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  • 101
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    PERGAMON-ELSEVIER SCIENCE LTD
    In:  EPIC3Organic Geochemistry, PERGAMON-ELSEVIER SCIENCE LTD, 113, pp. 124-127, ISSN: 0146-6380
    Publication Date: 2017-09-17
    Description: We have analyzed the dissolved organic carbon, OC, in ocean basement fluids using Fourier Transform-Ion Cyclotron Resonance-Mass Spectrometry (FT-ICR-MS). The compounds identified at the two sites, near the Juan de Fuca and Mid-Atlantic Ridges (North Pond), differ substantially from each other and from seawater. Compared to Juan de Fuca, North Pond organics had a lower average molecular weight (349 vs. 372 g/mol), 50% more identifiable compounds (2181 vs. 1482), and demonstrably lower average nominal oxidation state of carbon (-0.70 vs. -0.56). The North Pond fluids were also found to have many more Nand S-bearing compounds. Based on our data, the marine subsurface can alter the types of dissolved OC, DOC, compounds in seawater.
    Repository Name: EPIC Alfred Wegener Institut
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  • 102
    Publication Date: 2017-12-01
    Description: Greenland's bed topography is a primary control on ice flow, grounding line migration, calving dynamics and subglacial drainage. Moreover, fjord bathymetry regulates the penetration of warm Atlantic Water (AW) that rapidly melts and undercuts Greenland's marine-terminating glaciers. Here, we present a new compilation of Greenland bed topography that assimilates seafloor bathymetry and ice thickness data through a mass conservation (MC) approach. A new 150-m horizontal resolution bed topography/bathymetric map of Greenland is constructed with seamless transitions at the ice/ocean interface, yielding major improvements over previous datasets, particularly in the marine-terminating sectors of northwest and southeast Greenland. Our map reveals the total sea level potential of the Greenland Ice Sheet is 7.42±0.05 m, which is 7 cm greater than previous estimates. Furthermore, it explains recent calving front response of numerous outlet glaciers and reveals new pathways by which AW can access glaciers with marine-based basins, thereby highlighting sectors of Greenland that are most vulnerable to future oceanic forcing.
    Repository Name: EPIC Alfred Wegener Institut
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  • 103
    Publication Date: 2017-09-25
    Description: Compound-specific radiocarbon dating often requires working with small sample sizes (〈 100 µgC). This makes the radiocarbon dates of biomarker compounds very sensitive to biases caused by extraneous carbon of unknown composition, which is introduced to the samples during processing (i.e., isolating single compounds from a heterogeneous mixture) prior to AMS measurements (procedure blank). Contamination sources include solvents, column bleed (from preparative HPLC and GC), carry-over and atmospheric carbon during combustion and vacuum line handling. Reporting accurate radiocarbon dates thus requires a correction for the procedure blank. We present our approach to assess the F14C and the mass of the blanks introduced during the preparation procedures of lipid biomarkers and lignin phenols. The treatments of these compound classes differ significantly which may lead to different F14Cblank and mblank. In order to assess the procedure blanks, we isolated fatty acids and lignin phenols from differently sized aliquots (20-80 µgC) obtained from standard materials with known F14C. Each compound class was extracted from two standard materials (one fossil, one modern). The measured F14C of the processed aliquots were graphically correlated to 1/mass of the respective sample. For aliquots of both, fossil and modern standard materials, this yielded an inverse linear relationship between the F14C and the sample size. The intercept of the regression lines obtained from the aliquots of fossil and modern standards is used to infer F14Cblank and mblank. The uncertainties of F14Cblank (σF14Cblank) and mblank (σmblank) were determined by the regression coefficients R2 of the linear regressions. Assuming constant contamination during processing of individual samples, the F14Cblank and mblank can be used to correct AMS results of lignin and lipid samples by isotopic mass balance.
    Repository Name: EPIC Alfred Wegener Institut
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  • 104
    Publication Date: 2017-11-01
    Description: The last deglaciation was characterized by rising concentration in atmospheric CO2 (CO2atm) and a decrease in its radiocarbon content (Δ14Catm). Mobilization of 14C-depleted terrestrial organic carbon, which was previously frozen in extensive boreal permafrost soils, might have contributed to both changes, and was potentially caused by coastal erosion during deglacial sea-level rise and warming. Since parts of this potentially mobilized organic carbon was reburied in marine sediments, records of accumulation of terrigenous biomarkers and their compound-specific radiocarbon ages can provide insights into the timing and controls on permafrost decomposition. We present data from three marine sediment cores, two cores off the Amur River draining into the Sea of Okhotsk, and one core from the Northeastern Bering Sea adjacent to the Bering shelf (one the largest shelf areas flooded during the deglaciation) receiving input from the Yukon River. During the Last Glacial Maximum all catchments were completely covered with permafrost. Today, the Amur drainage basin is free of permafrost while the Yukon catchment is covered by discontinuous permafrost. All sites show three distinct deglacial maxima (at 16.5, 14.5, 11.5 ka BP) in accumulation of old terrigenous biomarkers (5-20 kyr old at the time of deposition). The peaks occurred during meltwater pulses suggesting that sea-level rise remobilized old terrestrial carbon from permafrost on the flooded shelfs. In the Bering Sea fossil, mature organic matter, mobilized by erosion of organic rich rocks during the retreat of Brooks Range glaciers and the Laurentide ice sheet additionally contributed to the first peak via increased fluvial runoff. Deglacial changes in abundance ratios of long-chain n-alkanes record gradual changes in vegetation type and wetland extent in the Amur-river catchment. Since wetland expansion is closely linked to permafrost thaw this implies that permafrost decomposition in the Amur drainage basin was a gradual process. By contrast sea-level rise caused abrupt decomposition events across the Okhotsk and Bering Shelfs. We extrapolate our localized findings to an overall potential carbon release during deglaciation of 285 PgC from coastal erosion in the Arctic Ocean and the related permafrost decomposition. By analysing some idealized scenarios using the global carbon cycle model BICYCLE we estimate the impact of such a release on the atmosphere. We find that it might have accounted for a deglacial rise in CO2atm of up to 15 ppm, and to a decline in ∆14Catm of 15‰. These results, if restricted to the three peak events connected to rapid sea-level rise, as supported by our data, might have contributed particularly to abrupt changes in CO2atm and ∆14Catm, corresponding to 15-20% of both, the observed rise in CO2atm of ~90 ppm, and the residual in ∆14Catm that is unexplained by changes in the 14C production rate.
    Repository Name: EPIC Alfred Wegener Institut
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  • 105
    Publication Date: 2018-08-10
    Description: Sediments of sub-Antarctic islands have been proposed to be important contributors to natural iron fertilization in the Southern Ocean [1, 2]. This potential contribution depends on biogeochemical processes within the sediment that may result in an iron benthic flux, most likely related to the degradation of organic matter (OM). Yet, the OM degradation pathways vary strongly among different sedimentary settings. We elucidate the role of environmental factors on the prevailing biogeochemical pathways and reaction rates at three contrasting sites of South Georgia, using comprehensive solid-phase and pore-water analyses, as well as transportreaction modelling. Samples were obtained along a transect from a glacial fjord towards the shelf during cruise ANTXXIX/ 4 of RV POLARSTERN in 2013. Oxygen penetration depth at all sites is 〈1 cm. Sediments recovered within the fjord are dominated by dissimilatory iron reduction (DIR) and show very high dissolved Fe2+ concentrations of up to 760 μM, while sulfide was not detected. In addition, Fe reduction below the sulfate/methane transition was observed. High input of reactive iron phases, possibly enhanced by bioturbation and bubble ebullition, appear to favour DIR as the dominant metabolic process for OM degradation in the basin like fjord. Shelf sediments outside the fjord are sulfidic throughout, with H2S formed primarily by anaerobic oxidation of methane. The conversion of Fe oxides into Fe sulfides significantly alters the initial sediment composition along the shelf, and impact the availability of iron to the water column. OM is of marine origin at all three sites (C:N~7), indicating that Fe oxide availability and reactivity rather than the carbon source determine whether iron or sulfate reduction dominantes. [1] Moore & Braucher (2008) Biogeosciences 5, 631-656. [2] Borrione et al., (2014) Biogeosciences 11, 1981–2001.
    Repository Name: EPIC Alfred Wegener Institut
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  • 106
    Publication Date: 2017-09-25
    Description: In November 2016, the first Mini-Carbon-Dating-System (MICADAS) manufactured by Ionplus AG was delivered and installed at the Alfred-Wegener-Institute (AWI), Germany. The new facility includes a graphitization unit (AGE3) connected with an elementar analyser (EA), a carbonate handling system (CHS), and a gas inlet system (GIS). The main goal for the facility at AWI will be the precise and independent dating of carbonaceous materials in marine sediments, sea-ice, and water to address various processes of the global carbon cycling. A particular focus will be on sediments from the high latitude oceans, in which radiocarbon-based age models are often difficult to obtain due to the scarcity of carbonate microfossils. One advantage of the MICADAS is the potential to analyse samples, which contain only a small amount of carbon as CO2 gas. For example, it will be possible to determine 14C ages of samples of foraminifera from carbonate-lean sediments, allowing for paleoclimate reconstructions in key locations for Earth’s climate system such as the Southern ocean. Likewise, compound-specific 14C analyses receive growing attention in carbon cycle studies and require handling of small samples of typically 〈100µg carbon. The wide range of applications encompassing gas analyses of foraminifera and compound-specific analysis as well as analyses of graphite targets requires establishing routine protocols of various methods of sample preparation, as well as thorough assessment of the respective carbon blanks. We report on our standard procedures for samples of organic matter from sediments or water including carbonate removal, combustion and graphitization using the AGE3 coupled to the EA, as well as on the methodology applied for carbonate samples using the CHS system and the GIS. We have investigated different sample preparation protocols and present the initial results using materials of known age. Additionally, we present the first results of our assessment of process blanks.
    Repository Name: EPIC Alfred Wegener Institut
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  • 107
    Publication Date: 2017-09-20
    Description: Continuously intensifying aquaculture demands reductions in pathogen infections without increased therapeutics use. A potential solution is the use of prebiotic feed additives like β-glucan and mannan oligosaccharides (MOS). This study focusses (1) on the effect of prebiotics glucan/MOS on growth and fitness of Starry flounder and (2) on the viability of Starry flounder as an aquaculture candidate (as it is considered in South Korea). Over 56- days, juvenile Starry flounder were fed with glucan/MOS enhanced diet and a control diet. Feeding behavior, growth rate, morphological and blood physiological parameters were monitored. Fish fed glucan/MOS enriched diets exhibited significantly increased growth over the experimental period (GLM, p〈0.01). Concentrations of cholesterol (P=0.043) and albumin (P=0.016) were significantly increased in the blood plasma of fish fed glucan/MOS. Whole body proximate analysis revealed significantly elevated crude protein (P=〈0.001) and lipid (P=〈0.005) in fish fed glucan/MOS compared to the control. Significant improvements in growth, numerous fitness factors and product quality parameters can be achieved through glucan/MOS supplementation to P. stellatus. The observed growth performance and the feed conversion ratio, especially at low water temperatures, suggest Starry flounder is indeed a promising candidate for aquaculture in temperate regions. More detailed investigation, highlighting the economic and market perspective, is needed before introduction to commercial production.
