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  • 1
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    Unusual marine unicellular symbiosis with the nitrogen-fixing cyanobacterium UCYN-A (2016)
    Springer Nature
    In:  Nature Microbiology, 2 (16214).
    Details
    Publikationsdatum: 2020-06-24
    Beschreibung: Nitrogen fixation — the reduction of dinitrogen (N2) gas to biologically available nitrogen (N) — is an important source of N for terrestrial and aquatic ecosystems. In terrestrial environments, N2-fixing symbioses involve multicellular plants, but in the marine environment these symbioses occur with unicellular planktonic algae. An unusual symbiosis between an uncultivated unicellular cyanobacterium (UCYN-A) and a haptophyte picoplankton alga was recently discovered in oligotrophic oceans. UCYN-A has a highly reduced genome, and exchanges fixed N for fixed carbon with its host. This symbiosis bears some resemblance to symbioses found in freshwater ecosystems. UCYN-A shares many core genes with the 'spheroid bodies' of Epithemia turgida and the endosymbionts of the amoeba Paulinella chromatophora. UCYN-A is widely distributed, and has diversified into a number of sublineages that could be ecotypes. Many questions remain regarding the physical and genetic mechanisms of the association, but UCYN-A is an intriguing model for contemplating the evolution of N2-fixing organelles.
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  • 2
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    Weak ENSO asymmetry due to weak nonlinear air–sea interaction in CMIP5 climate models (2016)
    Springer
    In:  Advances in Atmospheric Sciences, 33 (3). pp. 352-364.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: State-of-the-art climate models have long-standing intrinsic biases that limit their simulation and projection capabilities. Significantly weak ENSO asymmetry and weakly nonlinear air–sea interaction over the tropical Pacific was found in CMIP5 (Coupled Model Intercomparison Project, Phase 5) climate models compared with observation. The results suggest that a weak nonlinear air–sea interaction may play a role in the weak ENSO asymmetry. Moreover, a weak nonlinearity in air–sea interaction in the models may be associated with the biases in the mean climate—the cold biases in the equatorial central Pacific. The excessive cold tongue bias pushes the deep convection far west to the western Pacific warm pool region and suppresses its development in the central equatorial Pacific. The deep convection has difficulties in further moving to the eastern equatorial Pacific, especially during extreme El Ni˜no events, which confines the westerly wind anomaly to the western Pacific. This weakens the eastern Pacific El Ni˜no events, especially the extreme El Ni˜no events, and thus leads to the weakened ENSO asymmetry in climate models. An accurate mean state structure (especially a realistic cold tongue and deep convection) is critical to reproducing ENSO events in climate models. Our evaluation also revealed that ENSO statistics in CMIP5 climate models are slightly improved compared with those of CMIP3. The weak ENSO asymmetry in CMIP5 is closer to the observation. It is more evident in CMIP5 that strong ENSO activities are usually accompanied by strong ENSO asymmetry, and the diversity of ENSO amplitude is reduced.
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  • 3
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    Spatial and seasonal reef calcification in corals and calcareous crusts in the central Red Sea (2016)
    Springer
    In:  Coral Reefs, 35 (2). pp. 681-693.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: The existence of coral reef ecosystems critically relies on the reef carbonate framework produced by scleractinian corals and calcareous crusts (i.e., crustose coralline algae). While the Red Sea harbors one of the longest connected reef systems in the world, detailed calcification data are only available from the northernmost part. To fill this knowledge gap, we measured in situ calcification rates of primary and secondary reef builders in the central Red Sea. We collected data on the major habitat-forming coral genera Porites, Acropora, and Pocillopora and also on calcareous crusts (CC) in a spatio-seasonal framework. The scope of the study comprised sheltered and exposed sites of three reefs along a cross-shelf gradient and over four seasons of the year. Calcification of all coral genera was consistent across the shelf and highest in spring. In addition, Pocillopora showed increased calcification at exposed reef sites. In contrast, CC calcification increased from nearshore, sheltered to offshore, exposed reef sites, but also varied over seasons. Comparing our data to other reef locations, calcification in the Red Sea was in the range of data collected from reefs in the Caribbean and Indo-Pacific; however, Acropora calcification estimates were at the lower end of worldwide rates. Our study shows that the increasing coral cover from nearshore to offshore environments aligned with CC calcification but not coral calcification, highlighting the potentially important role of CC in structuring reef cover and habitats. While coral calcification maxima have been typically observed during summer in many reef locations worldwide, calcification maxima during spring in the central Red Sea indicate that summer temperatures exceed the optima of reef calcifiers in this region. This study provides a foundation for comparative efforts and sets a baseline to quantify impact of future environmental change in the central Red Sea.
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  • 4
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    Chemical Flux Associated with Spatially and Temporally Variable Submarine Groundwater Discharge, and Chemical Modification in the Subterranean Estuary at Gloucester Point, VA (USA) (2016)
    Springer
    In:  Estuaries and Coasts, 39 (1). pp. 1-12.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: Submarine groundwater discharge represents a major but poorly constrained component of coastal marine chemical budgets. In the current study, the geochemical behavior of 224Ra, inorganic nitrogen species, and Fe in shallow coastal groundwater was characterized to improve estimates of chemical flux via submarine groundwater discharge (SGD) at a site in the York River estuary, VA (USA). Directly measured SGD rates varied between 3.9 ± 1.2 cm day−1 offshore, and 8.9 ± 2.6 cm day−1 close to shore. A clear inverse relationship was observed between SGD and tidal height, reflecting the hydraulic gradient between groundwater and surface water. Discharge rates varied spatially in conjunction with the subterranean estuary location, and there was a strong inverse correlation between seepage rates and seepage salinity. Dissolved 224Ra activity in the mixing zone reached levels up to 6 dpm L−1 and co-varied with salinity in the groundwater but not in the surface water or seepage water. Instead, a consistent sigmoidal trend of Ra with pH was observed, which matched previous laboratory experiment results. Dissolved NH4 + reached concentrations up to 120 μM in the groundwater and appeared to mix conservatively with respect to salinity in the subterranean estuary. In contrast, NOx (NO2 − + NO3 −) was low in both fresh groundwater and surface water and showed non-conservative enrichment (up to 23 μM) within the subterranean estuary. Dissolved Fe also showed non-conservative excess in the subterranean estuary, reaching concentrations up to 50 μM. SGD-derived chemical fluxes were estimated using several different commonly used approaches: average groundwater concentrations, pore water constituent-salinity trends coupled with directly collected seepage salinity, constituent concentrations in directly collected seepage, and concentrations in shallowest groundwater samples. Different flux estimates were compared with a “variable endmember” approach based on the observed geochemical distribution and inferred behavior.
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  • 5
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    Dynamics of exrtrusive dome growth and variations in chemical and mineralogical composition of Young Shiveluch andesites in 2001–2013 (2016)
    Springer
    In:  Journal of Volcanology and Seismology, 10 (6). pp. 360-381.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: This paper discribes characteristic features of the extrusive dome growth of the Young Shiveluch Volcano in 2001–2013 and analyzes variations in the chemical and mineralogic composition of magmas erupted during this period. It is shown that, compared with the earlier phases in the dome growth during 1980–1981 and 1993–1995, the andesites that were erupted in the 2000s are less homogeneous in bulk composition, crystal contents and contain phenocrysts, which differ in composition and the conditions of crystallization. These compositional feature of rocks are interpreted as resulting from convection in a shallow magma chamber, with the convection being caused by the arrival of a fresh portion of deep magma.
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  • 6
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    Development of Mining Technology and Equipment for Seafloor Massive Sulfide Deposits (2016)
    Chinese Mechanical Engineering Society | Springer
    In:  Chinese Journal of Mechanical Engineering, 29 (5). pp. 863-870.
    Details
    Publikationsdatum: 2020-07-27
    Beschreibung: Seafloor massive sulfide(SMS) deposits which consist of Au, Ag, Cu, and other metal elements, have been a target of commercial mining in recent decades. The demand for established and reliable commercial mining system for SMS deposits is increasing within the marine mining industry. The current status and progress of mining technology and equipment for SMS deposits are introduced. First, the mining technology and other recent developments of SMS deposits are comprehensively explained and analyzed. The seafloor production tools manufactured by Nautilus Minerals and similar mining tools from Japan for SMS deposits are compared and discussed in turn. Second, SMS deposit mining technology research being conducted in China is described, and a new SMS deposits mining tool is designed according to the environmental requirement. Finally, some new trends of mining technology of SMS deposits are summarized and analyzed. All of these conclusions and results have reference value and guiding significance for the research of SMS deposit mining in China.
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  • 7
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    Simulation by CMIP5 models of the atlantic multidecadal oscillation and its climate impacts (2016)
    Springer
    In:  Advances in Atmospheric Sciences, 33 (12). pp. 1329-1342.
    Details
    Publikationsdatum: 2020-04-23
    Beschreibung: This study focuses on the climatic impacts of the Atlantic Multidecadal Oscillation (AMO) as a mode of internal variability. Given the difficulties involved in excluding the effects of external forcing from internal variation, i.e., owing to the short record length of instrumental observations and historical simulations, we assess and compare the AMO and its related climatic impacts both in observations and in the “Pre-industrial” experiments of models participating in CMIP5. First, we evaluate the skill of the 25 CMIP5 models’ “Historical” simulations in simulating the observational AMO, and find there is generally a considerable range of skill among them in this regard. Six of the models with higher skill relative to the other models are selected to investigate the AMO-related climate impacts, and it is found that their “Pre-industrial” simulations capture the essential features of the AMO. A positive AMO favors warmer surface temperature around the North Atlantic, and the Atlantic ITCZ shifts northward leading to more rainfall in the Sahel and less rainfall in Brazil. Furthermore, the results confirm the existence of a teleconnection between the AMO and East Asian surface temperature, as well as the late withdrawal of the Indian summer monsoon, during positive AMO phases. These connections could be mainly caused by internal climate variability. Opposite patterns are true for the negative phase of the AMO.
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  • 8
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    When in life does density dependence occur in fish populations? (2016)
    Wiley-Blackwell
    In:  Fish and Fisheries, 18 (4). pp. 656-667.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: Fisheries advice is based on demographic calculations, which assume that density-dependent processes regulating recruitment occur only in early life. This assumption is challenged by laboratory and lake studies and some recent indications from marine systems that demonstrate density-dependent regulation late in life. By accounting for spatial dynamics of a population, something that has previously been ignored in models of fish, we show that density-dependent regulation is determined by the size of the habitat: in small habitats, for example small lakes, regulation occurs late in life, while it can occur early in large habitats. When regulation happens late in life, fisheries yield is maximized by exploitation of mainly juvenile fish, while exploiting mature fish maximizes yield if regulation happens early. We review and interpret observations of density dependence in the light of the theory. Our results challenge the current assumption that density dependence always occurs early in life and highlights the need for an increased understanding of density-dependent processes. This can only come about by a change of focus from determining stock-recruitment relationships towards understanding when and how density-dependent regulation occurs in nature.
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  • 9
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    Inferring spatial structure from population genetics and spatial synchrony in demography of Baltic Sea fishes: implications for management (2016)
    Wiley-Blackwell
    In:  Fish and Fisheries, 18 (2). pp. 324-339.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: The spatial structure of species is important for their dynamics and evolution, but also for management and conservation. There are numerous ways of inferring spatial structures, and information from multiple methods is becoming more common to examine how different processes shape the spatial structures of species to improve fish management. Here, we investigate the spatial structure of a suite of Baltic Sea fish species based on the following: (i) spatial (presumably neutral) genetic differentiation, reviewed from the literature, and (ii) spatial synchrony in abundance changes from time series of fishery‐independent surveys, which we currently find to be underused given the amount of data available. For each of these two methods, species were classified as having a distinct, continuous or no/weak spatial structure. In addition, based on each source of information, we estimated the spatial scale of management units for species. The results show that only among species confined to the coastal zone the two sources of information yielded a congruence of the spatial structure (displaying a continuous spatial structure). In contrast, offshore species show weak spatial genetic structure but stronger spatial structure of synchrony in abundance. Based on this, we suggest that population genetic structure and synchrony in abundance should be used as complementary information as they reflect different spatial processes and suggest that management actions should differ with respect to scale depending on the management targets applied. We propose similar analysis should be applied to areas outside the Baltic Sea, and other stock identification methods, to improve management of fish resources.
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  • 10
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    The Changing Face of Reef Building (2016)
    Springer
    In:  In: Coral Reefs at the Crossroads. , ed. by Hubbard, D. K., Rogers, C. S., Lipps, J. H. and Stanley, G. D. Coral Reefs of the World, 6 . Springer, Dordrecht, pp. 127-153. ISBN 978-94-017-7567-0
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    Publikationsdatum: 2017-03-22
    Materialart: Book chapter , NonPeerReviewed
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  • 11
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    Meere: Herausforderung Ozean (2016)
    Springer
    In:  In: Handbuch Umweltethik. , ed. by Ott, K., Dierks, J. and Voget-Kleschin, L. Springer, Berlin, Germany, pp. 273-280. ISBN 978-3-476-05193-6
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    Publikationsdatum: 2017-01-17
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  • 12
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    Zircon in amphibolites from Naxos, Aegean Sea, Greece: origin, significance and tectonic setting (2016)
    Wiley-Blackwell
    In:  Journal of Metamorphic Geology .
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    Publikationsdatum: 2020-07-23
    Beschreibung: We report U–Pb zircon ages of c. 700–550 Ma, 262–220 Ma, 47–38 Ma and 15–14 Ma from amphibolites on Naxos Island in the Aegean extensional province of Greece. The zircon has complex internal structures. Based on cathodoluminescence response, zoning and crosscutting relationships a minimum of four zircon growth stages are identified: inherited core, magmatic core, inner metamorphic (?) rim and an outer metamorphic rim. Trace element compositions of the amphibolites suggest igneous differentiation and crustal assimilation. Zircon solubility as a function of saturation temperatures, Zr content and melt composition indicates that the zircon did not originally crystallize in the mafic bodies but was inherited from felsic precursor rocks, and subsequently assimilated into the mafic intrusives during emplacement. Zircon inheritance is corroborated by the complex, xenocrystic nature of the zircon in one sample. Ages of c. 700–550 Ma and 262–220 Ma are assigned to inherited zircon. Available geochemical data suggest that the 15–14 Ma metamorphic rims grew in situ in the amphibolites, corresponding to a high-grade metamorphic event at this time. However, the geochemical data cannot conclusively establish if the c. 40 Ma zircon rims also grew in situ, or whether they were inherited along with the xenocrystic cores. Two scenarios for emplacement of the mafic intrusives are discussed: (i) Intrusion during late-Triassic to Jurassic ocean basin development of the Aegean realm, in which case the 40 Ma zircon rims would have grown in situ, and (ii) emplacement in the Miocene as a result mafic underplating during large-scale extension. In this case, only the 15–14 Ma metamorphic outer rims would have formed in situ in the amphibolitic host rocks.
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  • 13
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    Conserved effects of salinity acclimation on thermal tolerance and hsp70 expression in divergent populations of threespine stickleback (Gasterosteus aculeatus) (2016)
    Springer
    In:  Journal of Comparative Physiology B - Biochemical Systemic and Environmental Physiology, 186 (7). pp. 879-889.
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    Publikationsdatum: 2019-02-01
    Beschreibung: In natural environments, organisms must cope with complex combinations of abiotic stressors. Here, we use threespine stickleback (Gasterosteus aculeatus) to examine how changes in salinity affect tolerance of high temperatures. Threespine stickleback inhabit a range of environments that vary in both salinity and thermal stability making this species an excellent system for investigating interacting stressors. We examined the effects of environmental salinity on maximum thermal tolerance (CTMax) and 70 kDa heat shock protein (hsp70) gene expression using divergent stickleback ecotypes from marine and freshwater habitats. In both ecotypes, the CTMax of fish acclimated to 20 ppt was significantly higher compared to fish acclimated to 2 ppt. The effect of salinity acclimation on the expression of hsp70-1 and hsp70-2 was similar in both the marine and freshwater stickleback ecotype. There were differences in the expression profiles of hsp70-1 and hsp70-2 during heat shock, with hsp70-2 being induced earlier and to a higher level compared to hsp70-1. These data suggest that the two hsp70 isoforms may have functionally different roles in the heat shock response. Lastly, acute salinity challenge coupled with heat shock revealed that the osmoregulatory demands experienced during the heat shock response have a larger effect on the hsp70 expression profile than does the acclimation salinity.
