assigned to the early-branching dinoflagellate subgroup Noctilucales, which is weakly supported by phylogenetic analyses of small subunit ribosomal RNA, the single characterized gene from any member of the order. However, an analysis based on 221 proteins from the transcriptome places Abedinium as a distinct lineage, separate from and basal to Noctilucales and the rest of the core dinoflagellates. The transcriptome also contains evidence of a cryptic plastid functioning in the biosynthesis of isoprenoids, iron–sulfur clusters, and heme, a mitochondrial genome with all three expected protein-coding genes (cob, cox1, and cox3), and the presence of some but not all dinoflagellate-specific chromatin packaging proteins.
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    Estimating stock status from relative abundance and resilience (2020)
    Oxford Univ. Press
    Details
    Publikationsdatum: 2023-02-08
    Beschreibung: The Law of the Sea as well as regional and national laws and agreements require exploited populations or stocks to be managed so that they can produce maximum sustainable yields. However, exploitation level and stock status are unknown for most stocks because the data required for full stock assessments are missing. This study presents a new method (AMSY) that estimates relative population size when no catch data are available using time-series of catch-per-unit-effort or other relative abundance indices as the main input. AMSY predictions for relative stock size were not significantly different from the “true” values when compared with simulated data. Also, they were not significantly different from relative stock size estimated by data-rich models in 88% of the comparisons within 140 real stocks. Application of AMSY to 38 data-poor stocks showed the suitability of the method and led to the first assessments for 23 species. Given the lack of catch data as input, AMSY estimates of exploitation come with wide margins of uncertainty which may not be suitable for management. However, AMSY seems to be well suited for estimating productivity as well as relative stock size and may, therefore, aid in the management of data-poor stocks.
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  • 19
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    Powering the 21st century by wind energy—Options, facts, figures (2019)
    American Institute of Physics (AIP)
    In:  Applied Physics Reviews, 6 (3). 031303.
    Details
    Publikationsdatum: 2020-01-02
    Beschreibung: This review article aims to provide an overview and insight into the most relevant aspects of wind energy development and current state-of-the-art. The industry is in a very mature stage, so it seems to be the right time to take stock of the relevant areas of wind energy use for power generation. For this review, the authors considered the essential aspects of the development of wind energy technology: research, modeling, and prediction of wind speed as an energy source, the technology development of the plants divided into the mechanical and electrical systems and the plant control, and finally the optimal plant operation including the maintenance strategies. The focus is on the development in Europe, with a partial focus on Germany. The authors are employees of the Fraunhofer Institutes, Institute for Energy Economics and Energy Systems Technology and Institute for Wind Energy Systems, who have contributed to the development of this technology for decades.
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  • 20
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    Heinrich events show two-stage climate response in transient glacial simulations (2019)
    Copernicus
    In:  Climate of the Past, 15 . pp. 153-168.
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    Publikationsdatum: 2021-01-08
    Beschreibung: Heinrich events are among the dominant modes of glacial climate variability. During these events, massive iceberg armadas were released by the Laurentide Ice Sheet, sailed across the Atlantic, and caused large-scale climate changes. We study these events in a fully coupled complex ice sheet–climate model with synchronous coupling between ice sheets and oceans. The ice discharges occur as internal variability of the model with a recurrence period of 5kyr, an event duration of 1–1.5kyr, and a peak discharge rate of about 50mSv, roughly consistent with reconstructions. The climate response shows a two-stage behavior, with freshwater release effects dominating the surge phase and ice-sheet elevation effects dominating in the post-surge phase. As a direct response to the freshwater discharge during the surge phase, the deepwater formation in the North Atlantic decreases and the North Atlantic deepwater cell weakens by 3.5Sv. With the reduced oceanic heat transport, the surface temperatures across the North Atlantic decrease, and the associated reduction in evaporation causes a drying in Europe. The ice discharge lowers the surface elevation in the Hudson Bay area and thus leads to increased precipitation and accelerated ice sheet regrowth in the post-surge phase. Furthermore, the jet stream widens to the north and becomes more zonal. This contributes to a weakening of the subpolar gyre, and a continued cooling over Europe even after the ice discharge. This two-stage behavior can explain previously contradicting model results and understandings of Heinrich Events.
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  • 21
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    Highly replicated sampling reveals no diurnal vertical migration but stable species-specific vertical habitats in planktonic foraminifera (2019)
    Oxford Univ. Press
    In:  Journal of Plankton Research, 41 (2). pp. 127-141.
    Details
    Publikationsdatum: 2022-01-31
    Beschreibung: Diurnal vertical migration (DVM) is a widespread phenomenon in the upper ocean, but it remains unclear to what degree it also involves passively transported micro- and meso-zooplankton. These organisms are difficult to monitor by in situ sensing and observations from discrete samples are often inconclusive. Prime examples of such ambiguity are planktonic foraminifera, where contradictory evidence for DVM continues to cast doubt on the stability of species vertical habitats, which introduces uncertainties in geochemical proxy interpretation. To provide a robust answer, we carried out highly replicated randomised sampling with 41 vertically resolved plankton net hauls taken within 26 hours in a confined area of 400 km2 in the tropical North Atlantic, where DVM in larger plankton occurs. Manual enumeration of planktonic foraminifera cell density consistently reveals the highest total cell concentrations in the surface mixed layer (top 50 m) and analysis of cell density in seven individual species representing different shell sizes, life strategies and presumed depth habitats reveals consistent vertical habitats not changing over the 26 hours sampling period. These observations robustly reject the existence of DVM in planktonic foraminifera in a setting where DVM occurs in other organisms.
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  • 22
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    Sponges from Zanzibar host diverse prokaryotic communities with potential for natural product synthesis (2019)
    Oxford Univ. Press
    In:  FEMS Microbiology Ecology, 95 (4). fiz026.
    Details
    Publikationsdatum: 2022-01-31
    Beschreibung: Sponges are one of the most dominant organisms in marine ecosystems. One reason for their success is their association with microorganisms that are besides the host itself responsible for the chemical defence. Sponge abundances have been increasing on coral reefs in the Western Indian Ocean (WIO) and are predicted to increase further with rising anthropogenic impacts on coral reefs. However, there is a paucity of information on chemical ecology of sponges from the WIO and their prokaryotic community composition. We used a combination of Illumina sequencing and a predictive metagenomic analysis to (i) assess the prokaryotic community composition of sponges from Zanzibar, (ii) predict the presence of KEGG metabolic pathways responsible for bioactive compound production and (iii) relate their presence to the degree of observed chemical defence in their respective sponge host. We found that sponges from Zanzibar host diverse prokaryotic communities that are host species-specific. Sponge-species and respective specimens that showed strong chemical defences in previous studies were also predicted to be highly enriched in various pathways responsible for secondary metabolite production. Hence, the combined sequencing and predictive metagenomic approach proved to be a useful indicator for the metabolic potential of sponge holobionts
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  • 23
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    Bacterial communities associated with individual transparent exopolymer particles (TEP) (2019)
    Oxford Univ. Press
    In:  Journal of Plankton Research, 41 (4). pp. 561-565.
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    Publikationsdatum: 2022-01-31
    Beschreibung: Transparent exopolymer particles (TEP) are polysaccharide-rich microgels that are prevalent in the marine environment and have important roles in the aggregation of organic matter and carbon export from the euphotic zone. TEP are readily colonized by bacteria and utilized by specialized taxa, such as Alteromonadaceae. However, bacterial community composition specifically attached to natural TEP remains largely unknown. In this study, we isolated individual TEP from Plymouth Sound (UK) and performed DNA sequencing of the TEP-attached bacterial communities. We also sampled the cognate bulk seawater total bacterial communities for comparison. The bacterial communities associated with individual TEP showed distinct differences compared to the total bulk bacterioplankton communities, with Alteromonadaceae significantly more abundant on TEP. The TEP-associated Alteromonadaceae consisted of two operational taxonomic units that were closely related to Marinobacter and Glaciecola, both previously associated with biogenic aggregates and microgel-rich habitats. This study provides novel insight into marine bacterial–microgel interactions.
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  • 24
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    On the pile-up effect and priors for Linf and M/K: Response to a Comment by Hordyk et al. on “A new approach for estimating stock status from length frequency data” (2019)
    Oxford Univ. Press
    Details
    Publikationsdatum: 2023-01-12
    Beschreibung: There is a recognized need for new methods with modest data requirements to provide preliminary estimates of stock status for data-limited stocks (e.g. Rudd and Thorson, 2018). Froese et al. (2018) provide such a method, which derives estimates of relative stock size from length frequency (LF) data of exploited stocks. They show that their length-based Bayesian biomass estimation method (LBB) can reproduce the “true” parameters used in simulated data and can approximate the relative stock size as estimated independently by more data-demanding methods in 34 real stocks. However, in a comment on LBB, Hordyk et al. (2019) claim (i) that the master equation of LBB is incomplete because it does not correct for the pile-up effect caused by aggregating length measurements into length classes or “bins”, (ii) that LBB is highly sensitive to equilibrium assumptions and wrongly uses maximum observed length (Lmax) for guidance in setting a prior for the estimation of asymptotic length (Linf), and (iii) that the default prior used by LBB for the ratio between natural mortality and somatic growth rate (M/K) of 1.5 (SD = 0.15) is inadequate for many exploited species. These comments are addressed below
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  • 25
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    The Chiloé Mw 7.6 earthquake of 25 December 2016 in Southern Chile and its relation to the Mw 9.5 1960 Valdivia earthquake (2018)
    Oxford Univ. Press
    In:  Geophysical Journal International, 213 (1). pp. 210-221.
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    Publikationsdatum: 2021-02-08
    Beschreibung: On 25 December 2016, a Mw 7.6 earthquake broke a portion of the Southern Chilean subduction zone south of Chiloé Island, located in the central part of the Mw 9.5 1960 Valdivia earthquake. This region is characterized by repeated earthquakes in 1960 and historical times with very sparse interseismic activity due to the subduction of a young (~15 Ma), and therefore hot, oceanic plate. We estimate the co-seismic slip distribution based on a kinematic finite fault source model, and through joint inversion of teleseismic body waves and strong motion data. The coseismic slip model yields a total seismic moment of 3.94×1020 Nm that occurred over ~30 s, with the rupture propagating mainly downdip, reaching a peak-slip of ~4.2 m. Regional moment tensor inversion of stronger aftershocks reveals thrust type faulting at depths of the plate interface. The fore- and aftershock seismicity is mostly related to the subduction interface with sparse seismicity in the overriding crust. The 2016 Chiloé event broke a region with increased locking and most likely broke an asperity of the 1960 earthquake. The updip limit of the main event, aftershocks, foreshocks and interseismic activity are spatially similar, located ~15 km offshore and parallel to Chiloé Islands west coast. The coseismic slip model of the 2016 Chiloé earthquake suggests a peak slip of 4.2 m that locally exceeds the 3.38 m slip deficit that has accumulated since 1960. Therefore, the 2016 Chiloé earthquake possibly released strain that has built up prior to the 1960 Valdivia earthquake.
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  • 26
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    Revision of the Ocinebrina aciculata species complex (Mollusca: Gastropoda: Muricidae) in the northeastern Atlantic Ocean and Mediterranean Sea (2018)
    Oxford Univ. Press
    In:  Journal of Molluscan Studies, 84 (1). pp. 19-29.
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    Publikationsdatum: 2021-02-08
    Beschreibung: We used a molecular phylogenetic approach to investigate species delimitation and diversification in the northeastern Atlantic and Mediterranean musseldrills of the Ocinebrina aciculata complex, based on molecular data from topotypical material of many of the nominal taxa. The complex is shown to consist of at least five species: Ocinebrina aciculata (Lamarck, 1822) from the Atlantic and western Mediterranean; O. cf. corallina (Scacchi, 1836) from the central Mediterranean Sea; O. reinai Bonomolo & Crocetta, 2012 from the Tyrrhenian Sea; O. corallinoides Pallary, 1912 from the Gulf of Gabès; and O. aegeensis n. sp. currently known from the Aegean Sea only. The new species is differentiated from the other taxa by very subtle morphological diagnostic features, although it is clearly identified by genetic distance and apomorphic DNA-sequence characters. The identity of Murex corallinus Scacchi, 1836 (type species of Ocinebrina Jousseaume, 1880) could not be defined with certainty, pending genetic comparison of specimens of the â €? large Tyrrhenian morphotype' (corresponding to the neotype, but not assayed herein) with the assayed â €? small morphotype'.
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  • 27
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    Metagenomic binning reveals versatile nutrient cycling and distinct adaptive features in alphaproteobacterial symbionts of marine sponges (2018)
    Oxford Univ. Press
    In:  FEMS Microbiology Ecology, 94 (6). fiy074.
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    Publikationsdatum: 2021-02-08
    Beschreibung: Marine sponges are early-branched metazoans known to harbor dense and diverse microbial communities. Yet the role of the so far uncultivable alphaproteobacterial lineages that populate these sessile invertebrates remains unclear. We applied a sequence composition-dependent binning approach to assemble one Rhodospirillaceae genome from the Spongia officinalis microbial metagenome and contrast its functional features with those of closely related sponge-associated and free-living genomes. Both symbiotic and free-living Rhodospirillaceae shared a suite of common features, possessing versatile carbon, nitrogen, sulfur and phosphorus metabolisms. Symbiotic genomes could be distinguished from their free-living counterparts by the lack of chemotaxis and motility traits, enrichment of genes required for the uptake and utilization of organic sulfur compounds—particularly taurine—, higher diversity and abundance of ABC transporters, and a distinct repertoire of genes involved in natural product biosynthesis, plasmid stability, cell detoxification and oxidative stress remediation. These sessile symbionts may more effectively contribute to host fitness via nutrient exchange, and also host detoxification and chemical defense. Considering the worldwide occurrence and high diversity of sponge-associated Rhodospirillaceae verified here using a tailored in silico approach, we suggest that these organisms are not only relevant to holobiont homeostasis but also to nutrient cycling in benthic ecosystems.
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  • 28
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    Resolving the fine-scale velocity structure of continental hyperextension at the Deep Galicia Margin using full-waveform inversion (2018)
    Oxford Univ. Press
    In:  Geophysical Journal International, 212 (1). pp. 244-263.
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    Publikationsdatum: 2021-02-08
    Beschreibung: Continental hyperextension during magma-poor rifting at the Deep Galicia Margin is characterised by a complex pattern of faulting, thin continental fault blocks, and the serpentinisation, with local exhumation, of mantle peridotites along the S-reflector, interpreted as a detachment surface. In order to understand fully the evolution of these features, it is important to image seismically the structure and to model the velocity structure to the greatest resolution possible. Travel-time tomography models have revealed the long-wavelength velocity structure of this hyperextended domain, but are often insufficient to match accurately the short-wavelength structure observed in reflection seismic imaging. Here we demonstrate the application of two-dimensional (2D) time-domain acoustic full-waveform inversion to deep water seismic data collected at the Deep Galicia Margin, in order to attain a high resolution velocity model of continental hyperextension. We have used several quality assurance procedures to assess the velocity model, including comparison of the observed and modelled waveforms, checkerboard tests, testing of parameter and inversion strategy, and comparison with the migrated reflection image. Our final model exhibits an increase in the resolution of subsurface velocities, with particular improvement observed in the westernmost continental fault blocks, with a clear rotation of the velocity field to match steeply dipping reflectors. Across the S-reflector there is a sharpening in the velocity contrast, with lower velocities beneath S indicative of preferential mantle serpentinisation. This study supports the hypothesis that normal faulting acts to hydrate the upper mantle peridotite, observed as a systematic decrease in seismic velocities, consistent with increased serpentinisation. Our results confirm the feasibility of applying the full-waveform inversion method to sparse, deep water crustal datasets.
