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  • Other Sources  (99)
  • Articles (OceanRep)  (99)
  • Elsevier  (60)
  • Institut für Polarökologie Kiel  (26)
  • AMS (American Meteorological Society)  (13)
  • 1985-1989  (92)
  • 1960-1964  (7)
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  • 1
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    Elsevier
    In:  Fisheries Research, 8 (1). pp. 35-44.
    Publication Date: 2017-01-10
    Description: In Moreton Bay, Queensland, the catch obtained using monofilament polyamide (PA) otter trawl-nets with multifilament polyethylene (PE) cod ends was compared with that obtained using multifilament PE trawl-nets of identical mesh opening (38 mm). Monofilament PA otter trawl-nets retained fewer small prawns ( 〈 24 mm carapace length) than conventional multifilament PE nets, but both nets caught similar quantities of larger prawns ( 〉 24 mm carapace length). The higher retention rate of small prawns by multifilament PE gear was reflected in the greater catch weights of Peraeus plebejus, Metapenaeus bennettae and Metapenaeopsis novaeguineae in those nets. Catch weights of larger prawn species such as Penaeus esculentus and Metapenaeus endeavouri did not differ between nets. Winter whiting (Sillago maculata) and squid (Loligo spp.) were trawled in similar abundance in both nets, although the monofilament retained fewer squid 〈 50 mm mantle length. More marketable ( 〉 15 cm carapace width) sand crabs (Portunus pelagicus) were caught in the monofilament net. There was not significant difference in the trash (noncommercial component) weight caught in both nets. Over the range of towing speeds tested (1.7–2.3 kn), use of monofilament nets significantly reduced total gear drag.
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  • 2
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    Institut für Polarökologie Kiel
    In:  Mitteilungen zur Kieler Polarforschung, 4 . pp. 7-10.
    Publication Date: 2017-09-11
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  • 3
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    Institut für Polarökologie Kiel
    In:  Mitteilungen zur Kieler Polarforschung, 4 . pp. 39-43.
    Publication Date: 2017-09-11
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  • 4
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    Institut für Polarökologie Kiel
    In:  Mitteilungen zur Kieler Polarforschung, 4 . pp. 11-13.
    Publication Date: 2017-09-11
    Description: Kurzfassung eines Vortrages zum Polartag in Bremerhaven am 23.2.1988
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  • 5
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    Institut für Polarökologie Kiel
    In:  Mitteilungen zur Kieler Polarforschung, 4 . pp. 28-33.
    Publication Date: 2019-04-16
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  • 6
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    Institut für Polarökologie Kiel
    In:  Mitteilungen zur Kieler Polarforschung, 4 . pp. 19-27.
    Publication Date: 2017-09-11
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  • 7
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    Institut für Polarökologie Kiel
    In:  Mitteilungen zur Kieler Polarforschung, 4 . pp. 34-38.
    Publication Date: 2019-04-16
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  • 8
    Publication Date: 2018-03-02
    Description: Sediments on high Arctic shelves result from modern processes and the effect of former glaciations. Based on data from the northern Barents Sea, an area with input from large and numerous surging glaciers, we define two principal zones with different environmental regimes and corresponding sedimentary facies: (1) a glacier-proximal zone influenced by grounding-line processes and the immediately adjacent areas affected by glacial sediment input, and (2) a glacier-distal, sea-ice and current-controlled zone, which also includes a wide sediment-starved region dominated by biogenic carbonate accumulation. Characteristic of the glacier-proximal zone are glacial surges which affect sedimentation rates and leave a diagnostic pattern of sea-floor morphologies. Extensive ice gouging causes a homogeneous sediment texture. In the glacier-distal zone, fine-grained mud supplied from sea ice and infrequent coarser material deposited from icebergs is reworked by modern oceanographic processes. On shallow banks, in 30–50 m of water, carbonates accumulate from a prolific bottom fauna formed in response to extensive reworking and nutrient supply.
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  • 9
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    Institut für Polarökologie Kiel
    In:  Mitteilungen zur Kieler Polarforschung, 4 . pp. 14-18.
    Publication Date: 2017-09-11
    Description: Auszug aus einem Arbeitsbericht
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  • 10
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    AMS (American Meteorological Society)
    In:  Journal of Physical Oceanography, 19 (10). pp. 1440-1448.