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  • 14
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    Marine gas hydrates (2016)
    Springer
    In:  In: Encyclopedia of Marine Geosciences. , ed. by Harff, J., Meschede, M., Petersen, S. and Thiede, J. Springer, Dordrecht, pp. 433-437. ISBN 978-94-007-6239-4
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    Publikationsdatum: 2017-09-22
    Beschreibung: Gas hydrates are non-stoichiometric solid compounds in which low-molecular-weight gases are trapped (guests) within water cavities (hosts). The presence of gas hydrates is controlled by temperature, pressure, and the availability of appropriate gases and water.
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  • 15
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    Food-limited growth of larval Atlantic herring Clupea harengus recurrently observed in a coastal nursery area (2016)
    Springer
    In:  Helgoland Marine Research, 70 (1). Art. No. 17.
    Details
    Publikationsdatum: 2019-07-19
    Beschreibung: Food-limited growth of larval fish, defined as growth rates lower than observed in other habitats or from laboratory experiments at a given temperature, is rarely reported in field studies. This would imply that either larval fishes are living in an environment characterized by plenty of food, that nutritional condition selective mortality (i.e., eliminating the weak) is very strong, or this impression is caused by misinterpretation of data concerning e.g., poor taxonomical resolution of potential prey items, i.e., total potential prey abundance is high, but positively selected food is actually scarce. We analyzed RNA:DNA derived growth rates of herring larvae (Clupea harengus L.) and taxonomically differentiated prey field data of six consecutive spring seasons from the Kiel Canal, an artificial waterway in northern Germany, in order to test if food-limited growth in larval fish can occur recurrently in coastal habitats. In all years analyzed, larval growth rates decreased simultaneously with prey abundance at the end of each larval season. Furthermore, larval growth rates were observed to be lower than mean growth rates observed in another herring larvae nursery area at temperatures above 15 °C. Asymptotic relationships between prey abundance and larval growth rates were observed, further supporting the hypothesis of food-limitation. As larval growth was best explained by the abundance of the numerically dominant calanoid copepod Eurytemora affinis, the paramount importance of the dominant prey item is highlighted. We conclude that food limitation can be a severe and re-occurring issue for larval fish in coastal habitats, and that certain prey items play a crucial role in determining larval growth rates, and therefore potentially recruitment.
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  • 16
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    Image-Based Large-Scale Geo-localization in Mountainous Regions (2016)
    Springer
    In:  In: Large-Scale Visual Geo-Localization. , ed. by Zamir, A., Hakeem, A., Van Gool, L., Shah, M. and Szeliski, R. Advances in Computer Vision and Pattern Recognition, 3 . Springer , Cham, Switzerland, pp. 205-223. ISBN 978-3-319-25779-2
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    Publikationsdatum: 2020-08-03
    Beschreibung: Given a picture taken somewhere in the world, automatic geo-localization of such an image is an extremely useful task especially for historical and forensic sciences, documentation purposes, organization of the world’s photographs and intelligence applications. While tremendous progress has been made over the last years in visual location recognition within a single city, localization in natural environments is much more difficult, since vegetation, illumination, seasonal changes make appearance-only approaches impractical. In this chapter, we target mountainous terrain and use digital elevation models to extract representations for fast visual database lookup. We propose an automated approach for very large-scale visual localization that can efficiently exploit visual information (contours) and geometric constraints (consistent orientation) at the same time. We validate the system at the scale of Switzerland (40000km2) using over 1000 landscape query images with ground truth GPS position.
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  • 17
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    Use of novel high-resolution 3D marine seismic technology to evaluate Quaternary fluvial valley development and geologic controls on shallow gas distribution, inner shelf, Gulf of Mexico (2016)
    Society of Exploration Geophysicists
    In:  Interpretation, 4 (1). SC35-SC49.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: The first deployment of the P-Cable™ high-resolution 3D (HR3D) seismic acquisition system in the Gulf of Mexico has provided unprecedented resolution of depositional, architectural, and structural features related to relative sea-level change recorded in the Quaternary stratigraphy. These details are typically beyond conventional 3D seismic resolution and/or excluded from commercial surveys, which are generally optimized for deeper targets. Such HR3D data are valuable for detailed studies of reservoir analogs, sediment delivery systems, fluid-migration systems, and geotechnical hazard assessment (i.e., drilling and infrastructure). The HR3D survey (31.5 km2) collected on the inner shelf (〈15 m water depth) offshore San Luis Pass, Texas, imaged the upper 500 m of stratigraphy using peak frequency of 150 Hz and 6.25 m2 bin size. These data provided an exceptionally well-imaged example of shallow subsurface depositional system and stratigraphic architecture development during a lowstand period. The system evolved from a meandering channel with isolated point-bar deposits to a transgressive estuary characterized by dendritic erosional features that were eventually flooded. In addition, HR3D data have identified a previously unidentified seismically discontinuous zone interpreted to be a gas chimney system emanating from a tested (drilled) nonproductive, three-way structure in the lower Miocene (1.5 km depth). Within the shallowest intervals (〈100 m) and at the top of the chimney zone, seismic attribute analysis revealed several high-amplitude anomalies up to 0.5 km2. The anomalies were interpreted as reaccumulated thermogenic gas, and their distribution conforms to the stratigraphy and structure of the Quaternary interval, in that they occupy local fault-bounded footwall highs within remnant coarser-grained interfluvial zones, which are overlain by finer grained, transgressive deposits.
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  • 18
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    Differentiating tidal and groundwater dynamics from barrier island framework geology: Testing the utility of portable multifrequency electromagnetic induction profilers (2016)
    Society of Exploration Geophysicists
    In:  Geophysics, 81 (5). E347-E361.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: Electromagnetic induction (EMI) techniques are becoming increasingly popular for near-surface coastal geophysical applications. However, few studies have explored the capabilities and limitations of portable multifrequency EMI profilers for mapping large-scale (101–102 km) barrier island hydrogeology. The purpose of this study is to investigate the influence of groundwater dynamics on apparent conductivity σa to separate the effects of hydrology and geology from the σa signal. Shore-normal and alongshore surveys were performed within a highly conductive barrier island/wind-tidal flat system at Padre Island National Seashore, Texas, USA. Assessments of instrument calibration and signal drift suggest that σa measurements are stable, but vary with height and location across the beach. Repeatability tests confirm σa values using different boom orientations collected during the same day are reproducible. Measurements over a 12 h tidal cycle suggest that there is a tide-dependent step response in σa, complicating data processing and interpretation. Shore-normal surveys across the barrier/wind-tidal flats show that σa is roughly negatively correlated with topography and these relationships can be used for characterizing different coastal habitats. For all surveys, σa increases with decreasing frequency. Alongshore surveys performed during different seasons and beach states reveal a high degree of variability in σa. Here, it is argued that surveys collected during dry conditions characterize the underlying framework geology, whereas these features are somewhat masked during wet conditions. Differences in EMI signals should be viewed in a relative sense rather than as absolute magnitudes. Small-scale heterogeneities are related to changing hydrology, whereas low-frequency signals at the broadest scales reveal variations in framework geology. Multiple surveys should be done at different times of the year and tidal states before geologic interpretations can confidently be made from EMI surveys in coastal environments. This strategy enables the geophysicist to separate the effects of hydrology and geology from the σa signal.
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  • 19
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    Efficiency of fisheries is increasing at the ecosystem level (2016)
    Wiley-Blackwell
    In:  Fish and Fisheries, 18 (2). pp. 199-211.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: Managing fisheries presents trade-offs between objectives, for example yields, profits, minimizing ecosystem impact, that have to be weighed against one another. These trade-offs are compounded by interacting species and fisheries at the ecosystem level. Weighing objectives becomes increasingly challenging when managers have to consider opposing objectives from different stakeholders. An alternative to weighing incomparable and conflicting objectives is to focus on win–wins until Pareto efficiency is achieved: a state from which it is impossible to improve with respect to any objective without regressing at least one other. We investigate the ecosystem-level efficiency of fisheries in five large marine ecosystems (LMEs) with respect to yield and an aggregate measure of ecosystem impact using a novel calibration of size-based ecosystem models. We estimate that fishing patterns in three LMEs (North Sea, Barents Sea and Benguela Current) are nearly efficient with respect to long-term yield and ecosystem impact and that efficiency has improved over the last 30 years. In two LMEs (Baltic Sea and North East US Continental Shelf), fishing is inefficient and win–wins remain available. We additionally examine the efficiency of North Sea and Baltic Sea fisheries with respect to economic rent and ecosystem impact, finding both to be inefficient but steadily improving. Our results suggest the following: (i) a broad and encouraging trend towards ecosystem-level efficiency of fisheries; (ii) that ecosystem-scale win–wins, especially with respect to conservation and profits, may still be common; and (iii) single-species assessment approaches may overestimate the availability of win–wins by failing to account for trade-offs across interacting species.
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  • 20
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    Developing an Event-Tree Probabilistic Tsunami Inundation Model for NE Atlantic Coasts: Application to a Case Study (2016)
    Springer
    In:  Pure and Applied Geophysics, 173 (12). pp. 3775-3794.
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    Publikationsdatum: 2019-02-01
    Beschreibung: This study constitutes a preliminary assessment of probabilistic tsunami inundation in the NE Atlantic region. We developed an event-tree approach to calculate the likelihood of tsunami flood occurrence and exceedance of a specific near-shore wave height for a given exposure time. Only tsunamis of tectonic origin are considered here, taking into account local, regional, and far-field sources. The approach used here consists of an event-tree method that gathers probability models for seismic sources, tsunami numerical modeling, and statistical methods. It also includes a treatment of aleatoric uncertainties related to source location and tidal stage. Epistemic uncertainties are not addressed in this study. The methodology is applied to the coastal test-site of Sines located in the NE Atlantic coast of Portugal. We derive probabilistic high-resolution maximum wave amplitudes and flood distributions for the study test-site considering 100- and 500-year exposure times. We find that the probability that maximum wave amplitude exceeds 1 m somewhere along the Sines coasts reaches about 60 % for an exposure time of 100 years and is up to 97 % for an exposure time of 500 years. The probability of inundation occurrence (flow depth 〉0 m) varies between 10 % and 57 %, and from 20 % up to 95 % for 100- and 500-year exposure times, respectively. No validation has been performed here with historical tsunamis. This paper illustrates a methodology through a case study, which is not an operational assessment.
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  • 21
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    Mineral composition of tephra layers in the Quaternary deposits of the Sea of Okhotsk:: Heavy minerals associations and their geochemistry (2016)
    Springer
    In:  Geochemistry International, 54 (2). pp. 167-196.
    Details
    Publikationsdatum: 2020-11-04
    Beschreibung: Heavy mineral associations from tephra layers in the Quaternary deposits of the Sea of Okhotsk and their chemical characteristics were studied by various techniques. It was shown that such investigations may have a bearing on the problems of tephrostratigraphic correlation. We assessed the possibility of application of the mineral composition of distal tephra for identification and, in particular, estimation of the relation of tephras to the explosive volcanism of back-arc and frontal zones of island arcs. The investigation of the compositions of minerals and use of mineral geothermometers and geobarometers (two-pyroxene, magnetite–ilmenite, and amphibole) provided evidence on the physicochemical parameters of melt crystallization during the explosive volcanic eruptions that produced the distal tephra layers. It was established that the pyroclastic material of some tephra layers was supplied during explosive eruptions not only from shallow magma chambers but also from deeper and higher temperature reservoirs. Together with the geochemical signatures of volcanic glasses, the obtained results on mineral associations and the geochemistry of mineral inclusions are applicable for the comparative analysis and correlation of tephras from marine and continental sequences, as well as for the identification of explosive volcanic products in adjacent land areas.
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  • 22
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    Maintained functional diversity in benthic communities in spite of diverging functional identities (2016)
    Wiley-Blackwell
    In:  Oikos, 125 (10). pp. 1421-1433.
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    Publikationsdatum: 2020-10-26
    Beschreibung: Ecological studies based on time-series often investigate community changes centered on species abundance or biomass but rarely expose the consequential functional aspects underlying such changes. Functional diversity measures have proven to be more accurate predictors for ecosystem functioning than traditional taxonomic approaches and hence gained much attention. There are only limited studies available that analyse the functional implications behind decadal changes of entire communities. We studied zoobenthic communities of two habitats, sheltered and exposed, of a coastal system subject to contrasting changes in community composition over the past four decades. Besides eutrophication and climate-related impacts, the system has been invaded by a non-native polycheate Marenzelleria spp., adding altered functional properties to the communities. The functional dispersion (FDis) metric was used as a measure for comparing the functional diversity of the contrasting habitats, with special focus on the role of Marenzelleria for the entire communities. We highlight changes in the functional identity of the communities, expressed as community-weighted means of trait expression (CWM), using multivariate techniques, and investigate the relationship between taxonomic and functional changes. Despite contrasting community developments in the two habitats, with characteristics traditionally suggesting different environmental quality, we found that the FDis in both habitats remained similar and increased with the introduction of Marenzelleria. Although showing maintained functional diversity across time and space, the functional identity (CWM) of communities changed irrespective of taxonomical differences. Examples include inter alia alterations in palatability proxies, feeding position and sediment transportation types, indicating changed functionality of zoobenthos in coastal systems. We show, when focussing on qualitative functional changes of communities, it is important to evaluate the underlying functional identity, and not only rely on measures of the diversity of functions per se, as the quality indication of expressed functional traits can be concealed when using multi-functionality approaches.
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  • 23
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    Thermal small-steps staircase and layer migration in the Atlantis II Deep, Red Sea (2016)
    Springer
    In:  Arabian Journal of Geosciences, 9 (392).
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    Publikationsdatum: 2019-02-01
    Beschreibung: Atlantis II Deep, a submarine basin of the Red Sea, is noteworthy because of its hydrothermally active brine pools. High-resolution temperature records from Poseidon Cruise during February 2011 revealed small steps thermal staircase in the lower transition zone from ≈2002 to 2008/2009 m depth at stations. Four vertically well-mixed convective layers, lower convective layer (LCL) and upper convective layers (UCL1–3), separated by high-temperature gradients at the interfaces were observed. The temperature of the layers UCL1–3 has dropped between 2008 and 2011. The top of UCL3 extends to about 2008/2009 m at stations and its average thickness has increased from 3.3 ± 0.5 m in 1992 to 7 m in 2011, whereas the thickness of layers UCL1–2 has decreased from 25.2 ± 0.3 m to 19.8 m and from 16.4 ± 0.5 m to 14.7 m, respectively, during this time. The upward buoyancy flux is 0.032 to 0.038 × 10−7 m2 s−3 which gives migration speed of UCL3 layer from 0.1 to 0.12 m year−1. With this speed, the thermal staircase ≈6 m thick will merge with UCL3 in 50 to 60 years increasing the thickness from 7 m to nearly 13 m.
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  • 24
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    Are genetic databases sufficiently populated to detect non-indigenous species? (2016)
    Springer
    In:  Biological Invasions, 18 (7). pp. 1911-1922.
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    Publikationsdatum: 2019-02-01
    Beschreibung: Correct species identifications are of tremendous importance for invasion ecology, as mistakes could lead to misdirecting limited resources against harmless species or inaction against problematic ones. DNA barcoding is becoming a promising and reliable tool for species identifications, however the efficacy of such molecular taxonomy depends on gene region(s) that provide a unique sequence to differentiate among species and on availability of reference sequences in existing genetic databases. Here, we assembled a list of aquatic and terrestrial non-indigenous species (NIS) and checked two leading genetic databases for corresponding sequences of six genome regions used for DNA barcoding. The genetic databases were checked in 2010, 2012, and 2016. All four aquatic kingdoms (Animalia, Chromista, Plantae and Protozoa) were initially equally represented in the genetic databases, with 64, 65, 69, and 61 % of NIS included, respectively. Sequences for terrestrial NIS were present at rates of 58 and 78 % for Animalia and Plantae, respectively. Six years later, the number of sequences for aquatic NIS increased to 75, 75, 74, and 63 % respectively, while those for terrestrial NIS increased to 74 and 88 % respectively. Genetic databases are marginally better populated with sequences of terrestrial NIS of plants compared to aquatic NIS and terrestrial NIS of animals. The rate at which sequences are added to databases is not equal among taxa. Though some groups of NIS are not detectable at all based on available data—mostly aquatic ones—encouragingly, current availability of sequences of taxa with environmental and/or economic impact is relatively good and continues to increase with time.