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  • 29
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    Integrating population genomics and biophysical models towards evolutionary-based fisheries management (2018)
    Oxford Univ. Press
    In:  ICES Journal of Marine Science, 75 (4). pp. 1245-1257.
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    Publikationsdatum: 2021-02-08
    Beschreibung: Overfishing and rapid environmental shifts pose severe challenges to the resilience and viability of marine fish populations. To develop and implement measures that enhance species’ adaptive potential to cope with those pressures while, at the same time, ensuring sustainable exploitation rates is part of the central goal of fisheries management. Here, we argue that a combination of biophysical modelling and population genomic assessments offer ideal management tools to define stocks, their physical connectivity and ultimately, their short-term adaptive potential. To date, biophysical modelling has often been confined to fisheries ecology whereas evolutionary hypotheses remain rarely considered. When identified, connectivity patterns are seldom explored to understand the evolution and distribution of adaptive genetic variation, a proxy for species’ evolutionary potential. Here, we describe a framework that expands on the conventional seascape genetics approach by using biophysical modelling and population genomics. The goals are to identify connectivity patterns and selective pressures, as well as putative adaptive variants directly responding to the selective pressures and, ultimately, link both to define testable hypotheses over species response to shifting ecological conditions and overexploitation.
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  • 30
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    A new approach for estimating stock status from length frequency data (2018)
    Oxford Univ. Press
    In:  ICES Journal of Marine Science, 75 (6). pp. 2004-2015.
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    Publikationsdatum: 2021-02-08
    Beschreibung: This study presents a new method (LBB) for the analysis of length frequency data from commercial catches. LBB works for species that grow throughout their lives, such as most commercially-important fish and invertebrates, and requires no input in addition to length frequency data. It estimates asymptotic length, length at first capture, relative natural mortality, and relative fishing mortality. Standard fisheries equations can then be used to approximate current exploited biomass relative to unexploited biomass. In addition, these parameters allow the estimation of length at first capture that would maximize catch and biomass for a given fishing effort, and estimation of a proxy for the relative biomass capable of producing maximum sustainable yields. Relative biomass estimates of LBB were not significantly different from the “true” values in simulated data and were similar to independent estimates from full stock assessments. LBB also presents a new indicator for assessing whether an observed size structure is indicative of a healthy stock. LBB results will obviously be misleading if the length frequency data do not represent the size composition of the exploited size range of the stock or if length frequencies resulting from the interplay of growth and mortality are masked by strong recruitment pulses.
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  • 31
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    Application of the perfectly matched layer in 3-D marine controlled-source electromagnetic modelling (2018)
    Oxford Univ. Press
    In:  Geophysical Journal International, 212 (1). pp. 333-344.
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    Publikationsdatum: 2021-02-08
    Beschreibung: In this study, the complex frequency-shifted perfectly matched layer (CFS-PML) in stretching Cartesian coordinates, is successfully applied to three-dimensional (3D) frequency-domain marine controlled-source electromagnetic (CSEM) field modelling. The Dirichlet boundary, which is usually used within the traditional framework of EM modeling algorithms, assumes the electric or magnetic field values are zero at the boundaries. This requires the boundaries be sufficiently far away from the sources in the area of interest. To mitigate the boundary artifacts, a large modelling area may be necessary even though cell sizes are allowed to grow toward the boundaries due to the diffusion of the electromagnetic wave propagation. Compared with the conventional Dirichlet boundary, the PML boundary is preferred as the modelling area of interest could be restricted to the target region and only a few absorbing layers surrounding can effectively depress the artificial boundary effect without losing the numerical accuracy. Furthermore, for joint inversion of seismic and marine CSEM data, if we used the PML for CSEM field simulation instead of the conventional Dirichlet, the modeling area for these two different geophysical data collected from the same survey area could the same, which is convenient for joint inversion grid matching. We apply the CFS-PML boundary to 3D marine CSEM modelling by using the staggered finite-difference (SFD) discretization. Numerical test indicates that the modeling algorithm using the CFS-PML also shows good accuracy compared to the Dirichlet. Furthermore, the modeling algorithm using the CFS-PML shows advantages in computational time and memory saving than that using the Dirichlet boundary. For the 3D example in this study, the memory saving using the PML is nearly 42 % and the time saving is around 48% compared to using the Dirichlet.
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  • 32
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    Sustainable use of Baltic Sea resources (2018)
    Oxford Univ. Press
    In:  ICES Journal of Marine Science, 75 (7). pp. 2434-2438.
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    Publikationsdatum: 2021-02-08
    Beschreibung: The BONUS symposium “Science delivery for sustainable use of the Baltic Sea living resources” held in Tallinn, Estonia, in October 2017 was an opportunity for the presentation and discussion of 107 papers that examined the state and dynamics of living resources of the Baltic Sea, and associated management challenges. The symposium included a half-day stakeholder panel discussion that addressed the main challenges related to sustainable management and matching research and policy/management needs. Based on the five symposium papers published in this Special Issue as well as the stakeholder panel discussion, it can be concluded that (i) new observations about the feeding ecology of clupeids supports a more complete understanding of trophic interactions in the pelagic realm and improved calibration of ecosystem models, (ii) to safequard sustainable and diverse fisheries resources, one should take into account the specific local characteristics of the fish community, (iii) to safeguard sustainable use of marine resources and mitigate cross-sectoral and transboundary conflicts, a risk-based approach should be adopted, and (iv) incorporation of scientific advice into management faces several obstacles including the reality that not all readily available knowledge is currently being incorporated into the decision-making process.
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  • 33
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    A three-dimensional view on biodiversity changes: spatial, temporal, and functional perspectives on fish communities in the Baltic Sea (2018)
    Oxford Univ. Press
    In:  ICES Journal of Marine Science, 75 (7). pp. 2463-2475.
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    Publikationsdatum: 2021-02-08
    Beschreibung: Fisheries and marine ecosystem-based management requires a holistic understanding of the dynamics of fish communities and their responses to changes in environmental conditions. Environmental conditions can simultaneously shape the spatial distribution and the temporal dynamics of a population, which together can trigger changes in the functional structure of communities. Here, we developed a comprehensive framework based on complementary multivariate statistical methodologies to simultaneously investigate the effects of environmental conditions on the spatial, temporal and functional dynamics of species assemblages. The framework is tested using survey data collected during more than 4000 fisheries hauls over the Baltic Sea between 2001 and 2016. The approach revealed the Baltic fish community to be structured into three sub-assemblages along a strong and temporally stable salinity gradient decreasing from West to the East. Additionally, we highlight a mismatch between species and functional richness associated with a lower functional redundancy in the Baltic Proper compared with other sub-areas, suggesting an ecosystem more susceptible to external pressures. Based on a large dataset of community data analysed in an innovative and comprehensive way, we could disentangle the effects of environmental changes on the structure of biotic communities-key information for the management and conservation of ecosystems.
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  • 34
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    Vertical structure of plankton communities in areas of European eel larvae distribution in the Sargasso Sea (2018)
    Oxford Univ. Press
    In:  Journal of Plankton Research, 40 (4). pp. 362-375.
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    Publikationsdatum: 2021-02-08
    Beschreibung: The European and American eels spawn in the subtropical convergence zone (STCZ) in the Sargasso Sea, a dynamic and relatively productive area that is strongly influenced by front and eddy formations and subducted high-saline water masses. To understand how the physical and biological environments may affect the early life history of eels, we conducted a detailed bio-physical investigation of the water column at a site of high eel larvae abundance. Diel measurements and sampling in the upper 300 m revealed strong variations in hydrographic conditions and mean depths of different taxonomic groups; however, characteristics patterns of distribution were apparent. Most species showed diel vertical migrations, ascending about 20-30 m at night, whereas examples of night-time downward migration were also seen. European eel larvae were among the species showing more extensive diel vertical migration: their population mean depth changed from 160 m at day to 100 m at night where abundance peaked at 45 m depth. Distribution and migration of eel larvae corresponded to patterns observed for small hydrozoans, supporting a proposed predator-prey linkage. The study demonstrates the diverse and vertically strongly structured plankton community of STCZ where larvae of eel and other fish find a wide range of potential niches.
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  • 35
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    Shift towards larger diatoms in a natural phytoplankton assemblage under combined high-CO2 and warming conditions (2018)
    Oxford Univ. Press
    In:  Journal of Plankton Research, 40 (4). pp. 391-406.
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    Publikationsdatum: 2021-03-19
    Beschreibung: An indoor mesocosm experiment was carried out to investigate the combined effects of ocean acidification and warming on the species composition and biogeochemical element cycling during a winter/spring bloom with a natural phytoplankton assemblage from the Kiel fjord, Germany. The experimental setup consisted of a "Control" (ambient temperature of similar to 4.8 degrees C and similar to 535 +/- 25 mu atm pCO(2)), a "High-CO2" treatment (ambient temperature and initially 1020 +/- 45 mu atm pCO(2)) and a "Greenhouse" treatment (similar to 8.5 degrees C and initially 990 +/- 60 mu atm pCO(2)). Nutrient replete conditions prevailed at the beginning of the experiment and light was provided at in situ levels upon reaching pCO(2) target levels. A diatom-dominated bloom developed in all treatments with Skeletonema costatum as the dominant species but with an increased abundance and biomass contribution of larger diatom species in the Greenhouse treatment. Conditions in the Greenhouse treatment accelerated bloom development with faster utilization of inorganic nutrients and an earlier peak in phytoplankton biomass compared to the Control and High CO2 but no difference in maximum concentration of particulate organic matter (POM) between treatments. Loss of POM in the Greenhouse treatment, however, was twice as high as in the Control and High CO2 treatment at the end of the experiment, most likely due to an increased proportion of larger diatom species in that treatment. We hypothesize that the combination of warming and acidification can induce shifts in diatom species composition with potential feedbacks on biogeochemical element cycling.
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  • 36
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    Light effects on phytoplankton morphometric traits influence nutrient utilization ability (2018)
    Oxford Univ. Press
    In:  Journal of Plankton Research, 40 (5). pp. 568-579.
    Details
    Publikationsdatum: 2021-02-08
    Beschreibung: Light and nutrients are essential resources for phytoplankton growth and considered to shape the size structure and other morphometric traits (surface:volume ratio, deviation from spherical shape) of phytoplankton communities. If morphometric traits influence the growth and resource use, shifts by one of the two factors should influence the capability to utilize the other factor. We performed a two-step experiment, where a natural phytoplankton community was first exposed to three different light levels (supposed to be limiting, saturating and slightly inhibiting for the majority of species) and grown until stationary phase. Then, the pre-conditioned communities were split into two nutrient treatments (control and saturating nutrient pulse) and again grown until stationary phase under the medium light intensity. During the experimental light phase, community mean cell-size increased with light, but surface:volume ratio and deviation from spherical shape decreased. Moreover, in response to the following nutrient pulse, the low light pre-conditioned communities showed the highest initial growth rates in response to the nutrient pulse. The high light pre-conditioned communities showed the highest conversion of the nutrient pulse into biomass during the stationary phase. These results demonstrate how the imprint of one environmental factor on trait distribution influences the ability to cope with another.
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  • 37
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    Quantifying top-down control and ecological traits of the scyphozoan Aurelia aurita through a dynamic plankton model (2018)
    Oxford Univ. Press
    In:  Journal of Plankton Research, 40 (6). pp. 678-692.
    Details
    Publikationsdatum: 2021-02-08
    Beschreibung: Aurelia aurita (Linneaus, 1758) is a cosmopolitan scyphozoan, probably the most investigated jellyfish in temperate and highly productive coastal ecosystems. Despite a prominent top-down control in plankton food webs, a mechanistic understanding of A. aurita population dynamics and trophic interactions has been barely addressed. Here we develop a food web dynamic model to assess A. aurita role in the seasonal plankton dynamics of the Kiel Fjord, southwestern Baltic Sea. The model couples low trophic level dynamics, based on a classical Nutrient Phytoplankton Zooplankton Detritus (NPZD) model, to a stage-resolved copepod model (referencing Pseudocalanus sp.) and a jellyfish model (A. aurita ephyra and medusa) as consumers and predators, respectively. Simulations showed the relevance of high abundances of A. aurita, which appear related with warm winter temperatures, promoting a shift from a copepod-dominated food web to a ciliate and medusa dominated one. The model captured the intraspecific competition triggered by the medusae abundance and characterized by a negative relationship between population density and individual size/weight. Our results provide a mechanistic understanding of an emergent trait such as size shaping the food web functioning, driving predation rates and population dynamics of A. aurita, driving its sexual reproductive strategy at the end of the pelagic phase.
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  • 38
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    Impact of Ocean Acidification and Warming on the bioenergetics of developing eggs of Atlantic herring Clupea harengus (2018)
    Oxford Univ. Press
    In:  Conservation Physiology, 6 (1). coy050.
    Details
    Publikationsdatum: 2018-12-17
    Beschreibung: Atlantic herring (Clupea harengus) is a benthic spawner, therefore its eggs are prone to encounter different water conditions during embryonic development, with bottom waters often depleted of oxygen and enriched in CO2. Some Atlantic herring spawning grounds are predicted to be highly affected by ongoing Ocean Acidification and Warming with water temperature increasing by up to +3°C and CO2 levels reaching ca. 1000 μatm (RCP 8.5). Although many studies investigated the effects of high levels of CO2 on the embryonic development of Atlantic herring, little is known about the combination of temperature and ecologically relevant levels of CO2. In this study, we investigated the effects of Ocean Acidification and Warming on embryonic metabolic and developmental performance such as mitochondrial function, respiration, hatching success (HS) and growth in Atlantic herring from the Oslo Fjord, one of the spawning grounds predicted to be greatly affected by climate change. Fertilized eggs were incubated under combinations of two PCO2 conditions (400 μatm and 1100 μatm) and three temperatures (6, 10 and 14°C), which correspond to current and end-of-the-century conditions. We analysed HS, oxygen consumption (MO2) and mitochondrial function of embryos as well as larval length at hatch. The capacity of the electron transport system (ETS) increased with temperature, reaching a plateau at 14°C, where the contribution of Complex I to the ETS declined in favour of Complex II. This relative shift was coupled with a dramatic increase in MO2 at 14°C. HS was high under ambient spawning conditions (6–10°C), but decreased at 14°C and hatched larvae at this temperature were smaller. Elevated PCO2 increased larval malformations, indicating sub-lethal effects. These results indicate that energetic limitations due to thermally affected mitochondria and higher energy demand for maintenance occur at the expense of embryonic development and growth.
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  • 39
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    A benchmark study of numerical implementations of the sea level equation in GIA modelling (2018)
    Oxford Univ. Press
    In:  Geophysical Journal International, 215 (1). pp. 389-414.
