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  • 1999  (54)
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  • 2020-2024  (61)
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  • 1
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    In:  Heidelberg, Springer, vol. 113, no. XVI:, pp. 1-14, (ISBN 1-56670-263-3)
    Publication Date: 1999
    Keywords: Handbook of geophysics ; Seismology ; Seismics (controlled source seismology) ; Early warning systems (earthquakes, volcanic eruptions, tsunamis etc.) ; Earthquake hazard ; KTB ; ICDP ; IOcean Drilling Program ; climate ; Antarctica ; Nuclear explosion ; Volcanology ; GeodesyY ; satellites ; remote ; sensing ; gas ; hydrates ; Geothermics ; Energy (of earthquakes) ; potable ; water ; waste ; soils ; evolution ; Geol. aspects ; geotechnics ; Engineering geophys. ; ores
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  • 2
    Publication Date: 2016-04-18
    Description: Fluxes of phosphate across the sediment–water interface have been measured using inhibitors of bacterial activity sterilization and chloramphenicol and a control in order to quantify the influence of bacterial abundance on them. Results show that phosphate concentration in the interstitial water decreased when bacteria were present, in relation to treated aquaria. The measured (Jo) and theoretical fluxes (Jd) of phosphate also were higher when bacterial activity was suppressed. Mass balance calculated for Carbon, Nitrogen and Phosphorus in the sediment revealed a loss of theses compounds when bacterial activity was suppressed, and a net accumulation of Carbon and Phosphorus, and loss of Nitrogen under natural conditions.
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  • 3
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    In:  In: Land-Ocean Systems in the Siberian Arctic : Dynamica and History. , ed. by Kassens, H., Bauch, H. A., Dmitrenko, I. A. and Eicken, H. Springer, Berlin (u.a.), pp. 693-711. ISBN 3-540-65676-6
    Publication Date: 2015-03-31
    Description: Russian and German scientists have investigated the extreme environmental system in and around the Laptev Sea in the Siberian Arctic. For the first time a major comprehensive research program combining the efforts of several projects addressed both oceanic and terrestrial processes, and their consequences for marine and terrestrial biota, landscape evolution as well as land-ocean interactions. The primary scientific goal of the multidisciplinary program was to decipher past climate variations and their impact on contemporary environmental changes. Extensive studies of the atmosphere, sea ice, water column, and sea-floor on the Laptev Sea Shelf, as well as of the vegetation, soil development, carbon cycle, permafrost behaviour and lake hydrology, and sedimentationon Taymyr Peninsula and Severnaya Zemlya Archipelago were performed during the past years under a framework of joint research activities. They included land and marine expeditions during spring (melting), summer (ice free), and autumn (freezing) seasons. The close bilateral cooperation between many institutions in Russia and Germany succeeded in drawing a picture of important processes shaping the marine and terrestrial environment in northern Central Siberia in Late Quaternary time. The success of the projects, which ended in late 1997, resulted in the definition and establishment of a new major research effort which will concentrate on establishing a better understanding of the paleoclimatic and paleoenvironmental record of the area. This is important because it allows to be able to judge rates and extremes of potential future environmental changes.
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  • 4
    Publication Date: 2018-05-29
    Description: Analogue experiments in part I led to the conclusion that pyroclastic flows depositing very highgrade ignimbrite move as dilute suspension currents. In the thermo–fluid–dynamical model developed, the degree of cooling of expanded turbulent pyroclastic flows dynamically evolves in response to entrainment of air and mass loss to sedimentation. Initial conditions of the currents are derived from column-collapse modeling for magmas with an initial H2O content of 1–3 wt.% erupting through circular vents and caldera ring-fissures. The flows spread either longitudinally or radially from source up to a runout distance that increases with higher mass flux but decreases with higher gas content, temperature, bottom slope and coarser initial grain size. Progressive dilution by entrainment and sedimentation causes pyroclastic currents to transform into buoyant ash plumes at the runout distance. The ash plumes reach stratospheric heights and distribute 30–80% of the erupted material as widespread co-ignimbrite ash. Pyroclastic suspension currents with initial mass fluxes of 107-1012 kg/s can spread for tens of kilometers with only limited cooling, although they move as supercritical, strongly entraining currents for the eruption conditions considered here. With increasing eruption mass flux, cooling during passage through the fountain diminishes while cooling during flow transport increases. The net effect is that eruption temperature exerts the prime control on emplacement temperature. Pyroclastic suspension currents can form welded ignimbrite across their entire extent if eruption temperature is To11.3.Tmw, the minimum welding temperature. High eruption rates, a large fraction of fine ash, and a ring-fissure vent favor the formation of extensive high-grade ignimbrite. For very hot eruptions produc ing sticky, partially molten pyroclasts, analysis of particle aggregation systematics shows that factors favoring longer runout also favor more efficient aggregation, which reduces runout. As a result, very high-grade ignimbrites cannot spread more than a few tens of kilometers from their source. In cooler pyroclastic currents, particles do not aggregate, and the sedimentation process may involve re-entrainment of particles, which potentially leads to more extensive cooling and longer runout; such effects, however, are only significant when net erosion of substrate occurs. Model results can be employed to estimate mass flux and duration of ignimbrite eruptions from measured ignimbrite masses and aspect ratios. The model also provides an alternative explanation of the observed decrease in H/Lratios with ignimbrite mass.
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  • 5
    Publication Date: 2017-06-29
    Description: Hydrothermal activity in the Central Bransfield Basin revealed an active low-temperature vent field on top of a submarine volcanic structure. A temperature anomaly was detected and the sea floor showed various patches of white silica (opal-A) precipitate exposures and some yellow–brown Fe-oxyhydroxide crusts. Enriched dissolved methane concentrations were encountered. Sediment was near 24°C just after the grab came on deck. No dense population of chemosynthetically based macrofauna known from other hydrothermal venting areas was present, except for pogonophora. The observations suggest that the sedimented hydrothermal field at Hook Ridge is a low-temperature end-member branch from a deeper hydrothermal source.
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  • 6
    Publication Date: 2018-06-06
    Description: Investigations of factors affecting feeding success in fish larvae require knowledge of the scales of variability of the feeding process itself and the indices used to assess this variability. In this study, we measured short-term (diel) variability in feeding rates of wild haddock (Melanogrammus aeglifinus) larvae four times per day during a 10-d cruise in the northern North Sea. Feeding activity was evaluated using indices of gut fullness, prey digestive state and biochemical measurements (tryptic enzyme activity). The gut fullness and the enzyme activity indices indicated moderate to high rates of food consumption throughout the cruise. Time series analysis of the three indices showed significant diel variability in all indices and enabled identification of significant lags between food uptake and peak digestive enzyme activity. The typical pattern of food consumption and digestion was characterized by maximal ingestion of prey early in the evening (19:00 hrs) and peak digestive enzyme activity at 01:00 hrs. The time scale over which enzyme activities reacted to prey ingestion was ca. 6 h, and is consistent with expectations from controlled laboratory experiments with other larval fish species. Significant diel variability in tryptic enzyme activity suggests that attempts to relate this measure of feeding success to other variables (e.g. food concentrations) should take care to accommodate natural cycles in feeding activity before making statistical comparisons.
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  • 7
    Publication Date: 2017-05-18
    Description: Facies analysis, fossil dating, and the study of the metamorphism in the Late Triassic to Early Cretaceous sedimentary successions in the central part of the Northern Calcareous Alps allow to reconstruct the tectonic evolution in the area between the South Penninic Ocean in the northwest and the Tethys Ocean with the Hallstatt Zone in the southeast. The Triassic as well as the Early and Middle Jurassic sediments were deposited in a rifted, transtensive continental margin setting. Around the Middle/Late Jurassic boundary two trenches in front of advancing nappes formed in sequence in the central part of the Northern Calcareous Alps. The southern trench (Late Callovian to Early Oxfordian) accumulated a thick succession of gravitatively redeposited sediments derived from the sedimentary sequences of the accreted Triassic–Liassic Hallstatt Zone deposited on the outer shelf and the margin of the Late Triassic carbonate platform. During a previous stage these sediments derived from sequences deposited on the more distal shelf (Salzberg facies zone of Hallstatt unit, Meliaticum), and in a later stage from more proximal parts (Zlambach facies zone of Hallstatt unit, Late Triassic reef belt). Low temperature–high pressure metamorphism of some Hallstatt limestones before redeposition is explained by the closure of parts of the Tethys Ocean in Middle to Late Jurassic times and associated subduction. In the northern trench (Late Oxfordian to Kimmeridgian) several hundred meters of sediment accumulated including redeposited material from a nearby topographic rise. This rise is interpreted as an advancing nappe front as a result of the subduction process. The sedimentary sealing by Tithonian sediments, documented by uniform deep-water sedimentation (Oberalm Formation), gives an upper time constraint for the tectonic events. In contrast to current models, which propose an extensional regime for the central and eastern Northern Calcareous Alps in the Late Jurassic, we propose a geodynamic model with a compressional regime related to the Kimmerian orogeny.
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  • 8
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    In:  In: Land-Ocean Systems in the Siberian Arctic : Dynamics and History. , ed. by Kassens, H., Bauch, H. A., Dmitrenko, I. A. and Eicken, H. Springer, Berlin (u.a.), pp. 587-599. ISBN 3-540-65676-6
    Publication Date: 2015-04-08
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  • 9
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    In:  In: Land-Ocean Systems in the Siberian Arctic : Dynamics and History. , ed. by Kassens, H., Bauch, H. A., Dmitrenko, I. A. and Eicken, H. Springer, Berlin (u.a.), pp. 667-682. ISBN 3-540-65676-6
    Publication Date: 2015-04-08
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  • 10
    Publication Date: 2015-08-27
    Description: We have employed electronmicroscopical methods (SEM, TEM) to document the microbial community associated with the marine sponge Aplysina cavernicola (formerly Verongia cavernicola, class Demospongiae). Five dominant bacterial types were identified, three of which resemble the morphotypes originally described by Vacelet (1975). One bacterial type possesses morphological properties that are characteristic of the genus Planctomyces. In addition, morphologically uniform bacteria which reside inside the nuclei of host cells were observed. Using in situ hybridization with fluorescently labelled rRNA probes directed against known bacterial groups, the phylogenetic affiliation of the mesohyl bacteria was assessed. It could be shown that the vast majority of mesohyl bacteria belongs to the domain Bacteria with a low GC content. Among the Bacteria, the delta-Proteobacteria were most abundant, followed by the gamma-Proteobacteria and representatives of the Bacteroides cluster. Clusters of Gram-positive bacteria with a high GC content were also found consistently in low amounts. No hybridization signal was obtained with probes specific to the domain Archaea, to the alpha- and beta-Proteobacteria and to the Cytophaga/Flavobacterium cluster. This study describes for the first time the application of the “top-to-bottom approach” using 16S rRNA probes and in situ hybridization to assess the microbial diversity in Aplysina sponges
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  • 11
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    In:  In: Land-Ocean Systems in the Siberian Arctic : Dynamics and History. , ed. by Kassens, H., Bauch, H. A., Dmitrenko, I. A. and Eicken, H. Springer, Berlin (u.a.), pp. 73-92. ISBN 3-540-65676-6
    Publication Date: 2016-01-19
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  • 12
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    In:  In: Land-Ocean Systems in the Siberian Arctic : Dynamics and History. , ed. by Kassens, H., Bauch, H. A., Dmitrenko, I. A. and Eicken, H. Springer, Berlin (u.a.), pp. 577-585. ISBN 3-540-65676-6
    Publication Date: 2015-04-08
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  • 13
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    In:  In: Land-Ocean Systems in the Siberian Arctic : Dynamics and History. , ed. by Kassens, H., Bauch, H. A., Dmitrenko, I. A. and Eicken, H. Springer, Berlin (u.a.), pp. 516-532. ISBN 3-540-65676-6
    Publication Date: 2015-04-08
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  • 14
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    In:  In: Land-Ocean Systems in the Siberian Arctic : Dynamics and History. , ed. by Kassens, H., Bauch, H. A., Dmitrenko, I. A. and Eicken, H. Springer, Berlin (u.a.), pp. 601-613. ISBN 3-540-65676-6
    Publication Date: 2015-04-08
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  • 15
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    In:  In: Land-Ocean Systems in the Siberian Arctic : Dynamics and History. , ed. by Kassens, H., Bauch, H. A., Dmitrenko, I. A. and Eicken, H. Springer, Berlin (u.a.), pp. 93-99. ISBN 3-540-65676-6
    Publication Date: 2015-04-08
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  • 16
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    In:  In: Land-Ocean Systems in the Siberian Arctic : Dynamics and History. , ed. by Kassens, H., Bauch, H. A., Dmitrenko, I. A. and Eicken, H. Springer, Berlin (u.a.), pp. 125-140. ISBN 3-540-65676-6
    Publication Date: 2015-04-08
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  • 17
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    In:  International Journal of Earth Sciences, 88 (2). pp. 325-336.