    Publication Date: 2020-08-04
    Description: Historical data from the region between the Greenwich meridian and the African continental shelf are used to compute the offshore geostrophic transport of the Benguela Current. At 32°S, the Benguela Current is located near the African coast, transporting about 21 Sv (1 Sv = 106 m3 s−1) of surface water toward the north relative to a potential density surface lying between the upper branch of Circumpolar Deep Water and the North Atlantic Deep Watar. Two warm core eddies of probable Agulhas Current origin an observed west of the Benguela Current at 32°S. Near 30°S, the Benguela Current turns toward the northwest and begins to separate from the eastern boundary. It carries about 18 Sv of surface water across 28°S. The current then turns mainly toward the west to flow over a relatively deep segment of the Walvis Ridge south of the Valdivia Bank. A surface current with northward surface of about 10 cm s−1 flows along the western side of the Valdivia Bank, while another northward surface current flows at about 20 cm s−1 some 300 km west of the bank. About 3 Sv of surface now do not leave the Cape Basin south of the Vaidivia Bank, but instead drift northward as a wide. sluggish flow out of the northern end of the Cape Basin. Because of the more southerly seaward extensions of most of the Benguela Current, there are no deep-reaching interactions observed between this current and the cyclonic gyre in the Angola Basin east of the Greenwich meridian. Beneath the surface layer, about 4–5 Sv of Antarctic Intermediate Water are carried northward across 32° and 28°S by the Benguela Current, essentially all of which turns westward to cross the Greenwich meridian south of 24°S.
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  • 11
    Publication Date: 2016-04-08
    Description: Clay- and silt-size mineral assemblages are described from eight piston cores from the fiords and shelf on the western margin of Baffin Bay, Arctic Canada. Radiocarbon dates indicate that all the cores extend back in time to the last local glacial/interglacial transition (i.e. 8–10 ka); four extend back to between 10 and 12 ka, and HU77-021-156, located on the Southeast Baffin Island shelf, includes the entire late Foxe glacial stage. Silt- and clay-size particles constitute ca 40 and 55%, respectively, by weight of the bulk sediment. The clay-size fraction is dominated by mica; feldspars and quartz are the main constituents of the silt fraction. The fiord sediments are mainly composed of local mineralogies, but on the shelf, and at times in the fiords, exotic mineral species occur. The most important of these are detrital carbonates, derived from erosion of the Paleozoic basins in Arctic Canada and/or northwest Greenland. Both calcite and dolomite occur; calcite is the major carbonate mineral in the “southern” cores, whereas dolomite is the most abundant in cores north of 66°N. Higher inputs of carbonate species occur during regional deglaciation, 7–10 ka, and during the last 5 ka (probably reflecting increased iceberg production from northwest Greenland). Thus variations in the precentages of the carbonate minerals indicate significant shifts in Late Quaternary glacial-sediment source areas and oceanographic regimes.
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  • 12
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    Elsevier
    In:  Marine Geology, 87 (2-4). pp. 323-328.
    Publication Date: 2016-04-11
    Description: Changes in composition of modern benthic ostracod faunas across the continental margin of southwestern Africa occur at boundaries between and within major water masses: a Mixed Layer-Antarctic Intermediate Water (AAIW) boundary at 200 m, an AAIW salinity minimum zone at 650 m, an AAIW bathyal thermocline at 1000 m, and the AAIW/North Atlantic Deep Water (NADW) boundary at 1500 m. In addition, two population changes occur within the NADW at 1.8–2.0 km and 2.0–3.0 km. The Antarctic Bottom Water assemblage is sparse and poorly preserved.
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  • 13
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    Elsevier
    In:  Estuarine, Coastal and Shelf Science, 28 (6). pp. 615-638.
    Publication Date: 2017-01-04
    Description: Measurements in the mixing zone of the Elbe estuary were performed during three consecutive tidal cycles with three types of instruments—a moored tripod with velocity and temperature/conductivity/light attenuation sensors, a profiling sonde with similar sensors lowered from an anchored vessel, and instrumented moorings. Acoustic-travel-time sensors were used for velocity measurements. Spectral analysis of 12·8 min pieces of the obtained time series gives results that are consistent with isotropic turbulence for part of the frequency space. Temporal changes of turbulent kinetic energy are correlated with tidal current velocity. A retardation is found between changes in tidal current and turbulent energy. Not all shear stress terms are in similar phase with tidal flow. Mean gradients, Reynolds stress terms, and turbulent salt flux terms are combined to determine eddy viscosity and eddy diffusion coefficients.