    Repository Name: EPIC Alfred Wegener Institut
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  • 108
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    ELSEVIER SCIENCE BV
    In:  EPIC3Palaeogeography Palaeoclimatology Palaeoecology, ELSEVIER SCIENCE BV, 483, pp. 147-156, ISSN: 0031-0182
    Publication Date: 2017-09-01
    Repository Name: EPIC Alfred Wegener Institut
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  • 109
    Publication Date: 2017-03-06
    Description: To improve our understanding of the role of phytoplankton for marine ecosystems and global biogeochemical cycles, information on the global distribution of major phytoplankton groups is essential. Although algorithms have been developed to assess phytoplankton diversity from space for over two decades, so far the application of these data sets has been limited. This scientific roadmap identifies user needs, summarizes the current state of the art, and pinpoints major gaps in long-term objectives to deliver space-derived phytoplankton diversity data that meets the user requirements. These major gaps in using ocean color to estimate phytoplankton community structure were identified as: (a) the mismatch between satellite, in situ and model data on phytoplankton composition, (b) the lack of quantitative uncertainty estimates provided with satellite data, (c) the spectral limitation of current sensors to enable the full exploitation of backscattered sunlight, and (d) the very limited applicability of satellite algorithms determining phytoplankton composition for regional, especially coastal or inland, waters. Recommendation for actions include but are not limited to: (i) an increased communication and round-robin exercises among and within the related expert groups, (ii) the launching of higher spectrally and spatially resolved sensors, (iii) the development of algorithms that exploit hyperspectral information, and of (iv) techniques to merge and synergistically use the various streams of continuous information on phytoplankton diversity from various satellite sensors' and in situ data to ensure long-term monitoring of phytoplankton composition.
    Repository Name: EPIC Alfred Wegener Institut
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  • 110
    Publication Date: 2017-03-10
    Repository Name: EPIC Alfred Wegener Institut
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  • 111
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    Alfred Wegener Institute
    In:  EPIC3Bremerhaven, Alfred Wegener Institute
    Publication Date: 2019-07-17
    Repository Name: EPIC Alfred Wegener Institut
    Type: Data Processing Reports , notRev
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  • 112
    Publication Date: 2017-09-10
    Description: Sediment delivery to the abyssal regions of the oceans is an integral process in the source to sink cycle of material derived from adjacent continents and islands. The Zambezi River, the largest in southern Africa, delivers vast amounts of material to the inner continental shelf of central Mozambique. The aim of this contribution is to better constrain sediment transport pathways to the abyssal plains using the latest, regional, high-resolution multibeam bathymetry data available, taking into account the effects of bottom water circulation, antecedent basin morphology and sea-level change. Results show that sediment transport and delivery to the abyssal plains is partitioned into three distinct domains; southern, central and northern. Sediment partitioning is primarily controlled by changes in continental shelf and shelf-break morphology under the influence of a clockwise rotating shelf circulation system. However, changes in sealevel have an overarching control on sediment delivery to particular domains. During highstand conditions, such as today, limited sediment delivery to the submarine Zambezi Valley and Channel is proposed, with increased sediment delivery to the deepwater basin being envisaged during regression and lowstand conditions. However, there is a pronounced along-strike variation in sediment transport during the sea-level cycle due to changes in the width, depth and orientation of the shelf. This combination of features outlines a sequence stratigraphic concept not generally considered in the strike-aligned shelf-slope-abyssal continuum.
    Repository Name: EPIC Alfred Wegener Institut
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  • 113
    Publication Date: 2017-04-24
    Description: With global climate change altering marine ecosystems, research on plankton ecology is likely to navigate uncharted seas. Yet, a staggering wealth of new plankton observations, integrated with recent advances in marine ecosystem modeling, may shed light on marine ecosystem structure and functioning. A EuroMarine foresight workshop on the “Impact of climate change on the distribution of plankton functional and phylogenetic diversity” (PlankDiv) identified five grand challenges for future plankton diversity and macroecology research: (1) What can we learn about plankton communities from the new wealth of high-throughput “omics” data? (2) What is the link between plankton diversity and ecosystem function? (3) How can species distribution models be adapted to represent plankton biogeography? (4) How will plankton biogeography be altered due to anthropogenic climate change? and (5) Can a new unifying theory of macroecology be developed based on plankton ecology studies? In this review, we discuss potential future avenues to address these questions, and challenges that need to be tackled along the way.
    Repository Name: EPIC Alfred Wegener Institut
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  • 114
    Publication Date: 2017-03-17
    Description: Killer whales (Orcinus orca) are highly social top predators distributed throughout the worldʼs oceans. They are divided into different ecotypes according to foraging specializations, phenotype, and social organization. For Northern Hemisphere killer whale ecotypes, acoustic behaviour has been shown to relate to foraging strategies and social organization. In contrast to the intensively studied Northern Hemisphere ecotypes, distribution patterns, social structures, and acoustic behaviour of the Southern Hemisphere killer whale ecotypes are poorly known. One of the Southern Hemisphere ecotypes, the Antarctic Ecotype C killer whale, is known to occur in regions with dense pack ice. The limited accessibility of these areas make passive acoustic monitoring (PAM) methods a very effective investigation tool to derive information on ecotype-specific abundance and distribution. During 2 d in February 2013, it was possible to collect concurrent visual and acoustic information of Ecotype C killer whales off the Antarctic continent. From these events, a call type catalogue was compiled. The 2,238 examined calls were subjectively classified into 26 discrete call types. Ten percent of the examined calls were re-classified by two additional independent observers to examine robustness of the classification. Mean classification accordance among observers was 68%. Most call types were composed of more than one call part. Sixty-five percent of all call types were monophonic, and 35% were biphonic. Almost two-third of all call types started with a short, broadband pulse. The variability within call types was relatively high. The Ecotype C vocal repertoire contained typical acoustic features such as biphonation, high call complexity, and generally high variability in frequency modulation. For future studies, the distinct characteristics of some of the call types described herein could potentially serve as acoustic markers for PAM-based differentiation of killer whale ecotypes in the Southern Ocean.
    Repository Name: EPIC Alfred Wegener Institut
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  • 115
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    Springer International Publishing
    In:  EPIC3Aquaculture Perspective of Multi-Use Sites in the Open Ocean: The Untapped Potential for Marine Resources in the Anthropocene, Aquaculture Perspective of Multi-Use Sites in the Open Ocean: The Untapped Potential for Marine Resources in the Anthropocene, Springer International Publishing, 47 p., pp. 23-69, ISBN: 978-3-319-51159-7
    Publication Date: 2018-02-15
    Description: Aquaculture of extractive species, such as bivalves and macroalgae, already supplies a large amount of the production consumed worldwide, and further production is steadily increasing. Moving aquaculture operations off the coast as well as combining various uses at one site, commonly called multi-use aquaculture, is still in its infancy. Various projects worldwide, pioneered in Germany and later accompanied by other European projects, such as in Belgium, The Netherlands, Norway, as well as other international projects in the Republic of Korea and the USA, to name a few, started to invest in robust technologies and to investigate in system design needed that species can be farmed to market size in high energy environments. There are a few running enterprises with extractive species offshore, however, multi-use scenarios as well as offshore IMTA concepts are still on project scale. This will change soon as the demand is dramatically increasing and space is limited.
    Repository Name: EPIC Alfred Wegener Institut
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  • 116
    Publication Date: 2017-03-27
    Description: The Long-Term Ecological Research (LTER) site HAUSGARTEN located in the eastern Fram Strait (79°N, 4°E) was established in 1999. Since then, year-round measurements of physical properties of the surface ocean and water column were carried out as well as biogeochemical and biological measurements of carbon fluxes to the seafloor. During a warm period in the years 2005-2007, a shift in the phytoplankton community and a decrease in phytodetritus export took place. In this study we further investigated how the dynamics of the sea ice cover and biological pump affected benthic bacterial community composition and activity. Bacterial community diversity was determined by Illumina tag sequencing. The changes in food supply caused by warming were reflected in shifts of bacterial types at the seafloor, resulting in interannual dynamics of the bacterial community structure. Our results indicate an immediate response of the benthic community to changes in surface ocean conditions, indicating that surface ocean dynamics induced by climate change are directly reflected at the seabed.
    Repository Name: EPIC Alfred Wegener Institut
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  • 117
    Publication Date: 2018-08-10
    Description: Measuring temperature and salinity profiles in the world's oceans is crucial to understanding ocean dynamics and its influence on the heat budget, the water cycle, the marine environment and on our climate. Since 1983 the German research vessel and icebreaker Polarstern has been the platform of numerous CTD (conductivity, temperature, depth instrument) deployments in the Arctic and the Antarctic. We report on a unique data collection spanning 33 years of polar CTD data. In total 131 data sets (1 data set per cruise leg) containing data from 10 063 CTD casts are now freely available at doi:10.1594/PANGAEA.860066. During this long period five CTD types with different characteristics and accuracies have been used. Therefore the instruments and processing procedures (sensor calibration, data validation, etc.) are described in detail. This compilation is special not only with regard to the quantity but also the quality of the data – the latter indicated for each data set using defined quality codes. The complete data collection includes a number of repeated sections for which the quality code can be used to investigate and evaluate long-term changes. Beginning with 2010, the salinity measurements presented here are of the highest quality possible in this field owing to the introduction of the OPTIMARE Precision Salinometer.
    Repository Name: EPIC Alfred Wegener Institut
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  • 118
    Publication Date: 2017-03-20
    Description: West African summer monsoon precipitation is characterized by distinct decadal variability. Due to its well-documented link to oceanic boundary conditions in various ocean basins it represents a paradigm for decadal predictability. In this study, we reappraise this hypothesis for several sub-regions of sub-Saharan West Africa using the new German contribution to the coupled model intercomparison project phase 5 (CMIP5) near-term prediction system. In addition, we assume that dynamical downscaling of the global decadal predictions leads to an enhanced predictive skill because enhanced resolution improves the atmospheric response to oceanic forcing and land-surface feedbacks. Based on three regional climate models, a heterogeneous picture is drawn: none of the regional climate models outperforms the global decadal predictions or all other regional climate models in every region nor decade. However, for every test case at least one regional climate model was identified which outperforms the global predictions. The highest predictive skill is found in the western and central Sahel Zone with correlation coefficients and mean-square skill scores exceeding 0.9 and 0.8, respectively.
    Repository Name: EPIC Alfred Wegener Institut
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  • 119
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    In:  EPIC3Gemeinsames IODP/ICDP Kolloquium 2017, BRaunschweig, Germany, 2017-03-14-2017-03-16
    Publication Date: 2017-03-31
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  • 120
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    Springer International Publishing
    In:  EPIC3Springer International Publishing, 404 p., ISBN: 978-3-319-51159-7
    Publication Date: 2018-02-15
    Description: This volume addresses the potential for combining large-scale marine aquaculture of macroalgae, molluscs, crustaceans, and finfish, with offshore structures, primarily those associated with energy production, such as wind turbines and oil-drilling platforms. The volume offers a comprehensive overview and includes chapters on policy, science, engineering, and economics aspects to make this concept a reality. The compilation of chapters authored by internationally recognized researchers across the globe addresses the theoretical and practical aspects of multiuse, and presents case studies of research, development, and demonstration-scale installations in the US and EU.
    Repository Name: EPIC Alfred Wegener Institut
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  • 121
    Publication Date: 2017-03-28
    Description: The range of environmental conditions in marine pelagic ecosystems is characterized by seasonality, particularly in mid and high latitudes. Annual cycles of light availability and water temperature are central to processes in pelagic food webs and drive the phenology of planktonic organisms. Using high resolution data of 24 phytoplankton species observed at Helgoland Roads (North Sea) during the period from 1962 to 2014, we analyzed the phenological response to long-term changes in the hydro-climatic conditions. We estimated timing by calculating the date of 50th percentile of cumulative abundance by taking into account both unimodal and bimodal (spring and autumn) peak structures. We show that species-specific preferences in combination with seasonally varying trends in environmental parameters led to a complex phenological response pattern. Species showing widely overlapping timing windows can exhibit different phenological responses. Both diatoms and dinoflagellates exhibit significant changes in seasonal peak timing (earlier/later), but some species show a remarkable constancy over the entire period. The intra-annual variability of timing strongly differs between different species, also due to basic differences in the environmental variability during the year. Shifts of the majority of species reflect long-term displacements in the occurrence of water temperature ranges within the year. On the long-term, only a few species show significant relationships between annual timing and peak abundance. Such complexity illustrates the uncertainty of making conclusions about potential future ecological development related to climate change.