    Publication Date: 2018-05-28
    Description:  The reflectance of sediments (gray level) were measured on 11 sediment cores from the Norwegian–Greenland–Iceland Sea (Nordic seas). The analyzed time interval covers the past five glacial–interglacial cycles. Although the results demonstrate that the gray-level method has a potential for stratigraphic purposes, it is indicated that gray-level changes in the Nordic seas are not necessarily driven by variations in the content of biogenic calcite. A detailed comparison of gray-level values with contents of total CaCO3 (carbonate) and total organic carbon (TOC) reveals no overall causal link between these proxies. However, specific glacial core sections with layers containing organic-rich sediment clasts as a consequence of iceberg-rafting seem to correlate well with law gray-level values. Of those cores which show relatively high and comparable carbonate values in the last three main interglacial intervals (stages 11, 5.5, and 1), stage 11 is always marked by the highest gray-level values. A close inspection of the surface structure of the foraminiferal tests as well as the conduction of reflectance measurements on these tests leads to the conclusion that enhanced carbonate corrosion occurred during stage 11. The test corrosion not only affected the reflectance of the tests by making them appear whiter, it also seems responsible for the comparatively high gray-level values of the total sediment in stage 11. In contrast, the relatively low gray-level values found in stages 5.5, and 1 are not associated with enhanced test corrosion. This observation implies that variable degrees of carbonate corrosion can have a profound effect on total sediment reflectance.
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  • 18
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    In:  In: Land-Ocean Systems in the Siberian Arctic : Dynamics and History. , ed. by Kassens, H., Bauch, H. A., Dmitrenko, I. A. and Eicken, H. Springer, Berlin (u.a.), pp. 553-560. ISBN 3-540-65676-6
    Publication Date: 2015-04-09
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  • 19
    Publication Date: 2017-10-09
    Description: Although blooms of opportunistic fast-growing macroalgae now occur frequently in coastal ecosystems affected by eutrophication, their initiation and control is little understood. Most previous studies have focused on the ecophysiology of adult algae only. We show that spores and/or germlings may represent critical stages in the life cycles and mass-developments of co-occurring opportunistic macroalgae in the Baltic (Pilayella littoralis and Enteromorpha spp.). We investigated the overwintering of spores, timing of germination, subsequent growth, and grazing on spores and germlings, in order to explain the initiation of mass blooms and species dominance patterns. In the field, Enteromorpha spp. showed 10- to 50-fold higher abundances of overwintering microscopic forms (up to 330 individuals cm-2) than P. littoralis. Moreover, we found continuous production of spores (up to 1.2 million settling spores m-2 h-1) from April to October in Enteromorpha spp., while there was evidence of only a short reproductive period in Pilayella. However, in spring, germlings and adults of P. littoralis appeared earlier in the field and reached a 10-fold higher biomass than Enteromorpha spp. In factorial laboratory experiments including temperature and light, there were clear differences in timing of germination. P. littoralis germinated at 5°C whereas Enteromorpha spp. required temperatures of 10-15°C for germination. In contrast, we detected only minor differences in growth response among adults of P. littoralis and Enteromorpha spp. Germination, not growth of adults, appeared to be the ecophysiological bottleneck for initiating mass spring development. Following the spring Pilayella bloom, Enteromorpha germlings occurred massively in the field (April-September), but rarely developed into adults. In laboratory feeding experiments we tested whether crustacean mesograzers common in summer may control development of Enteromorpha germlings. Both germination of settled spores and growth of germlings were reduced by 93-99% in the presence of grazers (Idotea chelipes and Gammarus locusta). Thus in addition to ecophysiological constraints, grazers, if present, may play a decisive role in the early life stages of macroalgal mass developments. These results mirror patterns of overwintering of seeds, germination control, seed and seedling predation in terrestrial plant communities.
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  • 20
    Publication Date: 2017-03-07
    Description: The distribution of partial pressure of carbon dioxide and the concentrations of nitrous oxide and methane were investigated in a cold water filament near the coastal upwelling region off Oman at the beginning of the southwest monsoon in 1997. The results suggest that such filaments are regions of intense biogeochemical activity which may affect the marine cycling of climatically relevant trace gases
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  • 21
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    In:  Journal of Applied Phycology, 11 . pp. 69-78.
    Publication Date: 2018-06-15
    Description: Seaweed responses to eutrophication and their role in coastal eutrophication processes were compared at 8 different sites along the European coasts from the Baltic to the Mediterranean as part of the EU-ENVIRONMENT Project Marine Eutrophication and benthic Macrophytes (EUMAC). Structural and functional changes of marine benthic vegetation typical of eutrophic waters, in particular mass development (blooms) of certain seaweeds, are not merely the result of increased nutrient loading, but must be attributed to complex interactions of primary and secondary effects during the eutrophication process. Due to species-specific physiological properties of the algae (nutrient kinetics, growth potential, light, temperature requirements), the combined effects of abiotic and biotic factors on juvenile or adult developmental stages control the development of algal blooms in different ways. In particular the role of light, temperature, water motion and oxygen depletion, as well as of grazers, on early and adult developmental stages of the algae are considered. The result are discussed in the context of coastal eutrophication control and management
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  • 22
    Publication Date: 2018-06-07
    Description: During the breeding season 1996/97 we compared the foraging and diving behaviour of adult Magellanic penguins (Spheniscus magellanicus), growth rates of their chicks and their breeding success at two colonies in the south of Chile. One of the colonies is located on Magdalena Island in the Strait of Magellan, where a commercial fishery existed several years ago; the other, on the shores of the yet unexploited Otway Sound. Thirty adult Magellanic penguins were equipped with time–depth recorders (TDR) to investigate their behaviour at sea. In each colony 15 adults returning from the sea were stomach flushed to analyse dietary composition. Chicks of TDR-nests and of 12 additional control nests were weighed regularly. Foraging effort was significantly higher at Magdalena than at Otway. The Magdalena-birds usually remained at sea overnight and foraged with a mean duration of 18 h, whereas the penguins of Otway Sound foraged during 1-d trips with a mean duration of only 9 h. Compared to Magdalena, penguins at Otway dived shallower (mean depth 14.9 vs 16.5 m), shorter (mean duration 57.8 vs 64.3 s) and showed more searching and feeding as opposed to travelling activity (on average 69 vs 55%) during the foraging trips. Compared to other breeding locations both colonies were characterised by high chick growth rates, high fledging body masses (〉3 kg) and early fledging date (after 70 to 80 d), and a very high reproductive success of 〉1.75 chicks per breeding pair. Comparison of the diet (almost exclusively sprats) with former investigations suggests for both areas an unchanged food structure over the last decade. The results in both colonies indicate ample food availability in the season 1996/97. However, compared to the much smaller Otway colony, penguins on Magdalena have to cope with more competition for food. Therefore, future prey limitation, through resumed fishery operations or effects of El Niño, might affect the penguin population on the island more negatively than in Otway Sound.
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  • 23
    Publication Date: 2021-06-16
    Description: The cephalopod remains from 206 Antarctic fur seal (Arctocephalus gazella) scats collected at Mossman Peninsula, South Orkney Islands (n = 105) and at Stranger Point, South Shetland Islands (n = 101) contained 148 beaks (57 lower and 91 upper). The lower beaks were sorted and measured. Identification of 33 of the lower beaks that were collected at Mossman Peninsula revealed two squid species, Brachioteuthis ?picta (n = 26) and Psychroteuthisglacialis (n = 7), with lower rostral lengths (LRL) of 2.0–3.5 mm, and 1.0–2.5 mm, respectively. Identification of 15 of the lower beaks collected at Stranger Point revealed the same squid species, with the LRL of B. ?picta ranging from 3.0–3.4 mm (n = 9), and that of P. glacialis from 2.0 to 3.5 mm (n = 6). Estimated squid sizes and wet masses indicate that Antarctic fur seals feed on the small sub-adult squid which inhabit the surface layers. We have compared the squid diet estimated for the seals with that reported for its congeners in lower latitudes and other Antarctic seals, and conclude that cephalopods do not form an important food resource for Antarctic fur seals.
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  • 24
    Publication Date: 2018-01-19
    Description: Investigations on the occurrence of trichodinid ciliates from fish caught in the Kiel Bight and Kiel Fjord (western Baltic Sea) were carried out between September 1996 and March 1997. Smears of the gills, fins, and skin of 120 Gadus morhua and 92 Platichthys flesus caught by fish traps and trammel nets revealed the presence of trichodinid ciliates. According to the fish species and locality, different prevalences and densities of trichodinid ciliates were found. Fish caught in the Kiel Bight revealed a lower prevalence of trichodinid ciliates on their gills (P. flesus 74.2%, G. morhua 3.8%) in comparison with fish of the same species and size caught in the Kiel Fjord (P. flesus 75.0%, G. morhua 26.2%). In both areas, P. flesus was more heavily infested than G. morhua. Seasonal changes in the prevalence of infestation of P. flesus between autumn and winter in the Kiel Fjord are proposed to be linked to an increase in bacterial biomass during winter. The fish ecology in combination with the total number of bacteria in the fish environment is discussed as an important factor influencing the abundance of trichodinid ciliates. The present data suggest the use of trichodinid ciliates as an indicator for eutrophication in brackish-water environments.
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  • 25
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    In:  In: Molecular Ecology of Aquatic Communities. , ed. by Zehr, J. P. and Voytek, M. A. Developments in Hydrobiology, 138 . Springer, Berlin, Germany, pp. 177-198. ISBN 978-94-010-5827-8
    Publication Date: 2018-06-29
    Description: Recent advances in using immunological and nucleic acid probes to detect the effects of environmental stress on phytoplankton growth rate and yield are reviewed here. The rationale for this approach is discussed in the context of the general response observed from microorganisms grown under stress imposed by various environmental factors. Retrenchment, or the observed down-regulation of metabolic processes under nutrient deficiency, is categorized as a general response that is of limited use in designing probes to stress induced by a specific nutrient. In contrast, compensation and the increase capacity for nutrient acquisition are specific responses that appear more promising for the development of such probes. Methods and approaches used to design immunological and nucleic acid probes for stress imposed by nutrient deficiency are reviewed. Specific examples for iron and nitrogen limitation are presented to demonstrate the potential use of nutrient stress indicators in natural populations of phytoplankton. Finally, the limitations of this approach and the importance of understanding the regulation of the genes and proteins used to prepare the probes are emphasized.
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  • 26
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    In:  Parasitology Research, 85 . pp. 638-646.
    Publication Date: 2018-01-19
    Description: The present study provides further data on the occurrence of Pseudoterranova decipiens in fish from two different sampling sites in the Antarctic. A total of 690 fish belonging to 33 species from the eastern Weddell Sea and 322 fish belonging to 12 species from the South Shetland Islands were examined. Altogether, 23 fish species were found to be infested and 11 new host records could be established. P. decipiens occurred at a water depth of between 80 and 820 m. Chaenocephalus aceratus and Notothenia coriiceps from the South Shetland Islands were the species with the highest prevalence (95%) and intensity (2-194 and 1-121, respectively) of infestation. Both are transport hosts, which mainly feed on benthic nototheniid fish species and accumulate the nematodes. Bathypelagic, pelagic, or mainly euphausid feeding fish species were only lightly infested, if at all. This demonstrates the benthic life cycle of P. decipiens in the Antarctic. The preferred site of infestation was the body cavity and the liver; no specimen could be isolated from the fish musculature. This might be explained by the low water temperatures. The infestation of fish from the Weddell Sea was distinctly lower than that of fish around the South Shetland Islands. Besides possible differences in final host populations at the two localities studied, the loss of eggs and larvae under the eastern Weddell Sea shelf ice and over the continental slope and differences in the availability of the first intermediate and macroinvertebrate hosts led to a lower level of infestation. Another role, although nondecisive, may be played by the reduced time of development and infectivity of eggs and larvae, respectively, in the extremely cold waters of the Weddell Sea. P. decipiens is not a rare but, rather a well-established parasite of the Antarctic fauna, which demonstrates the ability of this cosmopolitan species to complete its life cycle even under conditions of subzero temperatures.