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  • 25
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    Joint stochastic constraint of a large data set from a salt dome (2016)
    Society of Exploration Geophysicists
    In:  Geophysics, 81 (2). ID1-ID24.
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    Publikationsdatum: 2019-02-01
    Beschreibung: Understanding the uncertainty associated with large joint geophysical surveys, such as 3D seismic, gravity, and magnetotelluric (MT) studies, is a challenge, conceptually and practically. By demonstrating the use of emulators, we have adopted a Monte Carlo forward screening scheme to globally test a prior model space for plausibility. This methodology means that the incorporation of all types of uncertainty is made conceptually straightforward, by designing an appropriate prior model space, upon which the results are dependent, from which to draw candidate models. We have tested the approach on a salt dome target, over which three data sets had been obtained; wide-angle seismic refraction, MT and gravity data. We have considered the data sets together using an empirically measured uncertain physical relationship connecting the three different model parameters: seismic velocity, density, and resistivity, and we have indicated the value of a joint approach, rather than considering individual parameter models. The results were probability density functions over the model parameters, together with a halite probability map. The emulators give a considerable speed advantage over running the full simulator codes, and we consider their use to have great potential in the development of geophysical statistical constraint methods.
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  • 26
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    Trematodes on acid: editorial comment on the feature article by Guilloteau et al. (2016)
    Springer
    In:  Marine Biology, 163 (5). Article Nr. 95.
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    Publikationsdatum: 2019-02-01
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  • 27
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    Shear-wave velocity structure of the shallow sediments in the Bohai Sea from an ocean-bottom-seismometer survey (2016)
    Society of Exploration Geophysicists
    In:  Geophysics, 81 (3). ID25-ID36.
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    Publikationsdatum: 2019-02-01
    Beschreibung: To investigate the seismic velocity structure of the shallow sediments in the Bohai Sea of China, we conducted a shearwave velocity inversion of the surface-wave dispersion data from a survey of 12 ocean-bottom seismometers (OBSs) and 377 shots of a 9000 in3 air gun. With OBS station spacing of approximately 5 km and air-gun shot spacing of approximately 190 m, high-quality Scholte-wave data were recorded by the OBSs within 0.4–5 km offset. We retrieved the Scholtewave phase-velocity dispersion for the fundamental mode and first overtone in the frequency band of 0.9–3.0 Hz with the phase-shift method and inverted for the shear-wave velocity structure of the shallow sediments with a damped iterative least-squares algorithm. Pseudo-2D shear-wave velocity profiles with a depth of approximately 400 m revealed coherent features of relatively weak lateral velocity variation. We also estimated the uncertainty in shear-wave velocity structure based on the pseudo-2D profiles from six trial inversions with different initial models, which suggested a velocity uncertainty less than 30 m∕s for most parts of the 2D profiles. The layered structure with little lateral variation may be attributable to the continuous sedimentary environment in the Cenozoic sedimentary basin of the Bohai Bay basin. The shear-wave velocity of 200–300 m∕s in the top 100 m of the Bohai seafloor may provide important information for offshore site response studies in earthquake engineering. Furthermore, the very low shear-wave velocity structure (150–600 m∕s) down to 400 m depth could produce a significant traveltime delay of approximately 1 s in the shear-wave arrivals, which needs to be considered to avoid serious bias in shear-wave traveltime tomographic models.
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  • 28
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    Climatic and societal impacts of a volcanic double event at the dawn of the Middle Ages (2016)
    Springer
    In:  Climatic Change, 136 (3-4). pp. 401-412.
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    Publikationsdatum: 2019-02-01
    Beschreibung: Volcanic activity in and around the year 536 CE led to severe cold and famine, and has been speculatively linked to large-scale societal crises around the globe. Using a coupled aerosol-climate model, with eruption parameters constrained by recently re-dated ice core records and historical observations of the aerosol cloud, we reconstruct the radiative forcing resulting from a sequence of two major volcanic eruptions in 536 and 540 CE. We estimate that the decadal-scale Northern Hemisphere (NH) extra-tropical radiative forcing from this volcanic “double event” was larger than that of any period in existing reconstructions of the last 1200 years. Earth system model simulations including the volcanic forcing show peak NH mean temperature anomalies reaching more than −2 °C, and show agreement with the limited number of available maximum latewood density temperature reconstructions. The simulations also produce decadal-scale anomalies of Arctic sea ice. The simulated cooling is interpreted in terms of probable impacts on agricultural production in Europe, and implies a high likelihood of multiple years of significant decreases in crop production across Scandinavia, supporting the theory of a connection between the 536 and 540 eruptions and evidence of societal crisis dated to the mid-6th century.
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  • 29
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    Expelled subsalt fluids form a pockmark field in the eastern Red Sea (2016)
    Springer
    In:  Geo-Marine Letters, 36 (5). pp. 339-352.
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    Publikationsdatum: 2019-02-01
    Beschreibung: This study aimed to constrain the source area of fluids responsible for the formation of a pockmark field in the eastern Red Sea. The newly discovered field extends over an area of at least 1,000 km2 at a water depth of ~400 m. The pockmarks have modal diameters of 140–150 m and are either randomly distributed on the seafloor or aligned within valleys approximately 25 m deep and several kilometres in length. Seismic data show that chimneys and/or regions of acoustic turbidity prevail beneath the pockmark field down to the top of Miocene evaporites, which are widespread in the Red Sea. Four gravity cores were taken from the pockmark field. For most of the cores, geochemical analyses show that porewater has a higher Cl concentration than the local seawater and increased Cl/Br ratios, which indicate an origin from evaporites. The adsorbed hydrocarbons are of thermal origin, with C1/(C2+C3) ratios between 4 and 23 and stable carbon isotope data for methane varying from δ13C of –34 to –36.4‰ with respect to Vienna Pee Dee Belemnite. On the basis of the calculated maturity of the source rock of 1.2–1.4 Ro, local thermal gradients and sedimentation rates, its deeper depth boundary is approximated at 2,000 to 2,200 m. The results indicate that the adsorbed hydrocarbons sampled at the seafloor had to pass through an evaporite sequence of potentially several hundred metres to a few km in thickness. The most likely explanation for the increased permeability of the evaporite sequence is brittle deformation triggered by extensive local tectonic movements and supported by high fluid overpressure within the evaporite sequence.
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  • 30
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    Constraints on the magmatic evolution of the oceanic crust from plagiogranite intrusions in the Oman ophiolite (2016)
    Springer
    In:  Contributions to Mineralogy and Petrology, 171 ( Art.No. 46).
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    Publikationsdatum: 2019-02-01
    Beschreibung: We present major and trace element as well as Sr, Nd, and Hf isotope data on a suite of 87 plutonic rock samples from 27 felsic crustal intrusions in seven blocks of the Oman ophiolite. The rock compositions of the sample suite including associated more mafic rocks range from 48 to 79 wt% SiO2, i.e. from gabbros to tonalites. The samples are grouped into a Ti-rich and relatively light rare earth element (LREE)-enriched P1 group [(Ce/Yb)N 〉 0.7] resembling the early V1 lavas, and a Ti-poor and LREE-depleted P2 group [(Ce/Yb)N 〈 0.7] resembling the late-stage V2 lavas. Based on the geochemical differences and in agreement with previous structural and petrographic models, we define phase 1 (P1) and phase 2 (P2) plutonic rocks. Felsic magmas in both groups formed by extensive fractional crystallization of olivine, clinopyroxene, plagioclase, apatite, and Ti-magnetite from mafic melts. The incompatible element compositions of P1 rocks overlap with those from mid-ocean ridges but have higher Ba/Nb and Th/Nb trending towards the P2 rock compositions and indicating an influence of a subducting slab. The P2 rocks formed from a more depleted mantle source but show a more pronounced slab signature. These rocks also occur in the southern blocks (with the exception of the Tayin block) of the Oman ophiolite implying that the entire ophiolite formed above a subducting slab. Initial Nd and Hf isotope compositions suggest an Indian-MORB-type mantle source for the Oman ophiolite magmas. Isotope compositions and high Th/Nb in some P2 rocks indicate mixing of a melt from subducted sediment into this mantle.
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  • 31
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    Investigation of the atmospheric mechanisms related to the autumn sea ice and winter circulation link in the Northern Hemisphere (2016)
    Springer
    In:  Climate Dynamics, 46 (3-4). pp. 1185-1195.
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    Publikationsdatum: 2019-02-01
    Beschreibung: The relationship of Barents-Kara sea ice concentration in October and November with atmospheric circulation in the subsequent winter is examined using reanalysis and observational data. The analyses are performed on data with the 5-year running means removed to reduce the potential effects of slowly-varying external driving factors, such as global warming. We show that positive (negative) Barents-Kara sea ice concentration anomaly in autumn is associated with a positive (negative) North Atlantic Oscillation-like (NAO) pattern with lags of up to 3 months. The month-to-month variations in the lag relationships of the atmospheric anomalies related to November sea ice concentration are presented. Further analysis shows that the stratosphere-troposphere interaction may provide the memory in the system: positive (negative) sea ice concentration anomaly in November is associated with a strengthened (weakened) stratospheric polar vortex and these anomalies propagate downward leading to the positive (negative) NAO-like pattern in the late December to early January. This stratosphere mechanism may also play a role for Barents-Kara sea ice anomaly in December, but not for September and October. Consistently, Eliassen-Palm, eddy heat and momentum fluxes suggest that there is strong forcing of the zonal winds in November.
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  • 32
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    Temporal dietary shift in jellyfish revealed by stable isotope analysis (2016)
    Springer
    In:  Marine Biology, 163 (5, 112). pp. 1-9.
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    Publikationsdatum: 2019-09-23
    Beschreibung: A temporal change in the stable isotope (SI) composition of jellyfish in the Kiel Fjord, Western Baltic Sea, was documented by analyzing δ13C, δ15N and δ34S of bell tissue of Aurelia aurita and Cyanea capillata in the period between June and October 2011. A strong and significant temporal change in all SI values of A. aurita was found, including an increase of ~3 ‰ in δ13C, a decrease of ~4 ‰ in δ15N and sharp decline of ~7 ‰ in δ34S. While knowledge gaps in jellyfish isotope ecology, in particular the lack of reliable trophic enrichment factors, call for a conservative interpretation of our data, observed changes in particular in δ34S, as indicated by means of a MixSIR mixing model, would be consistent with a temporal dietary shift in A. aurita from mesozooplankton (〉150 µm) to microplankton and small re-suspended particles (0.8–20 µm) from the benthos. Presence of a hitherto unidentified food source not included in the model could also contribute to the shift. During the 2-month occurrence of C. capillata, its isotope composition remained stable and was consistent with a mainly mesozooplanktonic diet. Mixing model output, mainly driven by δ34S values, indicated a lower proportion of A. aurita in the diet of C. capillata than previously reported, and thus to a potentially lesser importance of intraguild predation among jellyfish in the Kiel Fjord. Overall, our results clearly highlighted the potential for substantial intraspecific isotopic seasonal variation in jellyfish, which should be taken into account in future feeding ecology studies on this group.
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  • 33
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    Selection of heat-shock resistance traits during the invasion of the seaweed Gracilaria vermiculophylla (2016)
    Springer
    In:  Marine Biology, 163 (5). Article Nr. 104.
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    Publikationsdatum: 2019-02-01
    Beschreibung: Most macroalgae and other aquatic organisms feature life cycles without a stage of dormancy and elevated stress resistance that is comparable to plant seeds. During anthropogenic transportation, they are therefore probably more exposed to stress than plant invaders, which could result in a more rigorous selection of stress-resistant phenotypes. However, selection of stress resistance during invasion processes of aquatic organisms has rarely been studied. We therefore compared the responses of native and non-native populations of the seaweed Gracilaria vermiculophylla to heat shock in common garden-type experiments. Specimens from six native populations in East Asia and from eight non-native populations in Europe and on the Mexican Pacific coast were acclimated to two sets of identical conditions before their resistance to heat shock was examined. The experiments were carried out twice—one time in the native range in Qingdao, China, and one time in the invaded range in Kiel, Germany—to rule out effects of specific local conditions. In both testing sites the non-native populations survived heat shock significantly better than the native populations. After three hours of heat shock G. vermiculophylla exhibited increased levels of heat-shock protein 70 (HSP70) and of a specific isoform of haloperoxidase, suggesting that both enzymes could be required for heat-shock stress management. However, the elevated resistance toward heat shock of non-native populations only correlated with an increased constitutive expression of heat-shock protein 70 (HSP70). The haloperoxidase isoform was more prominent in native populations, suggesting that not only increased HSP70 expression, but also reduced allocation into haloperoxidase expression after heat shock was selected during the invasion history. This selection probably happened early because the same combination of traits was detected in all realms within the non-native range.
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  • 34
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    Thermal stress markers in Colpophyllia natans provide an archive of site-specific bleaching events (2016)
    Springer
    In:  Coral Reefs, 35 (1). pp. 181-186.
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    Publikationsdatum: 2019-02-01
    Beschreibung: Tropical coral reef monitoring relies heavily on in situ diver observations. However, in many reef regions resources are not available to regularly monitor reefs. This lack of historical baseline data makes it difficult to determine how different reefs respond to environmental stressors and what the implications are for management. To test whether coral cores could be used to identify bleaching events retrospectively, three sites in Tobago with pre-existing reef data including water quality and bleaching observations were identified. Colpophyllia natans cores were examined for growth anomalies which occurred during periods of thermal stress. If present, anomalies were compared to in situ, real-time bleaching observations and water quality data. Interestingly, sites with better water quality during the 2005 thermal anomaly were less prone to bleaching. We suggest that by reducing terrestrial run-off (e.g., sediment and nutrients), and therefore improving marine water quality, reef managers could enhance near-shore coral reef resilience during high-temperature events.
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  • 35
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    Bridging the gap between omics and earth system science to better understand how environmental change impacts marine microbes (2016)
    Wiley-Blackwell
    In:  Global Change Biology, 22 (1). pp. 61-75.
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    Publikationsdatum: 2020-07-30
    Beschreibung: The advent of genomic-, transcriptomic- and proteomic-based approaches has revolutionized our ability to describe marine microbial communities, including biogeography, metabolic potential and diversity, mechanisms of adaptation, and phylogeny and evolutionary history. New interdisciplinary approaches are needed to move from this descriptive level to improved quantitative, process-level understanding of the roles of marine microbes in biogeochemical cycles and of the impact of environmental change on the marine microbial ecosystem. Linking studies at levels from the genome to the organism, to ecological strategies and organism and ecosystem response, requires new modelling approaches. Key to this will be a fundamental shift in modelling scale that represents micro-organisms from the level of their macromolecular components. This will enable contact with omics data sets and allow acclimation and adaptive response at the phenotype level (i.e. traits) to be simulated as a combination of fitness maximization and evolutionary constraints. This way forward will build on ecological approaches that identify key organism traits and systems biology approaches that integrate traditional physiological measurements with new insights from omics. It will rely on developing an improved understanding of ecophysiology to understand quantitatively environmental controls on microbial growth strategies. It will also incorporate results from experimental evolution studies in the representation of adaptation. The resulting ecosystem-level models can then evaluate our level of understanding of controls on ecosystem structure and function, highlight major gaps in understanding and help prioritize areas for future research programs. Ultimately, this grand synthesis should improve predictive capability of the ecosystem response to multiple environmental drivers.
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  • 36
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    Genotypic variation in tolerance to warming and acidification of early life-stage Fucus vesiculosus L. (Phaeophyceae) in a seasonally fluctuating environment (2016)
    Springer
    In:  Marine Biology, 163 (14). pp. 1-15.