    Repository Name: EPIC Alfred Wegener Institut
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  • 122
    Publication Date: 2017-04-01
    Description: The eastern side of the Fram Strait is significantly influenced by the northern-bound warm West Spitsbergen Current (WSC) whereas the western side is affected by the cold and less saline East Greenland Current (EGC) flowing in a southerly direction. These current regimes are major factors in regulating the ice coverage in the Fram strait. In turn, this coverage plays an important role in determining the flux of food to the seafloor. The objective of this study is to compare the macrofaunal community structure along two bathymetrical transects (1000 to 2500 m) at the LTER (Long-Term Ecology Research) observatory HAUSGARTEN; one transect in the eastern Fram Strait and a second in the western region of the strait. Material was collected during RV Polarstern expedition PS99.2 in June/July 2016 using an USNEL box corer with a sampling area of 0.25 m². Samples were processed through a 500 μm mesh size sieve. Results showed a higher macrofaunal density at the stations located in the eastern Fram Strait. Species richness, biomass and biodiversity showed a trend to decrease with increase in depth on both sides of the strait. An exception was observed at one station at 2500 m depth off Greenland, which was located in the marginal ice zone. Densities and species diversity were higher at this station than at the adjacent shallower sampling locations. Polychaetes were the generally most abundant taxon, followed by crustaceans and molluscs. Species composition along the two bathymetrical transects on both sides of the strait clearly changed with increasing depth. Sea ice coverage and depth, with the associated variabilities in food quality and quantity reaching the seafloor seemed to be crucial factors driving community patterns.
    Repository Name: EPIC Alfred Wegener Institut
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  • 123
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    Deutsche Geophysikalische Gesellschaft DGG
    In:  EPIC3DGG Jahrestagung 2017, Potsdam, 2017-03-27-2017-03-30Potsdam, Deutsche Geophysikalische Gesellschaft DGG
    Publication Date: 2017-04-03
    Description: When seawater, that penetrates the lithosphere through faults and fractures at mid-ocean ridges, gets in contact with mantle rocks serpentine may form. Serpentine bearing rocks are considerably weaker than their source rock thereby causing a drastic change in the rheological strength of the affected lithosphere. Serpentinization is limited by temperature and the availability of active fluid bearing faults. Its maximum depth was previously considered not to exceed 4 km beneath the sea floor. Yield strength envelopes (YSE) represent vertical profiles that predict the maximum stress supported by the lithosphere as a function of depth. We calculated YSEs for the axial lithosphere at an amagmatic Southwest Indian Ridge segment for different geotherms, serpentinization depths and mineralogical compositions in the ductile regime. Assuming the earthquake distribution is somehow linked to the rheological strength profile we then interpreted those YSEs that best correlate with the depth frequency distribution of local earthquakes. By doing so we could constrain the thermals structure, the mineralogical compositions and the deformation mode in the lithosphere. The YSEs show a thick mechanical lithosphere (30–35 km) at the ridge axis that is weakened in its uppermost 8-13 km due to serpentinization. Incorporating the axial morphology we propose a distinct mode of deformation that may also be applicable to other magma starved ultraslow spreading mid ocean ridge segments. Here, deformation and lithospheric accretion are essentially governed by deep reaching boundary faults that are well lubricated and hence aseismic due to extensive, deep-reaching serpentinization.
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  • 124
    Publication Date: 2017-04-07
    Description: The Asian shore crab Hemigrapsus sanguineus and its congener, the Asian brush-clawed crab H. takanoi, were first found in Europe in 1999 and 1994, respectively. Hemigrapsus sanguineus was initially detected in Le Havre (France) and in the Oosterschelde (The Netherlands). Now it occurs from northern France to the German Wadden Sea. Hemigrapsus takanoi was originally found in La Rochelle (France) and is now established from the Bay of Biscay to the German Wadden Sea. In 2014, a Baltic Sea population was detected in Kiel Fjord (Germany), most likely introduced via the Kiel Canal. Here we summarize the most recent findings on the northern expansion of H. sanguineus and H. takanoi and their competition with the native counterpart, the green shore crab Carcinus maenas. Two population studies in the intertidal areas around the rocky island of Helgoland and the Wadden Sea island of Sylt (Germany) revealed that the three species favor different levels of wave exposure. Our studies presented the highest densities of Hemigrapsus spp. in Europe so far with 144 H. sanguineus m-2 on Helgoland, and more than 200 ind. m-2 of either species on Sylt. The Baltic population of H. takanoi is increasing in Kiel Fjord and adjacent bays. Individuals of H. takanoi were recently found in Wismar Bay, further east along the Baltic coast. In the framework of a citizen-science project, specimen of both species were found at the Swedish west coast, representing the northernmost records in Europe so far. The success of established populations and the continuous extension of the distribution areas suggest that the presence and impact of both Hemigrapsus species on European coasts will significantly increase in the future.
    Repository Name: EPIC Alfred Wegener Institut
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  • 125
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    PERGAMON-ELSEVIER SCIENCE LTD
    In:  EPIC3Quaternary Science Reviews, PERGAMON-ELSEVIER SCIENCE LTD, 160, pp. 45-56, ISSN: 0277-3791
    Publication Date: 2017-06-01
    Description: About 16% of the Greenland Ice Sheet drains in the area of the Northeast Greenland shelf between 76°N and 80.5°N via marine terminating glaciers. Most of it is via the Northeast Greenland Ice Stream, the largest ice stream of Greenland. During ice ages, the ice sheet extended onto the continental shelf and modern-day cross-shelf troughs were filled by ice streams. In this study, high-resolution hydro-acoustic data acquired during three decades of research were jointly investigated to reveal the past glacial conditions. Our data shows that Westwind Trough and Norske Trough were filled by fast flowing ice streams that extended to the shelf edge during the last glacial maximum. In between the cross-shelf troughs, ice domes resided on shallow banks that may have contributed about a decimetre to global sea level. Most probably these ice domes initiated fast ice flow through sinks in the inter-trough area. In Westwind Trough, ice sheet retreat to the inner shelf after the last glacial maximum was intermittent. In contrast, in Norske Trough the ice sheet retreat appears relatively rapid with no evidences for phases of grounding line stabilization. Probably during the Younger Dryas, the ice sheet readvanced to a mid-shelf position in both troughs documented by grounding zone wedges. During this time, a thick ice shelf was present in Norske Trough releasing tabular icebergs. Ice sheet retreat from the mid-shelf to the coastline during Holocene deglaciation was rapid.
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  • 126
    Publication Date: 2017-03-17
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  • 127
    Publication Date: 2017-02-13
    Repository Name: EPIC Alfred Wegener Institut
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  • 128
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    PERGAMON-ELSEVIER SCIENCE LTD
    In:  EPIC3Quaternary Science Reviews, PERGAMON-ELSEVIER SCIENCE LTD, 163, pp. 135-151, ISSN: 0277-3791
    Publication Date: 2017-04-02
    Description: We present high-resolution multi-proxy records from a marine sediment core (SO201-2-85KL) from the western Bering Sea to assess orbital- and millennial-scale paleoceanographic conditions during two last glacial intervals, including both terminations. Based on changes in foraminiferal assemblages, grain-size content and previously published TOC and d13C records, we reconstruct variations in sea-surface biological productivity, intermediate-water oxygenation and sea-ice conditions during the last 180 kyr. Our data demonstrate remarkable differences between the penultimate (MIS 6) and last (MIS 4-2) glacial. Relatively high sea surface bioproductivity and reduced sea-ice cover are reconstructed for the penultimate glacial interval, whereas low bioproductivity and expanded sea-ice cover appear to be typical for the last glacial. Millennial-scale changes in intermediate water ventilation are inferred from faunal records for the middle part of the penultimate glacial. High-amplitude environmental variability during the penultimate glacial time in the Bering Sea resembles the well-known Dansgaard-Oeschger oscillations, and roughly corresponds to similar rapid climatic fluctuations found in North Atlantic records. The Termination II and I intervals display a similar succession of high-bioproductivity events, being more pronounced during the penultimate glacial-interglacial transition, probably due to the different orbital configuration. During the late phase of Termination II, two short intervals, characterized by high sea surface bioproductivity and low oxygen content of bottom waters, resemble the Bølling and Allerød warmings, whereas an episode with low bioproductivity occurs in between, similar to the Older Dryas. Our results provide support for a close circumpolar coupling between high-latitude environments on millennial timescales at least since the penultimate glacial.
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  • 129
    Publication Date: 2017-03-28
    Description: Particulate inorganic matter (PIM) is a key component in estuarine and coastal systems and plays a critical role in trace metal cycling. Better understanding of coastal dynamics and biogeochemistry requires improved quantification of PIM in terms of its concentration, size distribution, and mineral species composition. The angular pattern of light scattering contains detailed information about the size and composition of particles. These volume scattering functions(VSFs) were measured in Mobile Bay, Alabama, USA, a dynamic, PIM dominated coastal environment. From measured VSFs, we determined through inversion the particle size distributions (PSDs) of major components of PIM, amorphous silica and clay minerals. An innovation here is the extension of our reported PSDs significantly into the submicron range. The PSDs of autochthonous amorphous silica exhibit two unique features: a peak centered at about 0.8 μm between 0.2 and 4 μm and a very broad shoulder essentially extending from 4 μm to 〉100 μm. With an active and steady particle source from blooming diatoms, the shapes of amorphous silica PSDs for sizes 〈 10 μm varied little across the study area, but showed more particles of sizes 〉 10 μm inside the bay, likely due to wind-induced resuspension of larger frustules that have settled. Compared to autochthonous amorphous silica, the allochthonous clay minerals are denser and exhibit relatively narrower PSDs with peaks located between 1 and 4 μm. Preferential settling of larger mineral particles as well as the smaller but denser illite component further narrowed the size distributions of clay minerals as they were being transported outside the bay. The derived PSDs also indicated a very dynamic situation in Mobile Bay relative to the cold weather front that passed through during the experiment. With northerly winds of speeds up to 15 m s-1, both amorphous silica and clay minerals showed a dramatic increase in concentration and broadening in size distribution outside the exit of the barrier islands, indicative of wind-induced resuspension and subsequent advection of particles out of Mobile Bay. While collectively recognized as the PIM, amorphous silica and clay minerals, as shown in this study, possess very different size distributions. Considering how differences in PSDs and the associated particle areas will effect differences in sorption/desorption properties of these components, the results also demonstrate the potential of applying VSF-inversion in studying biogeochemistry in the estuarine-coastal ocean system.
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  • 130
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    In:  EPIC3ICOS-D Wissenschaftliche Versammlung, Offenbach, Germany, 2017-03-23-2017-03-24
    Publication Date: 2017-04-01
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  • 131
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    In:  EPIC3DLR Wissenschaftliches Kolloqium, DLR Oberpfaffenhofen, Weßling, 2017-03-20-2017-03-20
    Publication Date: 2017-10-17
    Description: Permafrost ist eine wichtige Komponente der Kryopshäre, die von der rapi-den Erwärmung der Polarregionen betroffen ist. Beobachtungen innerhalb des globalen Permafrost-Temperatur Messnetzwerks GTN-P (Global Terrestrial Network for Permafrost) zeigen eine Erwärmung an den meisten Mess-standorten mit besonders starken Erwärmungstrends in der hohen Arktis. Die mit der Erwärmung einhergehende Degradation und das Tauen von Permafrost in vertikaler als auch lateraler Ausdehnung führen zu einem Rückzug des Permafrosts in Richtung hoher Breiten und hoher Höhenlagen. Weil Per-mafrost massiv die Ökosystembedingungen in der etwa 23 Millionen Quadratkilometer großen Permafrost-Region dominiert, hat sein Rückzug starke Folgen für die dortige Hydrologie, Geomorphologie, biogeochemische Stoffflüsse, und Biota. Über den Kohlenstoffkreislauf – Permafrostböden speichern etwa 1500 Gt organischen Kohlenstoff, etwa doppelt so viel Kohlenstoff wie in der Atmosphäre enthalten ist – daher wirken sich diese Veränderungen auch auf globaler Ebene aus. Die Fernerkundung ist mittlerweile ein essentielles Werkzeug, um den Zustand und die Veränderungen von Permafrost und der zugehörigen periglazialen Landschaften zu dokumentieren und zu quantifizieren. In der Sektion Periglazialforschung des AWI, Forschungsstelle Potsdam, werden deshalb verschiedene optische und Radar-Fernerkundungsmethoden genutzt, um Landschaftsprozesse mit Permafrost-Veränderungen in Zusammenhang zu bringen oder um geeignete geophysikalische und biophysikalische Variablen für die Modellierung von Permafrost abzuleiten.