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  • 27
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    In:  In: Ice Physics and the Natural Environment. , ed. by Wettlaufer, J. S., Dash, J. G. and Untersteiner, N. NATO ASI Series, 56 . Springer, Heidelberg, Germany, pp. 341-346.
    Publication Date: 2020-03-30
    Description: The variability of sea ice in the polar regions is an important factor in the climate system particularly because of its strong influence on heat and freshwater transports as well as momentum exchange between ocean and atmosphere. To describe these effects accurately ice conditions need to be known over long time periods and wide regions. Models are able to produce such data but need to be verified by observations (Lemke et al., 1998). One classical model variable which can be validated quite well with remote sensing methods (SMMR, SSM/I) is the ice coverage. Modelled ice drift can be verified by comparing observed and simulated drift trajectories (Kreyscher et al., 1998). Ice thickness observations, however, are only rarely available from drillings, sonar measurements and laser altimeter recordings. Keywords
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  • 28
    Publication Date: 2016-09-08
    Description:  The El Niño-Southern Oscillation (ENSO) is investigated in a multicentury integration conducted with the coupled general circulation model (CGCM) ECHAM3/LSG. The quasiperiodic interannual oscillations of the simulated equatorial Pacific climate system are due to subsurface temperature anomaly propagation and a positive atmosphere-ocean feedback. The gravest internal wave modes contribute to the generation of these anomalies. The simulated ENSO has a characteristic period of 5–8 years. Due to the coarse resolution of the ocean model the ENSO amplitude is underestimated by a factor of three as compared to observations. The model ENSO is associated with the typical atmospheric teleconnection patterns. Using wavelet statistics two characteristic interdecadal modulations of the ENSO variance are identified. The origins of a 22 and 35 y ENSO modulation as well as the characteristic ENSO response to greenhouse warming simulated by our model are discussed.
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  • 29
    Publication Date: 2018-05-28
    Description: The Asian decapod Hemigrapsus penicillatus (de Haan, 1835) was first recorded in European waters in 1994. The first specimens were collected in the estuary of Charente Maritime on the west coast of France close to La Rochelle. The current range in Europe covers Spanish shallow water habitats of the Bay of Biscay to areas north of La Rochelle (France). Densities of up to 20 specimens per square metre occur. This species has a high temperature and salinity tolerace and will expand its distribution in European waters. It is not clear whether this crab was introduced by shipping in ballast water or as a fouling organism. Based on a study of ship hull fouling in German dry docks this account provides evidence that hull fouling is a likely vector for the introduction of this crab. In August 1993, six juvenile specimens of H. penicillatus were removed from the hull of a car-carrier. After its journey from Japan into European waters this vessel docked in the port of Bremerhaven (Germany) for a routine inspection and coating with antifouling paint.
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  • 30
    Publication Date: 2019-09-23
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  • 31
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    In:  Journal of Comparative Physiology B - Biochemical Systemic and Environmental Physiology, 169 (2). pp. 100-106.
    Publication Date: 2018-05-29
    Description: Open-flow oxygen and carbon dioxide respirometry was used in Neumünster Zoo (Germany) to examine the energy requirements of six Asian small-clawed otters (Amblonyx cinerea) at rest and swimming voluntarily under water. Our aim was to compare their energy requirements with those of other warm-blooded species to elucidate scale effects and to test whether the least aquatic of the three otter species differs markedly from these and its larger relatives. While at rest on land (16 °C, n = 26), otters (n = 6, mean body mass 3.1 ± 0.4 kg) had a respiratory quotient of 0.77 and a resting metabolic rate of 5.0 ± 0.8 Wkg−1(SD). This increased to 9.1 ± 0.8 Wkg−1 during rest in water (11–15 °C, n = 4) and to 17.6 ± 1.4 Wkg−1 during foraging and feeding activities in a channel (12 °C, n = 5). While swimming under water (n = 620 measurements) in an 11-m long channel, otters preferred a speed range between 0.7 ms−1 and 1.2 ms−1. Transport costs were minimal at 1 ms−1 and amounted to 1.47 ± 0.24 JN−1 m−1 (n = 213). Metabolic rates of small-clawed otters in air were similar to those of larger otter species, and about double those of terrestrial mammals of comparable size. In water, metabolic rates during rest and swimming were larger than those extrapolated from larger otter species and submerged swimming homeotherms. This is attributed to high thermoregulatory costs, and high body drag at low Reynolds numbers.
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  • 32
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    In:  Reviews in Fish Biology and Fisheries, 9 . pp. 375-378.
    Publication Date: 2016-09-14
    Description: Over the past eight years my colleagues and I have been involved in a major project to make key information on fishes available to users, especially in developing countries (Froese and Pauly, 1998; http://www. fishbase.org/). There are about 25 000 species of fishes in the world of which over 7 000 are used by humans as food, for sport or as pets. Dealing with such large numbers meant that we depended heavily on taxonomic works to ensure that we assigned relevant information to the correct species. Eight years through the project we have covered 22 000 species, 40 000 synonyms, 80 000 common names, and 14 000 references. We have worked with over 300 collaborators, among them many taxonomists, and we have visited many museums. In this contribution I present our experiences in the catchy categories of ‘good’, ‘bad’, and ‘ugly’, not to offend anyone, but to provoke reactions that hopefully will lead to some of the changes that we as users of taxonomic information would like to see.
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  • 33
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    In:  , ed. by Kassens, H., Bauch, H. A., Dmitrenko, I. A., Eicken, H., Hubberten, H. W., Melles, M., Thiede, J. and Timokhov, L. A. Springer, Berlin (u.a.), XI, 711 pp. ISBN 3-540-65676-6
    Publication Date: 2019-09-24
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  • 34
    Publication Date: 2021-06-17
    Description: Potential fecundity in Loligo vulgaris reynaudii was estimated to be about 17 000 eggs, calculated as the total number of discernible oocytes in the ovary and oviduct. Squid were observed to spawn up to 8140 eggs over a 36 h period in captivity. First estimations of actual fecundity are therefore between 8000 and 17 000 eggs. Factors complicating a more accurate estimation of actual fecundity in this species include difficulties with aquarium maintenance, their behaviour of spawning over a protracted period and in multiple sites, and atretic oocytes observed in both developing and mature ovaries. Detailed morphological and histological analysis of gonads collected at regular intervals over a complete spawning season will allow a more precise calculation of actual fecundity.
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  • 35
    Publication Date: 2021-06-17
    Description: The pattern and characteristics of diving in 14 female northern rockhopper penguins, Eudyptes chrysocome moseleyi, were studied at Amsterdam Island (37°50′S; 77°31′E) during the guard stage, using electronic time–depth recorders. Twenty-nine foraging trips (27 daily foraging trips and two longer trips including one night) with a total of 16 572 dives of ≥3 m were recorded. Females typically left the colony at dawn and returned in the late afternoon, spending an average of 12 h at sea, during which they performed ∼550 dives. They were essentially inshore foragers (mean estimated foraging range 6 km), and mainly preyed upon the pelagic euphausiid Thysanoessa gregaria, fishes and squid being only minor components of the diet. Mean dive depth, dive duration, and post-dive intervals were 18.4 m (max. depth 109 m), 57 s (max. dive duration 168 s), and 21 s (37% of dive duration), respectively. Descent and ascent rates averaged 1.2 and 1.0 ms−1 and were, together with dive duration, significantly correlated with dive depth. Birds spent 18% of their total diving time in dives reaching 15 to 20 m, and the mean maximum diving efficiency (bottom time:dive cycle duration) occurred for dives reaching 15 to 35 m. The most remarkable feature of diving behaviour in northern rockhopper penguins was the high percentage of time spent diving during daily foraging trips (on average, 69% of their time at sea); this was mainly due to a high dive frequency (∼44 dives per hour), which explained the high total vertical distance travelled during one trip (18 km on average). Diving activity at night was greatly reduced, suggesting that, as other penguins, E. chrysocome moseleyi are essentially diurnal, and locate prey using visual cues.
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  • 36
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    In:  In: Advancing Research on Living and Fossil Cephalopods. , ed. by Olóriz Saéz, F. and Rodríguez-Tovar, F. J. Springer, Boston, MA, pp. 17-21, 5 pp. ISBN 978-1-4615-4837-9
    Publication Date: 2021-05-11
    Description: The comparative morphometric analysis, which has proved valuable in vertebrates for the identification of features needed for further clarification of classifications, is lacking in the greater part of cephalopod literature (Voss, 1977; Roper, 1983). The taxonomy of sepiolids, especially that of Sepiola and Sepietta species, is quite difficult in practice (Naef, 1923; Mangold and Boletzky, 1987; Nesis, 1987; Guerra, 1992). In most cases the mantle has to be cut open to expose the organs of the mantle cavity, and the comparison of several specimens of different species and of both sexes is recommended (Bello, 1995). Adult and sub-adult males can be identified from the hectocotylous, females from the bursa copulatrix, inside the mantle cavity. In Sepietta neglecta and Sepietta oweniana the currently known characters are not sufficient to identify the females because both their external and internal morphology are identical (Guerra, 1992; Bello, 1995). The only difference referred to by Naef (1923) is that the tentacles of S. neglecta are smaller than those of S. oweniana and bear much smaller suckers. However this is evident only when specimens of equal size from the two species are examined together. The purpose of this paper is to verify whether the length of tentacular clubs, the thickness of tentacles and the diameter of club suckers reflect the growth rate, and are significantly different for the two species to define relative indices.
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  • 37
    Publication Date: 2021-06-18
    Description: Sexual selection studies in cephalopods indicate that sperm competition is a central feature of their mating systems, yet this has not been studied experimentally in any detail. In 1998 we staged 20 matings of the cuttlefish, Sepia officinalis L., in the laboratory. Males rapidly initiated mating in the “head-to-head” position, with no apparent courtship. Mating lasted an average of 10 min (range 7 to 14 min). For the first 6 min (on average 63% of the mating duration), the male flushed strong jets of water directly at the female's buccal membrane, which sometimes resulted in the expulsion of parts of spermatangia placed there in recent matings. Then, in a single discrete movement that lasted an average of only 14 s, the male's modified fourth left arm – the hectocotylus – wrapped around a single large bundle of spermatophores (ca. 150 to 300) and transferred them to the female's buccal membrane. For the remainder of the mating (average 3 min, range 1.5 to 5.0 min), the hectocotylus repeatedly broke the spermatophores open, and manipulated them, so that sperm were released and many spermatangia were attached along the ventral buccal membrane, near the paired seminal receptacles. Approximately 140 spermatangia were attached in rows 3 to 5 deep around the ventral buccal membrane in a single mating; the rest were usually discarded during mating. Histology revealed that each of the seminal receptacles consists of a series of sperm storage bulbs connected by a central duct, which leads to a single pore at the surface of the buccal membrane. Baseline data on sperm motility were obtained, but the mechanism by which sperm enter the seminal receptacle remains unknown. Females seemed to initiate termination of mating, then males guarded their mates temporarily. These results, combined with other recent laboratory experiments, provide evidence that sperm competition may be a major feature of the mating system of S. officinalis.
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  • 38
    Publication Date: 2021-06-18
    Description: Analysis of the isotope composition of calcareous structures of marine organisms has proved useful in providing biological data. The present study constitutes the first detailed work undertaken on the isotope composition of coleoid cephalopods. We analysed the carbon- and oxygen-isotope composition [δ13C (CO2− 3) and δ18O (CO2− 3), respectively] of the cuttlebone aragonite of wild and cultivated specimens of Sepia officinalis Linnaeus, 1758. δ13C (CO2− 3) ranged from −2.94 to 1.00‰, δ18O (CO2− 3) from −0.18 to 2.08‰. The carbon-isotope composition is not in equilibrium with the carbon species of the ambient seawater, and does not reflect the deposition of CaCO3 in seawater. The potential influence of environmental factors and biological processes on the carbon-isotope composition of the cuttlebone is discussed. In contrast to δ13C, the oxygen-isotope composition of cuttlebone aragonite appears to be in isotopic equilibrium with the ambient seawater. Seasonal changes in isotopic temperature revealed by our analyses agreed with changes in the temperature of the ambient seawater. CaCO3 was deposited all year round. A maximum life span of 2 yr, a year-round spawning season, and variable growth rates among and within individuals have been inferred from the isotopic temperatures.