    Details
    Publikationsdatum: 2021-02-08
    Beschreibung: The ocean load in glacial isostatic adjustment (GIA) modelling is represented by the so-called sea level equation (SLE). The SLE describes the mass redistribution of water between ice sheets and oceans on a deforming Earth. Despite various teams independently investigating GIA, there has been no systematic intercomparison among the numerical solvers of the SLE through which the methods may be validated. The goal of this paper is to present a series of synthetic examples designed for testing and comparing the numerical implementations of the SLE in GIA modelling. The 10 numerical codes tested combine various temporal and spatial parametrizations. The time-domain or Laplace-domain discretizations are used to solve the SLE through time, while spherical harmonics, finite differences or finite elements parametrize the GIA-related field variables spatially. The surface ice-water load and solid Earth’s topography are represented spatially either on an equiangular grid, a Gauss–Legendre or an equiarea grid with icosahedron-shaped spherical pixels. Comparisons are made in a series of five benchmark examples with an increasing degree of complexity. Due to the complexity of the SLE, there is no analytical solution to it. The accuracy of the numerical implementations is therefore assessed by the differences of the individual solutions with respect to a reference solution. While the benchmark study does not result in GIA predictions for a realistic loading scenario, we establish a set of agreed-upon results that can be extended in the future by including more complex case studies, such as solutions with realistic loading scenarios, the rotational feedback in the linear-momentum equation, and by considering a 3-D viscosity structure of the Earth’s mantle. The test computations performed so far show very good agreement between the individual results and their ability to capture the main features of sea-surface variation and the surface vertical displacement. The differences found can often be attributed to the different approximations inherent in the various algorithms. This shows the accuracy that can be expected from different implementations of the SLE, which helps to assess differences noted in the literature between predictions for realistic loading cases.
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  • 40
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    A statistical method to validate reconstructions of late-glacial relative sea level – Application to shallow water shells rated as low-grade sea-level indicators (2018)
    Copernicus
    In:  Climate of the Past Discussions . pp. 1-17.
    Details
    Publikationsdatum: 2018-09-12
    Beschreibung: In this study, we propose a statistical method to validate sea-level reconstructions using geological records known as sea-level indicators (SLIs). SLIs are often the only available data to retrace late-glacial relative sea level (RSL). Determining the RSL from SLI height is not straight forward, the elevation at which an SLI was found usually does not represent the past RSL. In contrast, it has to be related to past RSL by investigating sample’s type, habitat and deposition conditions. For instance, water distribution at which a specific specimen is found today can be related to the indicator's depositional height range. Furthermore, the precision of dating varies between geological samples, and, in case of radiocarbon dating, the age has to be calibrated using a non-linear calibration curve. To avoid an a-priori assumption like normal-distributed uncertainties, we define likelihood functions which take into account the indicative meaning’s available error information and calibration statistics represented by joint probabilities. For this conceptional study, we restrict ourselves to one type of indicators, shallow-water shells, which are usually considered as low-grade samples giving only a lower limit of former sea level, as the depth range in which they live spreads over several tens of meters, and does not follow a normal distribution. The presented method is aimed to serve as a strategy for glacial isostatic adjustment reconstructions, in this case for the German Paleo-Climate Modelling Initiative PalMod (https://www.palmod.de/en) and by extending it to other SLI types.
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  • 41
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    Harmonizing plant functional type distributions for evaluating Earth System Models (2018)
    Copernicus
    In:  Climate of the Past Discussions . pp. 1-51.
    Details
    Publikationsdatum: 2018-09-05
    Beschreibung: Dynamic vegetation models simulate global vegetation in terms of fractional coverages of a few plant functional types (PFTs). Although these models often share the same concept, they differ with respect to the number and kind of PFTs, complicating the comparability of simulated vegetation distributions. Pollen-based reconstructions are initially only available in form of time-series of individual taxa that are not distinguished in the models. Thus, to evaluate simulated vegetation distributions, the modelling results and pollen-based reconstructions have to be converted into a comparable format. The classical approach is the method of biomisation, but hitherto, PFT-based biomisation methods were only available for individual models. We introduce and evaluate a simple, universally applicable technique to harmonize PFT-distributions by assigning them into nine mega-biomes that follow the definitions commonly used for vegetation reconstructions. The method works well for all state-of the art dynamic vegetation models, independent of the spatial resolution or the complexity of the models. Large biome belts (such as tropical forest) are well represented, but regionally confined biomes (warm-mixed forest, Savanna) are only partly captured. Overall, the PFT-based biomisation is able to keep up with the conventional biomisation approach of forcing biome models (here: BIOME1) with the background climate states. The new method has, however, the advantage that it allows a more direct comparison and evaluation of the vegetation distributions simulated by Earth System Models. Thereby, the new method provides a powerful tool for the evaluation of Earth System Models in general.
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  • 42
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    Marine dipole–dipole controlled source electromagnetic and coincident-loop transient electromagnetic experiments to detect seafloor massive sulphides: effects of three-dimensional bathymetry (2018)
    Oxford Univ. Press
    In:  Geophysical Journal International, 215 (3). pp. 2156-2171.
    Details
    Publikationsdatum: 2021-02-08
    Beschreibung: Seafloor massive sulphides (SMSs) are regarded as a potential future resource to satisfy the growing global demand of metals including copper, zinc and gold. Aside from mining and retrieving profitable amounts of massive sulphides from the seafloor, the present challenge is to detect and delineate significant SMS accumulations, which are generally located near mid-ocean ridges and along submarine volcanic arc and backarc spreading centres. Currently, several geophysical technologies are being developed to detect and quantify SMS occurrences that often exhibit measurable contrasts in their physical parameters compared to the surrounding host rock. Here, we use a short, fixed-offset controlled source electromagnetic (CSEM) system and a coincident-loop transient electromagnetic (TEM) system, which in theory allow the detection of SMS in the shallow seafloor due to a significant electrical conductivity contrast to their surroundings. In 2016, CSEM and TEM experiments were carried out at several locations near the Trans- Atlantic Geotraverse hydrothermal field to investigate shallow occurrences of massive sulphides below the seafloor. Measurements were conducted in an area that contains distinct SMS sites located several kilometres off-axis from the Mid-Atlantic ridge, some of which are still connected to hydrothermal activity and others where hydrothermal activity has ceased. Based on the quality of the acquired data, both experiments were operationally successful. However, the data analysis indicates bias caused by three-dimensional (3D) effects of the rough bathymetry in the study area and, thus, data interpretation remains challenging. Therefore, we study the influence of 3D bathymetry for marine CSEM and TEM experiments, focusing on shallow 3D conductors located beneath mound-like structures.We analyse synthetic inversion models for attributes associated with 3D distortions of CSEM and TEM data that are not sufficiently accounted for in conventional 1D (TEM) and 2D (CSEM) interpretation schemes. Before an adequate quantification of SMS in the region is feasible, these 3D effects need to be studied to avoid over/underestimation of SMS using the acquired EM data. The sensitivity of CSEM and TEM to bathymetry is investigated by means of 3D forward modelling, followed by 1D (TEM) and 2D (CSEM) inversion of the synthetic data using realistic error conditions. Subsequently, inversion models of the synthetic 3D data are analysed and compared to models derived from the measured data to illustrate that 3D distortions are evident in the recorded data sets.
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  • 43
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    Deglacial permafrost carbon dynamics in MPI-ESM (2018)
    Copernicus
    In:  Climate of the Past Discussions . pp. 1-39.
    Details
    Publikationsdatum: 2018-09-14
    Beschreibung: We have developed a new module to calculate soil organic carbon (SOC) accumulation in perennially frozen ground in the land surface model JSBACH. Running this offline version of MPI-ESM we have modelled permafrost carbon accumulation and release from the Last Glacial Maximum (LGM) to the Pre-industrial (PI). Our simulated near-surface PI permafrost extent of 16.9Miokm2 is close to observational evidence. Glacial boundary conditions, especially ice sheet coverage, result in profoundly different spatial patterns of glacial permafrost extent. Deglacial warming leads to large-scale changes in soil temperatures, manifested in permafrost disappearance in southerly regions, and permafrost aggregation in formerly glaciated grid cells. In contrast to the large spatial shift in simulated permafrost occurrence, we infer an only moderate increase of total LGM permafrost area (18.3Miokm2) – together with pronounced changes in the depth of seasonal thaw. Reconstructions suggest a larger spread of glacial permafrost towards more southerly regions, but with a highly uncertain extent of non-continuous permafrost. Compared to a control simulation without describing the transport of SOC into perennially frozen ground, the implementation of our newly developed module for simulating permafrost SOC accumulation leads to a doubling of simulated LGM permafrost SOC storage (amounting to a total of ~150PgC). Despite LGM temperatures favouring a larger permafrost extent, simulated cold glacial temperatures – together with low precipitation and low CO2 levels – limit vegetation productivity and therefore prevent a larger glacial SOC build-up in our model. Changes in physical and biogeochemical boundary conditions during deglacial warming lead to an increase in mineral SOC storage towards the Holocene (168PgC at PI), which is below observational estimates (575PgC in continuous and discontinuous permafrost). Additional model experiments clarified the sensitivity of simulated SOC storage to model parameters, affecting long-term soil carbon respiration rates and simulated active layer depths. Rather than a steady increase in carbon release from the LGM to PI as a consequence of deglacial permafrost degradation, our results suggest alternating phases of soil carbon accumulation and loss as an effect of dynamic changes in permafrost extent, active layer depths, soil litter input, and heterotrophic respiration.
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  • 44
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    Sedproxy: a forward model for sediment archived climate proxies (2018)
    Copernicus
    In:  Climate of the Past Discussions . pp. 1-31.
    Details
    Publikationsdatum: 2018-09-14
    Beschreibung: Climate reconstructions based on proxy records recovered from marine sediments, such as alkenone records or geochemical parameters measured on foraminifera, play an important role in our understanding of the climate system. They provide information about the state of the ocean ranging back hundreds to millions of years and form the backbone of paleo-oceanography. However, there are many sources of uncertainty associated with the signal recovered from sediment archived proxies. These include seasonal or depth habitat biases in the recorded signal, a frequency dependent reduction in the amplitude of the recorded signal due to bioturbation of the sediment, aliasing of high frequency climate variation onto a nominally annual, decadal or centennial resolution signal, and additional sample processing and measurement error introduced when the proxy signal is recovered. Here we present a forward model for sediment archived proxies that jointly models the above processes, so that the magnitude of their separate and combined effects can be investigated. Applications include the interpretation and analysis of uncertainty in existing proxy records, parameter sensitivity analysis to optimize future studies, and the generation of pseudo-proxy records that can be used to test reconstruction methods. We provide examples, such as the simulation of individual foraminifera records, that demonstrate the usefulness of the forward model for paleoclimate studies. The model is implemented as a user-friendly R package, sedproxy, the use of which we hope will contribute to a better understanding of both the limitations and potential of marine sediment proxies to inform about past climate.
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  • 45
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    Constraining the timing of deglaciation of the High Alps and rates of subglacial erosion with cosmogenic nuclides (2017)
    Geozon Science Media
    Details
    Publikationsdatum: 2021-05-06
    Beschreibung: THESIS ABSTRACT
    Beschreibung: research
    Schlagwort(e): 551.7
    Sprache: Englisch
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  • 46
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    Spatially and temporally variable catchment-wide denudation rates – clues from the Alps (2017)
    Geozon Science Media
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    Publikationsdatum: 2021-05-06
    Beschreibung: THESIS ABSTRACT
    Beschreibung: research
    Schlagwort(e): 551.7
    Sprache: Englisch
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  • 47
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    Caught in the act: Anatomy of an ongoing benthic-planktonic transition in a marine protist (2017)
    Oxford Univ. Press
    In:  Journal of Plankton Research, 39 (3). pp. 436-449.
    Details
    Publikationsdatum: 2020-02-06
    Beschreibung: The transition from benthos to plankton requires multiple adaptations, yet so far it remains unclear how these are acquired in the course of the transition. To investigate this process, we analyzed the genetic diversity and distribution patterns of a group of foraminifera of the genus Bolivina with a tychopelagic mode of life (same species occurring both in benthos and plankton). We assembled a global sequence data set for this group from single-cell DNA extractions and occurrences in metabarcodes from pelagic environmental samples. The pelagic sequences all cluster within a single monophyletic clade within Bolivina. This clade harbors three distinct genetic lineages, which are associated with incipient morphological differentiation. All lineages occur in the plankton and benthos, but only one lineage exhibits no limit to offshore dispersal and has been shown to grow in the plankton. These observations indicate that the emergence of buoyancy regulation within the clade preceded the evolution of pelagic feeding and that the evolution of both traits was not channeled into a full transition into the plankton. We infer that in foraminifera, colonization of the planktonic niche may occur by sequential cooptation of independently acquired traits, with holoplanktonic species being recruited from tychopelagic ancestors
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  • 48
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    Seasonal variations of the sea surface microlayer at the Boknis Eck Times Series Station (Baltic Sea) (2017)
    Oxford Univ. Press
    In:  Journal of Plankton Research, 39 (6). pp. 943-961.
    Details
    Publikationsdatum: 2020-02-06
    Beschreibung: The sea surface microlayer (SML) is the uppermost layer of the water column that links the ocean and atmosphere. It accumulates a variety of biogenic surface-active and buoyant substances, including gelatinous material, such as transparent exopolymer particles (TEP) and Coomassie stainable particles (CSP), potentially affecting air–sea exchange processes. Here, we studied the influence of the annual cycle of phytoplankton production on organic matter (OM) accumulation in the SML relative to the subsurface water (SSW). Sampling was performed monthly from April 2012 to November 2013 at the Boknis Eck Time Series Station (Baltic Sea). For SML sampling, we used the Garrett screen, while SSW samples were collected by Niskin bottles at 1 m depth. Samples were analyzed for carbohydrates, amino acids, TEP, CSP, chlorophyll a (SSW only) and bacterial abundance. Our data showed that the SML reflected the SSW during most parts of the year, with changes mainly responding to bloom formation and decay. OM composition during phytoplankton blooms clearly differed from periods of higher bacterial abundance. Of all components investigated, only the enrichment of total carbohydrates in the SML was inversely related to the wind speed indicating that wind-driven mixing also affected the accumulation of OM in the SML during our study.
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  • 49
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    IODP workshop: developing scientific drilling proposals for the Argentina Passive Volcanic Continental Margin (APVCM) – basin evolution, deep biosphere, hydrates, sediment dynamics and ocean evolution (2017)
    Copernicus
    In:  Scientific Drilling, 22 . pp. 49-61.
    Details
    Publikationsdatum: 2017-11-01
    Beschreibung: The Argentine margin contains important sedimentological, paleontological and chemical records of regional and local tectonic evolution, sea level, climate evolution and ocean circulation since the opening of the South Atlantic in the Late Jurassic–Early Cretaceous as well as the present-day results of post-depositional chemical and biological alteration. Despite its important location, which underlies the exchange of southern- and northern-sourced water masses, the Argentine margin has not been investigated in detail using scientific drilling techniques, perhaps because the margin has the reputation of being erosional. However, a number of papers published since 2009 have reported new high-resolution and/or multichannel seismic surveys, often combined with multi-beam bathymetric data, which show the common occurrence of layered sediments and prominent sediment drifts on the Argentine and adjacent Uruguayan margins. There has also been significant progress in studying the climatic records in surficial and near-surface sediments recovered in sediment cores from the Argentine margin. Encouraged by these recent results, our 3.5-day IODP (International Ocean Discovery Program) workshop in Buenos Aires (8–11 September 2015) focused on opportunities for scientific drilling on the Atlantic margin of Argentina, which lies beneath a key portion of the global ocean conveyor belt of thermohaline circulation. Significant opportunities exist to study the tectonic evolution, paleoceanography and stratigraphy, sedimentology, and biosphere and geochemistry of this margin.