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    Publikationsdatum: 2019-09-23
    Beschreibung: Global change exposes brown algal Fucus vesiculosus populations to increasing temperature and pCO2, which may threaten individuals, in particular the early life-stages. Genetic diversity of F. vesiculosus populations is low in the Baltic compared to Atlantic populations. This might jeopardise their potential for adaptation to environmental changes. Here, we report on the responses of early life-stage F. vesiculosus to warming and acidification in a near-natural scenario maintaining natural and seasonal variation (spring 2013–2014) of the Kiel Fjord in the Baltic Sea, Germany (54°27ʹN, 10°11ʹW). We assessed how stress sensitivity differed among sibling groups and how genetic diversity of germling populations affected their stress tolerance. Warming increased growth rates of Fucus germlings in spring and in early summer, but led to higher photoinhibition in spring and decreased their survival in late summer. Acidification increased germlings’ growth in summer but otherwise showed much weaker effects than warming. During the colder seasons (autumn and winter), growth was slow while survival was high compared to spring and summer, all at ambient temperatures. A pronounced variation in stress response among genetically different sibling groups (full-sib families) suggests a genotypic basis for this variation and thus a potential for adaptation for F. vesiculosus populations to future conditions. Corroborating this, survival in response to warming in populations with higher diversity was better than the mean survival of single sibling groups. We conclude that impacts on early life-stages depend on the combination of stressors and season and that genetic variation is crucial for the tolerance to global change stress.
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  • 37
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    Temperature effects on seaweed-sustaining top-down control vary with season (2016)
    Springer
    In:  Oecologia, 180 (3). pp. 889-901.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: Rising seawater temperature and CO2 concentrations (ocean acidification) represent two of the most influential factors impacting marine ecosystems in the face of global climate change. In ecological climate change research, full-factorial experiments performed across seasons in multispecies, cross-trophic-level settings are essential as they permit a more realistic estimation of direct and indirect effects as well as the relative importance of the effects of both major environmental stressors on ecosystems. In benthic mesocosm experiments, we tested the responses of coastal Baltic Sea Fucus vesiculosus communities to elevated seawater temperature and CO2 concentrations across four seasons of one year. While increasing [CO2] levels had only minor effects, warming had strong and persistent effects on grazers, and the resulting effects on the Fucus community were found to be season dependent. In late summer, a temperature-driven collapse of grazers caused a cascading effect from the consumers to the foundation species, resulting in overgrowth of Fucus thalli by epiphytes. In fall/winter (outside the growing season of epiphytes), intensified grazing under warming resulted in a significant reduction in Fucus biomass. Thus, we were able to confirm the prediction that future increases in water temperatures will influence marine food-web processes by altering top-down control, but we were also able to show that specific consequences for food-web structure depend on the season. Since F. vesiculosus is the dominant habitat-forming brown algal system in the Baltic Sea, its potential decline under global warming implies a loss of key functions and services such as provision of nutrient storage, substrate, food, shelter, and nursery grounds for a diverse community of marine invertebrates and fish in Baltic Sea coastal waters.
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  • 38
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    Correcting North Atlantic Sea Surface Salinity Biases in the Kiel Climate Model: Influences on Ocean Circulation and Atlantic Multidecadal Variability (2016)
    Springer
    In:  Climate Dynamics, 47 (7). pp. 2543-2560.
    Details
    Publikationsdatum: 2020-11-23
    Beschreibung: A long-standing problem in climate models is the large sea surface salinity (SSS) biases in the North Atlantic. In this study, we describe the influences of correcting these SSS biases on the circulation of the North Atlantic as well as on North Atlantic sector mean climate and decadal to multidecadal variability. We performed integrations of the Kiel Climate Model (KCM) with and without applying a freshwater flux correction over the North Atlantic. The quality of simulating the mean circulation of the North Atlantic Ocean, North Atlantic sector mean climate and decadal variability is greatly enhanced in the freshwater flux-corrected integration which, by definition, depicts relatively small North Atlantic SSS biases. In particular, a large reduction in the North Atlantic cold sea surface temperature bias is observed and a more realistic Atlantic Multidecadal Variability simulated. Improvements relative to the non-flux corrected integration also comprise a more realistic representation of deep convection sites, sea ice, gyre circulation and Atlantic Meridional Overturning Circulation. The results suggest that simulations of North Atlantic sector mean climate and decadal variability could strongly benefit from alleviating sea surface salinity biases in the North Atlantic, which may enhance the skill of decadal predictions in that region.
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  • 39
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    Chemical characterization and quantification of the brown algal storage compound laminarin — A new methodological approach (2016)
    Springer
    In:  Journal of Applied Phycology, 28 (1). pp. 533-543.
    Details
    Publikationsdatum: 2019-08-06
    Beschreibung: The polysaccharide laminarin (β-1,3-glucan) is used as a long-term carbon storage compound in brown algae. This chemical storage form of carbon enables perennial brown algae in seasonally fluctuating ecosystems to uncouple growth from photosynthesis, i.e., most of these plants grow as seasonal anticipators in winter based on remobilization of laminarin, while in summer, growth typically ceased to fill up the storage pool. Because of this high ecological relevance, a reliable and precise method for determination and quantification of laminarin is needed. Therefore, a simple, efficient, cold water extraction method coupled to a new quantitative liquid chromatography-mass spectrometrical method (LC-MS) was developed. Laminarin was determined in 9 out of 12 brown algal species, and its expected typical molar mass distribution of 2000–7000 Da was confirmed. Furthermore, laminarin consisted of a complex mixture of different chemical forms, since 15 chemical laminarin species with distinct molecular weights were measured in 9 species of brown algae. Differences in chain length and number of laminarin species seem to be species specific and hence may indicate some chemotaxonomic value. Laminarin concentrations in the algal tissues ranged from 0.03 to 0.86 % dry weight (DW). The direct chemical characterization and quantification of laminarin by LC-MS represents a powerful method to verify the biochemical and ecological importance of laminarin for brown algae.
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  • 40
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    On the distribution of a coccinellid, Coccinella fulgida Brown (Coleoptera, Coccinellidae) in Notheast Asia (2016)
    Springer
    In:  (In Press / Accepted) Entomological Review .
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    Publikationsdatum: 2016-01-18
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  • 41
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    Diversity and antimicrobial potential of bacterial isolates associated with the soft coral Alcyonium digitatum from the Baltic Sea (2016)
    Springer
    In:  Antonie van Leeuwenhoek International Journal of General and Molecular Microbiology, 109 (1). pp. 105-119.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: It is well recognized that microorganisms associated with marine invertebrates, in particular sponges and hard corals, are an excellent source of new natural products. Therefore, the diversity of bacteria associated with marine invertebrates and their potential to produce bioactive compounds have received much attention in recent years. We report here for the first time on the biodiversity of bacteria associated with the soft coral Alcyonium digitatum, which is abundant in the Baltic Sea. In order to increase the cultured diversity, bacteria were isolated using four different media, identified with support of 16S rRNA gene sequences and screened for antimicrobial activity using two different media. Activity of crude extracts was tested against Bacillus subtilis, Staphylococcus epidermidis, Escherichia coli, and the yeast Candida albicans. A total of 251 coral-associated bacterial isolates were classified and found to belong to 41 species in 14 genera of the Firmicutes, Actinobacteria, Gammaproteobacteria, and Alphaproteobacteria. The genus Bacillus was most abundant and diverse with 17 recognized species. Forty-eight percent of all 251 isolates exhibited antimicrobial activity. All isolates of Bacillus methylotrophicus and Bacillus amyloliquefaciens displayed inhibition of at least three out of the four tested microorganisms. It became obvious during this study that the production of antibiotic substances not only is strain-specific, but in many cases also depends on the media composition and growth conditions. In addition, the antimicrobial potential of bacteria associated with A. digitatum may represent a promising source for antimicrobial substances.
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  • 42
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    Fluid venting and seepage at accretionary ridges: the Four Way Closure Ridge offshore SW Taiwan (2016)
    Springer
    In:  Geo-Marine Letters, 36 (3). pp. 165-174.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: Within the accretionary prism offshore SW Taiwan, widespread gas hydrate accumulations are postulated to occur based on the presence of a bottom simulating reflection. Methane seepage, however, is also widespread at accretionary ridges offshore SW Taiwan and may indicate a significant loss of methane bypassing the gas hydrate system. Four Way Closure Ridge, located in 1,500 m water depth, is an anticlinal ridge that would constitute an ideal trap for methane and consequently represents a site with good potential for gas hydrate accumulations. The analysis of high-resolution bathymetry, deep-towed sidescan sonar imagery, high-resolution seismic profiling and towed video observations of the seafloor shows that Four Way Closure Ridge is and has been a site of intensive methane seepage. Continuous seepage is mainly evidenced by large accumulations of authigenic carbonate precipitates, which appear to be controlled by the creation of fluid pathways through faulting. Consequently, Four Way Closure Ridge is not a closed system in terms of fluid migration and seepage. A conceptual model of the evolution of gas hydrates and seepage at accretionary ridges suggests that seepage is common and may be a standard feature during the geological development of ridges in accretionary prisms. The observation of seafloor seepage alone is therefore not a reliable indicator of exploitable gas hydrate accumulations at depth.
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  • 43
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    Temperature-driven changes in early life-history stages influence the Gulf of Riga spring spawning herring (Clupea harengus m.) recruitment abundance (2016)
    Springer
    In:  Hydrobiologia, 767 (1). pp. 125-135.
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    Publikationsdatum: 2019-08-06
    Beschreibung: Processes occurring during early life-history stages influence the year-class abundance of marine fish. We found that the abundance of 1-year-old spring spawning herring is statistically significantly determined by the number of post-flexion herring larvae in the Gulf of Riga (Baltic Sea). The abundance of consecutive developmental stages of larvae: yolk-sac, pre-flexion, flexion and post-flexion strongly correlated with each other, indicating that factors which already influence the yolk-sac stage are important in determining the abundance of post-flexion herring larvae. Winter air temperature before spawning determined the timing of maximum abundance of pre-flexion herring larvae, but not their main prey: copepod nauplii, implying that different mechanisms governing major preconditions for the formation of year-class strength. The abundance of post-flexion larvae displayed a potential dome-shaped relationship with sea surface temperature experienced after hatching. We suggest that increased summer temperatures, which exceed the physiological optimum negatively, affect the survival of post-flexion herring larvae. Overall, future climate warming poses an additional risk to larval herring survival and this may lead to a reduction in those herring stock which rely on recruitment from shallow coastal areas.
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  • 44
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    Food availability in an anthropogenically impacted habitat determines tolerance to hypoxia in the Asian green mussel Perna viridis (2016)
    Springer
    In:  Marine Biology, 163 (15). pp. 1-15.
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    Publikationsdatum: 2019-02-01
    Beschreibung: The Asian green mussel Perna viridis is tolerant to environmental stress, but its robustness varies between populations from habitats that differ in quality. So far, it is unclear whether local adaptations through stress-induced selection or phenotypic plasticity are responsible for these inter-population differences. We tested for the relevance of both mechanisms by comparing survival under hypoxia in mussels that were transplanted from an anthropogenically impacted (Jakarta Bay, Indonesia) to a natural habitat (Lada Bay, Indonesia) and vice versa. Mussels were retrieved 8 weeks after transplantation and exposed to hypoxia in the laboratory. Additional hypoxia tests were conducted with juvenile mussels collected directly from both sites. To elucidate possible relationships between habitat quality and mussel tolerance, we monitored concentrations of inorganic nutrients, temperature, dissolved oxygen, salinity, phytoplankton density and the mussels’ body condition index (BCI) for 20 months before, during and after the experiments. Survival under hypoxia depended mainly on the quality of the habitat where the mussels lived before the hypoxia tests and only to a small degree on their site of origin. Furthermore, stress tolerance was only higher in Jakarta than in Lada Bay mussels when the BCIs were substantially higher, which in turn correlated with the phytoplankton densities. We explain why phenotypic plasticity and high BCIs are more likely the causes of population-specific differences in hypoxia tolerance in P. viridis than stress-induced selection for robust genotypes. This is relevant to understanding the role of P. viridis as mariculture organism in eutrophic ecosystems and invasive species in the (sub)tropical world.
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  • 45
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    Image Based Geo-localization in the Alps (2016)
    Springer
    In:  International Journal of Computer Vision, 116 (3). pp. 213-225.
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    Publikationsdatum: 2019-02-01
    Beschreibung: Given a picture taken somewhere in the world, automatic geo-localization of such an image is an extremely useful task especially for historical and forensic sciences, documentation purposes, organization of the world’s photographs and intelligence applications. While tremendous progress has been made over the last years in visual location recognition within a single city, localization in natural environments ismuch more difficult, since vegetation, illumination, seasonal changes make appearance-only approaches impractical. In this work, we target mountainous terrain and use digital elevationmodels to extract representations for fast visual database lookup. We propose an automated approach for very large scale visual localization that can efficiently exploit visual information (contours) and geometric constraints (consistent orientation) at the same time.We validate the system at the scale of Switzerland (40,000 km2) using over 1000 landscape query images with ground truth GPS position.
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  • 46
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    Linking SO2 emission rates and seismicity by continuous wavelet transform: implications for volcanic surveillance at San Cristóbal volcano, Nicaragua (2016)
    Springer
    In:  International Journal of Earth Sciences, 105 (5). pp. 1453-1465.
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    Publikationsdatum: 2019-09-23
    Beschreibung: San Cristóbal volcano is the highest and one of the most active volcanoes in Nicaragua. Its persistently high activity during the past decade is characterized by strong degassing and almost annual VEI 1–2 explosions, which present a threat to the local communities. Following an eruption on 8 September 2012, the intervals between eruptions decreased significantly, which we interpret as the start of a new eruptive phase. We present here the results of semi-continuous SO2 flux measurements covering a period of 18 months, obtained by two scanning UV-DOAS instruments installed as a part of the network for observation of volcanic and atmospheric change project, and the results of real-time seismic amplitude measurements (RSAM) data. Our data comprise a series of small to moderately explosive events in December 2012, June 2013 and February 2014, which were accompanied by increased gas emissions and seismicity. In order to approach an early warning strategy, we present a statistical method for the joint analysis of gas flux and seismic data, by using continuous wavelet transform and cross-wavelet transform (XWT) methods. This analysis shows that the XWT coefficients of SO2 flux and RSAM are in good agreement with the occurrence of eruptive events and thus may be used to indicate magma ascent into the volcano edifice. Such multi-parameter surveillance efforts can be useful for the interpretation and surveillance of possible eruptive events and could thus be used by local institutions for the prediction of upcoming volcanic unrest.
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  • 47
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    Effects of using inclined parametric echosounding on sub-bottom acoustic imaging and advances in buried object detection (2016)
    Springer
    In:  Geo-Marine Letters, 36 (2). pp. 113-119.
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    Publikationsdatum: 2019-09-23
    Beschreibung: This study reports an adaptation of a parametric echosounder system using 15 kHz as secondary frequency to investigate the angular response of sub-bottom backscatter strength of layered mud, providing a new method for enhanced acoustic detection of buried targets. Adaptions to achieve both vertical (0°) and non-vertical inclination (1– 15°, 30°, 45° and 60°) comprise mechanical tilting of the acoustic transducer and electronic beam steering. Data were acquired at 18 m water depth at a study site characterized by a flat, muddy seafloor where a 0.1 m diameter power cable lies 1–2 m below the seafloor. Surveying the cable with vertical incidence revealed that the buried cable can hardly be discriminated against the backscatter strength of the layered mud. However, the backscatter strength of layered mud decreases strongly at 〉3±0.5° incidence and the layered mud echo pattern vanishes beyond 5°. As a consequence, the backscatter pattern of the buried cable is very pronounced in acoustic images gathered at 15°, 30°, 45° and 60° incidence. The size of the cable echo pattern increases linearly with incidence. These effects are attributed to reflection loss from layered mud at larger incidence and to the scattering of the 0.1 m diameter buried cable. Data analyses support the visual impression of superior detection of the cable with an up to 2.6-fold increase of the signal-to-noise ratio at 40° incidence compared to the vertical incidence case.
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  • 48
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    Effects of dietary purified rapeseed protein concentrate on hepatic gene expression in juvenile turbot (Psetta maxima) (2016)
    Wiley-Blackwell
    In:  Aquaculture Nutrition, 22 (1). pp. 170-180.