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  • 39
    Publication Date: 2021-07-26
    Description: Ontogenetic changes in morphometric and reproductive indices were studied using 166 individuals of the arctic gonatid squid Gonatus fabricii (7.3–322 mm pen length) collected in the southern part of the Norwegian Sea. Body proportions and consistency of the mantle and fins did not change in maturing and mature males. In contrast, during maturation the females first lost their tentacles, then the horny rings of their 4th arm suckers, and the muscular part of their body turned watery and gelatinous. Unlike most squid, G. fabricii females start mating at maturity stage III, and all but one female at stage IV had mated, as well as all spent females. Females had high values of both gonadosomatic index and maturity indices compared to those of the North Pacific gonatids, whereas gonadosomatic index values of males were low, probably due to slow functioning of both testis and spermatophoric gland, and long accumulation of spermatophores in the Needham's sac. It is suggested that the breakdown of female body tissues is an adaptation for a deepwater bathypelagic “brooding” of the negatively buoyant egg-mass caused by the high specific density of the secretion from the nidamental glands in gonatids.
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  • 40
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    In:  Marine Biotechnology, 1 (4). pp. 403-406.
    Publication Date: 2021-08-24
    Description: Attempts to study the genetic population structure of cephalopods are impeded by the low levels of genetic variation in these species. We have developed polymerase chain reaction (PCR) primers for six hypervariable microsatellite markers in order to analyze the molecular population structure in the Californian market squid Loligo opalescens. Each of these genomic loci has been cloned and fully sequenced. Here we report the sequence and properties of the six PCR primer sets for the amplification of hypervariable microsatellites. Heterozygosity levels in six squid samples from different locations are high for all loci tested.
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  • 41
    Publication Date: 2021-07-05
    Description: The functional properties of the haemocyanin ofVampyroteuthis infernalis (Cephalopoda: Vampyromorpha), measured at 5 °C, are reported and discussed in relation to hypoxia. The oxygen affinity of this haemocyanin (P50=0.47−0.55 kPa) is higher than any previously measured for a cephalopod. The high cooperativity (n50=2.20−2.23) and Bohr coefficient (−0.22) suggest a true transport function for this haemocyanin. This high-affinity haemocyanin, in conjunction with moderate gill diffusion capacity, provides a sufficient oxygen gradient from the environment to the blood to support the low routine oxygen consumption rate of V. infernalis.
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  • 42
    Publication Date: 2021-06-11
    Description: Between 1993 and 1995, the diving behavior and movement patterns of 23 weaned Weddell seal pups (Leptonychotes weddellii) were tracked in the Ross Sea. Antarctica, using satellite-linked time-depth recorders. Regression analyses revealed that for seals of between 8 and 27 weeks old, age was poorly correlated with the dive depth, duration, or frequency. However, changes in dive parameters suggested that Weddell seal pups were attempting to maximize dive time, but the manner in which this was done depended on age and time of day. Movement patterns indicated that most Weddell seal pups left their natal area by the end of February, and traveled north along the Antarctic continent coastline. Several individuals returned to McMurdo Sound, but others were last located more than 400 km from McMurdo. Routes followed suggest that pups can use the pack ice habitat, but prefer to remain closer to the coastline than do adults.
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  • 43
    Publication Date: 2021-06-17
    Description: Ovary maturation and spawning in the chokka squid Loligo vulgaris reynaudii were investigated by collecting squid from across their distributional range on the southeastern coast of South Africa between 1992 and 1993. Based on histological examination of the ovarian tissue and the separation of multiple modes in oocyte size-frequency distribution, ovary development was characterised by eight distinct stages. Our study confirms serial spawning in L. v. reynaudii.
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  • 44
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    In:  Helgoland Marine Research, 52 . pp. 219-234.
    Publication Date: 2018-05-28
    Description: About 80 non-indigenous species are assumed to have been introduced into the North Sea by transoceanic shipping and aquaculture. The number is certainly underestimated as most small organisms received insufficient attention at the species level. Also, the seafaring tradition of the North Sea countries is much longer than our biological surveys are. Most exotic invertebrates originate from the western Atlantic and were introduced by shipping, while most algae stem from the Pacific and came with the introduced oysters. A peak of newcomers was observed in the 1970s. Most of the arrivals became established in brackish environments, at harbor sites and in the vicinity of oyster farms, fouling on hard substrates or living as epibionts. A few live in sediments, are holoplanktonic or are parasites. At the open coast, approximately 6% of the macrobenthic species are exotics, while in estuaries their share is up to 20%. Most exotics have been encountered in the southern North Sea first, and many did not spread further north. About 25% of the established non-natives are widespread and attain locally high abundances. As a consequence, some inshore habitats are entirely dominated by exotics. The overall effect on the ecosystem seems to be more additive than one of displacement. This suggests that the coastal biota of the North Sea are quite capable of accommodating newcomers. However, this is no guarantee that the next introduced species may not cause severe ecological change or economic harm. There is a need to minimize the risk of unintentional introductions by ballast water treatment and by adhering to quarantine procedures in aquaculture. Current research on exotics in the North Sea is regarded as inadequate for proper evaluation and management requirements.
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  • 45
    Publication Date: 2018-06-07
    Description: Manila clams, Ruditapes philippinarum, removed from their natural environment and maintained for 9 weeks in continuously immersed conditions exhibited a clear endogenous circatidal rhythm in oxygen consumption. The clams exhibited a semidiurnal rhythmicity in oxygen consumption after showing a diurnal pattern in the first few days (5 to 7 d) of the experiment. The results of the present study indicate that activity rhythms of clams are controlled not only by exogenous factors, but also by an endogenous circatidal periodicity.
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  • 46
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    In:  In: The Prokaryotes. An evolving electronic resource for the microbiological community. A Handbook on the Biology of Bacteria. Ecophysiology, Isolation, Identification, Applications. , ed. by Dworkin, M., Falkow, S., Rosenberg, E., Schleifer, K. H. and Stackebrandt, E. Springer, New York. 3
    Publication Date: 2012-02-28
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  • 47
    Publication Date: 2022-03-10
    Description: A core from a coral colony of Porites lutea was analysed for stable oxygen isotopic composition*. A 200-year proxy record of sea surface temperatures from the Houtman Abrolhos Islands off west Australia was obtained from coral δ18O. At 29′S, the Houtman Abrolhos are the southernmost major reef complex of the Indian Ocean. They are located on the path of the Leeuwin Current, a southward flow of warm, tropical water, which is coupled to Indonesian throughflow. Coral δ18O primarily reflects local oceanographic and climatic variability, which is largely determined by spatial variability of the Leeuwin Current. However, coherence between coral δ18O and the current strength itself is relatively weak. Evolutionary spectral and singular spectrum analyses of coral δ18O demonstrate a high variability in spectral composition through time. Oscillations in the 5–7-y, 14–15-y, and quasi-biennial bands reflect teleconnections of local sea surface temperature (SST) to tropical Pacific climate variability. Deviations between local (coral-based) and regional (instrument) SST contain a cyclic component with a period of 15 y. Coral δ18O suggests a rise in SST by 0.6 ′C since AD 1944, consistent with available instrumental SST records. A long-term warming by 1.4 ′C since AD 1795 is inferred from the coral record
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  • 48
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    In:  World in transition: ways towards sustainable management of freshwater resources
    Publication Date: 2022-03-21
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  • 49
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    In:  World in transition: strategies for managing global environmental risks
    Publication Date: 2022-03-21
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  • 50
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    In:  Auswirkungen von Klimaänderungen auf aquatische Systeme | Handbuch der Umweltveränderungen Ökotoxikologie, 3A: Aquatische Syste
    Publication Date: 2022-03-21
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  • 51
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    In:  Modeling environmental conflict | Environmental change and security. A European perspective
    Publication Date: 2022-03-21
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  • 52
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    In:  Beyond El Nino: Decadal and interdecadal climate variability | Beyond El Nino: decadal and interdecadal climate variability
    Publication Date: 2022-03-21
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  • 53
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    In:  Umweltgerechtes Verhalten in verschiedenen Lebensstil- Kontexten | Umweltgerechtes Handeln - Barrieren und Brücken
    Publication Date: 2022-03-21
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  • 54
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    In:  Welt im Wandel: Strategien zur Bewältigung globaler Umweltrisiken
    Publication Date: 2022-03-21
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  • 55
    Publication Date: 2023-01-04
    Description: Millions of tons of plastic waste are released into the marine environment every year. While they steadily accumulate, synthetic polymers provide a habitat for microorganisms. This denominated Plastisphere has been studied in detail over the past ten years. So have the enzymes responsible for microbial degradation, which are unfortunately lacking for most sorts of plastics. Therefore, the BMBF-funded project PLASTISEA is focusing on bioprospecting the marine treasure trove for novel plastic acting enzymes.
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  • 56
    Publication Date: 2023-01-04
    Description: Many of the socio-economic and environmental challenges of the 21st century like the growing energy and food demand, rising sea levels and temperatures put stress on marine ecosystems and coastal populations. This requires a significant strengthening of our monitoring capacities for processes in the water column, at the seafloor and in the subsurface. However, present-day seafloor instruments and the required infrastructure to operate these are expensive and inaccessible. We envision a future Internet of Underwater Things, composed of small and cheap but intelligent underwater nodes. Each node will be equipped with sensing, communication, and computing capabilities. Building on distributed event detection and cross-domain data fusion, such an Internet of Underwater Things will enable new applications. In this paper, we argue that to make this vision a reality, we need new methodologies for resource-efficient and distributed cross-domain data fusion. Resource-efficient, distributed neural networks will serve as data-analytics pipelines to derive highly aggregated patterns of interest from raw data. These will serve as (1) a common base in time and space for fusion of heterogeneous data, and (2) be sufficiently small to be transmitted efficiently in resource-constrained settings.
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  • 57
    Publication Date: 2023-01-04
    Description: Die Messung submariner Bodendeformationen an den Flanken von Inselvulkanen hilft dabei, ihre Stabilität und die Gefahr von Hangrutschungen einzuschätzen, ist aber inherent schwierig für Gebiete, die unter Wasser liegen. Wiederholte Seismik- oder Fächerecholot-Vermessungen können größere Gebiete abdecken, aber Auflösung und Lokalisierung sind bestimmten Grenzen unterworfen. Optische Daten andererseits sind besser aufgelöst, aber limitiert in ihrer räumlichen Abdeckung, und Meeresbodengeodäsie wiederum liefert nur punktuelle Information. In diesem Artikel schlagen wir vor, verschiedene Arten von Fernerkundungsdaten zusammenzubringen und auch mit bestehenden statischen und dynamischen Modellen zu verschneiden. Aufgrund ihrer verschiedenen Modalitäten, Unsicherheiten und Skalierungen ist dies jedoch schwierig und bedarf einer Fusion. Zusammen mit anderen Aspekten (Erdbeben, Strömungen etc.) sollen die fusionierten Daten und Modelle langfristig neue Einblicke in das dynamische System des sich verändernden Meeresbodens, die dafür verantwortlichen Faktoren sowie die Auswirkungen instabiler submariner Hänge auf andere Meeressysteme bieten.
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  • 58
    Publication Date: 2023-01-04
    Description: A central promise of cross-domain fusion (CDF) is the provision of a “bigger picture” that integrates different disciplines and may span very different levels of detail. We present a number of settings that call for this bigger picture, with a particular focus on how information from several domains can be made easily accessible and visualizable for different stakeholders. We propose harnessing an approach that is now well established in interactive maps, which we refer to as the “Google maps approach” (Google LLC, Mountain View, CA, USA), which combines effective filtering with intuitive user interaction. We expect this approach to be applicable to a range of CDF settings.
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  • 59
    Publication Date: 2023-01-02
    Description: Consistently high data quality is essential for the development of novel loss functions and architectures in the field of deep learning. The existence of such data and labels is usually presumed, while acquiring high-quality datasets is still a major issue in many cases. Subjective annotations by annotators often lead to ambiguous labels in real-world datasets. We propose a data-centric approach to relabel such ambiguous labels instead of implementing the handling of this issue in a neural network. A hard classification is by definition not enough to capture the real-world ambiguity of the data. Therefore, we propose our method “Data-Centric Classification & Clustering (DC3)” which combines semi-supervised classification and clustering. It automatically estimates the ambiguity of an image and performs a classification or clustering depending on that ambiguity. DC3 is general in nature so that it can be used in addition to many Semi-Supervised Learning (SSL) algorithms. On average, our approach yields a 7.6% better F1-Score for classifications and a 7.9% lower inner distance of clusters across multiple evaluated SSL algorithms and datasets. Most importantly, we give a proof-of-concept that the classifications and clusterings from DC3 are beneficial as proposals for the manual refinement of such ambiguous labels. Overall, a combination of SSL with our method DC3 can lead to better handling of ambiguous labels during the annotation process. (Source code is available at https://github.com/Emprime/dc3).