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  • 50
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    Origin and Evolution of Silicic Magmas in Oceanic Arcs; an in situ Study from St Lucia, Lesser Antilles (2017)
    Oxford Univ. Press
    In:  Journal of Petrology, 58 (7). pp. 1279-1318.
    Details
    Publikationsdatum: 2020-02-06
    Beschreibung: Processes linked with the genesis, evolution and emplacement of silicic complexes in arcs are still poorly constrained. Of particular interest are the depth of magma production, the relative contribution of crystal fractionation versus crustal partial melting and the timescales involved. The Soufrière Volcanic Complex (SVC) on St Lucia is one of the largest silicic centres in the Lesser Antilles arc. Here we present the results of a detailed mineralogical study, including in situ Sr isotopes in plagioclase and in situ δ18O in dated zircons, of both SVC and Pre-SVC volcanic rocks to place constraints on the processes intrinsic to the development and evolution of the silicic complex. These data suggest that the production of silicic magma in the SVC occurs in two stages. The first stage involves differentiation of mafic magma by crustal assimilation and mineral fractionation in the middle–lower crust of the arc to produce magmas with intermediate compositions. These intermediate magmas are water-rich (∼7 wt %) and have high 87Sr/86Sr, Ba, Sr and La/Sm (∼5) compared with Pre-SVC lavas. Near-constant trace element and isotopic compositions throughout the SVC lifespan indicate that the same process was persistent over the last 600 kyr. In the second stage, the intermediate magmas are transferred to a shallower and more differentiated chamber (∼6 km depth). During ascent, any crystals or xenocrysts residual from stage one in the deeper chamber become fully resorbed and the magma crystallizes calcic amphibole microphenocrysts, followed by anorthite-rich plagioclase close to or at the water saturation depth. During mixing upon recharge within the shallow chamber, anorthite-rich plagioclase from the recharging magma is partially resorbed; so are the crystals in equilibrium with the resident differentiated magma. The recharge event probably causes chamber-wide convection. Mixing is thought to trigger eruption of the silicic complex magmas.
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  • 51
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    Genetic diversity and evolution in eukaryotic phytoplankton: revelations from population genetic studies (2017)
    Oxford Univ. Press
    In:  Journal of Plankton Research, 39 (2). pp. 165-179.
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    Publikationsdatum: 2020-02-06
    Beschreibung: Eukaryotic phytoplankton exhibit an enormous species richness, displaying a range of phylogenetic, morphological and physiological diversity. Yet, until recently, very little was known about the diversity, genetic variation and evolutionary processes within species and populations. An approach to explore this diversity and to understand evolution of phytoplankton is to use population genetics as a conceptual framework and methodology. Here, we discuss the patterns, processes and questions that population genetic studies have revealed in eukaryotic phytoplankton. First, we describe the main biological processes generating genetic variation. We specifically discuss the importance of life-cycle complexity for genetic and phenotypic diversity and consider how such diversity can be maintained during blooms when rapid asexual proliferation dominates. Next, we explore how genetic diversity is partitioned over time and space, with a focus on the processes shaping this structure, in particular selection and genetic exchange. Our aim is also to show how population genetics can be used to make inferences about realized dispersal and sexual recombination, as these processes are so difficult to study directly. Finally, we highlight important open questions and suggest promising avenues for future studies that will be made possible by new sequencing technologies
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  • 52
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    Spatial prediction of demersal fish diversity in the Baltic Sea: comparison of machine learning and regression-based techniques (2017)
    Oxford Univ. Press
    In:  ICES Journal of Marine Science, 74 (1). pp. 102-111.
    Details
    Publikationsdatum: 2020-02-06
    Beschreibung: Marine spatial planning (MSP) is considered a valuable tool in the ecosystem-based management of marine areas. Predictive modelling may be applied in the MSP framework to obtain spatially explicit information about biodiversity patterns. The growing number of statistical approaches used for this purpose implies the urgent need for comparisons between different predictive techniques. In this study, we evaluated the performance of selected machine learning and regression-based methods that were applied for modelling fish community indices. We hypothesized that habitat features can influence fish assemblage and investigated the effect of environmental gradients on demersal fish diversity (species richness and Shannon–Weaver Index). We used fish data from the Baltic International Trawl Surveys (2001–2014) and maps of six potential predictors: bottom salinity, depth, seabed slope, growth season bottom temperature, seabed sediments and annual mean bottom current velocity. We compared the performance of six alternative modelling approaches: generalized linear models, generalized additive models, multivariate adaptive regression splines, support vector machines, boosted regression trees and random forests. We applied repeated 10-fold cross-validation, using accuracy as the measure of model quality. Finally, we selected random forest as the best performing algorithm and implemented it for the spatial prediction of fish diversity from the Baltic Proper to the Kattegat. To obtain information on the data reliability and confidence of the developed models, which are essential for MSP, we estimated the uncertainty of predictions with standard deviation of predictions obtained from all the trees in the ensemble random forest method. We showed how state-of-the-art predictive techniques, based on easily available data and simple Geographic Information System tools, can be used to obtain reliable spatial information about fish diversity. Our comparative work highlighted the potential of machine learning method to reduce prediction error in modelling of demersal fish diversity in the framework of MSP.
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  • 53
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    The Mozambique Ridge: a document of massive multistage magmatism (2017)
    Oxford Univ. Press
    In:  Geophysical Journal International, 208 (1). pp. 449-467.
    Details
    Publikationsdatum: 2020-02-06
    Beschreibung: The Mozambique Ridge, a prominent basement high in the southwestern Indian Ocean, consists of four major geomorphological segments associated with numerous phases of volcanic activity in the Lower Cretaceous. The nature and origin of the Mozambique Ridge have been intensely debated with one hypothesis suggesting a Large Igneous Province origin. High-resolution seismic reflection data reveal a large number of extrusion centres with a random distribution throughout the southern Mozambique Ridge and the nearby Transkei Rise. Intrabasement reflections emerge from the extrusion centres and are interpreted to represent massive lava flow sequences. Such lava flow sequences are characteristic of eruptions leading to the formation of continental and oceanic flood basalt provinces, hence supporting a Large Igneous Province origin of the Mozambique Ridge. We observe evidence for widespread post-sedimentary magmatic activity that we correlate with a southward propagation of the East African Rift System. Based on our volumetric analysis of the southern Mozambique Ridge we infer a rapid sequential emplacement between ∼131 and ∼125 Ma, which is similar to the short formation periods of other Large Igneous Provinces like the Agulhas Plateau.
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  • 54
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    Magmatic Evolution and Source Variations at the Nifonea Ridge (New Hebrides Island Arc) (2017)
    Oxford Univ. Press
    In:  Journal of Petrology, 58 (3). pp. 473-494.
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    Publikationsdatum: 2020-02-06
    Beschreibung: The Nifonea submarine volcano rises 1000 m above the seafloor of the Vate Trough back-arc basin behind the New Hebrides island arc. This large volcanic edifice has a caldera of ∼8 km diameter and is connected to two ∼20 km long volcanic rift zones in the back-arc basin. We present new chemical and isotope data for volcanic glasses and whole-rocks from both the volcano and its rift zones. Lavas from Nifonea volcano show an evolution towards more incompatible element enrichment, with the most enriched lavas being the youngest eruption products on the caldera floor. These are products of significant fractional crystallization, show minor contamination by hydrothermal fluids (〈0·3%) and reflect mixing of melts derived from depleted upper mantle and melts from an enriched source similar to those occurring in the North Fiji Basin. The enrichment in Nb of these lavas is comparable with that of some lavas from the New Hebrides island arc (e.g. Mota Lava island), where these coexist with typical island arc basalts. The lavas erupted along the rift zones in the Vate Trough back-arc basin are relatively depleted in incompatible elements, indicating melting of depleted upper mantle with a minor addition of a sediment-derived fluid. Our observations suggest that the mantle beneath Vate Trough is heterogeneous on a small scale (〈20 km) and that the occurrence of these enriched and fertile mantle portions has a stronger control on melting processes than the influx from the subducting slab, as all samples were recovered at a similar distance from the trench.
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  • 55
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    Overwintering effects on the spring bloom dynamics of phytoplankton (2017)
    Oxford Univ. Press
    In:  Journal of Plankton Research, 39 (5). pp. 772-780.
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    Publikationsdatum: 2020-02-06
    Beschreibung: The influence of winter on the selection of dominant taxa for the phytoplankton spring bloom was studied in batch culture experiments. Different natural phytoplankton assemblages from different phases of the temperate zone winter were exposed to varying periods of darkness (0, 6/7, 13 and 19 weeks) followed by a re-exposure to saturating light intensity for 14 days to experimentally simulate the onset of spring. The results showed that dark incubation has a strong effect on shaping the phytoplankton community composition. Many taxa disappeared in the absolute darkness. Dark survival ability might be an important contributing factor for the success of diatoms in spring. Different phytoplankton starting assemblages were dominated by the same bloom-forming diatoms, Skeletonema marinoi and Thalassosira spp., after dark incubation for only 6 weeks, irrespective of the high dissimilarities between phytoplankton communities. The growth capacity of surviving phytoplankton is almost unimpaired by darkness. Similar growth rates as that before darkness could be resumed for the surviving taxa with a potential lag time of 1–7 days dependent on taxon and the duration of darkness.
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  • 56
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    Ideas and perspectives: climate-relevant marine biologically driven mechanisms in Earth system models (2017)
    Copernicus
    In:  Biogeosciences, 14 (2). pp. 403-413.
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    Publikationsdatum: 2018-10-23
    Beschreibung: The current generation of marine biogeochemical modules in Earth system models (ESMs) considers mainly the effect of marine biota on the carbon cycle. We propose to also implement other biologically driven mechanisms in ESMs so that more climate-relevant feedbacks are captured. We classify these mechanisms in three categories according to their functional role in the Earth system: (1) "biogeochemical pumps", which affect the carbon cycling; (2) "biological gas and particle shuttles", which affect the atmospheric composition; and (3) "biogeophysical mechanisms", which affect the thermal, optical, and mechanical properties of the ocean. To resolve mechanisms from all three classes, we find it sufficient to include five functional groups: bulk phyto- and zooplankton, calcifiers, and coastal gas and surface mat producers. We strongly suggest to account for a larger mechanism diversity in ESMs in the future to improve the quality of climate projections.
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  • 57
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    Winter–spring climate effects on small-sized copepods in the coastal Baltic Sea (2017)
    Oxford Univ. Press
    In:  ICES Journal of Marine Science, 74 (7). pp. 1855-1864.
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    Publikationsdatum: 2020-02-06
    Beschreibung: The general positive effect of warmer winters on the abundance of small-sized zooplankton in the following spring and early summer has been reported from different parts of the Baltic Sea, but the mechanism of this link is not clear. Although causal links cannot be deduced with confidence from observational data, sufficiently detailed analyses can nevertheless provide insights to the potential mechanisms. We present an example of such an analysis, scrutinizing the effects of winter and spring hydroclimate on the abundance of small-sized dominant calanoid copepods (Eurytemora affinis and Acartia spp.), using data from 2080 zooplankton samples collected over 55 years (1957–2012) from a shallow coastal habitat (Pärnu Bay, Gulf of Riga) in the Baltic Sea. Our results indicated that the milder winters brought about higher abundances, and reduced seasonality of small-sized copepods, whereas ambient sea surface temperature (SST) mostly affected the relative abundance of adult stages. The sliding window correlation tests revealed temporal shifts in the effects of controlling variables: with the continuous increase in SST, the effect of winter temperature on the abundance of Acartia spp. weakened. In contrast, E. affinis was consistently affected by SST, but the effect of winter temperature was more pronounced during the period of on average colder winters.
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  • 58
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    The sponge microbiome project (2017)
    Oxford Univ. Press
    In:  GigaScience, 6 (8).
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    Publikationsdatum: 2020-02-06
    Beschreibung: Marine sponges (phylum Porifera) are a diverse, phylogenetically deep-branching clade known for forming intimate partnerships with complex communities of microorganisms. To date, 16S rRNA gene sequencing studies have largely utilised different extraction and amplification methodologies to target the microbial communities of a limited number of sponge species, severely limiting comparative analyses of sponge microbial diversity and structure. Here, we provide an extensive and standardised dataset that will facilitate sponge microbiome comparisons across large spatial, temporal and environmental scales. Samples from marine sponges (n = 3569 specimens), seawater (n = 370), marine sediments (n = 65) and other environments (n = 29) were collected from different locations across the globe. This dataset incorporates at least 269 different sponge species, including several yet unidentified taxa. The V4 region of the 16S rRNA gene was amplified and sequenced from extracted DNA using standardised procedures. Raw sequences (total of 1.1 billion sequences) were processed and clustered with a) a standard protocol using QIIME closed-reference picking resulting in 39,543 Operational Taxonomic Units (OTU) at 97% sequence identity, b) a de novo protocol using Mothur resulting in 518,246 OTUs, and c) a new high-resolution Deblur protocol resulting in 83,908 unique bacterial sequences. Abundance tables, representative sequences, taxonomic classifications and metadata are provided. This dataset represents a comprehensive resource of sponge-associated microbial communities based on 16S rRNA gene sequences that can be used to address overarching hypotheses regarding host-associated prokaryotes, including host-specificity, convergent evolution, environmental drivers of microbiome structure and the sponge-associated rare biosphere.
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  • 59
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    Benefits, costs and taxonomic distribution of marine phytoplankton body size (2017)
    Oxford Univ. Press
    In:  Journal of Plankton Research, 39 (3). pp. 494-508.
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    Publikationsdatum: 2020-02-06
    Beschreibung: Phytoplankton cell or colony sizes range from 〈1 µm to several cm, i.e. 4–5 orders of magnitude in linear dimensions, which is roughly equivalent to the log-size span within terrestrial vegetation. It is commonplace to assume that smaller phytoplankton have an advantage in growth related traits while larger ones are more resistant to losses. However, the current state of literature calls for a more differentiated view. It is still controversial, whether smaller phytoplankton have higher maximal growth rates (µmax) or if there is a peak of µmax at intermediate size (102 µm3 cell volume). Smaller phytoplankton have an advantage in nutrient acquisition at low concentrations while larger phytoplankton have an advantage in utilizing nutrient pulses and exploiting vertical gradients. At equal density, larger phytoplankton experience bigger sinking losses. Small phytoplankton (〈5–10 µm) are more affected mostly from grazing by protists and tunicates, while larger phytoplankton are more affected by copepod and krill grazing. Size spectra within the most important higher taxa show some conspicuous differences between marine and lake phytoplankton, e.g. the absence of very large diatoms (〉105 µm3) in lake phytoplankton and the absence of large (〉103 µm3) green algae in marine plankton. Overall, size is one of the most important traits for the performance of phytoplankton, but it is overly simplistic to equate small size with metabolic advantages
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  • 60
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    Disentangling Incomplete Lineage Sorting and Introgression to Refine Species-Tree Estimates for Lake Tanganyika Cichlid Fishes (2017)
    Oxford Univ. Press
    In:  Systematic Biology, 66 (4). pp. 531-550.