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    Publikationsdatum: 2019-02-01
    Beschreibung: Despite considerable progress in the production of alternative diets, small concentrations of antinutrients remain common in aquaculture nutrition, resulting in a perpetual limitation with regard to the inclusion of plant ingredients in aquafeeds. These compounds are known to impair the general performance of fish when fed for a prolonged period of time, potentially affecting the animal's susceptibility to stress, too. Therefore, a 12-week feeding trial was conducted to examine the chronic effects of purified rapeseed protein concentrate (RPC), containing low concentrations of glucosinolates and phytic acid, on the relative expression of multiple target genes in the liver of juvenile turbot (Psetta maxima, L.). Our results revealed divergent patterns of gene expression, suggesting different coping strategies dependent on the grade of RPC substitution. Data implies increased metabolic rate of turbot fed a 33% RPC-substituted diet due to an upregulation of cytochrome c oxidase mRNA, accompanied by minor adjustments in metabolic pathways. While no signs of reduced welfare were found, data adumbrate a beneficial hormetic reaction. In the highest treatment level (66% RPC), diminished fish condition and reduced growth performance coincided with a downregulation of insulin-like growth factor I, further indicating a potential impaired resistance to stress. An additional downregulation of transferrin hints towards an increased liability to bacterial infections.
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  • 49
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    Multiyear predictability of Northern Hemisphere surface air temperature in the Kiel Climate Model (2016)
    Springer
    In:  Climate Dynamics, 47 (3). pp. 793-804.
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    Publikationsdatum: 2019-02-01
    Beschreibung: The multiyear predictability of Northern Hemisphere surface air temperature (SAT) is examined in a multi-millennial control integration of the Kiel Climate Model, a coupled ocean–atmosphere–sea ice general circulation model. A statistical method maximizing average predictability time (APT) is used to identify the most predictable SAT patterns in the model. The two leading APT modes are much localized and the physics are discussed that give rise to the enhanced predictability of SAT in these limited regions. Multiyear SAT predictability exists near the sea ice margin in the North Atlantic and mid-latitude North Pacific sector. Enhanced predictability in the North Atlantic is linked to the Atlantic Multidecadal Oscillation and to the sea ice changes. In the North Pacific, the most predictable SAT pattern is characterized by a zonal band in the western and central mid-latitude Pacific. This pattern is linked to the Pacific Decadal Oscillation, which drives sea surface temperature anomalies. The temperature anomalies subduct into deeper ocean layers and re-emerge at the sea surface during the following winters, providing multiyear memory. Results obtained from the Coupled Model Intercomparison Project Phase 5 ensemble yield similar APT modes. Overall, the results stress the importance of ocean dynamics in enhancing predictability in the atmosphere.
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  • 50
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    Troposphere–stratosphere response to large-scale North Atlantic Ocean variability in an atmosphere/ocean coupled model (2016)
    Springer
    In:  Climate Dynamics, 46 (5-6). pp. 1397-1415.
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    Publikationsdatum: 2019-02-01
    Beschreibung: The instrumental records indicate that the basin-wide wintertime North Atlantic warm conditions are accompanied by a pattern resembling negative North Atlantic oscillation (NAO), and cold conditions with pattern resembling the positive NAO. This relation is well reproduced in a control simulation by the stratosphere resolving atmosphere–ocean coupled Max-Planck-Institute Earth System Model (MPI-ESM). Further analyses of the MPI-ESM model simulation shows that the large-scale warm North Atlantic conditions are associated with a stratospheric precursory signal that propagates down into the troposphere, preceding the wintertime negative NAO. Additional experiments using only the atmospheric component of MPI-ESM (ECHAM6) indicate that these stratospheric and tropospheric changes are forced by the warm North Atlantic conditions. The basin-wide warming excites a wave-induced stratospheric vortex weakening, stratosphere/troposphere coupling and a high-latitude tropospheric warming. The induced high-latitude tropospheric warming is associated with reduction of the growth rate of low-level baroclinic waves over the North Atlantic region, contributing to the negative NAO pattern. For the cold North Atlantic conditions, the strengthening of the westerlies in the coupled model is confined to the troposphere and lower stratosphere. Comparing the coupled and uncoupled model shows that in the cold phase the tropospheric changes seen in the coupled model are not well reproduced by the standalone atmospheric configuration. Our experiments provide further evidence that North Atlantic Ocean variability (NAV) impacts the coupled stratosphere/troposphere system. As NAV has been shown to be predictable on seasonal-to-decadal timescales, these results have important implications for the predictability of the extra-tropical atmospheric circulation on these time-scales
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  • 51
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    Joggins Cliff on Nova Scotia: the most spectacular view into Upper Carboniferous time (2016)
    Springer
    In:  International Journal of Earth Sciences, 105 (2). pp. 581-582.
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    Publikationsdatum: 2019-02-01
    Beschreibung: The Joggins Cliff (45°41′40″N; 64°27′02″W) exposes a unique section through Upper Carboniferous sequences (the “Coal Age Forests”), deposited in the Cumberland basin of northwestern Nova Scotia (Canada) around 315 Ma ago. It is designated a UNESCO world heritage site for the geological insights it contains, including details of the tropical Carboniferous amphibious environment and the first fossils of land-living reptiles (and therewith the first animals to give birth on land) in their environmental context. This is one of the marine basins of the Atlantic Canadian margin, which were filled from Devonian until the end of the Permian time. (...)
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  • 52
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    Effects of warming, nutrient enrichment and detritivore presence on litter breakdown and associated microbial decomposers in a simulated temperate woodland creek (2016)
    Springer
    In:  Hydrobiologia, 770 (1). pp. 243-256.
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    Publikationsdatum: 2019-02-01
    Beschreibung: Current scenarios of global environmental change predict rapid temperature increases, which can directly affect freshwater ecosystems. Leaf litter breakdown in aquatic environments constitutes a fundamental ecosystem process that is mediated by microbial decomposers and animal detritivores. In this study, we examined interactive effects of water temperature (two levels), nutrient concentration (two levels) and grazing pressure by Gammarus pulex (two levels) on breakdown rates of birch leaf litter, biomass and structure of the colonizing microbial community. Litter breakdown rates were stimulated by detritivores, with detritivore effects being enhanced by simultaneously increasing the temperature and adding the nutrients. The interaction between the three factors was synergistic and thus unpredictable from the effects of changes in individual factors. Bacterial community composition was affected by both detritivores and temperature, but less so by nutrient levels and fungal community composition changed upon detritivore activity but was independent of temperature and nutrients. These factors depended on each other in how they affected bacterial communities, but this did not prove true for fungal communities. Relative growth rates of G. pulex were not affected by temperature or nutrient level. We conclude that both abiotic and biotic factors that potentially affect ecosystem processes should be considered simultaneously in studies on effects of environmental change at the community and ecosystem level.
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  • 53
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    Macroepibenthic communities at the tip of the Antarctic Peninsula, an ecological survey at different spatial scales (2016)
    Springer
    In:  Polar Biology, 39 (5). pp. 829-849.
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    Publikationsdatum: 2019-07-16
    Beschreibung: The Southern Ocean ecosystem at the Antarctic Peninsula has steep natural environmental gradients, e.g. in terms of water masses and ice cover, and experiences regional above global average climate change. An ecological macroepibenthic survey was conducted in three ecoregions in the north-western Weddell Sea, on the continental shelf of the Antarctic Peninsula in the Bransfield Strait and on the shelf of the South Shetland Islands in the Drake Passage, defined by their environmental envelop. The aim was to improve the so far poor knowledge of the structure of this component of the Southern Ocean ecosystem and its ecological driving forces. It can also provide a baseline to assess the impact of ongoing climate change to the benthic diversity, functioning and ecosystem services. Different intermediate-scaled topographic features such as canyon systems including the corresponding topographically defined habitats ‘bank’, ‘upper slope’, ‘slope’ and ‘canyon/deep’ were sampled. In addition, the physical and biological environmental factors such as sea-ice cover, chlorophyll-a concentration, small-scale bottom topography and water masses were analysed. Catches by Agassiz trawl showed high among-station variability in biomass of 96 higher systematic groups including ecological key taxa. Large-scale patterns separating the three ecoregions from each other could be correlated with the two environmental factors, sea-ice and depth. Attribution to habitats only poorly explained benthic composition, and small-scale bottom topography did not explain such patterns at all. The large-scale factors, sea-ice and depth, might have caused large-scale differences in pelagic benthic coupling, whilst small-scale variability, also affecting larger scales, seemed to be predominantly driven by unknown physical drivers or biological interactions.
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  • 54
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    Sequence stratigraphy and controls on gas hydrate occurrence in the eastern Nankai Trough, Japan (2016)
    Society of Exploration Geophysicists
    In:  Interpretation, 4 (1). SA73-SA81.
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    Publikationsdatum: 2019-02-01
    Beschreibung: The first offshore gas hydrate production test was conducted within the gas-hydrate-concentrated zone (reservoir) of the eastern Nankai Trough, which is considered to be a stratigraphic accumulation. However, the accumulation mechanism for this concentrated zone was not yet well understood. We used core and geophysical log data sets to determine the subsurface geologic architecture and stratigraphic evolution most likely responsible for the stratigraphic accumulation of gas hydrate in the eastern Nankai Trough. Seven depositional sequences were identified based on grain size, bed thickness, sedimentary structure, and stacking patterns. The sequence boundaries were also identified by terminations of seismic reflection. These sequences were attributed to a fourth to fifth-order eustatic sea-level changes because the stacking pattern cycle was in phase with global oxygen isotope curves; the cycle was also identified in the onshore formation during the same period. The reservoir was interpreted as falling-stage systems tract (FSST) and lowstand systems tract (LST). FSST and LST consisted mostly of trough-fill channel deposits. The deposits were represented by alternations of very fine- to fine-grained sand and silt. The reservoir is located in association with the structural wing of the Daini-Atsumi Knoll. The uplift of the knoll was strongly controlled by tectonic events associated with subduction of the pacific plate during Pleistocene time. The muddy deposits above the reservoir were interpreted as condensed section. We identified channel facies pinched out against structural highs, and together, these result in stratigraphic traps. Consequentially, the gas hydrate trapping system was constrained by sedimentary facies, systems tracts, and geographic and tectonic setting. Concepts and data generated in this study can be used for gas hydrate petroleum system analysis such as basin simulation.
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  • 55
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    Gas hydrate and free gas detection using seismic quality factor estimates from high-resolution P-cable 3D seismic data (2016)
    Society of Exploration Geophysicists
    In:  Interpretation, 4 (1). SA39-SA54.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: We have estimated the seismic attenuation in gas hydrate and free-gas-bearing sediments from high-resolution P-cable 3D seismic data from the Vestnesa Ridge on the Arctic continental margin of Svalbard. P-cable data have a broad bandwidth (20–300 Hz), which is extremely advantageous in estimating seismic attenuation in a medium. The seismic quality factor (Q), the inverse of seismic attenuation, is estimated from the seismic data set using the centroid frequency shift and spectral ratio (SR) methods. The centroid frequency shift method establishes a relationship between the change in the centroid frequency of an amplitude spectrum and the Q value of a medium. The SR method estimates the Q value of a medium by studying the differential decay of different frequencies. The broad bandwidth and short offset characteristics of the P-cable data set are useful to continuously map the Q for different layers throughout the 3D seismic volume. The centroid frequency shift method is found to be relatively more stable than the SR method. Q values estimated using these two methods are in concordance with each other. The Q data document attenuation anomalies in the layers in the gas hydrate stability zone above the bottom-simulating reflection (BSR) and in the free gas zone below. Changes in the attenuation anomalies correlate with small-scale fault systems in the Vestnesa Ridge suggesting a strong structural control on the distribution of free gas and gas hydrates in the region. We argued that high and spatially limited Q anomalies in the layer above the BSR indicate the presence of gas hydrates in marine sediments in this setting. Hence, our workflow to analyze Q using high-resolution P-cable 3D seismic data with a large bandwidth could be a potential technique to detect and directly map the distribution of gas hydrates in marine sediments.
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  • 56
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    Seismic attenuation attributes with applications on conventional and unconventional reservoirs (2016)
    Society of Exploration Geophysicists
    In:  Interpretation, 4 (1). SB63-SB77.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: Seismic attenuation, generally related to the presence of hydrocarbon accumulation, fluid-saturated fractures, and rugosity, is extremely useful for reservoir characterization. The classic constant attenuation estimation model, focusing on intrinsic attenuation, detects the seismic energy loss because of the presence of hydrocarbons, but it works poorly when spectral anomalies exist, due to rugosity, fractures, thin layers, and so on. Instead of trying to adjust the constant attenuation model to such phenomena, we have evaluated a suite of seismic spectral attenuation attributes to quantify the apparent attenuation responses. We have applied these attributes to a conventional and an unconventional reservoir, and we found that those seismic attenuation attributes were effective and robust for seismic interpretation. Specifically, the spectral bandwidth attribute correlated with the production of a gas sand in the Anadarko Basin, whereas the spectral slope of high frequencies attribute correlated with the production in the Barnett Shale of the Fort Worth Basin.
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  • 57
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    Modeling gas hydrate petroleum systems of the Pleistocene turbiditic sedimentary sequences of the Daini-Atsumi area, eastern Nankai Trough, Japan (2016)
    Society of Exploration Geophysicists
    In:  Interpretation, 4 (1). SA95-SA111.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: We have performed 2D and 3D gas hydrate (GH) petroleum systems modeling for the Pleistocene turbiditic sedimentary sequences distributed in the Daini-Atsumi area in the eastern Nankai Trough to understand the accumulation mechanisms and their spatial distribution related to geologic and geochemical processes. High-resolution seismic facies analysis and interpretations were used to define facies distributions in the models. We have created a new biogenic methane generation model based on the biomarker analysis using core samples and incorporated it into our model. Our 2D models were built and simulated to confirm the parameters to be used for 3D modeling. Global sea level changes and paleogeometry estimated from 3D structural restoration results were taken into account to determine the paleowater depth of the deposited sedimentary sequences. Pressure and temperature distributions were modeled because they are the basic factors that control the GH stability zone. Our 2D modeling results suggested that the setting of biogenic methane generation depth is one of the most important controlling factors for GH accumulation in the Nankai Trough, which may be related to the timing of methane upward migration (expulsion) and methane solution process in pore water. Our 3D modeling results suggested that the distribution of sandy sediments and the formation dip direction are important controlling factors in the accumulation of GHs. We also found that the simulated amount of GH accumulation from the petroleum systems modeling compares well with independent estimations using 3D seismic and well data. This suggests that the model constructed in this study is valid for this GH system evaluation and that this type of evaluation can be useful as a supplemental approach to resource assessment.
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  • 58
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    High-resolution seismic velocity analysis as a tool for exploring gas hydrate systems: An example from New Zealand’s southern Hikurangi margin (2016)
    Society of Exploration Geophysicists
    In:  Interpretation, 4 (1). SA1-SA12.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: The existence of free gas and gas hydrate in the pore spaces of marine sediments causes changes in acoustic velocities that overprint the background lithological velocities of the sediments themselves. Much previous work has determined that such velocity overprinting, if sufficiently pronounced, can be resolved with conventional velocity analysis from long-offset, multichannel seismic data. We used 2D seismic data from a gas hydrate province at the southern end of New Zealand’s Hikurangi subduction margin to describe a workflow for highresolution velocity analysis that delivered detailed velocity models of shallow marine sediments and their coincident gas hydrate systems. The results showed examples of pronounced low-velocity zones caused by free gas ponding beneath the hydrate layer, as well as high-velocity zones related to gas hydrate deposits. For the seismic interpreter of a gas hydrate system, the velocity results represent an extra “layer” for interpretation that provides important information about the distribution of free gas and gas hydrate. By combining the velocity information from the seismic transect with geologic samples of the seafloor and an understanding of sedimentary processes, we have determined that high gas hydrate concentrations preferentially form within coarse-grained sediments at the proximal end of the Hikurangi Channel. Finer grained sediments expected elsewhere along the seismic transect might preclude the deposition of similarly high gas hydrate concentrations away from the channel.
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  • 59
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    Characterizing a turbidite system in Canterbury Basin, New Zealand, using seismic attributes and distance-preserving self-organizing maps (2016)
    Society of Exploration Geophysicists
    In:  Interpretation, 4 (1). SB79-SB89.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: Recent developments in seismic attributes and seismic facies classification techniques have greatly enhanced the capability of interpreters to delineate and characterize features that are not prominent in conventional 3D seismic amplitude volumes. The use of appropriate seismic attributes that quantify the characteristics of different geologic facies can accelerate and partially automate the interpretation process. Self-organizing maps (SOMs) are a popular seismic facies classification tool that extract similar patterns embedded with multiple seismic attribute volumes. By preserving the distance in the input data space into the SOM latent space, the internal relation among data vectors on an SOM facies map is better presented, resulting in a more reliable classification. We have determined the effectiveness of the modified algorithm by applying it to a turbidite system in Canterbury Basin, offshore New Zealand. By incorporating seismic attributes and distance-preserving SOM classification, we were able to observe architectural elements that are overlooked when using a conventional seismic amplitude volume for interpretation.