    Type: Book chapter , NonPeerReviewed
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  • 60
    Publication Date: 2023-01-19
    Description: The gas hydrate system off Mauritania is characterized by the undulating landward termination of a gas hydrate-related bottom simulating reflector (BSR). Some of the most landward sections of this BSR reach up to within 6 m of the seafloor. This suggests a shallow sulphate-methane-interface over an unusually large area. We attribute this to the presence of large amounts of methane due to the efficient burial of organic matter in a high-productivity oceanographic region, and the efficient channelling of methane along permeable turbidite beds towards the feather edge of the gas hydrate stability zone. This is consistent with the observation of steps in the BSR, where it cross-cuts other inferred permeable horizons. The high thermal conductivity of a salt dome in the southern part of the study area distorts the subsurface temperature field, giving the base of the hydrate stability zone a concave-down shape. Within this anticline of the BSR, high amplitudes and a horizontal reflection that crosses the sedimentary strata indicate the entrapment of free gas. We interpret this as a direct indication of a reduced hydraulic permeability of the hydrate-bearing sediment.
    Type: Book chapter , NonPeerReviewed
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  • 61
    Publication Date: 2023-01-24
    Description: Spectacular advances have been made in the field of machine vision over the past decade. While this discipline is traditionally driven by geometric models, neural networks have proven to be superior in some applications and have significantly expanded the limits of what is possible. At the same time, conventional graphic models describe the relationship between images and the associated scene with textures and light in a physically realistic manner and are an important part of photogrammetry. Differential renderers combine these approaches by enabling gradient-based optimization in fixed structures of a graphics pipeline and thus adapt the learning process of neural networks. This fusion of formalized knowledge and machine learning motivates the idea of a modular differentiable renderer in which physical and statistical models can be recombined depending on the use case. We therefore present Gemini Connector: an initiative for the modular development and combination of differentiable physical models and neural networks. We examine opportunities and problems and motivate the idea with the extension of a differentiable rendering pipeline to include models of underwater optics for the analysis of deep sea images. Finally, we discuss use cases, especially within the Cross-Domain Fusion initiative.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 62
    Publication Date: 2023-02-02
    Description: Interactive exploration of Earth system simulations may have great potential to improve the scientific modeling process. It will allow monitoring of the state of the simulation via dashboards presenting real-time diagnostics within a digital twin world. We present the state of the art for Earth system modeling in this context. Cross-domain data handling and fusion will make it possible to integrate model and observation data in the context of digital twins of the ocean. Domain-driven modularization of monolithic Earth system models allows one to recover interfaces for such a cross-domain fusion. Reverse engineering with static and dynamic analysis enables modularization of Earth system models. The modularization does not only help with restructuring existing Earth system models, it also makes it possible to integrate additional scientific domains into the interactive simulation environment.
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  • 63
    Publication Date: 2023-09-28
    Description: Well-constrained and widely distributed bottom simulating reflectors in various geological settings across both passive and active margins make the area offshore southwestern Taiwan an excellent location to study gas hydrate dynamics and fluid flow systems. Seismic data reveal the presence of subsurface fluid flow systems and ubiquitous free gas and gas hydrates. This article aims to summarize and map the different types of seismic observations related to the gas hydrate system. The spatial distribution of seismic indicators for gas accumulation, fluid migration, and the presence of gas hydrates suggests that topographic highs on both passive and active margins are sites of particularly efficient free gas accumulation and gas hydrate formation. Seismic indicators observed in fold and thrust structures suggest that the fluid system in the active margin is structurally controlled and that the highest gas hydrate saturation levels are found in the cores of thrust anticlines on the lower slope of the active margin area.
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  • 64
    Publication Date: 2023-09-28
    Description: This article reviews extensive geophysical survey data, ocean drilling results and long-term seafloor monitoring that constrain the distribution and concentration of gas hydrates within the accretionary prism of the northern Cascadia subduction margin, located offshore Vancouver Island in Canada. Seismic surveys and geologic studies conducted since the 1980s have mapped the bottom simulating reflector (BSR), detected gas hydrate occurrence and estimated gas hydrate and free gas concentrations. Additional constraints were obtained from seafloor-towed, controlled-source electromagnetic surveying. A component of these studies has been the examination of low-temperature seafloor vents and seeps that emit gas and fluids into the ocean. These features are identified seismically as chimney-like zones of reduced acoustic reflectivity within the sediment stratigraphy, functioning as conduits for gas and fluid migration from below the BSR to the seafloor. Gas hydrates have been recovered from the seafloor and from sediment cores at vent sites, mostly in massive (nodular) form and as a vein-like fracture filling. The Ocean Networks Canada cabled NEPTUNE observatory has gathered extensive continuous, long-term observations on gas hydrate dynamics at the seafloor and in boreholes at two nodes on the continental slope featuring high gas hydrate concentrations. Measurements taken at the observatory include a time-series of gas bubble emission rates, changes in the near-seafloor electromagnetic structure and seafloor compliance linked to gas hydrate formation and dissociation. Two Integrated Ocean Drilling Program (IODP) expeditions collected cores, measured downhole properties and deployed downhole instruments within the central accretionary prism. At IODP Site U1364, pore pressures are being monitored above and below the base of the gas hydrate stability zone at a slope setting using an “Advanced Circulation Obviation Retrofit Kit” (A-CORK). Downhole pore pressures, temperatures and electrical resistivities also are being monitored at IODP Site U1416 using the “Simple Cabled Instrument for Measuring Parameters In Situ” (SCIMPI) tool at a vent site from near-seafloor to just above the base of the gas hydrate stability zone.
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  • 65
    Publication Date: 2023-10-06
    Description: Uncertainties concerning deep-seabed mining relate to the expected impacts on the abyssal benthic and pelagic environment and its ecosystems but also include geopolitical, economic, societal and cultural uncertainty. The uncertain impacts from mining lead to anxiety and a low societal acceptance for the activity and are not the same for everybody at the same time. Hence, uncertainty is an important element of the risk involved in deep-seabed mining. This chapter describes the different risks involved, develops a methodology for risk assessment for the exploitation of marine mineral resources that takes into consideration the state of knowledge and evolving research on deep-sea ecosystems, and informs on possible environmental threshold values in relation to deep-seabed mining operations.
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  • 66
    Publication Date: 2023-10-06
    Description: This article presents the first evidence of bottom simulating reflectors (BSRs) on the continental margin of the western Indian Ocean, offshore Tanzania. The analysis of 2D and 3D seismic reflection data revealed two different types of BSRs. The Type 1 BSR, identified in water depths of 2250–2370 m west of the Seagap fault, shows a continuous reflection that mimics the seafloor, has a reverse polarity with respect to the seafloor and crosscuts the stratigraphy. Type 2 BSRs have been identified on the slope of the Tanzanian margin in water depths less than 1500 m. They are represented by a phase-reversed reflection that mimics the seafloor topography, revealing lateral variations in amplitude that are expressed as changes from high to moderate brightness. Modelling results show that gas hydrates of microbial origin (100% CH4) are stable in a minimum water depth of 740 m and a bottom water temperature of 9 °C, thus indicating a possible microbial origin for the type 2 BSRs. The thickest gas hydrate stability zone is observed within the Kerimbas Graben at water depths of up to 3621 m, with values ranging from 321.4–383.4 m for geothermal gradients of 5.4 °C/100 m and 6.4 °C/100 m, respectively. We suggest that the type 1 BSR may have a thermogenic gas source, as the observed BSR depths are deeper than the calculated base of the gas hydrate stability zone for 100% methane. The interpreted faults that crosscut the stratigraphy may have facilitated gas transport from deeper source rocks.
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  • 67
    Publication Date: 2024-01-08
    Description: The Clarion Clipperton Fracture Zone (CCZ) is a vast deep-sea region harboring a highly diverse benthic fauna, which will be affected by potential future deep-sea mining of metal-rich polymetallic nodules. Despite the need for conservation plans and monitoring strategies in this context, the majority of taxonomic groups remain scientifically undescribed. However, molecular rapid assessment methods such as DNA barcoding and Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) provide the potential to accelerate specimen identification and biodiversity assessment significantly in the deep-sea areas. In this study, we successfully applied both methods to investigate the diversity of meiobenthic copepods in the eastern CCZ, including the first application of MALDI-TOF MS for the identification of these deep-sea organisms. Comparing several different species delimitation tools for both datasets, we found that biodiversity values were very similar, with Pielou’s evenness varying between 0.97 and 0.99 in all datasets. Still, direct comparisons of species clusters revealed differences between all techniques and methods, which are likely caused by the high number of rare species being represented by only one specimen, despite our extensive dataset of more than 2000 specimens. Hence, we regard our study as a first approach toward setting up a reference library for mass spectrometry data of the CCZ in combination with DNA barcodes. We conclude that proteome fingerprinting, as well as the more established DNA barcoding, can be seen as a valuable tool for rapid biodiversity assessments in the future, even when no reference information is available.
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  • 68
    Publication Date: 2024-01-08
    Description: Deep-sea decapod crustaceans (Crustacea: Decapoda) collected during nine research cruises to the Clarion-Clipperton Zone (CCZ) in the NE Pacific Ocean and the Peru Basin in the SE Pacific Ocean were studied comprehensively using an integrative taxonomic approach. The abyssal seafloors of both areas are rich in economically interesting polymetallic nodules. All specimens were morphologically identified and genetically analysed using a fragment of the mitochondrial cytochrome c oxidase subunit I (COI). Eight species were collected, comprising three anomurans, three carideans, one dendrobranchiate, and one brachyuran, from water depths ranging between 4089 and 4511 m. COI sequences for representatives of the genera Parapagurus Smith, 1879, Ethusina SI Smith, 1884, and Bathystylodactylus Hanamura & Takeda, 1996 are provided for the first time. The molecular barcodes of the species provided herein will be valuable for the full taxonomic assignment of sequences produced in future metabarcoding and eDNA monitoring work. The new records extend the geographical distributional ranges or fill geographical gaps of the species reported, although none of the species is endemic to polymetallic nodule areas. This study is part of a taxonomic series aiming to describe the biodiversity of areas targeted for future deep-sea mining.
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  • 69
    Publication Date: 2024-02-02
    Description: Climate change arguably constitutes one of the greatest risks to the long-term health of the world’s environment. In 2015, the Intergovernmental Panel on Climate Change (IPCC) highlighted that the Earth’s climate system has consistently been warming since the 1950s and that a “large fraction of anthropogenic climate change resulting from CO2 emissions is irreversible on a multi-century to millennial time scale, except in the case of a large net removal of CO2 from the atmosphere over a sustained period”. Initial responses to climate change revolved around States attempting to reduce, rather than remove, greenhouse gas emissions. However, as the global economy expands, greenhouse gas emissions have continued to rise and cooperative arrangements aimed at reducing emissions have had limited, if any, impact. If recent predictions are to be believed, the remaining “carbon budget” needed to prevent average global temperatures from increasing by more than 1.5 °C may be exhausted by 2030. Climate Analytics estimates that the current Nationally Determined Contributions (NDCs) made by States under the Paris Agreement indicate that average global temperatures will rise by 2.8 °C by 2100—almost double the stipulated efforts to limit the temperature increase to 1.5 °C above pre-industrial levels mentioned in Article 2(1)(a) of the Paris Agreement. The recent IPCC Special Report on 1.5 °C Global Warming concludes that without “increased and urgent mitigation ambition in the coming years, leading to a sharp decline in greenhouse gas emissions by 2030, global warming will [cause] irreversible loss of the most fragile ecosystems and crisis after crisis for the most vulnerable people and societies”.