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    Publikationsdatum: 2020-10-26
    Beschreibung: Adaptive radiation is thought to be responsible for the evolution of a great portion of the past and present diversity of life. Instances of adaptive radiation, characterized by the rapid emergence of an array of species as a consequence to their adaptation to distinct ecological niches, are important study systems in evolutionary biology. However, because of the rapid lineage formation in these groups, and occasional gene flow between the participating species, it is often difficult to reconstruct the phylogenetic history of species that underwent an adaptive radiation. In this study, we present a novel approach for species-tree estimation in rapidly diversifying lineages, where introgression is known to occur, and apply it to a multimarker data set containing up to 16 specimens per species for a set of 45 species of East African cichlid fishes (522 individuals in total), with a main focus on the cichlid species flock of Lake Tanganyika. We first identified, using age distributions of most recent common ancestors in individual gene trees, those lineages in our data set that show strong signatures of past introgression. This led us to formulate three hypotheses of introgression between different lineages of Tanganyika cichlids: the ancestor of Boulengerochromini (or of Boulengerochromini and Bathybatini) received genomic material from the derived H-lineage; the common ancestor of Cyprichromini and Perissodini experienced, in turn, introgression from Boulengerochromini and/or Bathybatini; and the Lake Tanganyika Haplochromini and closely related riverine lineages received genetic material from Cyphotilapiini. We then applied the multispecies coalescent model to estimate the species tree of Lake Tanganyika cichlids, but excluded the lineages involved in these introgression events, as the multispecies coalescent model does not incorporate introgression. This resulted in a robust species tree, in which the Lamprologini were placed as sister lineage to the H-lineage (including the Eretmodini), and we identify a series of rapid splitting events at the base of the H-lineage. Divergence ages estimated with the multispecies coalescent model were substantially younger than age estimates based on concatenation, and agree with the geological history of the Great Lakes of East Africa. Finally, we formally tested the three hypotheses of introgression using a likelihood framework, and find strong support for introgression between some of the cichlid tribes of Lake Tanganyika. [Adaptive radiation; Cichlidae; introgression; Lake Tanganyika; species network.]
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  • 61
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    Bewertung der Grundwassergeschütztheit anhand der Verweilzeit in der Grundwasserüberdeckung (2016)
    Geozon Science Media
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    Publikationsdatum: 2021-03-29
    Beschreibung: Die Verweilzeitberechnung ist eine sehr anschauliche Methode zur Bewertung der Geschütztheit einer Wasserfassung oder eines Grundwasserleiters. Sie berücksichtigt alle relevanten Einflussfaktoren und ist aus Sicht der Autoren anderen Verfahren zur Geschütztheitsbewertung vorzuziehen. Es wird eine Methode vorgestellt, mit der die Geschütztheit der Wasserfassungen im Raum Pasewalk bewertet wurde und die auch landesweit anwendbar ist. Die methodischen Grundlagen von Verweilzeitberechnungen werden untersucht und spezifiziert und es erfolgt eine Diskussion der Interpolationsmöglichkeiten.
    Beschreibung: research
    Schlagwort(e): 551 ; 554.3 ; Sickerwasser ; Verweilzeit ; Sickerstrecke ; Grundwasserflurabstand ; DIN 19732 ; Grundwasserneubildung ; Grundwasserüberdeckung ; Grundwassergeschütztheit ; Verweilzeitberechnung
    Sprache: Deutsch
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  • 62
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    Geologische Landesaufnahme in Mecklenburg-Vorpommern seit 1990 (2016)
    Geozon Science Media
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    Publikationsdatum: 2021-03-29
    Beschreibung: Der Geologische Dienst M-V sammelt und dokumentiert im Rahmen der Landesaufnahme Daten zur Geologie der Oberfläche und des Tieferen Untergrundes, zur Hydrogeologie, zur Bodenkunde sowie zur Rohstoffgeologie und wertet diese Daten unter vielfältigen Aspekten der Daseinsvorsorge aus. Als Ergebnis entstanden seit 1990 mehrere moderne Informationssysteme, Kartenwerke und andere Produkte. Neben der Publikation von analogen Karten erfolgt in den letzten Jahren verstärkt eine digitale Informationsbereitstellung in Form von digitalen Produkten; verstärkt werden auch Informationen über das Kartenportal Umwelt in der Internetpräsentation des Landesamtes veröffentlicht (www.umweltkarten.mv-regierung.de).
    Beschreibung: research
    Schlagwort(e): 551 ; 554.3 ; Geologie ; Mecklenburg-Vorpommern ; Landesaufnahme ; Geologische Karte ; Kartenportal Umwelt ; Bohrdatenspeicher
    Sprache: Deutsch
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  • 63
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    Multiproxy-Untersuchungen zur Paläoökologie und -hydrologie eines spätglazial- bis frühholozänen Flachsees im nordostdeutschen Küstengebiet (Glowe-Paläosee/Insel Rügen) (2016)
    Geozon Science Media
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    Publikationsdatum: 2021-05-06
    Beschreibung: The paper presents results of multiproxy-investigations of a 3 m long sediment section from the Glowe Palaeolake, covering the period Pre-Bølling to the middle of the Preboreal. The Lateglacial and early Holocene landscape development comprising climate fluctuations, lake evolution, lake-level variations and vegetation history is reconstructed using pollen, diatom, macrofossil, molluscs as well as sedimentological and geochemical data based on 14C-dating. The palaeolake appeared due to the decay of the permafrost during the Bølling and developed in the Allerød into a 3–4 m deep, species-poor and macrophyte-rich stillwater. The submerse vegetation and fauna decreased during the Younger Dryas, but returned fast and with higher density in the Preboreal. Phases of cooler climate can be parallelized with the Gerzensee oscillation, the Younger Dryas and the Rammelbeek oscillation, which each are palynologically bipartite. In contrast, indications for the Older Dryas were only scarce. The cooler phases were characterized by intensified allochthonous clastic input into the lake. During the Younger Dryas the input was dominated by solifluction processes, while during the Allerød and the Preboreal predominantly fluvial processes occurred. The most significant changes in the palaeoecology of the lake were caused by the rapid warming at the onset of the Preboreal. During the phases of warmer climate the vegetation development was influenced by the vicinity to the Baltic Ice Lake, which caused – compared to more southerly regions – a delayed spread of Pinus. Also, the long term climate changes determined the alterations in the chemical sediment composition, the diatom flora and the macrophyte vegetation. Short term variations, which caused the closely spaced sediment layering mainly in the older part of the sediment section cannot be explained so far. The course of the outcropping stratigraphic units was used to construct a lake-level curve. It shows a rapid rise in the early Allerød and a subsequent slower rise until the highstand in the Younger Dryas. In the early Preboreal, a fast lake-level fall occurred, the palaeolake silted up and dried out in the middle of the Preboreal.
    Beschreibung: research
    Schlagwort(e): 551.7 ; geochemistry ; radiocarbon dating ; vegetation history ; late glacial ; pollen ; molluscs ; early holocene ; diatoms ; macrofossils ; lake sediments ; northern Central Europe ; palaeolake ; climate fluctuation ; lake-level variation
    Sprache: Deutsch
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    Editorial Vol. 65, No.1 (2016)
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    Publikationsdatum: 2021-05-06
    Beschreibung: editorial
    Schlagwort(e): 551.7
    Sprache: Englisch
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  • 65
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    Sanierung der Altlast am ehemaligen Gaswerk Neubrandenburg (2016)
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    Publikationsdatum: 2021-03-29
    Beschreibung: Das ehemalige Gaswerk liegt innerhalb der Stadt Neubrandenburg „Am Güterbahnhof“, umgeben von Altbausubstanz mit gewerblicher Nutzung und Wohnbebauung. Die Produktion von Stadtgas aus Steinkohle begann hier 1867. Eine Erweiterung erfolgte im Ersten Weltkrieg durch die Inbetriebnahme einer Wassergasanlage zur Streckung des Steinkohlengases, einer Benzolgewinnungsanlage und einer Sulfatfabrik. Im Zweiten Weltkrieg kam es zur Zerstörung der drei Gasbehälter und von Teilen der Bebauung. Nach 1945 wurde das Gaswerk mit einem Gasbehälter wieder aufgebaut. In den letzten Nutzungsjahren traten zahlreiche Havarien durch übergelaufene Teer- und Ammoniakgruben sowie durch verstopfte Leitungen auf. 1971 erfolgten die Stilllegung des Gaswerkes und ein teilweiser Rückbau der oberirdischen Anlagen.
    Beschreibung: research
    Schlagwort(e): 551 ; 554.3 ; Neubrandenburg ; Grundwasser ; Gaswerk ; Sanierung ; Altlast ; Kontamination ; Historie
    Sprache: Deutsch
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  • 66
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    Die Findlinge im Revier Waldsee, Mecklenburg (2016)
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    Publikationsdatum: 2021-03-29
    Beschreibung: Im Revier Waldsee, zwischen Neustrelitz und Feldberg in der Mecklenburgischen Seenplatte, sind überwiegend Bildungen des Sanders vor der Pommerschen Haupteisrandlage verbreitet. In den Sanderflächen treten vereinzelt sehr große Findlinge auf. Die zwei größten aufgefundenen Findlinge werden petrographisch beschrieben und als schützenswerte Geotope empfohlen.
    Beschreibung: research
    Schlagwort(e): 551 ; 554.3 ; Geologie ; Mecklenburg-Vorpommern ; Findlinge ; Feldberger Seenlandschaft
    Sprache: Deutsch
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  • 67
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    Der Findling an der Eugen-Geinitz-Sicht in Usadel (2016)
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    Publikationsdatum: 2021-03-29
    Beschreibung: Bei dem für die Eugen-Geinitz-Sicht in Usadel ausgewählten Findling (Fundort: vermutlich Kiesgrube Siedenbüssow) handelt es sich um ein seltenes monomiktes Konglomerat, dessen Herkunft – und damit auch sein Bildungsalter – bisher nicht genau bestimmt werden kann. In einer sandigen bis feinkiesigen, rötlich-violetten Matrix befinden sich zahlreiche helle, mäßig gerundete Gesteinsbruchstücke bis 12 cm Größe aus kristallinem Quarz (Gangquarz). Konglomerate mit einer ähnlichen Zusammensetzung sind als lokale Einschaltungen in mesoproterozoischen Sandsteinen und Grauwacken an der Hohen Küste in Nordschweden bekannt und möglicherweise als isolierte Vorkommen im gesamten Verbreitungsgebiet jotnischer Rotsedimente zu finden. Aufgrund der Zusammensetzung und des relativ geringen Verfestigungsgrades kann aber auch eine Zuordnung zur klastischen Abfolge der jüngstproterozoisch-unterkambrischen Nexö-Formation Bornholms nicht völlig ausgeschlossen werden, deren basale Schichten ebenfalls unter terrestrischen, oxidativen Bedingungen abgelagert wurden.
    Beschreibung: research
    Schlagwort(e): 551 ; 554.3 ; Mecklenburg-Vorpommern ; geschiebe ; monomiktes Konglomerat ; Nexö-Formation ; Eugen-Geinitz-Sicht ; Jotnischer Sandstein
    Sprache: Deutsch
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  • 68
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    Reconsidering the current stratigraphy of the Alpine Lateglacial (2016)
    Geozon Science Media
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    Publikationsdatum: 2021-05-06
    Beschreibung: The sedimentary and morphological evidence for Lateglacial glacier fluctuations in the Lienz area provides a strong case against the currently used pentapartite stratigraphic subdivision of the Alpine Lateglacial (ALG; c. 19–11.7 ka) i.e. the timespan between the Würmian Pleniglacial (= Alpine Last Glacial Maximum; AlpLGM) and the beginning of the Holocene. The results of comprehensive geological mapping (including the detection of mass movements) supported by geochronological data and pollen analysis revealed that the ALG- record of the Schobergruppe mountains and the Lienz Dolomites can be subdivided into four unconformity-bounded (allostratgraphic) units which are linked to three climatostratigraphically-defined phases of glacier activity. Delta deposits and till of local glaciers document the phase of ice-decay after the AlpLGM. Between this period and the Bølling/Allerød (B/A) interstadial only one glacier stabilisation with massive end moraines, correlated with the Gschnitz stadial, is evident. Multiple end moraines prove the presence of very active glacier tongues during the Younger Dryas aged Egesen stadial. The 10Be exposure dating of an end moraine, previously attributed to the Daun stadial (pre-B/A interstadial) based on ΔELA values, provided an age of 12.8 ± 0.6 ka indicating it is of Younger Dryas age. This case highlights the pitfalls of the commonly used ΔELA-based stratigraphic ALG subdivision and the subsequent derivation of palaeoclimatic implications. ΔELAs are still considered as a useful tool for correlation on the local scale e.g. in one mountain group with a quite comparable topography and lithology and taking into account the limitations, especially the impact of debris cover. However, our results show that a stratigraphic correlation across the whole Alpine chain via ΔELAs is not a successful approach potentially leading to bias and, eventually, to circular arguments.
    Beschreibung: research
    Schlagwort(e): 551.7 ; palynology ; alps ; late pleistocene ; lateglacial ; younger dryas ; geological mapping ; allostratigraphy ; climatostratigraphy ; exposure dating ; deformable bed
    Sprache: Englisch
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  • 69
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    Faunistisch bemerkenswerte und für Mecklenburg-Vorpommern neue Arten der Kurzflügelkäfer (Coleoptera: Staphylinidae) – Teil 5 (2016)
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    Publikationsdatum: 2021-03-29
    Beschreibung: Nachweise von 106 Arten der Kurzflügelkäfer in Mecklenburg-Vorpommern (MV) zwischen 1989 und 2016 werden dokumentiert und diskutiert. Anhand aktueller Nachweise mit dem Autokescher wird die Verbreitung und Häufigkeit einiger Arten in MV neu bewertet. Zwei Arten sind neu für die Fauna des Bundeslandes: 〈i〉Cousya longitarsis〈/i〉 (Thomson, 1867) and 〈i〉Philonthus ebeninus〈/i〉 (Gravenhorst, 1802). Xerotherme Standorte, sandige Ufer von Fließgewässern und Salzwiesen sind in MV selten bzw. werden oftmals massiv beeinträchtigt. Diese Habitate beherbergen jedoch eine Vielzahl ökologisch anspruchsvoller Arten und sollten deshalb besonders geschützt werden.