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  • 60
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    Seismic interpretation, attribute analysis, and illumination study for targets below a volcanic-sedimentary succession, Santos Basin, offshore Brazil (2016)
    Society of Exploration Geophysicists
    In:  Interpretation, 4 (1). SB37-SB50.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: During the past decade, a significant exploration effort into deeper water and deeper targets in offshore areas brought more knowledge about the distribution of igneous rocks in the sedimentary basins along many continental margins. Nonhomogeneous illumination effects may occur below shallow, high-impedance igneous rock bodies. The seismic processing, depth imaging, interpretation, and attribute analysis require a special attention when these magmatic bodies affect the illumination of deeper targets. Usually, those structures are not considered in illumination studies, and the salt diapirs govern the analysis. In this work, seismic attributes are quite relevant to constrain the geologic model used to simulate the amplitude maps of the deeper target and to quantify the shadow effects observed on it. These amplitude shadows may either create (false) or hide (true) attribute anomalies. We have modeled a Tertiary volcano-sedimentary succession (VSS) mapped in the northeastern Santos Basin, offshore Brazil, to simulate the effect in the amplitude response of deeper targets. There were multiple magmatic events through the Santos Basin Cretaceous-Tertiary sedimentary succession, intrusive and extrusive. The igneous extrusive rocks intercalated with sediments forming VSS marked by lowand high-amplitude responses with tough lateral discontinuity. The amplitude found well-preserved architectural elements interpreted as lava flows and volcanoes, contrasting with layered sediments. We have defined geobodies constrained by relative impedance and 3D edge detection to build the 3D geologic model of the igneous successions used for seismic simulation. From the geobodies, we modeled two VSS to run the P-waves ray-tracing propagation to simulate the migrated amplitude map of the deeper Lower Albian sequence top. We computed the P-velocity and the density from well logs, and the seismic acquisition geometry was similar to the original. Comparison between real and simulated amplitudes showed the impact of shadow zones caused by shallower igneous bodies.
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  • 61
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    Introduction to special section: Exploration and characterization of gas hydrates (2016)
    Society of Exploration Geophysicists
    In:  Interpretation, 4 (1). SAi-SAii.
    Details
    Publikationsdatum: 2019-02-01
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  • 62
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    Prediction and validation of gas hydrate saturation distribution in the eastern Nankai Trough, Japan: Geostatistical approach integrating well-log and 3D seismic data (2016)
    Society of Exploration Geophysicists
    In:  Interpretation, 4 (1). SA83-SA94.
    Details
    Publikationsdatum: 2020-07-28
    Beschreibung: Accurate reservoir potential evaluation requires reliable 3D reservoir models. Geostatistical simulation techniques can reproduce the heterogeneity and quantify the uncertainty in a reservoir. We have applied sequential Gaussian simulation with collocated cokriging to generate the spatial distribution of gas hydrate (GH) saturation around a gas production test site in the eastern Nankai Trough. The simulation was performed using well-log data obtained from the exploration and production tests as a primary variable and inversion-derived seismic impedance data as a secondary variable under the good correlations between two variables. The integrated model adequately described the reservoir heterogeneity and effectively interpolated the seismic trend with respect to the well data. To confirm the usability of the seismic data for the accurate representation of the GH saturation distribution, we ran two model simulations: one using well data only and the other using well and seismic data. Each model was validated using the well-log data obtained at the production test site that were not included during the simulation. The model generated using well and seismic data appropriately reproduced the trend of well-log data at the production test site, especially for the low-GH-saturation unit within the reservoir. However, the model generated using well data only was insufficient to predict the trend of the well data. The results demonstrated that the seismic data were effective for the prediction of the GH saturation distribution, and integration of the well and seismic data could improve the accuracy of the reservoir model.
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  • 63
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    Characterization of gas hydrate distribution using conventional 3D seismic data in the Pearl River Mouth Basin, South China Sea (2016)
    Society of Exploration Geophysicists
    In:  Interpretation, 4 (1). SA25-SA37.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: A new 3D seismic reflection data volume acquired in 2012 has allowed for the detailed mapping and characterization of gas hydrate distribution in the Pearl River Mouth Basin in the South China Sea. Previous studies of core and logging data showed that gas hydrate occurrence at high concentrations is controlled by the presence of relatively coarse-grained sediment and the upward migration of thermogenic gas from the deeper sediment section into the overlying gas hydrate stability zone (BGHSZ); however, the spatial distribution of the gas hydrate remains poorly defined. We used a constrained sparse spike inversion technique to generate acousticimpedance images of the hydrate-bearing sedimentary section from the newly acquired 3D seismic data volume. High-amplitude reflections just above the bottom-simulating reflectors (BSRs) were interpreted to be associated with the accumulation of gas hydrate with elevated saturations. Enhanced seismic reflections below the BSRs were interpreted to indicate the presence of free gas. The base of the BGHSZ was established using the occurrence of BSRs. In areas absent of well-developed BSRs, the BGHSZ was calculated from a model using the inverted P-wave velocity and subsurface temperature data. Seismic attributes were also extracted along the BGHSZ that indicate variations reservoir properties and inferred hydrocarbon accumulations at each site. Gas hydrate saturations estimated from the inversion of acoustic impedance of conventional 3D seismic data, along with well-log-derived rock-physics models were also used to estimate gas hydrate saturations. Our analysis determined that the gas hydrate petroleum system varies significantly across the Pearl River Mouth Basin and that variability in sedimentary properties as a product of depositional processes and the upward migration of gas from deeper thermogenic sources control the distribution of gas hydrates in this basin.
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  • 64
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    Phylogenetic Relationship and Secondary Metabolite Production of Marine Fungi Producing the Cyclodepsipeptides Scopularide A and B (2016)
    Springer
    In:  Marine Biotechnology, 18 (4). pp. 466-474.
    Details
    Publikationsdatum: 2019-09-23
    Beschreibung: Strains originally affiliated to the genera Scopulariopsis and Microascus were compared regarding the scopularide production in order to investigate their ability to produce the cyclodepsipeptides and select the best suited candidate for subsequent optimisation processes. Phylogenetic calculations using available sequences of the genera Scopulariopsis and Microascus revealed that most of the sequences clustered within two closely related groups, comprising mainly Scopulariopsis/Microascus brevicaulis and Microascus sp., respectively. Interestingly, high yields of scopularide A were exhibited by three strains belonging to S./M. brevicaulis, while lower titres were observed for two strains of Microascus sp. Close phylogenetic distances within and between the two groups supported the proposed combination of both genera into one holomorph group. Short phylogenetic distances did not allow a clear affiliation at the species level on the basis of ribosomal DNA sequences, especially for Microascus sp. strains. Additionally, several sequences originating from strains assigned to Scopulariopsis exhibited a polyphyletic nature. The production pattern is in accordance with the phylogenetic position of the strains and significant production of scopularide B could only be observed for the S./M. brevicaulis strain LF580. Thus, the phylogenetic position marks the biotechnologically interesting strains and matters in optimisation strategies. In conclusion, the ability of all five strains to produce at least one of the scopularides suggests a distribution of the responsible gene cluster within the holomorph group. Setting the focus on the production of the cyclodepsipeptides, strain LF580 represents the best candidate for further strain and process optimisation
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  • 65
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    Shallow 3D Reflection Seismics (2016)
    Springer
    In:  In: Encyclopedia of Earthquake Engineering. , ed. by Beer, M., Kougioumtzoglou, I. A., Patelli, E. and Au, S. K. Springer, Berlin, Heidelberg, pp. 1-9. ISBN 978-3-642-36197-5
    Details
    Publikationsdatum: 2017-05-30
    Beschreibung: High-resolution 3D reflection seismology for near-surface applications is a noninvasive geophysical approach that uses sound wave reflected from subsurface discontinuities to infer and delineate the discontinuities. It results in high-resolution 3D structural images of the subsurface displaying mainly the interfaces between geological units and faults. The attributes “near surface” or “shallow” refer to sounding depths of typically some 10 m to 1 km. The 3D seismic method has been developed since the late 1960s. It is applied on- and offshore. This article gives an overview of the aims, principles, and realizations of shallow 3D reflection seismics. More details on field technique and data processing can be found, for example, in Meunier (2011) and Biondi (2006).
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  • 66
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    Link between anomalously cold winters in Russia and sea-ice decline in the Barents Sea (2016)
    MAIK Nauka/Interperiodica | Springer
    In:  Izvestiya, Atmospheric and Oceanic Physics, 52 (3). pp. 225-233.
    Details
    Publikationsdatum: 2020-08-05
    Beschreibung: There were several anomalously cold winter weather regimes in Russia in the early 21st century. These regimes were usually associated with a blocking anticyclone south of the Barents Sea. Numerical simulations with an atmospheric general circulation model (AGCM) using prescribed sea-ice concentration (SIC) data for different periods during the last 50 years showed that a rapid sea-ice area decline in the Barents Sea in the last decade could bring about the formation of such a blocking anticyclone and cooling over northern Eurasia. The SIC reduction in the former period, from the second half of the 1960s to the first half of the 1990s, results in a weaker response of opposite sign. This suggests a nonlinear atmospheric circulation response to the SIC reduction in the Barents Sea, which has been previously found in the idealized AGCM simulations. An impact of the Barents Sea SIC reduction on the North Atlantic Oscillation (NAO), in particular, on the formation of the anomalously low NAO index, is found. The results indicate an important role that the Barents Sea, a region with the largest variability of the ocean–atmosphere heat exchange in the Arctic in wintertime, plays in generating anomalous weather regimes in Russia.
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  • 67
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    Mating tactics in the sub-Antarctic deep-sea squid Onykia ingens (Cephalopoda: Onychoteuthidae) (2016)
    Springer
    In:  Polar Biology, 39 (7). pp. 1319-1328.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: The behavior of polar deep-sea nekton is very poorly known. To obtain insight into mating behavior of the abundant and ecologically important sub-Antarctic deep-sea squid Onykia ingens, our goals were to (1) quantify spermatophore production; (2) determine the preferred location for spermatangia deposition; (3) investigate whether male and female O. ingens mate with multiple mates; and (4) discuss the location of implanted spermatangia in light of mating behavior and egg fertilization. Toward this end, we examined male and female O. ingens specimens from Falkland Island and New Zealand waters. Male O. ingens store up to 198 spermatophores (mean 103 +/- A 61; n = 12) in their reproductive system, which are produced over a period of considerable somatic growth (200-400 mm ML), and which may have a considerable size range. Males insert their long extendible terminal organ in the mantle cavity of the female, potentially through the funnel, to deposit spermatophores in one or more of four regions on the female's body. Most implanted spermatangia (52.5 %) were found in the funnel region, but many were also found inside the mantle cavity closer to the oviducts. Males with longer terminal organs therefore may be able to position closer to the oviducts where fertilization chances are higher than for spermatangia located in the funnel region. The number of implanted spermatangia per individual female (4-60, mean 29 +/- A 20; n = 24), the multiregional spermatangia deposition, and the different outer appearance of spermatangia, suggested that females have multiple mating events. Since males produce more spermatophores (up to 200) than the number of spermatangia in one region (〈 60), it is likely that males too mate with more than one female. We show how quantitative assessment of reproductive characteristics can provide insight into the reproductive behavior of deep-sea species for which in situ observations are currently lacking.
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  • 68
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    A Possible Source Mechanism of the 1946 Unimak Alaska Far-Field Tsunami: Uplift of the Mid-Slope Terrace Above a Splay Fault Zone (2016)
    Springer
    In:  Pure and Applied Geophysics, 173 (12). pp. 4189-4201.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: In 1946, megathrust seismicity along the Unimak segment of the Alaska subduction zone generated the largest ever recorded Alaska/Aleutian tsunami. The tsunami severely damaged Pacific islands and coastal areas from Alaska to Antarctica. It is the charter member of “tsunami” earthquakes that produce outsized far-field tsunamis for the recorded magnitude. Its source mechanisms were unconstrained by observations because geophysical data for the Unimak segment were sparse and of low resolution. Reprocessing of legacy geophysical data reveals a deep water, high-angle reverse or splay thrust fault zone that leads megathrust slip upward to the mid-slope terrace seafloor rather than along the plate boundary toward the trench axis. Splay fault uplift elevates the outer mid-slope terrace and its inner area subsides. Multibeam bathymetry along the splay fault zone shows recent but undated seafloor disruption. The structural configuration of the nearby Semidi segment is similar to that of the Unimak segment, portending generation of a future large tsunami directed toward the US West coast.
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  • 69
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    Using the critical salinity (S crit) concept to predict invasion potential of the anemone Diadumene lineata in the Baltic Sea (2016)
    Springer
    In:  Marine Biology, 163 (11, Art. No. 227).
    Details
    Publikationsdatum: 2019-09-23
    Beschreibung: It is widely assumed that the ability of an introduced species to acclimate to local environmental conditions determines its invasion success. The sea anemone Diadumene lineata is a cosmopolitan invader and shows extreme physiological tolerances. It was recently discovered in Kiel Fjord (Western Baltic Sea), although the brackish conditions in this area are physiologically challenging for most marine organisms. This study investigated salinity tolerance in D. lineata specimens from Kiel Fjord in order to assess potential geographical range expansion of the species in the Baltic Sea. In laboratory growth assays, we quantified biomass change and asexual reproduction rates under various salinity regimes (34: North Sea, 24: Kattegat, 14: Kiel Fjord, 7: Baltic Proper). Furthermore, we used 1H-NMR-based metabolomics to analyse intracellular osmolyte dynamics. Within four weeks D. lineata exhibited a fivefold population growth through asexual reproduction at high salinities (34 and 24). Biomass increase under these conditions was significantly higher (69 %) than at a salinity of 14. At a salinity of 7, anemones ceased to reproduce asexually, their biomass decreased and metabolic depression was observed. Five main intracellular osmolytes were identified to be regulated in response to salinity change, with osmolyte depletion at a salinity of 7. We postulate that depletion of intracellular osmolytes defines a critical salinity (Scrit) that determines loss of fitness. Our results indicate that D. lineata has the potential to invade the Kattegat and Skagerrak regions with salinity 〉10. However, salinities of the Baltic Proper (salinity 〈8) currently seem to constitute a physiological limit for the species.
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  • 70
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    Strain and flow in the metamorphic core complex of Ios Island (Cyclades, Greece) (2016)
    Springer
    In:  International Journal of Earth Sciences, 105 (7). pp. 2097-2110.
    Details
    Publikationsdatum: 2019-09-23
    Beschreibung: We have analysed strain and flow kinematics in the footwall of the South Cyclades Shear Zone (SCSZ), an important tectonic boundary within the Attic-Cycladic Crystalline Complex exposed on Ios Island, Cyclades, Aegean Sea. Coarse-grained augen gneisses in the basement unit flooring the SCSZ and forming a metamorphic core complex are excellently suited to measure finite strain using the Fry method and estimate the vorticity number (Wk) of flow with the “blocked-object” method. The results show that Oligo-Miocene exhumation of the basement unit during extension brought approximately 70 % N–S crustal stretching and up to 40 % subvertical shortening in a plane strain environment (k = 0.99). Linear down-section strain decrease constrains a zone of contact deformation of the SCSZ of about 1.5 km thick. Kinematic vorticity number estimates suggest little deviation from pure shear (Wk = 0.26). Finite strain and Wk are not correlated, indicating that the Ios basement and the overlying cover units were stretched compatibly. While the SCSZ is a localized zone of high strain, net displacement, however, may be restricted to about ten kilometres. This has important repercussions on large-scale tectonic models for extension in the Aegean.