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  • 70
    Publication Date: 2024-02-07
    Description: Climate change alters species distributions by shifting their fundamental niche in space through time. Such effects may be exacerbated by increased inter-specific competition if climate alters species dominance where competitor ranges overlap. This study used census data, telemetry and stable isotopes to examine the population and foraging ecology of a pair of Arctic and temperate congeners across an extensive zone of sympatry in Iceland, where sea temperatures varied substantially. The abundance of Arctic Brünnich’s guillemot Uria lomvia declined with sea temperature. Accessibility of refugia in cold water currents or fjords helped support higher numbers and reduce rates of population decline. Competition with temperate Common guillemots Uria aalge did not affect abundance, but similarities in foraging ecology were sufficient to cause competition when resources are limiting. Continued warming is likely to lead to further declines of Brünnich’s guillemot, with implications for conservation status and ecosystem services
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 71
    Publication Date: 2024-02-07
    Description: In addition to being a major threat to biodiversity and ecosystem functioning, biological invasions also have profound impacts on economies and human wellbeing. However, the threats posed by invasive species often do not receive adequate attention and lack targeted management. In part, this may result from different or even ambivalent perceptions of invasive species which have a dual effect for stakeholders—being simultaneously a benefit and a burden. For these species, literature that synthesizes best practice is very limited, and analyses providing a comprehensive understanding of their economics are generally lacking. This has resulted in a critical gap in our understanding of the underlying trade-offs surrounding management efforts and approaches. Here, we explore qualitative trends in the literature for invasive species with dual effects, drawing from both the recently compiled InvaCost database and international case studies. The few invasive species with dual roles in InvaCost provide evidence for a temporal increase in reporting of costs, but with benefits relatively sporadically reported alongside costs. We discuss methods, management, assessment and policy frameworks dedicated to these species, along with lessons learned, complexities and persisting knowledge gaps. Our analysis points at the need to enhance scientific understanding of those species through inter- and cross-disciplinary efforts that can help advance their management.
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  • 72
    Publication Date: 2024-02-07
    Description: Interannual sea surface temperature (SST) variations in the tropical Atlantic Ocean lead to anomalous atmospheric circulation and precipitation patterns with important ecological and socioeconomic consequences for the semiarid regions of sub-Saharan Africa and northeast Brazil. This interannual SST variability is characterized by three modes: an Atlantic meridional mode featuring an anomalous cross-equatorial SST gradient that peaks in boreal spring; an Atlantic zonal mode (Atlantic Nino mode) with SST anomalies in the eastern equatorial Atlantic cold tongue region that peaks in boreal summer; and a second zonal mode of variability with eastern equatorial SST anomalies peaking in boreal winter. Here we investigate the extent to which there is any seasonality in the relationship between equatorial warm water recharge and the development of eastern equatorial Atlantic SST anomalies. Seasonally stratified cross-correlation analysis between eastern equatorial Atlantic SST anomalies and equatorial heat content anomalies (evaluated using warm water volume and sea surface height) indicate that while equatorial heat content changes do occasionally play a role in the development of boreal summer Atlantic zonal mode events, they contribute more consistently to Atlantic Nino II, boreal winter events. Event and composite analysis of ocean adjustment with a shallow water model suggest that the warm water volume anomalies originate mainly from the off-equatorial northwestern Atlantic, in agreement with previous studies linking them to anomalous wind stress curl associated with the Atlantic meridional mode.
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  • 73
    Publication Date: 2024-02-07
    Description: A new box model is employed to simulate the oxygen-dependent cycling of nutrients in the Peruvian oxygen minimum zone (OMZ). Model results and data for the present state of the OMZ indicate that dissolved iron is the limiting nutrient for primary production and is provided by the release of dissolved ferrous iron from shelf and slope sediments. Most of the removal of reactive nitrogen occurs by anaerobic oxidation of ammonium where ammonium is delivered by aerobic organic nitrogen degradation. Model experiments simulating the effects of ocean deoxygenation and warming show that the productivity of the Peruvian OMZ will increase due to the enhanced release of dissolved iron from shelf and slope sediments. A positive feedback loop rooted in the oxygen-dependent benthic iron release amplifies, both, the productivity rise and oxygen decline in ambient bottom waters. Hence, a 1% decline in oxygen supply reduces oxygen concentrations in sub-surface waters of the continental margin by 22%. The trend towards enhanced productivity and amplified deoxygenation will continue until further phytoplankton growth is limited by the loss of reactive nitrogen. Under nitrogen-limitation, the redox state of the OMZ is stabilized by negative feedbacks. A further increase in productivity and transition to sulfidic conditions is only possible if the rate of nitrogen fixation increases drastically under anoxic conditions. Such a transition would lead to a wide-spread accumulation of toxic sulfide with detrimental consequences for fishery yields in the Peruvian OMZ that currently provides a significant fraction of the global fish catch.
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  • 74
    Publication Date: 2024-02-07
    Description: Wetlands are amongst the world’s most important ecosystems, providing direct and indirect benefits to local communities. However, wetlands worldwide continue to be degraded due to unsustainable use and improper resource management. In this paper, we assess the perceptions, importance, management and utilisation of wetlands among local community members using a household questionnaire and field observations within the seven Thulamela municipality wetlands, Vhembe Biosphere Reserve in South Africa. Seven wetlands were chosen for the study, with 140 household respondents randomly selected for a questionnaire survey. The study indicated that wetlands were beneficial in supporting local communities through resource provisioning. The unemployment rate and household respondents’ income were the main contributors to increased wetland dependency and utilisation. We found that urban and rural developments, unregulated use and extensive agricultural practices (i.e., cultivation, livestock grazing) have resulted in wetland degradation. We observed that the local communities around the wetlands were interested in the benefits they receive from wetlands when compared to their conservation. Furthermore, the study observed poor wetland co-management or collaboration among the local stakeholders. This has resulted in a lack of openly known, active platforms to discuss wetlands management issues. These results highlight that centralized, top–down approaches to wetland use are insufficient for maintaining and managing wetland ecosystems, posing a challenge to sustainable wetland management. Therefore, there is a need to develop a shared understanding through bottom-up approaches to wetland management nested within national regulatory frameworks, ideally combined with awareness building and knowledge sharing on ecological benefits and management of wetlands.
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  • 75
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    Springer
    Publication Date: 2024-02-07
    Description: This world atlas presents a comprehensive overview of the gas-hydrate systems of our planet with contributions from esteemed international researchers from academia, governmental institutions and hydrocarbon industries. The book illustrates, describes and discusses gas hydrate systems, their geophysical evidence and their future prospects for climate change and continental margin geohazards from passive to active margins. This includes passive volcanic to non-volcanic margins including glaciated and non-glaciated margins from high to low latitudes. Shallow submarine gas hydrates allow a glimpse into the past from the Last Glacial Maximum (LGM) to modern environmental conditions to predict potential changes in future stability conditions while deep submarine gas hydrates remained more stable. This demonstrates their potential for rapid reactions for some gas hydrate provinces to a warming world, as well as helping to identify future prospects for environmental research. Three-dimensional and high-resolution seismic imaging technologies provide new insights into fluid flow systems in continental margins, enabling the identification of gas and gas escape routes to the seabed within gas hydrate environments, where seabed habitats may flourish. The volume contains a method section detailing the seismic imaging and logging while drilling techniques used to characterize gas hydrates and related dynamic processes in the sub seabed. This book is unique, as it goes well beyond the geophysical monograph series of natural gas hydrates and textbooks on marine geophysics. It also emphasizes the potential for gas hydrate research across a variety of disciplines. Observations of bottom simulating reflectors (BSRs) in 2D and 3D seismic reflection data combined with velocity analysis, electromagnetic investigations and gas-hydrate stability zone (GHSZ) modelling, provide the necessary insights for academic interests and hydrocarbon industries to understand the potential extent and volume of gas hydrates in a wide range of tectonic settings of continental margins. Gas hydrates control the largest and most dynamic reservoir of global carbon. Especially 4D, 3D seismic but also 2D seismic data provide compelling sub-seabed images of their dynamical behavior. Sub-seabed imaging techniques increase our understanding of the controlling mechanisms for the distribution and migration of gas before it enters the gas-hydrate stability zone. As methane hydrate stability depends mainly on pressure, temperature, gas composition and pore water chemistry, gas hydrates are usually found in ocean margin settings where water depth is more than 300 m and gas migrates upward from deeper geological formations. This highly dynamic environment may precondition the stability of continental slopes as evidenced by geohazards and gas expelled from the sea floor. This book provides new insights into variations in the character and existence of gas hydrates and BSRs in various geological environments, as well as their dynamics. The potentially dynamic behavior of this natural carbon system in a warming world, its current and future impacts on a variety of Earth environments can now be adequately evaluated by using the information provided in the world atlas.
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  • 76
    Publication Date: 2024-02-07
    Description: Widespread indications of free and hydrate gas accumulations and mud volcanoes were imaged using multichannel seismic reflection, chirp sub-bottom profiler, multibeam bathymetry, and deep-towed side-scan sonar data collected along the Southwestern Black Sea margin, offshore Akçakoca. These indications are typically associated with sedimentary ridges along the continental slope and rise, particularly with the “Ereğli Plateau” (850–1350 m water depth), where 20 mud volcanoes were found. Two types of bottom-simulating reflections (BSR) were identified, both mimicking the seafloor relief: Type-1 crosscuts the sedimentary reflections with amplitudes similar to the surrounding strata, while Type-2 shows higher amplitudes that terminate against the base of the gas hydrate stability zone. These types were observed over large portions of the continental rise, indicating the base of gas hydrate accumulations. Analyses of the BSR depth indicate that thermogenic gas is possibly present in the gas hydrates. A fault-driven hypothetical model was then developed to describe the formation of gas hydrate and mud volcanoes and the effect of submarine fluid flow in the area. According to this model, Type-1 BSRs form through biogenic gas accumulations. The presence of fault regions with Type-2 BSRs suggests active fluid transfer between permeable and impermeable units, where the fault surfaces act as possible conduits for thermogenic gases produced in the deeper sediments and transported into the shallower subsurface where then thermogenic biogenic gases coexist.
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  • 77
    Publication Date: 2024-02-07
    Description: Salinity is a common stressor restricting the distribution of various decapod crustaceans. The interactive effects of such regional stressors with global climate change drivers are important to be considered when aiming to realistically predict the potential of a species’ dispersal and further spread into new habitats. Within species, their larval stages commonly determine a species tolerance and with this their potential to invade and successfully develop a sustaining population. This laboratory study investigated the combined effect of salinity (6 levels, 10–25) and temperature (19 and 23 °C) on larval survival, development to megalopa, and feeding (in Zoea I, III, and V) of the decapod Hemigrapsus takanoi. Larval development and survival to megalopa were generally favored by increasing salinity. While no larva developed to the megalopa stage at 23 °C and a salinity of 16, in 19 °C some larvae could successfully develop under a salinity as low as 16. All larval stages fed generally more with increasing salinity and temperature, but there was no interaction between the two factors. The results revealed that the H. takanoi population from Kiel Fjord (southwestern Baltic Sea) is capable of completing its larval development under the current Kiel Fjord environmental conditions. The geographical spread of this H. takanoi population into the wider Baltic Proper may, however, be restricted mainly due to the inability to establish and maintain a self-sustaining population under lower salinity conditions. Furthermore, the projected desalination of the Baltic Sea together with rising temperatures due to global warming and heat waves in summer may likely exert additional stress to this existing population, unless H. takanoi adapts at appropriate rates.
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  • 78
    Publication Date: 2024-02-07
    Description: Maio Island (Cabo Verde Archipelago) is composed of uplifted Early Mesozoic MORB-type pillow lavas and deep-sea sediments, unconformably overlain and intruded by Miocene igneous rocks. Combined structural analyses and 40Ar–39Ar dating were used to constrain the Miocene evolution of Maio. Structures and ages of uplifted Mesozoic sequences and crosscutting Miocene dykes showed that numerous intrusive events were associated with the intense growth of an igneous core complex in the middle to upper crust, causing semi-circular doming and partial disruption of the Mesozoic strata. Two nosean nephelinite dykes cut the Valanginian Batalha Formation and yielded phlogopite 40Ar–39Ar ages of 10.405 ± 0.033 Ma and 10.570 ± 0.053 Ma (2σ errors). A nosean nephelinite dyke that cuts the overlying Valanginian to Early Aptian Morro Formation yielded an age of 9.273 ± 0.020 Ma. Combined with existing K–Ar and 40Ar–39Ar ages, this confirmed a main period of island growth between ~ 16 and 8.7 Ma. We re-interpreted extensive polymict conglomerates, which occur below the Late Miocene Monte Penoso Formation, as landslide deposits. A nephelinite lava clast yielded a phlogopite 40Ar–39Ar age of 8.666 ± 0.0274 Ma, which represents a maximum age for these landslides and thus confined a period of large-scale flank collapses and erosion to between 8.7 and 6.7 Ma. Flank collapses and further mass wasting during this period may have rejuvenated the igneous activity, i.e., resulting in the formation of the Tortonian/Messinian Monte Penoso and Malhada Pedra Formations, due to decompression-induced melting at upper mantle depths. Such interaction between flank collapses and rejuvenated volcanism may be a key to better understand ocean island evolution worldwide.