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  • 132
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    In:  EPIC3Polar Prediction Workshop, Bremerhaven, 2017-03-27-2017-03-30
    Publication Date: 2017-04-03
    Description: Sea ice deformation localizes along Linear Kinematic Features (LKFs) that are relevant for the air/ocean/sea-ice interaction and for shipping andmarine operations. At high resolution (〈 5km) viscous-plastic sea ice models start to resolve LKFs. Here, we study the short-range (up to 10 days) potential predictability of LKFs in Arctic sea ice using ensemble simulations of an ocean/sea-ice model with a grid point separation of 4.5 km. We analyze the sensitivity of predictability to idealized initial perturbations, mimicking the uncertainties in sea ice analyses, and to growing uncertainty of the atmospheric forcing caused by the chaotic nature of the atmosphere. The similarity between pairs of ensemble members is quantified by Pearson correlation and Modified Hausdorff Distance (MHD). In our perfect model experiments, the potential predictability of LKFs, based on the MHD, drops below 0.6 after 4 days in winter. We find that forcing uncertainty (due to limited atmospheric predictability) largely determines LKF predictability on the 10-day time scale, while uncertainties in the initial state impact the potential predictability only within the first 4 days.
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  • 133
    Publication Date: 2017-05-04
    Description: We present a simulation of Antarctic iceberg drift and melting that includes small, medium-sized, and giant tabular icebergs with a realistic size distribution. For the first time, an iceberg model is initialized with a set of nearly 7000 observed iceberg positions and sizes around Antarctica. The study highlights the necessity to account for larger and giant icebergs in order to obtain accurate melt climatologies. We simulate drift and lateral melt using iceberg-draft averaged ocean currents, temperature, and salinity. A new basal melting scheme, originally applied in ice shelf melting studies, uses in situ temperature, salinity, and relative velocities at an iceberg's bottom. Climatology estimates of Antarctic iceberg melting based on simulations of small (≤ 2.2 km), 'small-to-medium'-sized (≤ 10 km), and small-to-giant icebergs (including icebergs 〉 10 km) exhibit differential characteristics: successive inclusion of larger icebergs leads to a reduced seasonality of the iceberg meltwater flux and a shift of the mass input to the area north of 58 °S, while less meltwater is released into the coastal areas. This suggests that estimates of meltwater input solely based on the simulation of small icebergs introduce a systematic meridional bias; they underestimate the northward mass transport and are, thus, closer to the rather crude treatment of iceberg melting as coastal runoff in models without an interactive iceberg model. Future ocean simulations will benefit from the improved meridional distribution of iceberg melt, especially in climate change scenarios where the impact of iceberg melt is likely to increase due to increased calving from the Antarctic ice sheet.
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  • 134
    Publication Date: 2017-03-17
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  • 135
    Publication Date: 2017-03-29
    Description: Lakes are dominant and diverse landscape features in the Arctic, but conventional land cover classification schemes typically map them as a single uniform class. Here, we present a detailed lake-centric geospatial database for an Arctic watershed in northern Alaska. We developed a GIS dataset consisting of 4362 lakes that provides information on lake morphometry, hydrologic connectivity, surface area dynamics, surrounding terrestrial ecotypes, and other important conditions describing Arctic lakes. Analyzing the geospatial database relative to fish and bird survey data shows relations to lake depth and hydrologic connectivity, which are being used to guide research and aid in the management of aquatic resources in the National Petroleum Reserve in Alaska. Further development of similar geospatial databases is needed to better understand and plan for the impacts of ongoing climate and land-use changes occurring across lake-rich landscapes in the Arctic.
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  • 136
    Publication Date: 2017-04-07
    Repository Name: EPIC Alfred Wegener Institut
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  • 137
    Publication Date: 2021-07-23
    Description: Global warming will continue to warm the Arctic resulting in the degradation of permafrost soils which leads to large-scale ground subsidence. Vast regions of the Arctic are covered with ice-rich silts, known as yedoma, containing large ice wedges. The formation of thermokarst lakes is one of the most important forms of permafrost degradation. Consequently, large amounts of previously freeze-locked organic carbon (OC) can be mobilized and released, which is of global significance for the carbon cycle. The aim of this research was to reconstruct the late Quaternary depositional environment and organic carbon characteristics of a thermokarst affected landscape, to better understand the processes involved in thermokarst development and identify the vulnerability of the organic carbon. Fieldwork was conducted on Baldwin Peninsula during the summer expedition in 2016 in West Alaska. Yedoma and drained thermokarst lake basin (DTLB) exposures were sampled and a thermokarst lake core was taken. Sedimentological and biochemical parameters, as well as lipid biomarkers were analyzed. A land cover classification map was made from the peninsula using Landsat imagery and a digital terrain model. By extrapolation of the field data, an estimation of the OC quantity on the peninsula and the loss since the Late Pleistocene was made. Yedoma deposition started 〉 50 cal ka BP whereas the DTLB deposits and thermokarst lake sediments originate from the Holocene. The grain size distributions show that the yedoma and DTLB deposits accumulated in a dominantly aeolian, stable regime. Yedoma was deposited in a drier and colder climate than the DTLB, as indicated by the lower BIT index (mean BIT: 0.94 for yedoma and 1.00 for DTLB) and MBT index. About 53 Mt of OC is stored in the frozen deposits on Baldwin Peninsula and it is estimated that the net loss since the Late Pleistocene is 3 Mt OC. The frozen DTLB deposits contain the largest share of OC (36 Mt, 70%). However, the yedoma deposits contain the most labile OC, as has been shown by the CPI (mean: 11.6 for yedoma and 8.8 for DTLB). This OC has been freeze-locked and not or barely altered by microbial degradation. The OC is terrestrially derived for the yedoma and DTLB deposits. The thermokarst lake shows a lacustrine input (mean δ13C -28.5‰). Because of the high ice content of the deposits on the Baldwin Peninsula, the deposits are highly susceptible and vulnerable to permafrost thaw. The high quality of the stored OC in the yedoma deposits makes these carbon pools an important source for microbial alteration. This poses an important input of carbon to the carbon cycle.
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  • 138
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    In:  EPIC3Internation Carbon Dioxide Conference 10, Interlaken, Switzerland, 2017-08-21-2017-08-25
    Publication Date: 2017-09-20
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  • 139
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    In:  EPIC3Koordinationsworkshop SPP-1158, Erlangen, 2017-09-20-2017-09-22
    Publication Date: 2018-05-25
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  • 140
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    Institut für Flugführung
    In:  EPIC3Institut für Flugführung, 84 p.
    Publication Date: 2017-10-04
    Description: The development of the third installment of the climate model EC-Earth is nearing its completion. The quality of EC-Earth simulations in the current state is analysed in comparison to a number of other climate models that are currently in use at the Alfred Wegener Institute’s Climate Sciences Department. By varying a set of greenhouse gases and orbital parameters, four scenarios of Present Day, Pre-Industrial, Last Interglacial and Mid-Holocene climate are designed. EC-Earth is set up and applied to simulate these climate scenarios. In conjunction with observational data, reanalysis data and proxy based climate reconstructions, these simulations are used to measure the quality of EC-Earth climate simulations. The variables examined for this purpose are land and sea surface temperature, air temperature, precipitation, and sea ice concentration. Furthermore, the ability of EC-Earth to reproduce global ocean currents and known climate patterns, such as the El Nino Southern Oscillation, is checked in order to gain insight into the variability of the simulated climate. EC-Earth is found to be in an advanced state of development with a rough setup process but mostly stable simulations. Both Present Day climate and paleoclimates are reproduced more accurately than in other climate models that are in use at Alfred Wegener Institute. Remaining issues to be solved are underestimated strength of important ocean currents and a high latitude warm bias in Present Day simulations.
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  • 141
    Publication Date: 2021-06-09
    Description: Sedimentary hydrocarbon remnants of eukaryotic C26–C30 sterols can be used to reconstruct early algal evo- lution. Enhanced C29 sterol abundances provide algal cell membranes a density advantage in large temperature fluctuations. Here, we combined a literature review with new analyses to generate a comprehensive inventory of unambiguously syngenetic steranes in Neoproterozoic rocks. Our results show that the capacity for C29 24- ethyl-sterol biosynthesis emerged in the Cryogenian, that is, between 720 and 635 million years ago during the Neoproterozoic Snowball Earth glaciations, which were an evolutionary stimulant, not a bottleneck. This bio- chemical innovation heralded the rise of green algae to global dominance of marine ecosystems and highlights the environmental drivers for the evolution of sterol biosynthesis. The Cryogenian emergence of C29 sterol biosynthesis places a benchmark for verifying older sterane signatures and sets a new framework for our understanding of early algal evolution.
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  • 142
    Publication Date: 2017-09-22
    Description: This project started in October 2015 with a crazy idea: prepare and submit a funding application for an international, multidisciplinary and non-traditional scientific outreach project… within the next 48 hours. Well, it worked out. A group of highly motivated young researchers from Canada and Europe united to combine arts and science and produce a series of outreach comic strips about permafrost (frozen ground). The aim of the project is to present and explain scientific research conducted across the circumpolar Arctic, placing emphasis on field work and the rapidly changing northern environment. The target audience is kids, youth, parents and teachers, with the general goal of making permafrost science more fun and accessible to the public. Because guess what : permafrost represents an area of more than twenty million km2 in the Northern Hemisphere, a huge area. As the climate warms, permafrost thaws and becomes unstable for houses, roads and airports. This rapid thawing of previously frozen ground also disrupts plant and animal habitats, impacts water quality and the ecology of lakes, and releases carbon into the atmosphere as greenhouse gases, making climate change even stronger. Hence permafrost and its response to climate change concerns us all. The project received initial support from the International Permafrost Association (IPA) as a targeted ‘Action Group’, and since then several other sponsors have joined the project. Here we are, now, two years after this first idea. What you are about to read is the result of an iterative process of exchanging ideas between artists and scientists. We first made an application call and received 49 applications from artists in 16 countries. Through a formal review process, we then selected two artists to work on this project: Noémie Ross from Canada, and Heta Nääs from Finland. With input from scientists, Noémie and Heta created fantastic cartoons that explain some of the changes happening to the environment in permafrost areas, how they affect people and wildlife, and what scientists are doing to better understand these changes to help people find innovative ways to adapt. We wish everyone plenty of fun reading this booklet and we would like to thank all those who supported this project.
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  • 143
    Publication Date: 2017-09-24
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  • 144
    Publication Date: 2017-09-25
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  • 145
    Publication Date: 2017-09-15
    Description: This contribution focuses on two applications of the FESOM model family. On the one hand, recent runs with the finite volume code FESOM2 on large global meshes with regional focus are presented. FESOM's shallow water branch TsunAWI is the subject of the second part. TsunAWI, still based on finite elements, is used as an operational model in the Indonesia Tsunami Early Warning System (InaTEWS). InaTEWS derives tsunami forecasts in two different ways: from scenarios in a pre-computed database or from an on-the-fly simulation. The pre-computed scenarios are based on TsunAWI simulations with inundation on a triangular mesh with a resolution ranging from 20km in the deep ocean to 300m - 50m in coastal areas. The on-the-fly propagation model EasyWave (Andrey Babeyko, GFZ) solves the linear shallow water equations on a regular finite-difference grid with a resolution of about 1 km and the coast line as a vertical wall. EasyWave is used after a tsunami has been generated in an area not covered by the database or after seismic measurements show an earthquake mechanism not present in the database. As the numerical settings of both models are quite different, variations in the outputs are to be expected; nevertheless, the differences in the warning levels should not be too large for identical sources. In the current study, we systematically compare the warning products like estimated wave height and estimated time of arrival by the two approaches.