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  • 14
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    Elsevier
    In:  Earth and Planetary Science Letters, 94 (3-4). pp. 291-300.
    Publication Date: 2016-08-02
    Description: Compressional-wave (P-wave) velocities and magnetic susceptibilities were measured on gravity (GGC) and piston cores (PC) and Ocean Drilling Program (ODP) Leg 108 advanced piston cores (APC) from the equatorial Atlantic to test our hypothesis that climatically driven changes in terrigenous and biogenic fluxes, and in carbonate dissolution control the interrelationships between the two signals. In Pleistocene sediments deposited above the calcium compensation depth (CCD) we observed changes in P-wave velocity and magnetic susceptibility that are (1) inversely correlated, and (2) coherent to changes in glacial-interglacial climate. Glacials show low P-wave velocities and relatively high magnetic susceptibilities. In contrast, interglacials show high P-wave velocities and relatively low magnetic susceptibilities. These temporal changes in P-wave velocity and magnetic susceptibility reflect the climatic history recorded in the sediments and are related to: (1) the production of biogenic carbonate, mainly planktonic foraminifera, and (2) the terrigenous sediment supply that contains magnetic minerals. Below the CCD this pattern disappears and consistently low P-wave velocities and distinctly higher magnetic susceptibilities prevail. The distinct decrease of large P-wave velocity fluctuations is due to the dissolution of carbonate sediments which cause a distinct decrease in sand grain sizes and a consistently low carbonate content (〈 10%). Dilution of magnetic material by the carbonate fraction is minor and the high magnetic susceptibility values and the relatively high amplitude variations in magnetic susceptibility are due to changes in the magnetic mineral concentration of the terrigenous (non-carbonate) fraction. In early Pliocene sediments we also observed covarying velocity and magnetic susceptibility signals that may reflect a predominatly terrigenous control on sedimentation. Our preliminary results demonstrate that a combined use of non-destructive measurements of acoustic and rock-magnetic signals provides a potential paleoceanographic tool for characterizing: (1) glacial-interglacial pelagic sedimentation, (2) pelagic sedimentation above the CCD, (3) increases in carbonate dissolution, and (4) areas below the CCD. Furthermore, rock magnetic fluctuations in sediments below the CCD may provide an important stratigraphic tool for the deep carbonate-free basins of the world's oceans.
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  • 15
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    Elsevier
    In:  Aquacultural Engineering, 8 (1). pp. 47-65.
    Publication Date: 2020-06-11
    Description: The life cycle of loliginid squids has been completed in recirculating seawater systems. Two systems were required: a 2 m diameter circular culture tank (CT) with adjoining 2 m circular filter tank (3000 liters total volume of natural seawater) for culture of hatchlings, 1–60 days old; and a 6 × 2·6 × 1 m raceway culture tank (RW) with a smaller adjoining rectangular filter tank (14 850 liters total volume of artificial seawater) for the grow-out of adults. Both systems were equipped with temperature control apparatus, modular filter units (particle filters and activated carbon), foam fractionators, biological filters (crushed oyster shell) and UV sterilizers. The systems carried low bioloads, 〈 1·0 g/m3 and as high as 0·8 kg/m3, respectively. Water quality was excellent: NH4N was below 0·01 mg/liter in the CT and 0·10 mg/liter in the RW: NO2N was below 0·01 mg/liter in the CT and 0·03 mg/liter in the RW; NO3N was below 12 mg/liter in the CT and below 50 mg/liter in the RW; and pH was above 8·0 in both systems. The design of the systems proved to be behaviorally and physiologically suitable for squids and two species grew to adult size and produced viable young. These systems are compared to other squid maintenance and rearing systems and marine recirculating seawater systems.