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  • 79
    Publication Date: 2024-02-07
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  • 80
    Publication Date: 2024-02-07
    Description: Human activities are changing the Arctic environment at an unprecedented rate resulting in rapid warming, freshening, sea ice retreat and ocean acidification of the Arctic Ocean. Trace gases such as nitrous oxide (N2O) and methane (CH4) play important roles in both the atmospheric reactivity and radiative budget of the Arctic and thus have a high potential to influence the region's climate. However, little is known about how these rapid physical and chemical changes will impact the emissions of major climate-relevant trace gases from the Arctic Ocean. The combined consequences of these stressors present a complex combination of environmental changes which might impact on trace gas production and their subsequent release to the Arctic atmosphere. Here we present our current understanding of nitrous oxide and methane cycling in the Arctic Ocean and its relevance for regional and global atmosphere and climate and offer our thoughts on how this might change over coming decades.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 81
    Publication Date: 2024-02-07
    Description: The rate of biological invasions is growing unprecedentedly, threatening ecological and socioeconomic systems worldwide. Quantitative understandings of invasion temporal trajectories are essential to discern current and future economic impacts of invaders, and then to inform future management strategies. Here, we examine the temporal trends of cumulative invasion costs by developing and testing a novel mathematical model with a population dynamical approach based on logistic growth. This model characterises temporal cost developments into four curve types (I–IV), each with distinct mathematical and qualitative properties, allowing for the parameterization of maximum cumulative costs, carrying capacities and growth rates. We test our model using damage cost data for eight genera (Rattus, Aedes, Canis, Oryctolagus, Sturnus, Ceratitis, Sus and Lymantria) extracted from the InvaCost database—which is the most up-to-date and comprehensive global compilation of economic cost estimates associated with invasive alien species. We find fundamental differences in the temporal dynamics of damage costs among genera, indicating they depend on invasion duration, species ecology and impacted sectors of economic activity. The fitted cost curves indicate a lack of broadscale support for saturation between invader density and impact, including for Canis, Oryctolagus and Lymantria, whereby costs continue to increase with no sign of saturation. For other taxa, predicted saturations may arise from data availability issues resulting from an underreporting of costs in many invaded regions. Overall, this population dynamical approach can produce cost trajectories for additional existing and emerging species, and can estimate the ecological parameters governing the linkage between population dynamics and cost dynamics.
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  • 82
    Publication Date: 2024-02-07
    Description: Biological invasions are one of the top drivers of the ongoing biodiversity crisis. An underestimated consequence of invasions is the enormity of their economic impacts. Knowledge gaps regarding economic costs produced by invasive alien species (IAS) are pervasive, particularly for emerging economies such as India—the fastest growing economy worldwide. To investigate, highlight and bridge this gap, we synthesised data on the economic costs of IAS in India. Specifically, we examine how IAS costs are distributed spatially, environmentally, sectorally, taxonomically, temporally, and across introduction pathways; and discuss how Indian IAS costs vary with socioeconomic indicators. We found that IAS have cost the Indian economy between at least US$ 127.3 billion to 182.6 billion (Indian Rupees ₹ 8.3 trillion to 11.9 trillion) over 1960–2020, and these costs have increased with time. Despite these massive recorded costs, most were not assigned to specific regions, environments, sectors, cost types and causal IAS, and these knowledge gaps are more pronounced in India than in the rest of the world. When costs were specifically assigned, maximum costs were incurred in West, South and North India, by invasive alien insects in semi-aquatic ecosystems; they were incurred mainly by the public and social welfare sector, and were associated with damages and losses rather than management expenses. Our findings indicate that the reported economic costs grossly underestimate the actual costs, especially considering the expected costs given India’s population size, gross domestic product and high numbers of IAS without reported costs. This cost analysis improves our knowledge of the negative economic impacts of biological invasions in India and the burden they can represent for its development. We hope this study motivates policymakers to address socio-ecological issues in India and launch a national biological invasion research programme, especially since economic growth will be accompanied by greater impacts of global change.
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  • 83
    Publication Date: 2024-02-07
    Description: Global studies imply that cephalopods have benefited from climate change. However, in most areas, species-specific long-term cephalopod data sets do not exist to support this implication and to analyse the response of cephalopods to environmental changes. Our results illustrate that historical studies, in combination with recent data sets, can fill this gap, enabling descriptions of ecological changes over a long time. We show substantial changes in the cephalopod biodiversity of the North Sea at species level over the past 100 years. Some species, which seemed to migrate into the North Sea only for spawning or foraging in the nineteenth century, occur permanently in the North Sea nowadays. This applies, for example, to the loliginids Loligo forbesii and Alloteuthis subulata. The ommastrephids Todaropsis eblanae and Illex coindetii, now constantly present as well, had been described only as accidental migrants 100 years ago.
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  • 84
    Publication Date: 2024-02-07
    Description: Marine sponges (phylum Porifera) form symbioses with diverse microbial communities that can be transmitted between generations through their developmental stages. Here, we integrate embryology and microbiology to review how symbiotic microorganisms are transmitted in this early-diverging lineage. We describe that vertical transmission is widespread but not universal, that microbes are vertically transmitted during a select developmental window, and that properties of the developmental microbiome depends on whether a species is a high or low microbial abundance sponge. Reproduction, development, and symbiosis are thus deeply rooted, but why these partnerships form remains the central and elusive tenet of these developmental symbioses.
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  • 85
    Publication Date: 2024-02-07
    Description: Over the last decade, field investigations, laboratory experiments, geophysical exploration and petrological, geochemical and numerical modelling have provided insight into the mechanisms of phreatic and hydrothermal eruptions. These eruptions are driven by sudden flashing of ground- or hydrothermal water to steam and are strongly influenced by the interaction of host rock and hydrothermal system. Aquifers hosted in volcanic edifices, calderas and rift environments can be primed for instability by alteration processes affecting rock permeability and/or strength, while magmatic fluid injection(s), earthquakes or other subtle triggers can promote explosive failure. Gas emission, ground deformation and seismicity may provide short- to medium-term forerunner signals of these eruptions, yet a definition of universal precursors remains a key challenge. Looking forward in the next 10 years, improved warning and hazard assessment will require integration of field and experimental data with models combining case studies, as well as development of new monitoring methods integrated by machine learning approaches.
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  • 86
    Publication Date: 2024-02-07
    Description: Background: Spliceosomal introns are parts of primary transcripts that are removed by RNA splicing. Although introns apparently do not contribute to the function of the mature transcript, in vertebrates they comprise the majority of the transcribed region increasing the metabolic cost of transcription. The persistence of long introns across evolutionary time suggests functional roles that can offset this metabolic cost. The teleosts comprise one of the largest vertebrate clades. They have unusually compact and variable genome sizes and provide a suitable system for analysing intron evolution. Results: We have analysed intron lengths in 172 vertebrate genomes and show that teleost intron lengths are relatively short, highly variable and bimodally distributed. Introns that were long in teleosts were also found to be long in mammals and were more likely to be found in regulatory genes and to contain conserved sequences. Our results argue that intron length has decreased in parallel in a non-random manner throughout teleost evolution and represent a deviation from the ancestral state. Conclusion: Our observations indicate an accelerated rate of intron size evolution in the teleosts and that teleost introns can be divided into two classes by their length. Teleost intron sizes have evolved primarily as a side-effect of genome size evolution and small genomes are dominated by short introns (〈256 base pairs). However, a non-random subset of introns has resisted this process across the teleosts and these are more likely have functional roles in all vertebrate clades.
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  • 87
    Publication Date: 2024-02-07
    Description: Sponges are interesting animal models for regeneration studies, since even from dissociated cells, they are able to regenerate completely. In particular, explants are model systems that can be applied to many sponge species, since small fragments of sponges can regenerate all elements of the adult, including the oscula and the ability to pump water. The morphological aspects of regeneration in sponges are relatively well known, but the molecular machinery is only now starting to be elucidated for some sponge species. Here, we have used an explant system of the demosponge Halichondria panicea to understand the molecular machinery deployed during regeneration of the aquiferous system. We sequenced the transcriptomes of four replicates of the 5–day explant without an osculum (NOE), four replicates of the 17–18–day explant with a single osculum and pumping activity (PE) and also four replicates of field–collected individuals with regular pumping activity (PA), and performed differential gene expression analysis. We also described the morphology of NOE and PE samples using light and electron microscopy. Our results showed a highly disorganised mesohyl and disarranged aquiferous system in NOE that is coupled with upregulated pathways of ciliogenesis, organisation of the ECM, and cell proliferation and survival. Once the osculum is formed, genes involved in “response to stimulus in other organisms” were upregulated. Interestingly, the main molecular machinery of vasculogenesis described in vertebrates was activated during the regeneration of the aquiferous system. Notably, vasculogenesis markers were upregulated when the tissue was disorganised and about to start forming canals (NOE) and angiogenic stimulators and ECM remodelling machineries were differentially expressed once the aquiferous system was in place (PE and PA). Our results are fundamental to better understanding the molecular mechanisms involved in the formation of the aquiferous system in sponges, and its similarities with the early onset of blood-vessel formation in animal evolution.
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  • 88
    Publication Date: 2024-02-07
    Description: New U‒Pb (LA-ICP-MS) geochronological data have been obtained on accessory zircons from granodiorites and on detrital zircons from stream-sediment samples from the Shipunsky massif in the Eastern Kamchatka region. The age of accessory zircons from amphibole–biotite granodiorites has been estimated at 49–44 Ma. Detrital zircons have the Late Paleocene–Early Eocene age from ~57 to ~49 Ma. Based on the geological and geochronological data, the massif was formed in two stages: a gabbroid intrusion (56‒51 Ma) and the quartz diorite-granodiorite intrusion (49‒44 Ma). In terms of the petrographic and geochemical characteristics of the Upper Cretaceous–Eocene volcanic rocks in the Shipunsky Peninsula and granitoids in the Shipunsky massif, they were formed in the suprasubduction setting. The Shipunsky granitoids belong to the I-type granites. The Shipunsky massif was formed as a part of the Kronotsky intraoceanic paleoarc during the Paleocene–Eocene in two stages. The southern segment of the Kronotsky paleoarc collided with the Kamchatka continental margin and the deformed rocks of this massif were brought to the surface.
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  • 89
    Publication Date: 2024-02-07
    Description: Purpose: The objective of this study was to provide insights into the most recent responses of sediments to climate change and their capability to sequester atmospheric carbon (C). Methods: Three sediment cores were collected, one from the western Black Sea, and two from the southern Adriatic Sea. Cores were extruded and sectioned into 1 cm or 0.5 cm intervals. Sections were frozen, weighed, freeze-dried, and then weighed again to obtain dry weights. Freeze-dried samples were dated by using lead 210 (210Pb) and cesium 137/ americium 241 (137Cs/241Am). Organic and inorganic C were determined by combustion. Particle size distribution was determined using a Beckman Coulter particle size analyzer (LS 13,320; Beckman Coulter Inc.). Mineralogical analyses were carried out by a Philips X’Pert powder diffractometer. Results: Sedimentation and organic and inorganic C accumulation rates increased with time in both the Black Sea and the Adriatic Sea. The increase in accumulation rates continued after the global introduction in the early 1970s of controls on the release of phosphorus (P) into the environment and despite the reduced sediment yield of major rivers (Po and Danube). Therefore, the increased accumulation of organic and inorganic C in the sediments cannot be assigned only to nutrient availability. Instead, we suggest that the increase in organic C is the consequence of the increase in atmospheric C, which has made more carbon dioxide (CO2) available to phytoplankton, thus enabling more efficient photosynthesis. This process known as CO2 fertilization may increase the organic C accumulation in sediments. Simultaneously, the increase of sea temperatures decreases the calcite solubility resulting in increases of the inorganic C accumulation. Conclusion: Our results suggest that long-term, general increases in accumulation rates of organic and inorganic C in sediments are the consequence of increases in atmospheric C. This shows that coastal sediments play an important role in C uptake and thus in regulating the Earth’s climate.