    Beschreibung: research
    Schlagwort(e): 910 ; fauna ; rare species ; riparian species
    Sprache: Deutsch
    Materialart: article , publishedVersion
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  • 70
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    Weitere Blattwespen (Hymenoptera: Symphyta) des Zoologischen Institutes der Universität Rostock, insbesondere aus den Sammlungen Jahn und Haupt (2016)
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    Publikationsdatum: 2021-03-29
    Beschreibung: Blattwespen des Zoologischen Institutes der Universität Rostock, insbesondere die Sammlungen Jahn und Haupt, wurden revidiert. Das Material aus den Familien Argidae, Cephidae, Cimbicidae, Diprionidae, Orussidae, Pamphiliidae, Siricidae, Tenthredinidae und Xiphydriidae stammt aus zehn deutschen Bundesländern, hauptsächlich aus Brandenburg und Hessen. Für folgende Taxa fehlen Hinweise in den Checklisten für die jeweiligen Bundesländer in der Entomofauna Germanica (Blank et al. 2001): Für Brandenburg 〈i〉Tenthredo arcuata〈/i〉 Forster, 1771 und 〈i〉Cimbex connatus〈/i〉 (Schrank, 1776), für Hessen 〈i〉Sterictiphora angelicae〈/i〉 (Panzer, 1799) und 〈i〉Tenthredopsis tarsata〈/i〉 (Fabricius, 1804), für Mecklenburg-Vorpommern 〈i〉Orussus abietinus〈/i〉 (Scopoli, 1763), für Sachsen 〈i〉Macrodiprion nemoralis〈/i〉 (Enslin, 1917), für Nordrhein-Westfalen 〈i〉Pamphilius betulae〈/i〉 Linnaeus, 1758, für Rheinland-Pfalz 〈i〉Urocerus gigas〈/i〉 Linnaeus, 1758. Daneben finden sich Einzelfunde aus Frankreich, Liechtenstein, Polen, Slowakei, Spanien und der Schweiz.
    Beschreibung: research
    Schlagwort(e): 910 ; fauna ; deutschland ; europa ; Blattwespen ; Symphyta ; Verbreitung
    Sprache: Deutsch
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  • 71
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    Unterkambrischer Sandstein mit kegelförmigen organischen Strukturen des Conichnus-Typs – ein Fundbericht (2016)
    Geozon Science Media
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    Publikationsdatum: 2021-03-29
    Beschreibung: Es wird ein unterkambrisches Sandsteingeschiebe von Rügen mit 14 kegelförmigen Strukturen vom Conichnus-Typ in Vergesellschaftung mit dem Spurenfossil Monocraterion vorgestellt.
    Beschreibung: research
    Schlagwort(e): 551 ; 554.3 ; geschiebe ; Sandstein ; Bornholm ; Conichnus
    Sprache: Deutsch
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  • 72
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    Eiszerfallsformen, Esker sowie subglaziale und subaerische Talbildungen am Lütjensee / Forst Seebergen (Stormarn, Schleswig-Holstein) (2016)
    Geozon Science Media
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    Publikationsdatum: 2021-03-29
    Beschreibung: This article presents investigations of a diverse landscape in the young moraine area of southeastern Schleswig-Holstein (Stormarn county). The northern part of the study area represents a large basin, possibly a glacier basin influenced by glaciofluvial meltwaters or by dead ice. Organic sedimentation occurred in this basin from the Late-glacial (Bölling/Alleröd interstadial complex), followed by a longer lake phase and the growth of a fen after c. 5.000 14C a B.P. The central area of the basin was formed as ice-disintegration landscape – including kames, eskers and esker-like features. Ring-like glaciofluvial landform structures are interpreted as subcircular eskers. Kettle bogs developed in the centres of these landforms from c. 5.000 14C a BP (Atlantic/Subboreal) onwards. The southern and south-eastern part of the study area represents a smoothed moraine zone, that includes a glaciotectonically influenced Saalian core of till, sand and glacilacustrine sediment. Parallel aligned gullies were predominantly formed as tunnel valleys. Some parts of the channels are infilled with glaciolacustrine clays. Several channels, asymmetric in cross-profile, were shaped by periglacial slope denudation.
    Beschreibung: research
    Schlagwort(e): 551 ; weichselian late glacial ; valley formation ; subcircular esker ; kame ; ice decay landforms
    Sprache: Deutsch
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  • 73
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    Late Holocene glacier fluctuations in the eastern Nyainqêntanglha Range, southeastern Tibet (2016)
    Geozon Science Media
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    Publikationsdatum: 2021-05-06
    Beschreibung: THESIS ABSTRACT
    Beschreibung: research
    Schlagwort(e): 551.7 ; tibet ; late holocene ; glacier fluctuation
    Sprache: Englisch
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  • 74
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    The aeolian sedimentary system along the transition between the Qilian Shan and northern Chinese drylands during the late Quaternary (2016)
    Geozon Science Media
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    Publikationsdatum: 2021-05-06
    Beschreibung: THESIS ABSTRACT
    Beschreibung: research
    Schlagwort(e): 551.7 ; china ; late quaternary ; drylands ; aeolian sedimentary system
    Sprache: Englisch
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  • 75
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    The tablelands in the Puli Basin (central Taiwan) – a geochronological and geomorphological approach to Late Quaternary fluvial sedimentary and erosional processes (2016)
    Geozon Science Media
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    Publikationsdatum: 2021-05-06
    Beschreibung: THESIS ABSTRACT
    Beschreibung: research
    Schlagwort(e): 551.7 ; late quaternary ; tablelands ; Taiwan ; sedimentary process ; erosional process
    Sprache: Englisch
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  • 76
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    Subaqueous conglomerates above pre-LGM basal till: Another element of the ‘classic’ interglacial mountain-flank succession (Hötting Breccia Auct.) north of Innsbruck, Austria (2016)
    Geozon Science Media
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    Publikationsdatum: 2021-03-29
    Beschreibung: The “Hötting Breccia” near Innsbruck is a classic interglacial mountain-flank succession mainly comprising lithified alluvial fans and scree slopes. Directly NW of Innsbruck, a pre-LGM (Riss?) basal till 〉20 m in thickness overlies a plucked rock surface that records eastward ice flow. The till is dominated by clasts of carbonate rocks from the Northern Calcareous Alps; index clasts of the LGM ice stream are absent. The basal till is overlain by a package of conglomerate nearly 1 km in preserved lateral extent that dip at 20–30° South and show the same clast spectrum as the underlying till. The conglomerate – hitherto assigned to the Hötting Breccia – accumulated from fan deltas and/or scree slopes shed into a standing water body; it is overlain by younger, unlithified LGM to Holocene deposits. We suggest the following scenario: During decay of the ice stream that formed the basal till, the conglomerate package was deposited by paraglacial reworking of till into a lake or ice-marginal lake. The alluvial fans of the Hötting Breccia accumulated independently from the conglomerate package, and from a distinct alluvial-fan system. The age relation of the till/conglomerate package to the main part of the Hötting Breccia is unclear. Our results demonstrate that the rocks hitherto summarized as Hötting Breccia represent a compound of lithosomes of different origins and ages.
    Beschreibung: research
    Schlagwort(e): 551 ; quaternary ; interglacial ; alps ; till ; conglomerate ; Hötting Breccia ; index clasts
    Sprache: Englisch
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  • 77
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    Discussing surface crack structures in the Schorfheide region, NE Germany (2016)
    Geozon Science Media
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    Publikationsdatum: 2021-05-06
    Beschreibung: Express Report
    Beschreibung: research
    Schlagwort(e): 551.7 ; geomorphology ; late glacial ; airborne LiDAR ; northern Brandenburg ; digital elevation modelling ; Salt Tectonic ; Laacher Tephra
    Sprache: Englisch
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  • 78
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    Moränen versus Till: Empfehlungen für die Beschreibung, Interpretation und Klassifikation glazialer Landformen und Sedimente (2016)
    Geozon Science Media
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    Publikationsdatum: 2021-05-06
    Beschreibung: Internationally, the description and interpretation of glacial sediments and landforms largely follow a set of uniform guidelines and terminology. Sediments are normally described according to their lithofacies characteristics (e.g. diamicton, sorted sands), and only after closer inspection and investigation are genetic terms applied (e.g. till, glaciofluvial outwash). Mixing of sedimentological and geomorphological terminology does not occur. In German-speaking countries, however, the term moraine is used for glaciogenic sediments and landforms such as end moraines and also adopted for till plains (“ground moraine landscapes”, “old/young morainic landscapes” etc.). Similar traditions of the latter kind are sometimes found as a relict in Scandinavian texts, and an equally profound mixing of terms is found in much of the French literature. The authors argue here that this mixture not only leads to unnecessary confusion for students but also makes international communication more difficult, especially when the terminological inconsistencies are as extensive and non-systematic as in the German community at present. The present paper presents a systematic overview of the state-of-the-art of till terminology, thereby providing the necessary background information for a useful description and interpretation of field evidence for communicating results in German and hopefully aiding more efficient communication of German Quaternary geologists and geomorphologists internationally. The aim is to provide a sedimentological terminology that is in agreement with international standards and can readily be distinguished from geomorphological vocabulary. The authors recommend that usage of the term ground moraine, for example, is restricted to certain landform associations encountered in NW Central Europe, and excluded from use when discussing sediments. For primary glaciogenic sediments sensu stricto the term till should be used only where appropriate sedimentological evidence exists. A process-based subdivision of till types (e.g. deformation, lodgement till) is not useful in most cases, because as a community we do not have the tools to reliably distinguish such processes at a macro-scale. This recognition has led to the creation of the highly useful umbrella term subglacial traction till and its distinction from overridden primary sediments that are termed glaciotectonite. The present contribution translates the older terminology to the internationally-accepted terminology that follows the scientifically-robust approach of splitting descriptive terminology – based on a lithofacies approach (e.g. diamicton) – from the latter interpretative stage (e.g. subglacial traction till, debris flow deposit). The authors present translations of the different till schemes that have existed through time and link these to the current state of the art, citing several examples and clear diagnostic criteria to distinguish various types of diamictic sediments. This contribution stresses that the majority of diamictons encountered in glacial environments, especially in ice-marginal settings, are not usually and certainly not automatically subglacial traction tills.
    Beschreibung: research
    Schlagwort(e): 551.7 ; grundmoräne ; quartärgeologie ; moräne ; sedimentologie ; terminologie ; sedimentology ; till ; moraines ; diamicton ; glacial sediments ; Quaternary Geology ; subglazialer Traktionstill ; glaziale Sedimente ; Diamikton ; Lithofaziesaufnahme ; subglacial traction till ; debris flow ; lithofacies approach
    Sprache: Deutsch
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    ElevatedpCO2drives lower growth and yet increased calcification in the early life history of the cuttlefish Sepia officinalis (Mollusca: Cephalopoda) (2016)
    Oxford Univ. Press
    In:  ICES Journal of Marine Science, 73 (3). pp. 970-980.
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    Publikationsdatum: 2019-02-01
    Beschreibung: Ocean acidification is an escalating environmental issue and associated changes in the ocean carbonate system have implications for many calcifying organisms. The present study followed the growth of Sepia officinalis from early-stage embryos, through hatching, to 7-week-old juveniles. Responses of cuttlefish to elevated pCO(2) (hypercapnia) were investigated to test the impacts of near-future and extreme ocean acidification conditions on growth, developmental time, oxygen consumption, and yolk utilization as proxies for individual fitness. We further examined gross morphological characteristics of the internal calcareous cuttlebone to determine whether embryonically secreted shell lamellae are impacted by environmental hypercapnia. Embryonic growth was reduced and hatching delayed under elevated pCO(2), both at environmentally relevant levels (0.14 kPa pCO(2) similar to predicted ocean conditions in 2100) and extreme conditions (0.40 kPa pCO(2)). Comparing various metrics from control and intermediate treatments generally showed no significant difference in experimental measurements. Yet, results from the high pCO(2) treatment showed significant changes compared with controls and revealed a consistent general trend across the three treatment levels. The proportion of animal mass contributed by the cuttlebone increased in both elevated pCO(2) treatments. Gross cuttlebone morphology was affected under such conditions and cuttlebones of hypercapnic individuals were proportionally shorter. Embryonic shell morphology was maintained consistently in all treatments, despite compounding hypercapnia in the perivitelline fluid; however, post-hatching, hypercapnic animals developed denser cuttlebone laminae in shorter cuttlebones. Juvenile cuttlefish in acidified environments thus experience lower growth and yet increased calcification of their internal shell. The results of this study support recent findings that early cuttlefish life stages are more vulnerable towards hypercapnia than juveniles and adults, which may have negative repercussions on the biological fitness of cuttlefish hatchlings in future oceans.
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  • 80
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    Slave to the rhythm: seasonal signals in otolith microchemistry reveal age of eastern Baltic cod (Gadus morhua) (2016)
    Oxford Univ. Press
    In:  ICES Journal of Marine Science, 73 (4). pp. 1019-1032.
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    Publikationsdatum: 2019-02-01
    Beschreibung: Annual growth zones in cod otoliths from the eastern Baltic stock are less discrete than in other cod stocks leading to biased age reading, which recently led to a failure of age-based assessment in the eastern Baltic cod stock. In this study, we explored the applicability of minor and trace element patterns in cod otoliths for age determination. By first identifying elements of interest in a stock without ageing problems, western Baltic cod, we then tested their applicability on another stock without ageing problems, North Sea cod, and finally applied this knowledge to estimate age of eastern Baltic cod. In western Baltic cod, matching patterns with respect to occurrence of minima and maxima in both otolith opacity and element concentrations were found for Cu, Zn, and Rb, and inverse patterns with Mg and Mn. No match was found for Pb, Ba, and Sr. In the test stock, the North Sea cod, the same patterns in Cu, Zn, Rb, Mg, and Mn signals occurred. All eastern Baltic cod with low visual contrast between growth zones exhibited clearly defined synchronous cycles in Cu, Zn, Rb and Pb. Using a combined finite differencing method and structural break models approach, the statistical significance of the local profile minima were identified, based on which their age could be estimated. Despite extensive environmental differences between the three areas examined, the element concentrations of Cu, Zn, and Rb were strongly correlated in all individuals with similar correlations in all three areas, suggesting that the incorporation mechanisms are the same for these elements and independent of environmental concentrations.
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  • 81
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    Effects of high CO2 and warming on a Baltic Sea microzooplankton community (2016)
    Oxford Univ. Press
    In:  ICES Journal of Marine Science, 73 (3). pp. 772-782.
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    Publikationsdatum: 2019-02-01
    Beschreibung: Global warming and ocean acidification are among the most important stressors for aquatic ecosystems in the future. To investigate their direct and indirect effects on a near-natural plankton community, a multiple-stressor approach is needed. Hence, we set up mesocosms in a full-factorial design to study the effects of both warming and high CO2 on a Baltic Sea autumn plankton community, concentrating on the impacts on microzooplankton (MZP). MZP abundance, biomass, and species composition were analysed over the course of the experiment. We observed that warming led to a reduced time-lag between the phytoplankton bloom and an MZP biomass maximum. MZP showed a significantly higher growth rate and an earlier biomass peak in the warm treatments while the biomass maximum was not affected. Increased pCO2 did not result in any significant effects on MZP biomass, growth rate, or species composition irrespective of the temperature, nor did we observe any significant interactions between CO2 and temperature. We attribute this to the high tolerance of this estuarine plankton community to fluctuations in pCO2, often resulting in CO2 concentrations higher than the predicted end-of-century concentration for open oceans. In contrast, warming can be expected to directly affect MZP and strengthen its coupling with phytoplankton by enhancing its grazing pressure.
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  • 82
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    Ocean acidification does not alter grazing in the calanoid copepods Calanus finmarchicus and Calanus glacialis (2016)
    Oxford Univ. Press
    In:  ICES Journal of Marine Science, 73 (3). pp. 927-936.