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  • 71
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    Extending interpretations of natural fractures from the wellbore using 3D attributes: The Carnarvon Basin, Australia (2016)
    Society of Exploration Geophysicists
    In:  Interpretation, 4 (1). SB107-SB129.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: Natural fractures can be identified in wellbores using electric resistivity image logs; however, the challenge of predicting fracture orientations, densities, and probable contribution to subsurface fluid flow away from the wellbore remains. Regional interpretations of fracture sets are generally confined to areas featuring an extensive reservoir analog outcrop. We have made use of extensive data sets available in Western Australia’s Northern Carnarvon Basin to map subsurface natural fractures, contributing to a regional understanding of fracture sets that can be applied to broader parts of the basin. The Northern Carnarvon Basin is composed of distinct structural domains that have experienced differing tectonic histories. Interpretation of regional fractures was achieved through an integrated approach, incorporating electric resistivity image logs from 52 Carnarvon Basin wells and seismic attribute analysis of two 3D seismic data sets: Bonaventure_3D (6687 km2) and HC_93_3D (1414 km2). Integration of these two data sets allows for a regionally extensive identification of natural fractures away from well control. Fractures of differing age and character are identified within the basin: Outboard areas are dominated by fractures likely to be open to fluid flow that are parallel to subparallel to the approximately east– west present-day maximum horizontal stress, providing possible flow conduits between potential damage zones identified alongside the north–northeast/south–southwest-striking faults that constitute the major structural trend of the basin, and inboard areas dominated by northeast–southwest to north–northeast/south–southeast fractures formed in fault damage-zones alongside normal, and inverted-normal, faults at those orientations. Finally, fractures observed in wells from the Rankin Platform and Dampier Subbasin occur at neither of these orientations; rather, they closely parallel the strikes of local faults. Additionally, variation is seen in fracture strikes due to isotropic present-day stress magnitudes. This methodology extends fracture interpretations from the wellbore and throughout the region of interest, constituting a regional understanding of fracture sets that can be applied to broader parts of the basin.
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  • 72
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    Turbulent high-latitude oceanic intrusions - details of non-smooth apparent isopycnal transport West of Svalbard (2016)
    Springer
    In:  Ocean Dynamics, 66 (6). pp. 785-794.
    Details
    Publikationsdatum: 2019-09-23
    Beschreibung: Filament intrusions are observed in high-resolution temperature (T) measurements from a 100-m and several month-long mooring in the Fram Strait in around 400-m water depth at the continental slope West of Svalbard (Spitsbergen, Norway). In this dynamic environment, a wide variety of intrusive layers are observed with thicknesses between 5 and 80 m with warmer water between cooler waters above and below. The layers typically last from several hours up to 1 day, exceeding the local buoyancy period but not lasting as long as intrusive layers in the open ocean. The intrusions are a result of an intermingling of Arctic and North-Atlantic waters and generated in the basins interior and locally via internal wave steepening upon the sloping bottom. Freely propagating semidiurnal lunar internal tides cannot exist without background vorticity at these high latitudes. Strongly nonlinear turbulent bores are not observed at the tidal periodicity, but wave fronts occur at the sub-inertial frequency of dominant baroclinic instability. The fronts are in part associated with near-buoyancy frequency internal waves (breaking). The details of the moored T observations and their spectral content demonstrate the non-smooth, relatively turbulent development including convective overturning and shear-induced instabilities when intrusions disperse in presumably salinity-compensated isopycnal layers.
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  • 73
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    Hydrate quantification: Integrating full-waveform inversion, seismic attributes, and rock physics (2016)
    Society of Exploration Geophysicists
    In:  Interpretation, 4 (1). SA55-SA71.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: Hydrate quantification from seismic data is a two-pronged challenge. The first is creating a velocity field with high enough resolution and accuracy such that it is a meaningful representation of hydrate variability in the host sediments. The second is constructing a rock-physics model that accounts for the appropriate growth of the hydrate and allows for the interpretation of the velocity field in terms of hydrate saturation. In this paper, both challenges are addressed in a quantification workflow that uses 2D seismic and colocated well logs. The study area is situated in the Krishna-Godavari Basin, offshore eastern Indian coast, where hydrate was discovered in the National Gas Hydrate Program Expedition 01 (NGHP-01). The workflow hinges on a rock-physics model that expresses total hydrate saturation in terms of primary (matrix) and secondary (fractures, faults, voids, etc.) porosities and their respective primary and secondary saturations and incorporates hydrate-filled secondary porosity into the rock as an additional grain type using the Hashin-Shtrikman bounds. The model is first applied to a set of well logs at a colocated site, NGHP-01-10, following which the application is extended into the seismic domain by (1) the incoherency attribute as a proxy for secondary porosity and (2) a full-waveform inversionbased P-wave velocity (VP) model as a proxy for primary saturation. The remaining — the primary porosity and secondary saturation — are assumed to remain the same across the seismic profile as at the site NGHP-01-10. The resulting, seismically estimated, hydrate saturation compares well with saturations from core depressurization at colocated sites NGHP-01-10 and NGHP-01-13. The quantification workflow presented here is potentially adaptable to other geographical areas with the caveat that empirical relations between porosity, saturation, and seismic attributes may have to be locally established.
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  • 74
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    Withstanding multiple stressors: ephyrae of the moon jellyfish (Aurelia aurita, Scyphozoa) in a high-temperature, high-CO2 and low-oxygen environment (2016)
    Springer
    In:  Marine Biology, 163 (9).
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: Global change is affecting marine ecosystems through a combination of different stressors such as warming, ocean acidification and oxygen depletion. Very little is known about the interactions among these factors, especially with respect to gelatinous zooplankton. Therefore, in this study we investigated the direct effects of pH, temperature and oxygen availability on the moon jellyfish Aurelia aurita, concentrating on the ephyral life stage. Starved one-day-old ephyrae were exposed to a range of pCO2 (400–4000 ppm) and three different dissolved oxygen levels (from saturated to hypoxic conditions), in two different temperatures (5 and 15 °C) for 7 days. Carbon content and swimming activity were analysed at the end of the incubation period, and mortality noted. General linearized models were fitted through the data, with the best fitting models including two- and three-way interactions between pCO2, temperature and oxygen concentration. The combined effect of the stressors was small but significant, with the clearest negative effect on growth caused by the combination of all three stressors present (high temperature, high CO2, low oxygen). We conclude that A. aurita ephyrae are robust and that they are not likely to suffer from these environmental stressors in a near future.
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  • 75
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    Hydrothermalism (2016)
    Springer
    In:  In: Encyclopedia of Marine Geosciences. , ed. by Harff, J., Meschede, M., Petersen, S. and Thiede, J. Springer, Dordrecht, pp. 344-357. ISBN 978-94-007-6239-4
    Details
    Publikationsdatum: 2018-01-19
    Beschreibung: Definition Hydrothermalism refers to the convective circulation of seawater through oceanic lithosphere with possible contributions of volatiles and metals from underlying magma chambers.
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  • 76
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    Marine Mineral Resources (2016)
    Springer
    In:  In: Encyclopedia of Marine Geosciences. , ed. by Harff, J., Meschede, M., Petersen, S. and Thiede, J. Springer, Dordrecht, pp. 475-480. ISBN 978-94-007-6239-4
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    Publikationsdatum: 2018-01-19
    Beschreibung: Definition Marine mineral resources are accumulations of minerals that form at or below the seabed and from which metals, minerals, elements, or aggregate might be extracted as a resource. They are distinguished from energy resources such as oil, gas, or gas hydrates and living resources such as fish, although many of the metals potentially available are essential for green-energy applications.
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  • 77
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    Technology in Marine Geosciences (2016)
    Springer
    In:  In: Encyclopedia of Marine Geosciences. , ed. by Harff, J., Meschede, M., Petersen, S. and Thiede, J. Springer, Dordrecht, pp. 825-835. ISBN 978-94-007-6239-4
    Details
    Publikationsdatum: 2018-01-19
    Beschreibung: This chapter describes the most commonly used technologies and instruments for observing and sampling in the field of marine geosciences and refers to a number of special papers within this encyclopedia and beyond. This chapter is meant as an introduction showing the variability and broad scale of intruments being used. Since technology is a vast and rapidly changing field, numerous specific instruments used throughout marine geoscience are undouptfully missing in this compilation.
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  • 78
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    Volcanogenic Massive Sulfides (2016)
    Springer
    In:  In: Encyclopedia of Marine Geosciences. , ed. by Harff, J., Meschede, M., Petersen, S. and Thiede, J. Springer, Dordrecht, pp. 917-923. ISBN 978-94-007-6239-4
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    Publikationsdatum: 2018-01-19
    Beschreibung: Definition Volcanogenic Massive Sulfides. Accumulations of dominantly sulfide minerals that form at sites of focused hydrothermal discharge on the seafloor. Also refers to a class of ore deposit mined from ancient oceanic crust that is now exposed on land.
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  • 79
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    Marine CSEM data constrained by seismic and synthetic studies for gas hydrates exploration (2016)
    Society of Exploration Geophysicists
    In:  SEG Technical Program Expanded Abstracts, 35 . pp. 901-906.
    Details
    Publikationsdatum: 2017-06-08
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  • 80
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    PSDM and VMB — Let’s talk (2016)
    Society of Exploration Geophysicists
    In:  Interpretation, 4 (1). 5F-6F.
    Details
    Publikationsdatum: 2019-02-01
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  • 81
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    Seismic attributes for description of reef growth and channel system evolution — Case study of Intisar E, Libya (2016)
    Society of Exploration Geophysicists
    In:  Interpretation, 4 (1). SB1-SB11.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: A 3D seismic survey over the Intisar E field in the Ajdabiya Trough of the Sirte Basin, Libya, revealed a channel-like feature in Eocene carbonates that wraps around the pinnacle reef that contains the reservoir. We have used coherence, curvature, and spectral decomposition seismic attributes to determine the morphology and gray-level co-occurrence matrix attributes to define seismic facies within the feature. These indicated that the channel originated by submarine scouring caused by downslope movement of turbidity currents. Erosion was followed by the deposition of successive layers of carbonate debris in the channel. Stratigraphic correlations with the adjacent pinnacle reef revealed that the channel was cut during the late stage of reef growth, and a second channel formed after the Intisar E reef ceased to grow. Differences in seafloor elevation over the reef probably diverted turbidity currents so channels were not cut into the reef, breaching the reservoir. This interpreted geologic history may explain why some pinnacle reefs in the Intisar complex contained giant reservoirs, whereas others were barren.
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  • 82
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    Seismic attribute detection of faults and fluid pathways within an active strike-slip shear zone: New insights from high-resolution 3D P-Cable™ seismic data along the Hosgri Fault, offshore California (2016)
    Society of Exploration Geophysicists
    In:  Interpretation, 4 (1). SB131-SB148.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: Poststack data conditioning and neural-network seismic attribute workflows are used to detect and visualize faulting and fluid migration pathways within a 13.7 km2 13.7 km2 3D P-Cable™ seismic volume located along the Hosgri Fault Zone offshore central California. The high-resolution 3D volume used in this study was collected in 2012 as part of Pacific Gas and Electric’s Central California Seismic Imaging Project. Three-dimensional seismic reflection data were acquired using a triple-plate boomer source (1.75 kJ) and a short-offset, 14-streamer, P-Cable system. The high-resolution seismic data were processed into a prestack time-migrated 3D volume and publically released in 2014. Postprocessing, we employed dip-steering (dip and azimuth) and structural filtering to enhance laterally continuous events and remove random noise and acquisition artifacts. In addition, the structural filtering was used to enhance laterally continuous edges, such as faults. Following data conditioning, neural-network based meta-attribute workflows were used to detect and visualize faults and probable fluid-migration pathways within the 3D seismic volume. The workflow used in this study clearly illustrates the utility of advanced attribute analysis applied to high-resolution 3D P-Cable data. For example, results from the fault attribute workflow reveal a network of splayed and convergent fault strands within an approximately 1.3 km wide shear zone that is characterized by distinctive sections of transpressional and transtensional dominance. Neural-network chimney attribute calculations indicate that fluids are concentrated along discrete faults in the transtensional zones, but appear to be more broadly distributed amongst fault bounded anticlines and structurally controlled traps in the transpressional zones. These results provide high-resolution, 3D constraints on the relationships between strike-slip fault mechanics, substrate deformation, and fluid migration along an active fault system offshore central California.
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  • 83
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    Encyclopedia of Marine Geosciences (2016)
    Springer
    In:  , ed. by Harff, J., Meschede, M., Petersen, S. and Thiede, J. Encyclopedia of Earth Sciences Series . Springer, Dordrecht, XXXIII, 961 pp. ISBN 978-94-007-6237-4 (Print)
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: This Encyclopedia comprises the current knowledge in marine geosciences whereby not only basic but also applied and technical sciences are covered. Through this concept a broad scale of users in the field of marine sciences and techniques is addressed, from students and scholars in academia to engineers and decision makers in industry and politics. Globally growing demand of energy and mineral resources, reliable future projection of climate processes and the protection of coasts to mitigate the threats of disasters and hazards require a comprehensive understanding of the structure, ongoing processes and genesis of the marine geosphere. Beyond the “classical” research fields in marine geology in current time more general concepts have been evolved integrating marine geophysics, hydrography, marine biology, climatology and ecology. As an umbrella the term “marine geosciences” has been broadly accepted for this new complex field of research and the solutions of practical tasks in the marine realm.
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  • 84
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    Reefs (Biogenic) (2016)
    Springer
    In:  In: Encyclopedia of Marine Geosciences. , ed. by Harff, J., Meschede, M., Petersen, S. and Thiede, J. Springer, Dordrecht, pp. 718-721. ISBN 978-94-007-6239-4
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    Publikationsdatum: 2018-01-19
    Beschreibung: Reefs are in situ organic deposits which exhibit different sizes from few cubic meters to several hundreds of kilometers length and even several hundreds of meters in thickness (Spalding et al., 2001). Modern reefs are formed predominantly by stony corals which is the equivalent of the taxonomic order Scleractinia. Corals and other calcifying organisms produce hard skeletons, which lead to the accumulation of biogenic carbonates as a result of individual growth, bioerosion, sedimentation, and cementation due to wave energy during several hundreds of years. On millennial and much longer timescales, sea-level changes are the major driving force of reef growth. Today coral reefs cover more than 284,000 km2 (Spalding et al., 2001) and they are the largest marine structures on earth formed by biota, having a long geological record and ...
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  • 85
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    Radiogenic Tracers (2016)
    Springer
    In:  In: Encyclopedia of Marine Geosciences. , ed. by Harff, J., Meschede, M., Petersen, S. and Thiede, J. Springer, Dordrecht, pp. 699-700. ISBN 978-94-007-6239-4
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    Publikationsdatum: 2018-01-19
    Beschreibung: Isotopes can be characterized to be stable, cosmogenic, radioactive, or radiogenic. Stable isotopes do not change their relative abundance in the environment as long as no isotopes are added or extracted from the system. Cosmogenic isotopes are produced by high energetic cosmic rays in the upper layers of the atmosphere and are usually radioactive also. Radioactive isotopes change their abundance in the environment according to their half-life (T1/2), whereas radiogenic isotopes are not radioactive itself but change their abundance according to the half-life of their mother isotope. There are several important radiogenic systems known, and the most important are 238U/206Pb, 190Pt/186Os, 147Sm/143Nd, 87Rb/87Sr, 187Re/187Os, 176Lu/176Hf, 232Th/208Pb, 40 K/40Ar, 40 K/40Ca, 235U/207Pb, 129I/129Xe, 10Be/10B, 26Al/26 Mg, 36Cl/36Ar, 14C/14 N, etc. For the geological sciences, the most important radiogenic isotope systems are the radiogenic system ...
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  • 86
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    Sclerochronology (2016)
    Springer
    In:  In: Encyclopedia of Marine Geosciences. , ed. by Harff, J., Meschede, M., Petersen, S. and Thiede, J. Springer, Dordrecht, p. 747. ISBN 978-94-007-6239-4
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    Publikationsdatum: 2018-01-19
    Beschreibung: Sclerochronology is the record of different periodicities expressed as chemical and physical variations in mineralized endo- or exoskeletons of living, fossil, and even extinct aquatic organisms. Sclerochronological periodicities are documented in growth increments of different shapes and sizes, depending on the time span they represent (Schöne and Surge, 2005). Such increments may portray days, lunar cycles, months, or years. Their individual width and pattern reflect either specific taxonomically related and therefore biologically controlled signals or environmental conditions in which the organism grew. These skeletal chronologies may comprise individual lifetimes of organisms ranging from several decades to several hundreds of years. Prominent organisms are scleractinian corals, calcified sponges, mollusk shells, or otoliths from fish. Along with the record of growth increments, the chemical composition of the mineralized skeleton based on elemental ratios such as Sr/Ca and Mg/Ca or ...