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  • 146
    Publication Date: 2017-11-06
    Description: A suite of oxygenated volatile organic compounds (OVOCs – acetaldehyde, acetone, propanal, butanal and butanone) were measured concurrently in the surface water and atmosphere of the South China Sea and Sulu Sea in November 2011. A strong correlation was observed between all OVOC concentrations in the surface seawater along the entire cruise track, except for acetaldehyde, suggesting similar sources and sinks in the surface ocean. Additionally, several phytoplankton groups, such as haptophytes or pelagophytes, were also correlated to all OVOCs indicating that phytoplankton may be an important source for marine OVOCs in the South China and Sulu Seas. Humic and protein like fluorescent dissolved organic matter (FDOM) components seemed to be additional precursors for butanone and acetaldehyde. The atmospheric OVOC mixing ratios were relative high compared with literature values, suggesting the coastal region of North Borneo as a local hot spot for atmospheric OVOCs. The flux of atmospheric OVOCs was largely into the ocean for all 5 gases, with a few important exceptions near the coast of Borneo. The calculated amount of OVOCs entrained into the ocean seemed to be an important source of OVOCs to the surface ocean. When the fluxes were out of the ocean, marine OVOCs were found to be enough to control the local measured OVOC distribution in the atmosphere. Based on our model calculations, at least 0.4 ppb of marine derived acetone and butanone can reach the upper troposphere, where they may have an important influence on hydrogen oxide radical formation over the western Pacific Ocean.
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  • 147
    Publication Date: 2017-10-10
    Description: Networks of eddy-covariance (EC) towers such as AmeriFlux, ICOS and NEON are vital for providing the necessary distributed observations to address grand challenges in earth system and carbon cycle science. NEON, once fully operational with 47 tower sites, will represent the largest single-provider EC network globally. Its standardized observation and data processing suite is designed specifically for inter-site comparability and analysis of continental-scale ecological change, including rich contextual data such as airborne remote sensing and in-situ sampling bouts. First carbon cycle products become available in 2017, including data and software. These products strive to incorporate lessons-learned through collaborations with AmeriFlux, ICOS, LTER and others, to suggest novel systemic solutions, and to synergize ongoing research efforts across science communities. Here, we present an overview of the ongoing product release, alongside efforts to integrate and synergize with existing infrastructures, networks and communities. Near-real-time carbon cycle observations in “basic” and “expanded”, self-describing HDF5 formats become accessible from the NEON Data Portal, including an Application Program Interface. A pilot project is underway to investigate their subsequent ingest into the AmeriFlux processing pipeline, together with inclusion in FLUXNET globally harmonized data releases. Software for reproducible, extensible and portable data analysis and science operations management also becomes available. This includes the eddy4R family of R-packages underlying the carbon cycle data product generation, together with the ability to directly participate in open development via GitHub version control and Dockerhub image hosting. In addition, templates for science operations management include a web-based field maintenance application and a graphical user interface to simplify problem tracking and resolution along the entire data chain. We hope that this first release of NEON carbon cycle products can initiate further collaboration and synergies in challenge areas, and would appreciate input and discussion on continued development.
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  • 148
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    SPP Antarktisforschung
    In:  EPIC3SPP Antarktisforschung Koordinationsworkshop, Erlangen, 2017-09-20-2017-09-22Erlangen, SPP Antarktisforschung
    Publication Date: 2017-09-26
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  • 149
    Publication Date: 2017-10-08
    Description: Pine Island Glacier currently experiences the largest negative ice sheet mass balance in comparison to other outlet glaciers in Antarctica and hence is the largest contributor to modern sea-level rise. Ice loss of this glacial outlet and neighbouring ones has increased greatly over the recent decades through ice thinning and flow acceleration that also resulted in rapid grounding line retreat, most likely as a result of basal melting induced by the inflow of warm Circumpolar Deep Water onto the shelf. Due to the glacier’s topographic setting, a bed that deepens beyond the grounding line to the deep interior basin of the West Antarctic Ice Sheet (WAIS), it has been suggested that this increased ice loss may be a precursor of WAIS collapse. Despite the increased mass loss, however, the calving front of Pine Island Glacier remained more or less stable in a position west of a pinning point located at the northern part of the glacier and its orientation remained similar (10-30° east of north) since the earliest observations in the mid-20th century. Large icebergs where calved at intervals of a few years, e.g. the B-31 calving event (720 km²) in November 2013, but subsequently the calving front re-advanced close to or even beyond its former position. In 2015 this pattern changed with a calving event initiated by a large rift oriented 55° east of north and the calving front for the first time retreated east of the pinning point. The rifts that initiated this calving event were proposed to have formed by expansion of basal crevasses due to ocean forcing. In 2017 we were able to access the formerly ice-shelf covered area during RV Polarstern expedition PS104. Bathymetric data from this area revealed a bathymetric knoll with minimum water depth of ~375 m that was the former pinning point of the glacier. A new rift 8-9 km upstream of the calving line that may initiate the next calving event within a year was visited by helicopter. Satellite data acquired in the last decades suggest that unpinning from the bathymetric knoll likely took place in 2006. We use these data collected during expedition PS104 in combination with the satellite data to investigate the impact of glacier unpinning on Pine Island Glacier calving dynamics.
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  • 150
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    Edition Falkenberg
    In:  EPIC3Klüger nutzen – besser schützen Bremer Forschung an tropischen Küsten, Bremen, Edition Falkenberg, 160 p., pp. 63-66, ISBN: 978-3-95494-134-6
    Publication Date: 2017-09-26
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  • 151
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    In:  EPIC3Remote Sensing, 9(5)
    Publication Date: 2017-09-25
    Description: Inhomogenities in the sea ice motion field cause deformation zones, such as leads, cracks and pressure ridges. Due to their long and often narrow shape, those structures are referred to as Linear Kinematic Features (LKFs). In this paper we specifically address the identification and characterization of variations and discontinuities in the spatial distribution of the total deformation, which appear as LKFs. The distribution of LKFs in the ice cover of the polar oceans is an important factor influencing the exchange of heat and matter at the ocean-atmosphere interface. Current analyses of the sea ice deformation field often ignore the spatial/geographical context of individual structures, e.g., their orientation relative to adjacent deformation zones. In this study, we adapt image processing techniques to develop a method for LKF detection which is able to resolve individual features. The data are vectorized to obtain results on an object-based level. We then apply a semantic postprocessing step to determine the angle of junctions and between crossing structures. The proposed object detection method is carefully validated. We found a localization uncertainty of 0.75 pixel and a length error of 12% in the identified LKFs. The detected features can be individually traced to their geographical position. Thus, a wide variety of new metrics for ice deformation can be easily derived, including spatial parameters as well as the temporal stability of individual features.
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  • 152
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    ELSEVIER SCIENCE BV
    In:  EPIC3Journal of Experimental Marine Biology and Ecology, ELSEVIER SCIENCE BV, 497, pp. 61-70, ISSN: 0022-0981
    Publication Date: 2017-10-03
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  • 153
    Publication Date: 2019-07-17
    Description: The identification of a new suite of toxins, called azaspiracids (AZA), as the cause of human illnesses after the consumption of shellfish from the Irish west coast in 1995, resulted in interest in understanding the global distribution of these toxins and of species of the small dinoflagellate genus Azadinium, known to produce them. Clonal isolates of four species of Azadinium, A. poporum, A. cuneatum, A. obesum and A. dalianense were obtained from incubated sediment samples collected from Puget Sound, Washington State in 2016. These Azadinium species were identified using morphological characteristics confirmed by molecular phylogeny. Whereas AZA could not be detected in any strains of A. obesum, A. cuneatum and A. dalianense, all four strains of A. poporum produced a new azaspiracid toxin, based on LC–MS analysis, named AZA-59. The presence of AZA-59 was confirmed at low levels in situ using a solid phase resin deployed at several stations along the coastlines of Puget Sound. Using a combination of molecular methods for species detection and solid phase resin deployment to target shellfish monitoring of toxin at high-risk sites, the risk of azaspiracid shellfish poisoning can be minimized.
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  • 154
    Publication Date: 2018-08-10
    Description: The past ice sheet conditions in the southern Weddell Sea Embayment (WSE) are only poorly known. Studies from this area have led to two contradicting scenarios of maximum ice extent during the Last Glacial Maximum (LGM). The first scenario is mainly based on terrestrial data indicating only very limited ice sheet thickening in the hinterland and suggests a grounding-line position on the inner shelf. The alternative scenario is based on marine geological and geophysical data and concludes that the LGM grounding line was located on the outer shelf, about 650 km further offshore than in the other scenario. Three hypotheses have been brought forward to explain these two apparently contradictory scenarios. A) An ice plain was present on the shelf that enabled a large ice extent while maintaining little ice thickness in the hinterland. B) The maximum grounded ice advance lasted for a short period only and was probably caused by a short-termed touch down of an ice shelf on the outer shelf, which did not cause sufficient ice sheet thickening in the hinterland to be traced today. C) Due to an ice flow switch, Filchner Trough was fed by an area further to the west where ice had thickened at the LGM. Besides the poorly constrained LGM ice extent, studies suggest a complex development of its retreat speed and drainage pattern in succession of the LGM that needs to be further constraint. For example, radar data from ice rises in the southwestern hinterland of the WSE suggest that ice flow switches occurred as late as the Mid-Holocene and cosmogenic exposure ages indicate an early Holocene ice sheet thickness in the Ellsworth Mountains comparable to that of the LGM. We investigated multibeam bathymetry data (ATLAS Hydrosweep DS3), acoustic sub-bottom profiles (ATLAS Parasound P-70) and marine sediment cores collected from Filchner Trough during RV “Polarstern” expedition PS96 in Dec 2015-Feb 2016. Our key finding is a previously unknown stacked grounding zone wedge (GZW) located on the outer shelf. This GZW shows that the Filchner palaeo-ice stream stabilized at this position at least two times. Two sediment cores were recovered seaward of the GZW and on top of the lower part of the GZW, respectively. Radiocarbon dates from these cores indicate that (i) the GZW was formed in the Early Holocene and (ii) grounded ice did not extend seaward of the GZW at the LGM. Hence, our data provide evidence that the grounding line in Filchner Trough experienced dynamic changes in the Holocene and that no linear ice sheet retreat occurred within this trough after the LGM.
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  • 155
    Publication Date: 2017-09-27
    Description: Increasing concern about the impacts of climate change on ecosystems is prompting ecologists and ecosystem managers to seek reliable projections of physical drivers of change. The use of global climate models in ecology is growing, although drawing ecologically meaningful conclusions can be problematic. The expertise required to access and interpret output fromclimate and earth systemmodels is hampering progress in utilizing them most effectively to determine the wider implications of climate change. To address this issue, we present a joint approach between climate scientists and ecologists that explores key challenges and opportunities for progress. As an exemplar, our focus is the Southern Ocean, notable for significant change with global implications, and on sea ice, given its crucial role in this dynamic ecosystem. We combined perspectives to evaluate the representation of sea ice in global climate models. With an emphasis on ecologically-relevant criteria (sea ice extent and seasonality) we selected a subset of eight models that reliably reproduce extant sea ice distributions. While the model subset shows a similar mean change to the full ensemble in sea ice extent (approximately 50% decline in winter and 30% decline in summer), there is a marked reduction in the range. This improved the precision of projected future sea ice distributions by approximately one third, and means they are more amenable to ecological interpretation. We conclude that careful multidisciplinary evaluation of climate models, in conjunction with ongoing modeling advances, should form an integral part of utilizing model output.
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  • 156
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    Springer Nature
    In:  EPIC3Scientific Reports, Springer Nature, 7(11819)
    Publication Date: 2017-09-24
    Description: We present early Cretaceous to present paleobathymetric reconstructions and quantitative uncertainty estimates for the South Atlantic, offering a strong basis for studies of paleocirculation, paleoclimate and paleobiogeography. Circulation in an initially salty and anoxic ocean, restricted by the topography of the Falkland Plateau, Rio Grande Ridge and Walvis Rise, favoured deposition of thick evaporites in shallow water of the Brazilian-Angolan margins. This ceased as sea oor spreading propagated northwards, opening an equatorial gateway to shallow and intermediate circulation. This gateway, together with subsiding volcano-tectonic barriers would have played a key role in Late Cretaceous climate changes. Later deepening and widening of the South Atlantic, together with gateway opening at Drake Passage would lead, by mid-Miocene (∼15 Ma) to the establishment of modern-style thermohaline circulation.