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  • 16
    Publication Date: 2020-05-13
    Description: A comparative study of isodideimnine-1 and didemnin B is presented using spcctroecopic methods, partial degradation and partial synthesis. This leads to the conclusion of the presence of a single depsipeptide, namely didemnin B, with (3S,4R,5S) isostatine instead of the previous statine residue. An attempt to determine the whole conformation in solution of didemnin B by using 2D-NMR is also described.
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  • 17
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    Elsevier
    In:  Tectonophysics, 162 (1-2). pp. 51-85.
    Publication Date: 2019-05-06
    Description: Seismic refraction investigations along a 440-km long profije on the northern Baltic Shield have resolved the crustal structure in this area of Archaean to Early Proterozoic lithosphere formation. The profile, called the POLAR Profile, extends approximately along a SW-NE-oriented line from the Karelian Province in northern Finland across the Lapland Granulite Belt and the Kola Peninsula Province to the Varanger Peninsula in northeastern Norway. At six shotpoints, large explosions (200–1680 kg), and at three shotpoints, small explosions (80 kg) were detonated and recorded at an average station spacing of 2 km, providing high-quality record sections. A two-dimensional cross section of the crust was obtained by forward modelling using ray-tracing techniques. High-velocity bodies are found in the upper crust related to the Karasjok-Kittilä Greenstone Belt and the Lapland Granulite Belt. They extend to a depth of 6–13 km. In the Karelian Province in the southwest, a low-velocity zone was found between the depths of 8 and 14 km. The middle crust shows a slight increase in the average velocities from the southwest to the northeast, and a small velocity jump is found along a mid-crustal boundary between 18 and 21 km. The thickness of the middle crust varies between 16 and 18 km. The lower crust and the crust-mantle boundary (Moho) show considerable lateral variation. The top of the lower crust lies between 26 and 33 km, while its thickness decreases from 21 km in the southwest to 10–14 km beneath the Lapland Granulite Belt and the Inari Terrain, reaching 20 km again in the extreme northeast. The velocities also change laterally. The thin lower crust is characterized by rather low velocities (6.8–6.9 km/s), whereas in the southwest and northeast the velocities (6.9–7.3 km/s) resemble more typical shield structures. The Moho is found at 47 km in the Karelian Province, rises to 40 km beneath the Lapland Granulite Belt and descends to 46 km in the northeastern part of the Kola Peninsula Province. The upper mantle velocities at the Moho range from 8.1 km/s in the region of the thin crust, to 8.5 km/s and more beneath the Karelian Province. It is tempting to suggest that the anomalous lower crust underlying the Lapland Granulite Belt and the Inari Terrain may represent the remnants of an Early Proterozoic back-arc basin that was active prior to the 2.0 to 1.9 Ga plate convergence event, during which the Lapland Granulite Belt was thrust onto the Archaean basement of the Karelian Province. Another explanation is to assume that the velocity reduction in the anomalous lower crust was caused by a rather pronounced uplift of this region following the 1.9-Ga collision event.
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  • 18
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    Elsevier
    In:  Palaeogeography, Palaeoclimatology, Palaeoecology, 71 (1-2). pp. 97-118.
    Publication Date: 2019-05-06
    Description: Pore fluid venting associated with subduction-induced sediment deformation causes precipitation of calcium carbonate as prominent carbonate chimneys or cement in the accreted sediments across the active continental margin off Oregon and Washington. A depletion of interstitial Ca2+ with a maximum decrease of 50% relative to seawater Ca2+ over only 1.5m depth and reduction in porosity in the deformed sediments suggest that interstitial Ca2+ is removed to form calcium carbonate cement. In contrast, the pore waters of the undeformed abyssal plain sediments show no depletion in dissolved Ca2+. They are either enriched to a maximum of 5% or show no change in dissolved Ca2+. Here the background level of CaCO3 content in the sediment is only 0.1 to 1%. Calcium carbonate precipitation in the deformed sediments probably occurs as the result of upward migration and oxidation of biogenic methane and of the increase in carbonate saturation due to release of excess pore pressure during fluid venting. Upward advection of fluids at rates of 1–28 cm y−1 is predicted from diffusion-advection-reaction models applied to the downcore concentration profiles of dissolved Ca2+ and NH4+ in the tectonically-deformed sediments. The range of predicted flow rates is related to the type of calcium carbonate lithification; i.e. slow rates generate cement and fast rates generate chimneys. Carbonate mineral precipitation associated with pore fluid venting requires direct transfer of Ca2+ from the oceanic basement to the accretionary complex. Such a mechanism leads us to propose that the accretionary complexes of the global plate subduction zones are a major sink for crustal Ca2+. A global flux of crustal Ca2+ that is removed by carbonate mineral precipitation may be as muc3 as the hydrothermal Ca-input. This significant Ca-flux, not previously considered in the global geochemical budget, implies that pore fluid venting in subduction zones may also act as a global sink or source for other elements.