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  • 90
    Publication Date: 2024-02-07
    Description: Biological invasions are increasing worldwide, damaging ecosystems and socioeconomic sectors. Two decades ago, the “100 of the world’s worst” invasive alien species list was established by the IUCN to improve communications , identifying particularly damaging ‘flagship’ invaders globally (hereafter, worst). Whilst this list has bolstered invader awareness, whether worst species are especially economically damaging and how they compare to other invaders (hereafter, other) remain unknown. Here, we quantify invasion costs using the most comprehensive global database compiling them (InvaCost). We compare these costs between worst and other species against sectorial, taxonomic and regional descriptors, and examine temporal cost trends. Only 60 of the 100 worst species had invasion costs considered as highly reliable and actually observed estimates (median: US$ 43 million). On average, these costs were significantly higher than the 463 other invasive species recorded in InvaCost (median: US$ 0.53 million), although some other species had higher costs than most worst species. Damages to the environment from the worst species dominated, whereas other species largely impacted agriculture. Disproportionately highest worst species costs were incurred in North America, whilst costs were more evenly distributed for other species; animal invasions were always costliest. Proportional management expenditures were low for the other species, and surprisingly, over twice as low for the worst species. Temporally, costs increased more for the worst than other taxa; however, management spending has remained very low for both groups. Nonetheless, since 40 species had no robust and/or reported costs, the “true” cost of “some of the world’s worst” 100 invasive species still remains unknown.
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  • 91
    Publication Date: 2024-02-07
    Description: Dimethyl sulphide (DMS) and carbon monoxide (CO) are climate-relevant trace gases that play key roles in the radiative budget of the Arctic atmosphere. Under global warming, Arctic sea ice retreats at an unprecedented rate, altering light penetration and biological communities, and potentially affect DMS and CO cycling in the Arctic Ocean. This could have socio-economic implications in and beyond the Arctic region. However, little is known about CO production pathways and emissions in this region and the future development of DMS and CO cycling. Here we summarize the current understanding and assess potential future changes of DMS and CO cycling in relation to changes in sea ice coverage, light penetration, bacterial and microalgal communities, pH and physical properties. We suggest that production of DMS and CO might increase with ice melting, increasing light availability and shifting phytoplankton community. Among others, policy measures should facilitate large-scale process studies, coordinated long term observations and modelling efforts to improve our current understanding of the cycling and emissions of DMS and CO in the Arctic Ocean and of global consequences.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 92
    Publication Date: 2024-02-07
    Description: Climate change and deoxygenation are affecting fish stocks on a global scale, but disentangling the impacts of these stressors from the effects of overfishing is a challenge. This study was conducted to distinguish between climate change and mismanagement as possible causes for the drastic decline in spawning stock size and reproductive success in cod (Gadus morhua) and herring (Clupea harengus) in the Western Baltic Sea, when compared with the good or satisfactory status and reproductive success of the other commercial species in the area. Available data on water temperature, wind speed, and plankton bloom during the spawning season did not reveal conclusive correlations between years with good and bad reproductive success of cod or herring. Notably, the other commercial species in the area have very similar life history traits suggesting similar resilience against stress caused by climate change or fishing. The study concludes that severe, sustained overfishing plus inappropriate size selectivity of the main fishing gears have caused the decline in spawning stock biomass of cod and herring to levels that are known to have a high probability of impaired reproductive success. It is pointed out that allowed catches were regulated by management and adhered to by the fishers, meaning that unregulated fishing did not occur. Thus, mismanagement (quotas that were too high and gears that selected too small sizes) and not climate change appears to be the primary cause of the bad status of cod and herring in the Western Baltic Sea.
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  • 93
    Publication Date: 2024-02-07
    Description: Ecological and socioeconomic impacts from biological invasions are rapidly escalating worldwide. While effective management underpins impact mitigation, such actions are often delayed, insufficient or entirely absent. Presently, management delays emanate from a lack of monetary rationale to invest at early invasion stages, which precludes effective prevention and eradication. Here, we provide such rationale by developing a conceptual model to quantify the cost of inaction, i.e., the additional expenditure due to delayed management, under varying time delays and management efficiencies. Further, we apply the model to management and damage cost data from a relatively data-rich genus (Aedes mosquitoes). Our model demonstrates that rapid management interventions following invasion drastically minimise costs. We also identify key points in time that differentiate among scenarios of timely, delayed and severely delayed management intervention. Any management action during the severely delayed phase results in substantial losses (〉50% of the potential maximum loss). For Aedes spp., we estimate that the existing management delay of 55 years led to an additional total cost of approximately $ 4.57 billion (14% of the maximum cost), compared to a scenario with management action only seven years prior (〈 1% of the maximum cost). Moreover, we estimate that in the absence of management action, long-term losses would have accumulated to US$ 32.31 billion, or more than seven times the observed inaction cost. These results highlight the need for more timely management of invasive alien species—either pre-invasion, or as soon as possible after detection—by demonstrating how early investments rapidly reduce long-term economic impacts.
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  • 94
    Publication Date: 2024-02-07
    Description: Biological hard tissues are a rich source of design concepts for the generation of advanced materials. They represent the most important library of information on the evolution of life and its environmental conditions. Organisms produce soft and hard tissues in a bottom-up process, a construction principle that is intrinsic to biologically secreted materials. This process emerged early on in the geological record, with the onset of biological mineralization. The phylum Brachiopoda is a marine animal group that has an excellent and continuous fossil record from the early Cambrian to the Recent. Throughout this time interval, the Brachiopoda secreted phosphate and carbonate shells and populated many and highly diverse marine habitats. This required great flexibility in the adaptation of soft and hard tissues to the different marine environments and living conditions. This review presents, juxtaposes and discusses the main modes of mineral and biopolymer organization in Recent, carbonate shell-producing, brachiopods. We describe shell tissue characteristics for taxa of the orders Rhynchonellida, Terebratulida, Thecideida and Craniida. We highlight modes of calcite and organic matrix assembly at the macro-, micro-, and nano-scales based on results obtained by Electron Backscatter Diffraction, Atomic Force Microscopy, Field Emission Scanning Electron Microscopy and Scanning Transmission Electron Microscopy. We show variation in composite hard tissue organization for taxa with different lifestyles, visualize nanometer-scale calcite assemblies for rhynchonellide and terebratulide fibers, highlight thecideide shell microstructure, texture and chemistry characteristics, and discuss the feasibility to use thecideide shells as archives of proxies for paleoenvironment and paleoclimate reconstructions.
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  • 95
    Publication Date: 2024-02-07
    Description: Cloud-native applications constitute a recent trend for designing large-scale software systems. However, even though several cloud-native tools and patterns have emerged to support scalability, there is no commonly accepted method to empirically benchmark their scalability. In this study, we present a benchmarking method, allowing researchers and practitioners to conduct empirical scalability evaluations of cloud-native applications, frameworks, and deployment options. Our benchmarking method consists of scalability metrics, measurement methods, and an architecture for a scalability benchmarking tool, particularly suited for cloud-native applications. Following fundamental scalability definitions and established benchmarking best practices, we propose to quantify scalability by performing isolated experiments for different load and resource combinations, which asses whether specified service level objectives (SLOs) are achieved. To balance usability and reproducibility, our benchmarking method provides configuration options, controlling the trade-off between overall execution time and statistical grounding. We perform an extensive experimental evaluation of our method’s configuration options for the special case of event-driven microservices. For this purpose, we use benchmark implementations of the two stream processing frameworks Kafka Streams and Flink and run our experiments in two public clouds and one private cloud. We find that, independent of the cloud platform, it only takes a few repetitions (≤ 5) and short execution times (≤ 5 minutes) to assess whether SLOs are achieved. Combined with our findings from evaluating different search strategies, we conclude that our method allows to benchmark scalability in reasonable time.
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  • 96
    Publication Date: 2024-02-07
    Description: Mapping radon (222 Rn) distribution patterns in the coastal sea is a widely applied method for localizing and quantifying submarine groundwater discharge (SGD). While the literature reports a wide range of successful case studies, methodical problems that might occur in shallow wind-exposed coastal settings are generally neglected. This paper evaluates causes and effects that resulted in a failure of the radon approach at a distinct shallow wind-exposed location in the Baltic Sea. Based on a simple radon mass balance model, we discuss the effect of both wind speed and wind direction as causal for this failure. We show that at coastal settings, which are dominated by gentle submarine slopes and shallow waters, both parameters have severe impact on coastal radon distribution patterns, thus impeding their use for SGD investigation. In such cases, the radon approach needs necessarily to allow for the impact of wind speed and wind direction not only during but also prior to the field campaign.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 97
    Publication Date: 2024-02-07
    Description: Contains various examples and applications of visual data exploration and computational approaches. Includes a framework and its application for the evaluation of the success of research projects Provides in depth examples of SMART monitoring and data FAIRness
    Type: Book , NonPeerReviewed
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  • 98
    Publication Date: 2024-02-07
    Description: Sediment geotechnical properties are an important component of geohazard analyses and studies on submarine slope failures on continental margins. The northern Cascadia margin is a region of repeated subduction earthquakes and related geohazards including devastating tsunamis. Despite several drilling campaigns at this margin mostly for gas hydrate studies, sediment geotechnical properties are lacking to date. We therefore investigated a set of 20 half-round samples from four drill sites of Integrated Ocean Drilling Program (IODP) Expedition 311 along a margin-perpendicular transect. Samples were analysed for Atterberg properties (liquid limit, plasticity limit, plasticity index) and consolidation state (pre-consolidation stress, over-consolidation ratio, initial void ratio and compression index). Results of these parameters are in good agreement with similar studies at the southern Cascadia margin from Ocean Drilling Program (ODP) Leg 204 and are regarded robust, despite the long time-span between sample recovery in 2005 and our analyses. Individual results are interpreted at each of the drill sites and reflect the overall tectonic state of the location within the accretionary prism. An interplay of site-specific tectonic forcing, including thrust faulting, uplift, folding, and erosion appears to govern the depth-dependent consolidation state of the sediments.
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  • 99
    Publication Date: 2024-02-07
    Description: During trip out of the drill string at the end of a drilling operation (logging while tripping) borehole temperatures can be measured without the need for additional operational time. A simple interpretation of the measured borehole temperatures is difficult due to the interfering influences of the drilling operations, mainly due to flushing the borehole during drilling. In this study, we present borehole temperature data from drilling campaigns with the sea floor drill rig MARUM-MeBo200 at the Danube Deep Sea Fan (Black Sea) and west of Taiwan (South China Sea). The temperature measurements were conducted with a PT1000 temperature sensor which is integrated in a memory acoustic borehole logging tool. We developed a modeling approach in order to simulate the drilling perturbations and subsequent evolution of the temperature field within the borehole. By fitting the model data to the measured time dependent temperature depth profiles, we estimated the undisturbed heat flux at the drill sites. This study shows that knowledge of the pattern of drilling operations with alternating phases of drilling/flushing and drill string handling is crucial for comparing temperatures measured during logging while tripping and simulated temperatures.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 100
    Publication Date: 2024-02-07
    Description: Seaweed bioinvasions increasingly affect coastal environments around the world, which increases the need for predictive models and mitigation strategies. The biotic interactions between seaweed invaders and invaded communities are often considered a key determinant of invasion success and failure and we here revise the current evidence that the capacity of seaweed invaders to deter enemies in newly reached environments correlates with their invasion success. Particularly efficient chemical defences have been described for several of the more problematic seaweed invaders during the last decades. However, confirmed cases in which seaweed invaders confronted un-adapted enemies in newly gained environments with deterrents that were absent from these environments prior to the invasion (so-called “novel weapons”) are scarce, although an increasing number of invasive and non-invasive seaweeds are screened for defence compounds. More evidence exists that seaweeds may adapt defence intensities to changing pressure by biological enemies in newly invaded habitats. However, most of this evidence of shifting defence was gathered with only one particular model seaweed, the Asia-endemic red alga Agarophyton vermiculophyllum, which is particularly accessible for direct comparisons of native and non-native populations in common garden experiments. A. vermiculophyllum interacts with consumers, epibionts and bacterial pathogens and in most of these interactions, non-native populations have rather gained than lost defensive capacity relative to native conspecifics. The increases in the few examined cases were due to an increased production of broad-spectrum deterrents and the relative scarcity of specialized deterrents perhaps reflects the circumstance that seaweed consumers and epibionts are overwhelmingly generalists.
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