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  • 87
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    Seasonally fluctuating chemical microfouling control in Fucus vesiculosus and Fucus serratus from the Baltic Sea (2016)
    Springer
    In:  Marine Biology, 163 (203).
    Details
    Publikationsdatum: 2019-09-23
    Beschreibung: Microfouling in temperate seas underlies seasonal variations. Thus, perennial macroalgae are exposed to fluctuating levels of fouling pressure. Only few studies have examined the link between fouling pressure and algal fouling control. We assessed whether microfouling control of F. vesiculosus and F. serratus against prokaryotes and pennate diatoms fluctuates with season and correlates with microfouling pressure in a 1-year field survey. Microfouler recruitment on glass (reference surface) and on Fucus, microfouling control strength of Fucus surface metabolites (tested by an in situ bioassay approach) and Fucus tissue mannitol content (used as proxy for energy availability) were determined monthly. Microfouling pressure (settled cells per unit time and area) and microfouling control of Fucus varied seasonally. Both Fucus species exhibited cuticula shedding in all seasons. We conclude that microfouling control in both Fucus species showed a lagged or synchronized relationship with mannitol or microfouling pressure.
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  • 88
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    The deep-water squid Octopoteuthis sicula Rüppell, 1844 (Cephalopoda: Octopoteuthidae) as the single species of the genus occurring in the Mediterranean Sea (2016)
    Springer
    In:  Marine Biology, 163 (Art. Nr. 192).
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: The genus Octopoteuthis includes squids inhabiting meso- and bathypelagic waters worldwide. Of the seven presently named species distributed in the world’s oceans, only Octopoteuthis sicula has been reported for certain in the Mediterranean Sea to date. However, mixed and confusing descriptions of the systematic characters useful for identifying the species occur in the literature. Similarly, molecular analysis results available for the genus are contradictory and inconsistent. The research herein was undertaken firstly to clarify the systematic status of the genus in the Mediterranean Sea and confirm the presence of a single species, namely O. sicula. Additional goals were the assessment of the validity of systematic characters to identify the species and the analysis of beak morphology to provide useful tools in prey–predator relationship studies. Octopoteuthis specimens from various areas of the Mediterranean Sea and the Atlantic and Pacific oceans were compared, and the analysis of traditional morphological characters was combined with molecular genetics and the study of beaks. Molecular genetics and beak morphology results support the existence of a single species in the Mediterranean Sea. Additional evidence would suggest that this species is also distributed in the north-eastern Atlantic. The morphological characters reported in the literature to identify O. sicula did not identify Mediterranean specimens, with the exception of the two tail photophores. All information collected supports the need for a reconsideration of morphological characters used to identify Octopoteuthis species.
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  • 89
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    Submarine Slides (2016)
    Springer
    In:  In: Encyclopedia of Marine Geosciences. , ed. by Harff, J., Meschede, M., Petersen, S. and Thiede, J. Springer, Dordrecht, pp. 817-821. ISBN 978-94-007-6239-4
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    Publikationsdatum: 2018-01-19
    Beschreibung: Failure of submarine slopes results in underwater landslides, a mass movement of sediment and rock that spills down ocean margin slopes (Hampton and Locat, 1996). Visual observations during submarine mass movement are few, and therefore landslides are commonly recognized by the remnant morphology they leave behind. These remnant slope failure features have been observed along the world’s continental margins, on the slopes of volcanic islands, and volcanic island arcs. Initiation of landslides commonly results from dynamic events, generally earthquakes. Landslides are most frequent along margins where converging lithospheric plates form subduction zones and the shear between the upper and lower plates create large earthquakes, however, some large landslides occur without tectonic or seismic triggers. Sedimentary processes have caused failure from loading or unloading. Submarine landslides in the spectrum from fast to slow can be catastrophic, incremental, or creeping. Large ca ...
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  • 90
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    Paleoceanography (2016)
    Springer
    In:  In: Encyclopedia of Marine Geosciences. , ed. by Harff, J., Meschede, M., Petersen, S. and Thiede, J. Springer, Dordrecht, pp. 628-632. ISBN 978-94-007-6239-4
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    Publikationsdatum: 2018-01-19
    Beschreibung: Paleoceanography is the science of the history of the world ocean and its subbasins, of their physiography, benthic and planktonic biota, water masses and their properties, circulation patterns of surface, intermediate, and bottom water masses. Quantitative paleoceanography can in essence only be done from pelagic and hemipelagic sediments of the Mesozoic and Cenozoic ocean, basically from the age of the oldest undisturbed ocean crust to modern times. It is closely linked to the time of collecting ocean-wide geophysical data (marine seismics, magnetics), of deep-sea drilling and our increasing ability to collect long sediment cores, providing a global coverage and long, undisturbed time series of paleoceanographic data. It is henceforth a young subdiscipline of the marine geosciences.
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  • 91
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    Axial Volcanic Ridges (2016)
    Springer
    In:  In: Encyclopedia of Marine Geosciences. , ed. by Harff, J., Meschede, M., Petersen, S. and Thiede, J. Springer, Dordrecht, pp. 36-39. ISBN 978-94-007-6239-4
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    Publikationsdatum: 2018-01-19
    Beschreibung: The surface expression of volcanic activity is extremely variable at different spreading rates (see “Spreading Rates and Ridge Morphology”), as a result of the differing eruption styles associated with each. Axial volcanic ridges (AVRs), sometimes called neo-volcanic ridges, have been recognized at many slow-spreading Mid-Atlantic Ridge (MAR) spreading segments (e.g., Ballard and Van Andel, 1977; Karson et al., 1987; Smith and Cann, 1992; Parson et al., 1993; Sempere et al., 1993; Lawson et al., 1996; Bideau et al., 1998; Gracia et al., 1998; Navin et al., 1998; Briais et al., 2000; Peirce and Sinha, 2008; Searle et al., 2010) and some ultraslow-spreading segments elsewhere (Mendel et al., 2003). AVRs are elong ...
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  • 92
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    Submarine landslides offshore Vancouver Island along the northern Cascadia margin, British Columbia: why preconditioning is likely required to trigger slope failure (2016)
    Springer
    In:  Geo-Marine Letters, 36 (5). pp. 323-337.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: Bathymetric data reveal abundant submarine landslides along the deformation front of the northern Cascadia margin that might have significant tsunami potential. Radiocarbon age dating showed that slope failures are early to mid-Holocene. The aim of this study is the analysis of slope stability to investigate possible trigger mechanisms using the factor of safety analysis technique on two prominent frontal ridges. First-order values for the earthquake shaking required to generate instability are derived. These are compared to estimated ground accelerations for large (M=5 to 8) crustal earthquakes to giant (M=8 to 9) megathrust events. The results suggest that estimated earthquake accelerations are insufficient to destabilize the slopes, unless the normal sediment frictional resistance is significantly reduced by, for example, excess pore pressure. Elevated pore pressure (overpressure ratio of 0.4) should significantly lower the threshold for earthquake shaking, so that a medium-sized M=5 earthquake at 10 km distance may trigger submarine landslides. Preconditioning of the slopes must be limited primarily to the mid- to early Holocene as slope failures are constrained to this period. The most likely causes for excess pore pressures include rapid sedimentation at the time of glacial retreat, sediment tectonic deformation, and gas hydrate dissociation as result of ocean warming and sea level rise. No slope failures comparable in size and volume have occurred since that time. Megathrust earthquakes have occurred frequently since the most recent failures in the mid-Holocene, which emphasizes the importance of preconditioning for submarine slope stability.
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  • 93
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    In situ growth rates of deep-water octocorals determined from 3D photogrammetric reconstructions (2016)
    Springer
    In:  Coral Reefs, 35 (4). pp. 1227-1239.
    Details
    Publikationsdatum: 2019-02-01
    Beschreibung: Growth rates of deep-water corals provide important information on the recovery potential of these ecosystems, for example from fisheries-induced impacts. Here, we present in situ growth dynamics that are currently largely unknown for deep-water octocorals, calculated by applying a non-destructive method. Videos of a boulder harbouring multiple colonies of Paragorgia arborea and Primnoa resedaeformis in the Northeast Channel Coral Conservation Area at the entrance to the Gulf of Maine at 863 m depth were collected in 2006, 2010 and 2014. Photogrammetric reconstructions of the boulder and the fauna yielded georeferenced 3D models for all sampling years. Repeated measurements of total length and cross-sectional area of the same colonies allowed the observation of growth dynamics. Growth rates of total length of Paragorgia arborea decreased over time with higher rates between 2006 and 2010 than between 2010 and 2014, while growth rates of cross-sectional area remained comparatively constant. A general trend of decreasing growth rates of total length with size of the coral colony was documented. While no growth was observed for the largest colony (165 cm in length) between 2010 and 2014, a colony 50–65 cm in length grew 3.7 cm yr−1 between 2006 and 2010. Minimum growth rates of 1.6–2.7 cm yr−1 were estimated for two recruits (〈23 cm in 2014) of Primnoa resedaeformis. We successfully extracted biologically meaningful data from photogrammetric models and present the first in situ growth rates for these coral species in the Northwest Atlantic.
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  • 94
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    Seasonal dynamics of mesozooplankton in the Arctic Kongsfjord (Svalbard) during year-round observations from August 1998 to July 1999 (2016)
    Springer
    In:  Polar Biology, 39 (10). pp. 1859-1878.
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    Publikationsdatum: 2019-02-01
    Beschreibung: We conducted a year-round mesozooplankton study in the Arctic Kongsfjord from August 1998 until July 1999 to investigate seasonal abundance and vertical as well as stage distributions of the prevalent taxa. It is the first investigation in Kongsfjord that covers the Arctic winter season and provides reasonable estimates also of small-sized copepod species. Abundant smaller copepods comprised Oithona similis, Pseudocalanus minutus, Microcalanus spp., Triconia borealis and Acartia longiremis. Among the larger copepods, Calanus finmarchicus, C. glacialis, C. hyperboreus and Metridia longa dominated. The thecosome pteropod Limacina helicina was also an important component. Abundance maxima occurred in November (988,669 ind. m−2) with one to two orders of magnitude higher numbers as compared to all other months (39,832–200,067 ind. m−2). The summers of 1998 and 1999 were characterized by intrusions of Atlantic water, but the community was not entirely dominated by advected boreal species. During winter, the majority of the mesozooplankton occurred below 100 m. Advection is the most likely reason for the accumulation of zooplankton at depth in winter, but local production may also contribute to high overwintering numbers. Much lower abundances of most species in spring suggest high winter mortality and emphasize the importance of sufficient reproductive success during the previous summer to ensure enough winter survivors as seed stock for the coming reproductive season. This study was conducted prior to the recent warming trend in the Arctic. Therefore, it provides valuable baseline data and allows comparing present and future states of the zooplankton community in Kongsfjord.
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    Hotspot-Ridge Interaction (2016)
    Springer
    In:  In: Encyclopedia of Marine Geosciences. , ed. by Harff, J., Meschede, M., Petersen, S. and Thiede, J. Springer, Dordrecht, pp. 328-329. ISBN 978-94-007-6239-4
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    Publikationsdatum: 2018-01-19
    Beschreibung: The exchange of material (magma, mantle rock) between an intraplate mantle melting anomaly (hotspot, thought to be caused in places by the presence of a mantle plume) and the global spreading ridge system. Evidence for the interaction is found in the depth of the spreading axis, its morphology, the chemistry of the lavas (both on the spreading axis and possibly at the hotspot), and sometimes by the presence of linear volcanic ridges between spreading axis and hotspot. These linear volcanic ridges generally do not show clear age-progressive volcanism, in contrast to the volcanoes of the hotspot itself.
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  • 96
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    Seamounts (2016)
    Springer
    In:  In: Encyclopedia of Marine Geosciences. , ed. by Harff, J., Meschede, M., Petersen, S. and Thiede, J. Springer, Dordrecht, pp. 754-760. ISBN 978-94-007-6239-4
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    Publikationsdatum: 2019-09-23
    Beschreibung: Seamounts are literally mountains rising from the seafloor. More specifically, they are “any geographically isolated topographic feature on the seafloor taller than 100 m, including ones whose summit regions may temporarily emerge above sea level, but not including features that are located on continental shelves or that are part of other major landmasses” (Staudigel et al., 2010). The term “guyot” can be used for seamounts having a truncated cone shape with a flat summit produced by erosion at sea level (Hess, 1946), development of carbonate reefs (e.g., Flood, 1999), or partial collapse due to caldera formation (e.g., Batiza et al., 1984). Seamounts 〈1,000 m tall are sometimes referred to as “knolls” (e.g., Hirano et al., 2008). “Petit spots” are a newly discovered subset of sea knolls confined to the bulge of subducting oceanic plates of oceanic plates seaward of deep-sea trenches (Hirano et al., 2006).
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    Mg/Ca Paleothermometry (2016)
    Springer
    In:  In: Encyclopedia of Marine Geosciences. , ed. by Harff, J., Meschede, M., Petersen, S. and Thiede, J. Springer, Dordrecht, pp. 499-501. ISBN 978-94-007-6239-4
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    Publikationsdatum: 2018-01-19
    Beschreibung: Mg/Ca paleothermometry. Geochemical proxy used in paleoceanography to reconstruct past temperatures of the ocean surface. Reliable sea surface temperature (SST) estimates are crucial to the reconstruction and modeling of past climate change. Reconstructions of the thermal state of the ocean, in turn, may help to assess the significance of instrumentally observed climate variability and may validate global circulation models used to predict future climate change. Most promising in this respect is the Mg/Ca paleothermometry, which is based on the temperature dependence of the substitution of magnesium into biogenic calcite. It has long been known that tropical calcitic shells of marine organisms are generally more enriched in magnesium than subpolar shells (e.g., Savin and Douglas, 1973). But in particular for the important group of foraminifera (marine protozoa), a well-defined and species-specific calibration of the shell Mg/Ca ratio on ocean temperature was missing until the ...
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  • 98
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    Marine Geosciences: A Short, Eclectic, and Weighted Historic Account (2016)
    Springer
    In:  In: Encyclopedia of Marine Geosciences. , ed. by Harff, J., Meschede, M., Petersen, S. and Thiede, J. Springer, Dordrecht, pp. 437-448. ISBN 978-94-007-6239-4
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    Publikationsdatum: 2018-01-19
    Beschreibung: Marine geosciences are covering all phenomena and processes related to the formations of shallow shelf seas and of the deep ocean. They draw on modern dynamics of seafloor and sediment formation, marine geophysics and tectonics, volcanology, geochemistry, microbiology, biology, and paleontology of marine organisms. They are of great economic importance because of the wealth of nonliving marine resources.
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  • 99
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    Treibhauseffekt, Wetter, Klima, Klimawandel (2016)
    Springer
    In:  In: Erkenntnis, Wissenschaft und Gesellschaft: Wie Forschung Wissen schafft. , ed. by Buchmüller, W. and Jacobeit, C. Springer, Heidelberg, Germany, pp. 137-150. ISBN 978-3-662-49911-5
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    Publikationsdatum: 2017-12-01
    Materialart: Book chapter , NonPeerReviewed
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    A successful non-native predator, round goby, in the Baltic Sea: generalist feeding strategy, diverse diet and high prey consumption (2016)
    Springer
    In:  Hydrobiologia, 777 (1). pp. 271-281.
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    Publikationsdatum: 2019-02-01
    Beschreibung: The round goby Neogobius melanostomus has successfully invaded much of the Baltic Sea. However, very little is known about the feeding habits of the species in this newly invaded environment. Our laboratory experiment showed that the round goby is able to effectively consume a diverse variety of prey when given the choice between dominant benthic invertebrates: bivalves (Macoma balthica, Mytilus trossulus, Cerastoderma glaucum) and amphipods (Gammarus spp.). In contrast consumption of the gastropod (Theodoxus fluviatilis) was very low in all provided combinations. Nevertheless, the round goby had no statistically significant preference towards any of the prey taxa. The round goby exhibited size-specific consumption of M.trossulus, with smaller individuals being consumed at least 25% more than larger size classes. In addition elevated prey density resulted in higher consumption of prey by the fish. The broad diet suggests that shifting densities of benthic invertebrate prey has little influence on the further dispersal of the round goby in the Baltic Sea as the species is potentially able to switch between several native invertebrate taxa. This opportunistic feeding behaviour has likely favoured this invasion and ensured success of the species in the invaded ecosystem.
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