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  • 157
    Publication Date: 2017-10-10
    Description: Arctic permafrost caps vast amounts of old, geologic methane (CH4) in subsurface reservoirs. Thawing permafrost opens pathways for this CH4 to migrate to the surface. However, the occurrence of geologic emissions and their contribution to the CH4 budget in addition to recent, biogenic CH4 is uncertain. Here we present a high-resolution (100 m × 100 m) regional (10,000 km²) CH4 flux map of the Mackenzie Delta, Canada, based on airborne CH4 flux data from July 2012 and 2013. We identify strong, likely geologic emissions solely where the permafrost is discontinuous. These peaks are 13 times larger than typical biogenic emissions. Whereas microbial CH4 production largely depends on recent air and soil temperature, geologic CH4 was produced over millions of years and can be released year-round provided open pathways exist. Therefore, even though they only occur on about 1% of the area, geologic hotspots contribute 17% to the annual CH4 emission estimate of our study area. We suggest that this share may increase if ongoing permafrost thaw opens new pathways. We conclude that, due to permafrost thaw, hydrocarbon-rich areas, prevalent in the Arctic, may see increased emission of geologic CH4 in the future, in addition to enhanced microbial CH4 production.
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  • 158
    Publication Date: 2018-08-10
    Description: Grounding-zone wedges (GZW) have been mapped on the sea floor in various sectors of the formerly glaciated continental shelf around Antarctica. In most cases, these wedges record periods of grounding-line stillstands during ice-sheet retreat following the Last Glacial Maximum (~26-19 ka BP). The presence of GZWs along the axis of a palaeo-ice stream trough therefore indicates episodic retreat of the grounding line from its LGM to modern position. However, information about their internal structure is sparse, and precise chronological constraints for both the onset and the duration of the stillstands they represent are still lacking. Consequently, the role of GZW formation in modulating post-LGM ice-sheet retreat cannot be reliably quantified. This information is vital, however, for calculating reliable retreat rates during the past, which are essential for evaluating and understanding the significance of modern retreat rates, particularly for the rapidly changing Amundsen Sea sector. Here we present a novel combination of swath bathymetric, reflection seismic, and sub-bottom sediment profiler data from a newly discovered stacked GZW in the Cosgrove-Abbot palaeo-ice stream trough in the eastern Amundsen Sea Embayment. In total, six generations of overlapping GZWs were mapped over a distance of ~40 km. We will present first estimates of GZW volumes through integration of the different geophysical datasets. Additionally, we recovered eight sediment cores, sampling most of the individual GZWs within the stack, which may allow us to establish age constraints for each grounding-line retreat episode. Together with the estimated GZW volumes, the ages from sediment cores may also enable the calculation of sediment flux rates at grounding lines, which remain elusive for Antarctic grounding lines. This knowledge will help refine available post-LGM retreat chronologies for the Amundsen Sea Embayment, which, in turn, serve as a basis for validating and improving ice-sheet models in an area where precise simulations of future retreat are urgently needed.
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  • 159
    Publication Date: 2017-09-27
    Description: Die Belastung der Meere und Ozeane mit Müll ist ein Umweltproblem globalen Ausmaßes. Seit der Entdeckung der Müllwirbel und des Mikroplastiks (Kunststoffpartikel 〈 5mm) ist diese Thematik wieder stark in den öffentlichen Fokus gerückt. Den mit Abstand größten Anteil des Mülls in den Meeren bilden langlebige Kunststoffe, deren jährliche Produktion inzwischen auf weltweit 322 Millionen Tonnen angestiegen ist. Es wird prognostiziert, dass der jährliche globale Eintrag von landbasiertem Kunststoffmüll von rund 8 Millionen Tonnen im Jahr 2010 auf bis zu 250 Millionen Tonnen im Jahr 2025 ansteigen wird. Dennoch verzeichneten die meisten der wenigen bestehenden Zeitreihen bislang keinen eindeutigen Anstieg über die Zeit von Müll im Meer. Seit 1999 betreibt das AWI Langzeituntersuchungen am Tiefsee-Observatorium HAUSGARTEN zwischen Grönland und Spitzbergen. Regelmäßig wiederholte Aufnahmen mit einer geschleppten Kamera in zeigten, dass der Müll am Meeresboden im Zeitraum zwischen 2002 und 2014 stark angestiegen ist. Damit ähnelt die Belastung in der Arktis der Mülldichte vergleichbarer Regionen in der Nähe von europäischen Ballungszentren. Auch an der Meeresoberfläche wurde treibender Müll und Mikroplastik entdeckt. An den Stränden Spitzbergens wird von Touristen mittlerweile nicht mehr nur die beeindruckende Aussicht genossen, sondern angeschwemmter Müll eingesammelt. Bereits über 80% der Eissturmvögel Spitzbergens verzehren heute Plastikmüll. Aus diesen Erkenntnissen heraus wurde das FRAM Pollution Observatory etabliert. In diesem Rahmen wird die Belastung von Müll / Mikroplastik im Meereis und Schnee, an der Meeresoberfläche, in der Wassersäule und Tiefsee-Sedimenten sowie an arktischen Stränden untersucht. In diesem Vortrag wird ein erster Ausschnitt der bisherigen Ergebnisse gezeigt und die Ursachen diskutiert. Bereits jetzt steht fest, dass das fragile Arktische Ökosystem parallel zum Klimawandel einem weiterem Umweltproblem ausgesetzt ist. Effektive Lösungen können nur durch grundlegende Veränderungen in unserem Verbrauch und Umgang mit Kunststoff auf internationaler Ebene herbeigeführt werden.
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  • 160
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    NATURE PUBLISHING GROUP
    In:  EPIC3Nature Geoscience, NATURE PUBLISHING GROUP, 10(7), pp. 518-523, ISSN: 1752-0894
    Publication Date: 2017-09-11
    Description: Glacial climate is marked by abrupt, millennial-scale climate changes known as Dansgaard–Oeschger cycles. The most pronounced stadial coolings, Heinrich events, are associated with massive iceberg discharges to the North Atlantic. These events have been linked to variations in the strength of the Atlantic meridional overturning circulation. However, the factors that lead to abrupt transitions between strong and weak circulation regimes remain unclear. Here we show that, in a fully coupled atmosphere–ocean model, gradual changes in atmospheric CO2 concentrations can trigger abrupt climate changes, associated with a regime of bi-stability of the Atlantic meridional overturning circulation under intermediate glacial conditions. We find that changes in atmospheric CO2 concentrations alter the transport of atmospheric moisture across Central America, which modulates the freshwater budget of the North Atlantic and hence deep-water formation. In our simulations, a change in atmospheric CO2 levels of about 15 ppmv—comparable to variations during Dansgaard–Oeschger cycles containing Heinrich events—is sufficient to cause transitions between a weak stadial and a strong interstadial circulation mode. Because changes in the Atlantic meridional overturning circulation are thought to alter atmospheric CO2 levels, we infer that atmospheric CO2 may serve as a negative feedback to transitions between strong and weak circulation modes.
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  • 161
    Publication Date: 2017-09-27
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  • 162
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    Copernicus
    In:  EPIC3Geoscientific Model Development, Copernicus, 11, pp. 753-769
    Publication Date: 2018-03-28
    Description: The Extrapolar SWIFT model is a fast ozone chemistry scheme for interactive calculation of the extrapolar stratospheric ozone layer in coupled general circulation models (GCMs). In contrast to the widely used prescribed ozone, the SWIFT ozone layer interacts with the model dynamics and can respond to atmospheric variability or climatological trends. The Extrapolar SWIFT model employs a repro-modelling approach, where algebraic functions are used to approximate the numerical output of a full stratospheric chemistry and transport model (ATLAS). The full model solves a coupled chemical differential equations system with 55 initial and boundary conditions (mixing ratio of various chemical species and atmospheric parameters). Hence the rate of change of ozone over 24  h is a function of 55 variables. Using covariances between these variables, we can find linear combinations in order to reduce the parameter space to the following nine basic variables: latitude, pressure altitude, temperature, local ozone column, mixing ratio of ozone and of the ozone depleting families (Cly, Bry, NOy and HOy). We will show that these 9 variables are sufficient to characterize the rate of change of ozone. An automated procedure fits a polynomial function of fourth degree to the rate of change of ozone obtained from several simulations with the ATLAS model. One polynomial function is determined per month which yields the rate of change of ozone over 24 h. A key aspect for the robustness of the Extrapolar SWIFT model is to include a wide range of stratospheric variability in the numerical output of the ATLAS model, also covering atmospheric states that will occur in a future climate (e.g. temperature and meridional circulation changes or reduction of stratospheric chlorine loading). For validation purposes, the Extrapolar SWIFT model has been integrated into the ATLAS model replacing the full stratospheric chemistry scheme. Simulations with SWIFT in ATLAS have proven that the systematic error is small and does not accumulate during the course of a simulation. In the context of a 10 year simulation, the ozone layer, simulated by SWIFT, shows a stable annual cycle, with inter-annual variations comparable to the ATLAS model. The application of Extrapolar SWIFT requires the evaluation of polynomial functions with 30–100 terms. Nowadays, computers can calculate such polynomial functions at thousands of model grid points in seconds. SWIFT provides the desired numerical efficiency and computes the ozone layer 104 times faster than the chemistry scheme in the ATLAS CTM.
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  • 163
    Publication Date: 2019-10-04
    Description: Polar oceans are poorly monitored despite the important role they play in regulating Earth’s climate system. Marine mammals equipped with biologging devices are now being used to fill the data gaps in these logistically difficult to sample regions. Since 2002, instrumented animals have been generating exceptionally large data sets of oceanographic CTD casts (〉500,000 profiles), which are now freely available to the scientific community through the MEOP data portal (http://meop.net). MEOP (Marine Mammals Exploring the Oceans Pole to Pole) is a consortium of international researchers dedicated to sharing animal-derived data and knowledge about the polar oceans. Collectively, MEOP demonstrates the power and cost-effectiveness of using marine mammals as data-collection platforms that can dramatically improve the ocean observing system for biological and physical oceanographers. Here, we review the MEOP program and database to bring it to the attention of the international community.
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  • 164
    Publication Date: 2017-10-10
    Description: Large differences in instrumentation, site setup, data format, and operating system stymie the adoption of a universal computational environment for processing and analyzing eddy-covariance (EC) data. This results in limited software applicability and extensibility in addition to often substantial inconsistencies in flux estimates. Addressing these concerns, this paper presents the systematic development of portable, reproducible, and extensible EC software achieved by adopting a development and systems operation (DevOps) approach. This software development model is used for the creation of the eddy4R family of EC code packages in the open-source R language for statistical computing. These packages are community developed, iterated via the Git distributed version control system, and wrapped into a portable and reproducible Docker filesystem that is independent of the underlying host operating system. The HDF5 hierarchical data format then provides a streamlined mechanism for highly compressed and fully self-documented data ingest and output. The usefulness of the DevOps approach was evaluated for three test applications. First, the resultant EC processing software was used to analyze standard flux tower data from the first EC instruments installed at a National Ecological Observatory (NEON) field site. Second, through an aircraft test application, we demonstrate the modular extensibility of eddy4R to analyze EC data from other platforms. Third, an intercomparison with commercial-grade software showed excellent agreement (R2  =  1.0 for CO2 flux). In conjunction with this study, a Docker image containing the first two eddy4R packages and an executable example workflow, as well as first NEON EC data products are released publicly. We conclude by describing the work remaining to arrive at the automated generation of science-grade EC fluxes and benefits to the science community at large. This software development model is applicable beyond EC and more generally builds the capacity to deploy complex algorithms developed by scientists in an efficient and scalable manner. In addition, modularity permits meeting project milestones while retaining extensibility with time.