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    Publikationsdatum: 2019-09-23
    Beschreibung: It is currently under debate whether organisms that regulate their acid–base status under environmental hypercapnia demand additional energy. This could impair animal fitness, but might be compensated for via increased ingestion rates when food is available. No data are yet available for dominant Calanus spp. from boreal and Arctic waters. To fill this gap, we incubated Calanus glacialis at 390, 1120, and 3000 µatm for 16 d with Thalassiosira weissflogii (diatom) as food source on-board RV Polarstern in Fram Strait in 2012. Every 4 d copepods were subsampled from all CO2 treatments and clearance and ingestion rates were determined. During the SOPRAN mesocosm experiment in Bergen, Norway, 2011, we weekly collected Calanus finmarchicus from mesocosms initially adjusted to 390 and 3000 µatm CO2 and measured grazing at low and high pCO2. In addition, copepods were deep frozen for body mass analyses. Elevated pCO2 did not directly affect grazing activities and body mass, suggesting that the copepods did not have additional energy demands for coping with acidification, neither during long-term exposure nor after immediate changes in pCO2. Shifts in seawater pH thus do not seem to challenge these copepod species.
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  • 83
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    Reply to Andersen et al.(2016) "Assumptions behind size-based ecosystem models are realistic" (2016)
    Oxford Univ. Press
    In:  ICES Journal of Marine Science, 73 (6). pp. 1656-1658.
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    Publikationsdatum: 2019-02-01
    Beschreibung: In a recent publication (Froese et al., ICES Journal of Marine Science; doi:10.1093/icesjms/fsv122), we presented a critique of the balanced harvesting (BH) approach to fishing. A short section dealt with the size-spectrum models used to justify BH, wherein we pointed out the lack of realism of these models, which mostly represented ecosystems as consisting of a single cannibalistic species. Andersen et al. (ICES Journal of Marine Science; doi:10.1093/icesjms/fsv211) commented on our paper and suggested that we criticized size-spectrum models in general and that we supposedly made several erroneous statements. We stress that we only referred to the size-spectrum models that we cited, and we respond to each supposedly erroneous statement. We still believe that the size-spectrum models used to justify BH were highly unrealistic and not suitable for evaluating real-world fishing strategies. We agree with Andersen et al. that BH is unlikely to be a useful guiding principle for ecosystem-based fisheries management, for many reasons. The use of unrealistic models is one of them.
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  • 84
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    The application of multi-omics and systems biology to identify therapeutic targets in chronic kidney disease (2016)
    Oxford Univ. Press
    In:  Nephrology Dialysis Transplantation, 31 (12). pp. 2003-2011.
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    Publikationsdatum: 2020-06-22
    Beschreibung: The quest for the ideal therapeutic target in chronic kidney disease (CKD) has been riddled with many obstacles stemming from the molecular complexity of the disease and its co-morbidities. Recent advances in omics technologies and the resulting amount of available data encompassing genomics, proteomics, peptidomics, transcriptomics and metabolomics has created an opportunity for integrating omics datasets to build a comprehensive and dynamic model of the molecular changes in CKD for the purpose of biomarker and drug discovery. This article reviews relevant concepts in omics data integration using systems biology, a mathematical modelling method that globally describes a biological system on the basis of its modules and the functional connections that govern their behaviour. The review describes key databases and bioinformatics tools, as well as the challenges and limitations of the current state of the art, along with practical application to CKD therapeutic target discovery. Moreover, it describes how systems biology and visualization tools can be used to generate clinically relevant molecular models with the capability to identify specific disease pathways, recognize key events in disease development and track disease progression.
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  • 85
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    Bayesian inversion of marine controlled source electromagnetic data offshore Vancouver Island, Canada (2016)
    Oxford Univ. Press
    In:  Geophysical Journal International, 204 (1). pp. 21-38.
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    Publikationsdatum: 2019-02-01
    Beschreibung: This paper applies nonlinear Bayesian inversion to marine controlled source electromagnetic (CSEM) data collected near two sites of the Integrated Ocean Drilling Program (IODP) Expedition 311 on the northern Cascadia Margin to investigate subseafloor resistivity structure related to gas hydrate deposits and cold vents. The Cascadia margin, off the west coast of Vancouver Island, Canada, has a large accretionary prism where sediments are under pressure due to convergent plate boundary tectonics. Gas hydrate deposits and cold vent structures have previously been investigated by various geophysical methods and seabed drilling. Here, we invert time-domain CSEM data collected at Sites U1328 and U1329 of IODP Expedition 311 using Bayesian methods to derive subsurface resistivity model parameters and uncertainties. The Bayesian information criterion is applied to determine the amount of structure (number of layers in a depth-dependent model) that can be resolved by the data. The parameter space is sampled with the Metropolis–Hastings algorithm in principal-component space, utilizing parallel tempering to ensure wider and efficient sampling and convergence. Nonlinear inversion allows analysis of uncertain acquisition parameters such as time delays between receiver and transmitter clocks as well as input electrical current amplitude. Marginalizing over these instrument parameters in the inversion accounts for their contribution to the geophysical model uncertainties. One-dimensional inversion of time-domain CSEM data collected at measurement sites along a survey line allows interpretation of the subsurface resistivity structure. The data sets can be generally explained by models with 1 to 3 layers. Inversion results at U1329, at the landward edge of the gas hydrate stability zone, indicate a sediment unconformity as well as potential cold vents which were previously unknown. The resistivities generally increase upslope due to sediment erosion along the slope. Inversion results at U1328 on the middle slope suggest several vent systems close to Bullseye vent in agreement with ongoing interdisciplinary observations.
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  • 86
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    Crustal structure and kinematics of the TAMMAR propagating rift system on the Mid-Atlantic Ridge from seismic refraction and satellite altimetry gravity (2016)
    Oxford Univ. Press
    In:  Geophysical Journal International, 206 (2). pp. 1382-1397.
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    Publikationsdatum: 2019-09-23
    Beschreibung: The TAMMAR segment of the Mid-Atlantic Ridge forms a classic propagating system centred about two degrees south of the Kane Fracture Zone. The segment is propagating to the south at a rate of 14 mm yr−1, 15 per cent faster than the half-spreading rate. Here, we use seismic refraction data across the propagating rift, sheared zone and failed rift to investigate the crustal structure of the system. Inversion of the seismic data agrees remarkably well with crustal thicknesses determined from gravity modelling. We show that the crust is thickened beneath the highly magmatic propagating rift, reaching a maximum thickness of almost 8 km along the seismic line and an inferred (from gravity) thickness of about 9 km at its centre. In contrast, the crust in the sheared zone is mostly 4.5–6.5 km thick, averaging over 1 km thinner than normal oceanic crust, and reaching a minimum thickness of only 3.5 km in its NW corner. Along the seismic line, it reaches a minimum thickness of under 5 km. The PmP reflection beneath the sheared zone and failed rift is very weak or absent, suggesting serpentinisation beneath the Moho, and thus effective transport of water through the sheared zone crust. We ascribe this increased porosity in the sheared zone to extensive fracturing and faulting during deformation. We show that a bookshelf-faulting kinematic model predicts significantly more crustal thinning than is observed, suggesting that an additional mechanism of deformation is required. We therefore propose that deformation is partitioned between bookshelf faulting and simple shear, with no more than 60 per cent taken up by bookshelf faulting.
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  • 87
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    Which environmental scales and factors matter for mesozooplankton communities in a shallow brackish water ecosystem? (2016)
    Oxford Univ. Press
    In:  Journal of Plankton Research, 38 (1). pp. 139-153.
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    Publikationsdatum: 2019-02-01
    Beschreibung: Aquatic invertebrate communities are influenced by interactions between the abiotic and biotic environment at multiple spatial and temporal scales. Studies of mesozooplankton community patterns in relation to spatial and temporal scales are rare. In this study, we examined scale-specific variability of mesozooplankton in the shallow coastal Baltic Sea and related this variability to key environmental proxies. Seasonality defined the majority of variability in taxonomic composition and abundance patterns, as well as in aggregated parameters of zooplankton. However, these properties also varied spatially at a large, 100-km scale. The variability in all properties except taxonomic composition was negligible at the smaller spatial scale. Taxonomic richness increased until moderate levels of total abundance, whereas peak blooms were always characterized by higher dark diversity. Shannon diversity was unrelated to total abundance. Observed spatio-temporal patterns were strongly related to abiotic forcing and uncoupled from phytoplankton standing stock and primary production. Results show the importance of seasonality over spatial variability and abiotic factors over phytoplankton variability for sub-boreal brackish coastal mesozooplankton at the spatial scales studied. Information loss from spatial generalization can be larger for taxonomic occurrences and rare species than for species abundances and aggregated community parameters such as total abundance or taxonomic richness.
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  • 88
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    Trench-perpendicular Geochemical Variation Between two Adjacent Kermadec Arc Volcanoes Rumble II East and West: the Role of the Subducted Hikurangi Plateau in Element Recycling in Arc Magmas (2016)
    Oxford Univ. Press
    In:  Journal of Petrology, 57 (7). pp. 1335-1360.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: Little is known about the effects that subducting an oceanic large igneous province (LIP) has on the petrogenesis of submarine arc volcanoes and their geochemical composition. The southern Kermadec arc represents a rare example where an LIP—the Hikurangi Plateau—is currently subducting and where its effect on mantle composition, element recycling and arc volcanism can be studied. We present mineral chemistry and whole-rock major and trace element, and Sr–Nd–Pb isotope data from samples recovered from the southern Kermadec arc volcanoes Rumble II East and Rumble II West, together with shipboard gravity and magnetic measurements. The Rumble II volcanoes (including a volcanic cone ∼10 km further west) form an ∼23 km long arc–backarc transect located ∼250 km north of New Zealand above the subducting Hikurangi Plateau. Although only a short distance apart, rocks from the two volcanoes have different mineral and whole-rock geochemical compositions. Lavas from Rumble II East are predominantly basaltic and contain primitive olivine phenocrysts (≤Fo91), high-Mg# clinopyroxene (≤96) and anorthitic plagioclase (≤An97). Geochemically these lavas are very diverse and cover a spectrum from low Th/Yb (〈0·15) at high Ba/Th (〉1014) to higher Th/Yb (〉0·15) at lower Ba/Th (〈844). This spectrum, together with 206Pb/204Pb and 143Nd/144Nd in the range of 18·74–18·83 and 0·51309–0·51298 respectively (at similar to slightly elevated 87Sr/86Sr), suggests a mantle wedge that has undergone previous melt extraction and significant fluid addition from the subducting Pacific Plate and that contains sediment and HIMU-type Hikurangi Plateau components. The geochemistry of the sediment–HIMU-type components is exemplified in an olivine pyroxenite (e.g. 206Pb/204Pb = 20·02; 87Sr/86Sr = 0·70516; 143Nd/144Nd = 0·5126). We propose that the olivine pyroxenite formed through melt or fluid–rock metasomatism and represents the first direct evidence of a near Moho arc mantle rock that shows the imprint from a subducting HIMU-type (Hikurangi) seamount. Conversely, lavas from Rumble II West and the cone ∼10 km to the west are generally more silica rich than Rumble II East lavas and mainly contain plagioclase with less ortho- and clinopyroxene + olivine phenocrysts. The low Ba/Th (〈470) and 206Pb/204Pb (〈18·74), a range of 143Nd/144Nd (0·51297–0·51307) and elevated Th/Yb (0·13–0·39) in these lavas can best be explained by minor sediment input into a less depleted mantle wedge. In addition, the geochemical composition of the Rumble II West lavas does not require involvement of a Hikurangi component, placing a spatial limit on Hikurangi material influencing regional melt generation beneath the backarc. Supported by a gravity model requiring two distinct magma chambers, the different geochemical compositions of Rumble II East and West lavas are inconsistent with a shared magma plumbing system. The different geochemical compositions of lavas from the two Rumble II volcanoes furthermore demonstrate that across-arc geochemical heterogeneities can occur within a few kilometres and may originate from both a geochemically heterogeneous mantle wedge and Moho transition layer, recording inherited geochemical heterogeneities beneath the volcanoes.
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  • 89
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    Flexible phytoplankton functional type (FlexPFT) model: size-scaling of traits and optimal growth (2016)
    Oxford Univ. Press
    In:  Journal of Plankton Research, 38 (4). pp. 977-992.
    Details
    Publikationsdatum: 2019-07-30
    Beschreibung: Recent studies have analysed valuable compilations of data for the size-scaling of phytoplankton traits, but these cannot be employed directly in most large-scale modelling studies, which typically do not explicitly resolve the relevant trait values. Although some recent large-scale modelling studies resolve species composition and sorting within communities, most do not account for the observed flexible response of phytoplankton communities, such as the dynamic acclimation often observed in laboratory experiments. In order to derive a simple yet flexible model of phytoplankton growth that can be useful for a wide variety of ocean modelling applications, we combine two trade-offs, one for growth and the other for nutrient uptake, under the optimality assumption, i.e. that intracellular resources are dynamically allocated to maximize growth rate. This yields an explicit equation for growth as a function of nutrient concentration and daily averaged irradiance. We furthermore show how with this model effective Monod parameter values depend on both the underlying trait values and environmental conditions. We apply this new model to two contrasting time-series observation sites, including idealized simulations of size diversity. The flexible model responds differently compared with an inflexible control, suggesting that acclimation by individual species could impact models of plankton diversity.
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  • 90
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    Spatio-temporal trends in stock mixing of eastern and western Baltic cod in the Arkona Basin and the implications for recruitment (2016)
    Oxford Univ. Press
    Details
    Publikationsdatum: 2022-04-26
    Beschreibung: In the Baltic Sea, two genetically distinct cod populations occur, the eastern and the western Baltic cod. Since 2006, cod abundance has increased substantially in the Arkona Basin (SD 24), the potential mixing area between the two stocks management areas, presumably due to spill-over from the eastern stock. In this study, the spatio-temporal dynamics of stock mixing were analysed using shape analysis of archived otoliths. Further, the impact of eastern cod immigration on recruitment in the western Baltic Sea was investigated using hydrographic drift modelling. The percentage of eastern Baltic cod in the Arkona Basin increased from ca. 30% before 2005 to 〉80% in recent years. Geographic patterns in stock mixing with a pronounced east–west trend suggest that immigration occurs north of Bornholm, but propagates throughout the Arkona Basin. The immigration cannot be attributed to spawning migration, as no seasonal trend in stock mixing was observed. Based on environmental threshold levels for egg survival and time-series of hydrography data, the habitat suitable for successful spawning of eastern cod was estimated to range between 20 and 50% of the maximum possible habitat size, limited by primarily low salinity. Best conditions occurred irregularly in May–end June, interspersed with years where successful spawning was virtually impossible. Using a coupled hydrodynamic modelling and particle-tracking approach, the drift and survival of drifters representing eastern cod eggs was estimated. On average, 19% of the drifters in the Arkona Basin survive to the end of the yolk-sac stage, with mortality primarily after bottom contact due to low salinity. The general drift direction of the surviving larvae was towards the east. Therefore, it is the immigration of eastern cod, rather than larval transport, that contributes to cod recruitment in the western Baltic Sea.