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  • 165
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    Alfred Wegener Institute
    In:  EPIC3Bremerhaven, Alfred Wegener Institute
    Publication Date: 2019-07-17
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  • 166
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    Alfred Wegener Institute
    In:  EPIC3Bremerhaven, Alfred Wegener Institute
    Publication Date: 2019-07-17
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  • 167
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    Alfred Wegener Institute
    In:  EPIC3Bremerhaven, Alfred Wegener Institute
    Publication Date: 2019-07-17
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  • 168
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    Alfred Wegener Institute
    In:  EPIC3Bremerhaven, Alfred Wegener Institute
    Publication Date: 2019-07-17
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  • 169
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    Alfred Wegener Institute
    In:  EPIC3Bremerhaven, Alfred Wegener Institute
    Publication Date: 2019-07-17
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  • 170
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    Alfred Wegener Institute
    In:  EPIC3Bremerhaven, Alfred Wegener Institute
    Publication Date: 2019-07-17
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  • 171
    Publication Date: 2017-09-26
    Description: Dansgaard–Oeschger oscillations constitute one of the most enigmatic features of the last glacial cycle. Their cold atmospheric phases have been commonly associated with cold sea-surface temperatures and expansion of sea ice in the North Atlantic and adjacent seas. Here, based on dinocyst analyses from the 48–30 ka interval of four sediment cores from the northern Northeast Atlantic and southern Norwegian Sea, we provide direct and quantitative evidence of a regional paradoxical seesaw pattern: cold Greenland and North Atlantic phases coincide with warmer sea-surface conditions and shorter seasonal sea-ice cover durations in the Norwegian Sea as compared to warm phases. Combined with additional palaeorecords and multi-model hosing simulations, our results suggest that during cold Greenland phases, reduced Atlantic meridional overturning circulation and cold North Atlantic sea-surface conditions were accompanied by the subsurface propagation of warm Atlantic waters that reemerged in the Nordic Seas and provided moisture towards Greenland summit.
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  • 172
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    Alfred Wegener Institute
    In:  EPIC3Bremerhaven, Alfred Wegener Institute
    Publication Date: 2019-07-17
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  • 173
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    American Geophysical Union
    In:  EPIC3Journal of Geophysical research: Ocean, American Geophysical Union, 122, pp. 1-18
    Publication Date: 2017-11-12
    Description: We collected Arctic Ocean water column samples for methane (CH4) and nitrous oxide (N2O) analysis on three separate cruises in the summer and fall of 2015, covering a ~10,000 km transect from the Bering Sea to Baffin Bay. This provided a three-dimensional view of CH4 and N2O distributions across contrasting hydrographic environments, from the oligotrophic waters of the deep Canada Basin and Baffin Bay, to the productive shelves of the Bering and Chukchi Seas. Percent saturation relative to atmospheric equilibrium ranged from 30-800% for CH4 and 75-145% for N2O, with the highest concentrations of both gases occurring in the northern Chukchi Sea. Nitrogen cycling in the shelf sediments of the Bering and Chukchi Seas likely constituted the major source of N2O to the water column, and the resulting high N2O concentrations were transported across the Arctic Ocean in eastward-flowing water masses. Methane concentrations were more spatially heterogeneous, reflecting a variety of localized inputs, including likely sources from sedimentary methanogenesis and sea ice processes. Unlike N2O, CH4 was rapidly consumed through microbial oxidation in the water column, as shown by the 13C enrichment of CH4 with decreasing concentrations. For both CH4 and N2O, sea-air fluxes were close to neutral, indicating that our sampling region was neither a major source nor sink of these gases. Our results provide insight into the factors controlling the distribution of CH4 and N2O in the North American Arctic Ocean, and an important baseline data set against which future changes can be assessed.
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  • 174
    Publication Date: 2017-09-26
    Description: Antarctic krill Euphausia superba (“krill”) constitute a fundamental food source for Antarctic seabirds and mammals, and a globally important fisheries resource. The future resilience of krill to climate change depends critically on the winter survival of young krill. To survive periods of extremely low production by pelagic algae during winter, krill are assumed to rely partly on carbon produced by ice algae. The true dependency on ice algae-produced carbon, however, is so far unquantified. This confounds predictions on the future resilience of krill stocks to sea ice decline. Fatty acid (FA) analysis, bulk stable isotope analysis (BSIA), and compound-specific stable isotope analysis (CSIA) of diatom- and dinoflagellate-associated marker FAs were applied to quantify the dependency of overwintering larval, juvenile, and adult krill on ice algae-produced carbon (αIce) during winter 2013 in the Weddell-Scotia Confluence Zone. Our results demonstrate that the majority of the carbon uptake of the overwintering larval and juvenile krill originated from ice algae (up to 88% of the carbon budget), and that the dependency on ice algal carbon decreased with ontogeny, reaching 〈56% of the carbon budget in adults. Spatio-temporal variability in the utilization of ice algal carbon was more pronounced in larvae and juvenile krill than in adults. Differences between αIce estimates derived from short- vs. long-term FA-specific isotopic compositions suggested that ice algae-produced carbon gained importance as the winter progressed, and might become critical at the late winter-spring transition, before the phytoplankton bloom commences. Where the sea ice season shortens, reduced availability of ice algae might possibly not be compensated by surplus phytoplankton production during wintertime. Hence, sea ice decline could seriously endanger the winter survival of recruits, and subsequently overall biomass of krill.
    Repository Name: EPIC Alfred Wegener Institut
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  • 175
    Publication Date: 2019-01-31
    Description: n the framework of atmospheric circulation regimes, we study whether the recent Arctic sea ice loss and Arctic Amplification are associated with changes in the frequency of occurrence of preferred atmospheric circulation patterns during the extended winter season from December to March. To determine regimes we applied a cluster analysis to sea-level pressure fields from reanalysis data and output from an atmospheric general circulation model. The specific set up of the two analyzed model simulations for low and high ice conditions allows for attributing differences between the simulations to the prescribed sea ice changes only. The reanalysis data revealed two circulation patterns that occur more frequently for low Arctic sea ice conditions: a Scandinavian blocking in December and January and a negative North Atlantic Oscillation pattern in February and March. An analysis of related patterns of synoptic-scale activity and 2 m temperatures provides a synoptic interpretation of the corresponding large-scale regimes. The regimes that occur more frequently for low sea ice conditions are resembled reasonably well by the model simulations. Based on those results we conclude that the detected changes in the frequency of occurrence of large-scale circulation patterns can be associated with changes in Arctic sea ice conditions.
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  • 176
    Publication Date: 2017-09-30
    Description: The sustainable development of the marine environment has resulted in the introduction of man-made structures (MMS) in the North Sea. These structures range from oil and gas platforms, buoys, wrecks to wind turbines, offering additional artificial habitat over predominantly soft-sediment areas. The expected effects from MMS in shallow shelf seas will modify benthic communities over various spatial and temporal scales with repercussions for overall ecosystem functioning. Research on large offshore structures have identified a suite of unique effects ranging from biodiversity changes with repercussions on local ecosystem functioning to the provision of habitat for fouling communities, acting as stepping stones and many other ecological modifications. Consequently, MMS might induce structural, functional and process-driven changes, which are different from those expected in natural soft bottom benthic systems. This study considers soft-sediment and introduced hard-substrate epifouling communities. The combination of these systems provides a unique ecological opportunity to ascertain biodiversity changes triggered by loss and gain of species provided by the addition of MMS. To date, our current understanding of how ecological functioning might be modified by the addition of these MMSs is still in its infancy. Our current analysis aimed at evaluating functional changes with a combination of biological traits analysis and energy flow changes calculated via modelled secondary production. Further, our study compared the different types of introduced MMS among the natural soft sediment communities, disentangling how the ecological functioning of the macrobenthos may be altered by the introduction of these structures, which provides improved concepts for current monitoring assessments.
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  • 177
    Publication Date: 2017-09-30
    Description: Marine renewable energy projects (MREs) are supported by mandatory environmental monitoring programmes due to assumed environmental impacts. These programmes concentrate on the resultant effects of single industrial projects onto biological and physical components contributing to the local ecosystem structure. To date, impact assessments at the ecosystem functioning level (e.g. trophic interactions, nutrient cycling) are largely lacking. This critical knowledge gap hampers our ability to answering the “so what” question when assessing environmental impacts, i.e. whether the observed impacts are classified as good, bad or neutral, and/or acceptable or unacceptable. When assessing MREs, there is a fundamental need to focus on ecosystem functioning at relevant spatial and temporal scales to properly understand ecological impacts and its consequences. Here, we make a science-based plea for an increased investment in large scale impact assessment of MREs focused on ecosystem functioning. This presentation will cover a selection of examples from MRE monitoring programmes, where the current knowledge has limited conclusions on the “so what” question. Further, applications will demonstrate how a proposed ecosystem functioning approach at an appropriate spatial and temporal scale could advance our current assessment. These examples will illustrate the need to expand the current level of MRE monitoring beyond that of community structure and of individual industrial projects. This work will advance and strengthen collaborative MRE monitoring strategies, facilitating scientists, developers and regulators to answer the much needed “so what” question when undertaking environmental assessments, and reassuring stakeholders with high confidence over these assessments.
    Repository Name: EPIC Alfred Wegener Institut
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  • 178
    Publication Date: 2017-09-30
    Description: Offshore marine renewables energy developments (MREDs), particularly in the light of extensive offshore wind farm development in shallow shelf seas, are expected to affect the structure and functioning of marine ecosystems. Several activities linked to the installation and operation of MREDs each have their differential impacts onto the ecosystem. The benthos plays key roles in the ecosystem, supporting numerous ecosystem goods and services such as long-term carbon storage and food resources for higher trophic groups (e.g. fish, birds, mammals and including humans). Development of MREDs will initiate processes which are expected to affect benthic assemblages over various, currently unknown, spatial and temporal scales. This work provides a structured overview of ecological cause-effect relationships related to MREDs, based on a set of hypothesis-driven pathways supported by literature (〉230 publications reviewed). Furthermore, this work evaluated the sensitivity of benthic causeeffect relationships to potential effects of MREDs on different spatial and temporal scales and weighted the assessment by confidence in existing knowledge and the consistency of effects among habitats. The outcomes allowed identification of knowledge gaps about ecological processes, in order to prioritize the ‘known-unknowns’ and highlight priority research areas. Our results suggest that the sensitivity of the benthos to MREDs is much higher than previously indicated, particularly where cascading effects lead to changes in ecological functioning. Filling existing knowledge gaps and understanding ecological processes and patterns occurring at low-trophic levels, including those within the benthos, are essential to maintain ecological integrity key to the ecosystem and to society even under MREDs developments.
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  • 179
    Publication Date: 2017-09-28
    Repository Name: EPIC Alfred Wegener Institut
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  • 180
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    COMPANY OF BIOLOGISTS LTD
    In:  EPIC3Journal of Experimental Biology, COMPANY OF BIOLOGISTS LTD, 220(15), pp. 2685-2696, ISSN: 0022-0949
    Publication Date: 2019-07-16
    Description: Observations of climate impacts on ecosystems highlight the need for an understanding of organismal thermal ranges and their implications at the ecosystem level. Where changes in aquatic animal populations have been observed, the integrative concept of oxygen- and capacitylimited thermal tolerance (OCLTT) has successfully characterised the onset of thermal limits to performance and field abundance. The OCLTT concept addresses the molecular to whole-animal mechanisms that define thermal constraints on the capacity for oxygen supply to the organism in relation to oxygen demand. The resulting ‘total excess aerobic power budget’ supports an animal’s performance (e.g. comprising motor activity, reproduction and growth) within an individual’s thermal range. The aerobic power budget is often approximated through measurements of aerobic scope for activity (i.e. the maximumdifference between resting and the highest exerciseinduced rate of oxygen consumption), whereas most animals in the field rely on lower (i.e. routine) modes of activity. At thermal limits, OCLTT also integrates protective mechanisms that extend time-limited tolerance to temperature extremes – mechanisms such as chaperones, anaerobic metabolism and antioxidative defence. Here, we briefly summarise the OCLTT concept and update it by addressing the role of routine metabolism.We highlight potential pitfalls in applying the concept and discuss the variables measured that led to the development ofOCLTT.We propose that OCLTTexplains why thermal vulnerability is highest at the whole-animal level and lowest at the molecular level. We also discuss how OCLTT captures the thermal constraints on the evolution of aquatic animal life and supports an understanding of the benefits of transitioning from water to land.
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  • 181
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    In:  EPIC3Eos, 98, ISSN: 0096-3941
    Publication Date: 2018-01-02
    Description: The polar regions, with their continental ice sheets and partly ice covered oceans, play a crucial role in the Earth system. They are critical to understanding and predicting climate evolution and global sea level change. Airborne platforms offer the most amenable and powerful means of surveying these regions.
    Repository Name: EPIC Alfred Wegener Institut
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  • 182
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    PANGAEA
    In:  EPIC3Bremerhaven, PANGAEA
    Publication Date: 2017-10-16
    Repository Name: EPIC Alfred Wegener Institut
    Type: PANGAEA Documentation , notRev
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  • 183
    Publication Date: 2021-06-09
    Repository Name: EPIC Alfred Wegener Institut
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  • 184
    Publication Date: 2018-02-15
    Description: Due to changing temperature regimes in the North- and the Wadden Sea, a fish survey in the Sylt Rømø bight (SRB) was established in 2007 for at least ten years. The aim is to investigate the Wadden Sea fish fauna with special interest in changes of migration behavior, species composition and feeding habits. Seven stations are sampled monthly inside the SRB. Two additional stations, one outside the bight, one close to the Danish border are sampled as references four times a year. For sampling a mini bottom trawl, total length 17 m, trawl opening 7 m, height 3 m with a mesh size of 36 mm in the wings, 16 mm in the mid part and 6 mm in the cod end is used. At every station one haul in the water column and another at the bottom are sampled, for 15 minutes at a speed of approximately 2 knots. The data will help to give a more detailed picture of food chains and energy flows inside the Wadden Sea.
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  • 185
    Publication Date: 2018-02-15
    Description: Due to changing temperature regimes in the North- and the Wadden Sea, a fish survey in the Sylt Rømø bight (SRB) was established in 2007 for at least ten years. The aim is to investigate the Wadden Sea fish fauna with special interest in changes of migration behavior, species composition and feeding habits. Seven stations are sampled monthly inside the SRB. Two additional stations, one outside the bight, one close to the Danish border are sampled as references four times a year. For sampling a mini bottom trawl, total length 17 m, trawl opening 7 m, height 3 m with a mesh size of 36 mm in the wings, 16 mm in the mid part and 6 mm in the cod end is used. At every station one haul in the water column and another at the bottom are sampled, for 15 minutes at a speed of approximately 2 knots. The data will help to give a more detailed picture of food chains and energy flows inside the Wadden Sea.
    Repository Name: EPIC Alfred Wegener Institut
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  • 186
    Publication Date: 2018-02-15
    Description: Due to changing temperature regimes in the North- and the Wadden Sea, a fish survey in the Sylt Rømø bight (SRB) was established in 2007 for at least ten years. The aim is to investigate the Wadden Sea fish fauna with special interest in changes of migration behavior, species composition and feeding habits. Seven stations are sampled monthly inside the SRB. Two additional stations, one outside the bight, one close to the Danish border are sampled as references four times a year. For sampling a mini bottom trawl, total length 17 m, trawl opening 7 m, height 3 m with a mesh size of 36 mm in the wings, 16 mm in the mid part and 6 mm in the cod end is used. At every station one haul in the water column and another at the bottom are sampled, for 15 minutes at a speed of approximately 2 knots. The data will help to give a more detailed picture of food chains and energy flows inside the Wadden Sea.
    Repository Name: EPIC Alfred Wegener Institut
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  • 187
    Publication Date: 2018-02-15
    Description: Due to changing temperature regimes in the North- and the Wadden Sea, a fish survey in the Sylt Rømø bight (SRB) was established in 2007 for at least ten years. The aim is to investigate the Wadden Sea fish fauna with special interest in changes of migration behavior, species composition and feeding habits. Seven stations are sampled monthly inside the SRB. Two additional stations, one outside the bight, one close to the Danish border are sampled as references four times a year. For sampling a mini bottom trawl, total length 17 m, trawl opening 7 m, height 3 m with a mesh size of 36 mm in the wings, 16 mm in the mid part and 6 mm in the cod end is used. At every station one haul in the water column and another at the bottom are sampled, for 15 minutes at a speed of approximately 2 knots. The data will help to give a more detailed picture of food chains and energy flows inside the Wadden Sea.
    Repository Name: EPIC Alfred Wegener Institut
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  • 188
    Publication Date: 2018-02-15
    Description: Due to changing temperature regimes in the North- and the Wadden Sea, a fish survey in the Sylt Rømø bight (SRB) was established in 2007 for at least ten years. The aim is to investigate the Wadden Sea fish fauna with special interest in changes of migration behavior, species composition and feeding habits. Seven stations are sampled monthly inside the SRB. Two additional stations, one outside the bight, one close to the Danish border are sampled as references four times a year. For sampling a mini bottom trawl, total length 17 m, trawl opening 7 m, height 3 m with a mesh size of 36 mm in the wings, 16 mm in the mid part and 6 mm in the cod end is used. At every station one haul in the water column and another at the bottom are sampled, for 15 minutes at a speed of approximately 2 knots. The data will help to give a more detailed picture of food chains and energy flows inside the Wadden Sea.
    Repository Name: EPIC Alfred Wegener Institut
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  • 189
    Publication Date: 2018-02-15
    Description: Due to changing temperature regimes in the North- and the Wadden Sea, a fish survey in the Sylt Rømø bight (SRB) was established in 2007 for at least ten years. The aim is to investigate the Wadden Sea fish fauna with special interest in changes of migration behavior, species composition and feeding habits. Seven stations are sampled monthly inside the SRB. Two additional stations, one outside the bight, one close to the Danish border are sampled as references four times a year. For sampling a mini bottom trawl, total length 17 m, trawl opening 7 m, height 3 m with a mesh size of 36 mm in the wings, 16 mm in the mid part and 6 mm in the cod end is used. At every station one haul in the water column and another at the bottom are sampled, for 15 minutes at a speed of approximately 2 knots. The data will help to give a more detailed picture of food chains and energy flows inside the Wadden Sea.
    Repository Name: EPIC Alfred Wegener Institut
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  • 190
    Publication Date: 2018-02-15
    Repository Name: EPIC Alfred Wegener Institut
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  • 191
    Publication Date: 2018-02-15
    Repository Name: EPIC Alfred Wegener Institut
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  • 192
    Publication Date: 2017-11-06
    Description: IODP site U1417 in the Gulf of Alaska provides a continuous sedimentary record of environmental changes (e.g., in sea surface temperature (SST), marine productivity, ice-rafting) in the subpolar NE Pacific through the Plio-Pleistocene time interval. Here, we present a multi-proxy data set, which allows us to discriminate between different fertilization mechanisms that promoted primary productivity events in the study area between 1.5 Ma and 0.5 Ma. Based on biomarker, micropaleontological, XRF, and sedimentological data, we find that diatom growth benefited from iron-fertilization from aeolian dust, iceberg, and volcanic ash input. Glacial-interglacial SST fluctuations were superimposed by a slight cooling trend with a first pronounced temperature drop during MIS 38 and significantly lowered SSTs persisting through MIS 30 and MIS 28. While the diatom productivity pulses were mainly independent from SST changes, they coincide with terrigenous organic matter input and their occurrence during both glacial and interglacial periods suggest that iron supply from glacigenic dust was mainly controlled by local ice-sheet dynamics. This data set highlights the complexity of fertilization mechanisms in areas affected by evolving ice-sheets and their potential control on the biological carbon pump in subpolar ocean environments.
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  • 193
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    Wiley
    In:  EPIC3Global Biogeochemical Cycles, Wiley, ISSN: 0886-6236
    Publication Date: 2017-10-27
    Repository Name: EPIC Alfred Wegener Institut
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  • 194
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    In:  EPIC3Workshop on Airborne Activities in the Arctic: Science and Prospects, Leipzig, 2017-10-05-2017-10-06Leipzig
    Publication Date: 2019-06-06
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  • 195
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    PANGAEA
    In:  EPIC3Bremerhaven, PANGAEA
    Publication Date: 2017-10-29
    Repository Name: EPIC Alfred Wegener Institut
    Type: PANGAEA Documentation , notRev
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  • 196
    Publication Date: 2017-10-31
    Repository Name: EPIC Alfred Wegener Institut
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  • 197
    Publication Date: 2018-02-15
    Description: Due to changing temperature regimes in the North- and the Wadden Sea, a fish survey in the Sylt Rømø bight (SRB) was established in 2007 for at least ten years. The aim is to investigate the Wadden Sea fish fauna with special interest in changes of migration behavior, species composition and feeding habits. Seven stations are sampled monthly inside the SRB. Two additional stations, one outside the bight, one close to the Danish border are sampled as references four times a year. For sampling a mini bottom trawl, total length 17 m, trawl opening 7 m, height 3 m with a mesh size of 36 mm in the wings, 16 mm in the mid part and 6 mm in the cod end is used. At every station one haul in the water column and another at the bottom are sampled, for 15 minutes at a speed of approximately 2 knots. The data will help to give a more detailed picture of food chains and energy flows inside the Wadden Sea.
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  • 198
    Publication Date: 2018-02-15
    Description: Due to changing temperature regimes in the North- and the Wadden Sea, a fish survey in the Sylt Rømø bight (SRB) was established in 2007 for at least ten years. The aim is to investigate the Wadden Sea fish fauna with special interest in changes of migration behavior, species composition and feeding habits. Seven stations are sampled monthly inside the SRB. Two additional stations, one outside the bight, one close to the Danish border are sampled as references four times a year. For sampling a mini bottom trawl, total length 17 m, trawl opening 7 m, height 3 m with a mesh size of 36 mm in the wings, 16 mm in the mid part and 6 mm in the cod end is used. At every station one haul in the water column and another at the bottom are sampled, for 15 minutes at a speed of approximately 2 knots. The data will help to give a more detailed picture of food chains and energy flows inside the Wadden Sea.
    Repository Name: EPIC Alfred Wegener Institut
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  • 199
    Publication Date: 2018-02-15
    Description: Due to changing temperature regimes in the North- and the Wadden Sea, a fish survey in the Sylt Rømø bight (SRB) was established in 2007 for at least ten years. The aim is to investigate the Wadden Sea fish fauna with special interest in changes of migration behavior, species composition and feeding habits. Seven stations are sampled monthly inside the SRB. Two additional stations, one outside the bight, one close to the Danish border are sampled as references four times a year. For sampling a mini bottom trawl, total length 17 m, trawl opening 7 m, height 3 m with a mesh size of 36 mm in the wings, 16 mm in the mid part and 6 mm in the cod end is used. At every station one haul in the water column and another at the bottom are sampled, for 15 minutes at a speed of approximately 2 knots. The data will help to give a more detailed picture of food chains and energy flows inside the Wadden Sea.
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  • 200
    Publication Date: 2018-02-15
    Description: Due to changing temperature regimes in the North- and the Wadden Sea, a fish survey in the Sylt Rømø bight (SRB) was established in 2007 for at least ten years. The aim is to investigate the Wadden Sea fish fauna with special interest in changes of migration behavior, species composition and feeding habits. Seven stations are sampled monthly inside the SRB. Two additional stations, one outside the bight, one close to the Danish border are sampled as references four times a year. For sampling a mini bottom trawl, total length 17 m, trawl opening 7 m, height 3 m with a mesh size of 36 mm in the wings, 16 mm in the mid part and 6 mm in the cod end is used. At every station one haul in the water column and another at the bottom are sampled, for 15 minutes at a speed of approximately 2 knots. The data will help to give a more detailed picture of food chains and energy flows inside the Wadden Sea.
    Repository Name: EPIC Alfred Wegener Institut
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