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  • 91
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    Optimality-based Trichodesmium diazotrophy in the North Atlantic subtropical gyre (2016)
    Oxford Univ. Press
    Details
    Publikationsdatum: 2023-08-01
    Beschreibung: A recent optimality-based model for phytoplankton growth and diazotrophy was applied at two stations located in the oligotrophic western and the ultra-oligotrophic eastern subtropical North Atlantic. Contrary to the common view that diazotrophy is favoured by nitrogen (N) depletion relative to the Redfield equivalent of phosphorus (P), we find that optimality-based diazotrophy could explain N fixation in both regions in spite of relatively high N:P supply ratios. This is possible because the availability of an additional source of N for diazotrophs makes them strong competitors for P under oligotrophic conditions. The best reproduction of observations, especially of net primary production, is only achieved with preferential remineralization of P relative to N and atmospheric deposition. In line with observations, a higher rate of nitrogen fixation is predicted for the eastern site, owing to a larger niche for diazotrophs resulting from stronger oligotrophy and lower N:P supply ratios due to weaker atmospheric N deposition. Because the competitive advantage of diazotrophs under nutrient starvation diminishes with increasing supply N:P ratio, the predicted increase of atmospheric N deposition due to anthropogenic activity could negatively affect N2 fixation in the Atlantic Ocean.
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  • 92
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    Environmental development and local human impact in the Jeetzel valley (N Germany) since 10 ka BP as detected by geoarchaeological analyses in a coupled aeolian and lacustrine sediment archive at Soven (2015)
    Geozon Science Media
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    Publikationsdatum: 2021-05-06
    Beschreibung: While archaeological records indicate an intensive Mesolithic occupation of dune areas situated along river valleys, relatively little knowledge exists about environmental interactions in the form of land-use strategies and their possible local impacts. The combination of geoarchaeological, chronological, geochemical and palaeoecological research methods and their application both on a Mesoltihic site situated on top of a dune and the adjacent palaeochannel sediments allows for a detailed reconstruction of the local environmental development around the Soven site in the Jeetzel valley (Northern Germany) since ~10.5 ka cal BP. Based on the results, we identified four phases that may be related to local human impact twice during the Mesolithic, the Neolithic and the Iron Ages and are discussed on the backdrop of the regional settlement history. Although nearby Mesolithic occupation is evident on archaeological grounds, the identification of synchronous impacts on the vegetation in the local environmental records remains tentative even in respect of the broad methodical spectrum applied. Vice versa, human impact is strongly indicated by palaeoecological and geochemical proxies during the Neolithic period, but cannot be connected to archaeological records in the area so far. A younger phase of human impact – probably consisting of seasonal livestock farming in the wetlands – is ascribed to the Iron Age economy and comprises local soil erosion, raised concentrations of phosphates and urease, and the facilitation of grazing related taxa.
    Beschreibung: research
    Schlagwort(e): 551.7 ; aeolian sand ; pollen ; mesolithic ; iron age ; charcoal ; human impact ; OSL ; Neolithisation
    Sprache: Englisch
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  • 93
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    Periglaziäre, polygonal-verzweigte rinnenförmige Bildungen und glazitektonische Strukturen in Saale-Till am Elbe-Urstomtalrand bei Wedel (Schleswig-Holstein) (2015)
    Geozon Science Media
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    Publikationsdatum: 2021-05-06
    Beschreibung: Remarkable polygenetical structures were observed at a refinery rehabilitation site in Wedel/Holstein. The polygonal shaped, channel-like structures are incised in mid-Saalian clayey, chalk-rich till. They are symmetrically semicircular shaped and filled with calcareous, silty sands that can be interpreted as sandy reworked till with aeolian components. The width reaches from approx. 0.3 to 1.5 metres, the depth up to approx. 0.8 metres. Horizontal cracks up to more than 10 meters in lengths, occurring as narrow belts of sand with reddish colour, are often centrally aligned in the channel-like structures. The present-day red colour is not natural but related to pollution. These belts reach down to the bottom of the channel like structures. At the lower site of the channel-like structures glacitectonic fissures with a width up to a few centimetres were to be traced into a depth of several metres to the basis of the excavat ion. The genesis of the channel-like structures is discussed. e. g. a possible relation with the pre-existing glacitectonic joints resp. the expected periglacial paleohydrogeological setting.
    Beschreibung: research
    Schlagwort(e): 551.7 ; periglacial channels ; Weichselian periglacial ; frost wedges ; glacitectonism ; paleohydrogeology ; talik ; Elbe spillway
    Sprache: Deutsch
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  • 94
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    Chronostratigraphy of the Hochterrassen in the lower Lech valley (Northern Alpine Foreland) (2015)
    Geozon Science Media
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    Publikationsdatum: 2021-05-06
    Beschreibung: Hochterrassen (High or Higher Terraces) are a prominent geomorphological feature of the Northern Alpine Foreland and have traditionally been attributed to the Rissian glaciation. However, distinct morphological sublevels observed for this feature have often raised the question of their age. This issue is exemplarily investigated here on the Langweider and Rainer Hochterrassen in the lower Lech valley using different relative and numerical dating techniques. The lowest sublevel, the Übergangsterrasse is only preserved in small patches at the western rim of the Rainer Hochterrasse and is most probably of early Würmian age. The sublevel of the Jüngere Hochterrasse is older than the Last Interglacial, as indicated by luminescence ages of overlying loess/palaeosol sequence and the development of a luvisol on top of the terrace gravel. This terrace is composed of stacked gravel units that represent at least two accumulation phases correlating with Marine Isotope Stage (MIS) 6 for the top gravel and MIS 7 to MIS 10 (or older) for the basal gravel. It is not yet clear, if the deposition of the basal gravel unit corresponds to one or more aggradation phases during the Middle Pleistocene. The highest sublevel, the Ältere Hochterrasse also shows a compositon of two stacked gravel units but so far, no numerical ages have been achieved for these units.
    Beschreibung: research
    Schlagwort(e): 551.7 ; northern alpine foreland ; middle pleistocene ; luminescence dating ; Hochterrassen ; fluvial terraces
    Sprache: Englisch
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  • 95
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    Late Pleistocene spotted hyena den sites and specialized rhinoceros scavengers in the karstified Zechstein areas of the Thuringian Mountains (Central Germany) (2015)
    Geozon Science Media
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    Publikationsdatum: 2021-05-06
    Beschreibung: Crocuta crocuta spelaea (Goldfuss 1823) cranial and postcranial remains of the Pößneck region in the Zechstein Karst region of the Thuringian Mountains (Central Germany) were excavated historically in the Wüste Scheuer Cavity at Döbritz. Nearby, at the Krölpa gypsum karst open air site, additionally a woolly rhinoceros, partially scavenged by Ice Age spotted hyenas, was found. The amount at Wüste Scheuer Cavity includes chew damaged Coelodonta antiquitatis remains and is classified herein as communal den type. At both den/scavenging sites, only a small amount of prey material of Late Pleistocene megafauna of rare M. primigenius, mainly C. antiquitatis, E. c. przewalskii, and fewer B. priscus and R. tarandus was accumulated. The dominance of woolly rhinoceros, bison and Przewalski horse bones are typical for hyena bone assemblages in European low mountain regions, where mammoth was nearly absent as a result of topography. In the Thuringian Karst Mountains nine Late Pleistocene Ice Age spotted hyena den sites are identified. Solely hyena dens are present in Zechstein open air gypsum and limestone karstic regions of Bad Köstritz, Krölpa and Fuchsluken Cavities near Saalfeld. In the Wüste Scheuer their remains overlap with Middle Palaeolithic Neanderthal human camp sites, similar as in the Ilsen Cave at Ranis and Lindenthal Cave in Gera, which demonstrates competition for prey and shelter cavities. At such cave sites, bone remains were historically misinterpreted as „solely of Neanderthal human kitchen rubbish” or even as “bone tools” (e.g. “bone scrapers” = woolly rhinoceros tibia bones chewed by hyenas).
    Beschreibung: research
    Schlagwort(e): 551.7 ; late pleistocene ; Ice Age spotted hyenas ; den types ; Thuringian Mountains ; Central Germany
    Sprache: Englisch
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  • 96
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    Ein Uferprofil am Priesterbäker See: Slawenzeitlich-mittelalterliche Seespiegelschwankungen im Bereich der „Specker Seen“ (Mecklenburg) (2015)
    Geozon Science Media
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    Publikationsdatum: 2021-03-29
    Beschreibung: Eine durch einen Bodenschurf aufgeschlossene Boden-Sediment-Folge einer alten Seeterrasse im Einzugsgebiet des Priesterbäker Sees zeigt deutliche Fazieswechsel im Uferbereich des Gewässers. Die Abfolge von liegenden humosen Sanden, welche einen ehemaligen Verlandungssaum nachzeichnen, limnischen Sanden mit Bodenbildung und hangenden Flugsanden belegt Änderungen in der Sedimentation, welche mit säkularen Grundwasser- bzw. Seespiegelschwankungen zu erklären sind. Mit Hilfe von geophysikalischen Datierungen lassen sich gegenüber dem heutigen Niveau höhere Wasserstände für den Priesterbäker See bzw. die so genannten „Specker Seen“ östlich der Müritz während des 7.–9. und 12.–14. Jahrhunderts ableiten.
    Beschreibung: research
    Schlagwort(e): 551 ; 554.3 ; seespiegelschwankungen ; mecklenburg ; Seeterrasse ; Priesterbäker See ; Slawenzeit
    Sprache: Deutsch
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  • 97
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    Weichselzeitliche Kryocalcite als Hinweise für Eisseen in der Hüttenbläserschachthöhle (Iserlohn/NRW) (2015)
    Geozon Science Media
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    Publikationsdatum: 2021-05-06
    Beschreibung: C/O-stable isotope composition (VPDB) of speleothems from the Makkaronihalle of the Hüttenbläserschacht Cave in Iserlohn shows a clear separation between glacial and interglacial calcites. In contrast to normal speleothems (stalagmites, excentriques, crystals in cave ponds, draperies; δ18O: –4.0 to –6.1 ‰, δ13C: –4.9 to –10.9 ‰), rhombohedral crystal sinter and spherulitic speleoparticles are characterised by lower δ18O (–8.9 to –17.9 ‰) and higher δ13C values (+0.7 to –6.1 ‰). This suggests that these speleogenetic particles were formed in slowly freezing waterpools on ice during the transition from a stadial to an interstadial phase. Precise 230Th/U-dating shows younger Weichselian ages of 28.6 to 33.0 ka for these speleogenetic particles from north-west Germany. These formation periods indicate freezing conditions overlain by 34 m of hostrock and provide the minimum depth of permafrost penetration for the younger Weichselian in the area of the northern Sauerland (north-west Germany).
    Beschreibung: research
    Schlagwort(e): 551.7 ; permafrost ; Cryogenic calcites ; C/O isotopes ; Upper Weichselian ; ice caves ; north-western Germany
    Sprache: Deutsch
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  • 98
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    Spätsaalezeitliche und eemzeitliche Makrofaunen aus dem Kliffaufschluss Klein Klütz Höved (NW-Mecklenburg) (2015)
    Geozon Science Media
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    Publikationsdatum: 2021-05-06
    Beschreibung: On the basis of the work done by Strahl et al. (1994), the mollusc specimens in the Late Saalian glacial and Eemian interglacial sediments from the cliff outcrop of Klein Klütz Höved (NW Mecklenburg) were re-examined and, in the process, a few vertebrates (fishes, micromammals) were also found. The mollusc specimens from the Late Saalian sand and mud alone comprise approximately 40 species among which terrestrial varieties, e.g. Succinella oblonga, Pupilla loessica, P. pratensis, Vallonia tenuilabris or Vertigo genesii, are clearly predominant as far as the number of individual specimens is concerned. Among the limnic varieties were also found the glacial index species Pisidium obtusale f. lapponicum and P. stewarti. It was also possible to prove the northern-most presence for Germany of the steppe lemming Lagurus lagurus in the Late Saalian. In the Eemian mud, the molluscs found were almost exclusively limnic. This about 20 species comprising fauna is characte-ristic of a river system with calmer areas, oxbow lakes and in-coming springs. These fluvial conditions were confirmed by the freshwater bivalves Pisidium amnicum, P. supinum, P. moitessierianum, P. ponderosum and Unio tumidus. For the first time in Mecklenburg-Western Pomerania, evidence was found of the spring snail Belgrandia germanica as an interglacial index species. The limnic-fluvial section of the Eemian is topped by a cryoturbate structures. Its sandy, gravelly pockets contain marine molluscs. The index species for the marine Eemian found in the southern Baltic region are Polititapes senescens and Bittium reticulatum.
    Beschreibung: research
    Schlagwort(e): 551.7 ; molluscs ; Saalian deposits ; limnic and marine Eemian facies ; Belgrandia germanica ; micromammals ; Lagurus lagurus ; Mecklenburg-Western Pomerania
    Sprache: Deutsch
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  • 99
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    Klima, Grundwassernutzung oder Waldbewirtschaftung? Ursachen tendenziell fallender Grundwasserstände am Beispiel Südwest-Usedoms (2015)
    Geozon Science Media
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    Publikationsdatum: 2021-03-29
    Beschreibung: Tendenziell fallende Grundwasserstände können vielfältige Ursachen haben, z.B. die Änderung der klimatischen Bedingungen, Modifikationen der Landnutzung oder die Entnahme von Grundwasser. Am Beispiel Südwest-Usedoms wird dargestellt, wie mögliche Einflussfaktoren analysiert und quantifiziert werden können. Für das Untersuchungsgebiet zeigte sich, dass die über Jahrzehnte gesunkenen Grundwasserstände überwiegend aus der Kahlschlagbewirtschaftung des Waldes resultieren und damit weniger einen Trend als eine überjährliche Schwankung ausweisen.
    Beschreibung: research
    Schlagwort(e): 551 ; 554.3 ; forest ; Sickerwasser ; Grundwasser ; Grundwasserneubildung ; Wald ; Landschaftswasserhaushalt ; Trend ; Grundwasserentnahme ; geohydraulisches Modell ; Landscape water regime ; Groundwater ; Groundwater recharge ; percolate water ; Groundwater extraction ; Groundwater modelling ; Geohydraulic model ; Grundwasserströmung ; Modellierung
    Sprache: Deutsch
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  • 100
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    Bw horizon in Holocene slope deposits (Kratzeburg, NE Germany) – dating and pedological characteristics (2015)
    Geozon Science Media
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    Publikationsdatum: 2021-05-06
    Beschreibung: A soil-sediment sequence in NE Germany has provided information about the duration and intensity of formation of a Bw horizon in Holocene slope deposits. With a combination of optically stimulated luminescence (OSL), 14C- and archaeological dating methods, colluvial layers taken from a former castle wall trench constructed during the Bronze Age were dated. With this chronology, the relative age of the postsedimentary Bw horizon formation within the colluvial sediments was derived, resulting in the first valid pedochronological data (maximum and minimum age) for a Holocene Bw horizon in NE Germany. The horizon was formed within 2400 years. Weathering and brunification have altered the Holocene parent material. However, the geochemical characteristics of the Holocene soil formation are weak compared to Bw horizons from the Late Glacial and the Late Glacial to Holocene. The results presented here enhance our understanding of soil formation processes in northern Germany, while highlighting the role of colluvial layers as sedimentological tracers of Holocene soil formation processes.
    Beschreibung: research
    Schlagwort(e): 551.7 ; holocene ; ne germany ; dating ; Bw horizon ; Slope deposits ; soil formation
    Sprache: Englisch
    Materialart: article , Verlagsversion
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