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  • 19
    Publication Date: 2019-05-10
    Description: Ocean crustal carbon uptake during seafloor alteration at DSDP Sites 417A, 417D, and 418A exceeds the estimated loss of carbon during magmatic ridge outgassing. If these sites are representative for oceanic crust in general, 2.2–2.9 × 1012 moles of carbon are removed from the oceans per year as a net flux of carbon between the oceanic crust and seawater. Although most of this carbon occurs as calcium carbonate, this ocean crustal carbonate probably cannot be considered part of the marine calcium carbonate sink since much of the Ca in these carbonates must be derived from basalt alteration that is not balanced by a concomitant uptake of seawater Mg. Our present estimate cannot be satisfactorily applied to global carbon budgets, because of uncertainties in the bulk budget of ocean floor alteration and because of the uniqueness of our estimate. Yet, our data document that the formation of ocean crust provides a significant sink for carbon that should be included in models of the global cycling of carbon. Furthermore, magmatic outgassing during ocean crust emplacement and seafloor basalt alteration may provide a buffering mechanism for atmospheric carbon.
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  • 20
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    Elsevier
    In:  Tectonophysics, 160 (1-4). pp. 75-90.
    Publication Date: 2019-05-13
    Description: The imaging of a multichannel seismic record was improved by reprocessing using pre-stack techniques. The reprocessed record shows structures that indicate tectonic erosion and gravity collapse at the front of the Japan Trench margin. Much of the lower slope appears to be underlain by a detached, coherent block of continental crust. The lower slope has failed by mass wasting and the resulting apron of slump debris at the base of the slope has become involved in thrust faulting at the front of the subduction zone. Slumping continues as long as debris is removed from the front of the margin by subduction, and the apron cannot build up sufficiently to stabilize the failing lower slope. Truncated beds at the base of the upper plate indicate subcrustal erosion as well, this probably being the main cause of massive subsidence of the margin. Subsidence was the cause of oversteepening, destabilization and subsequent gravity collapse of the leading edge of the upper plate.
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  • 21
    Publication Date: 2019-05-06
    Description: The ice-proximal environment of the Nordaustlandet tidewater ice cap, Svalbard Archipelago, is one of the best analogues for understanding glacial geologic processes of northern continental shelves during initial Pleistocene deglaciation. Investigations of the proglacial region in 1980–1983 showed that the sedimentary environment is dominated by numerous meltwater outflows which discharge sediment-laden water from subglacial meltwater streams during the summer. Two large, stable meltwater outflows were observed in embayments along the southern part of the ice front. Landsat images show that both outflows have been in approximately the same position since at least 1976. They are located at the intersection of glacial drainage basins and centered over depressions in the underlying bedrock. An “outflow valley” extending away from the ice front was observed in front of the western meltwater outflow. Sidescan sonar profiling along the glacier front showed a 200 m wide gap in acoustic reflection at the base of the western meltwater outflow, probably caused by meltwater effluence. Enhanced sediment accumulations in this region, observed as a ≈ 3 ms sediment drape in front of the outflow, and large arcuate ridges in the outflow valley, testify to the transport efficiency of the subglacial meltwater stream. Several mounds, up to about 25 m high and 200 m wide, are observed on sidescan and 3.5 kHz profiles directly in front of the outflow. Although samples from these structures are absent, they are most likely composed of sediment and are similar to beaded eskers observed in Pleistocene glacimarine sequences indicating locally very high sedimentation rates. Fine-grained components of the subglacial discharge incorporated in the buoyant meltwater plume are usually entrained in a westerly coastal current. Elevated suspended particulate material concentrations are observed within the coastal waters in a region extending about 15 km perpendicular to the glacier front and at least 60 km along the ice front extending into the northwestern Barents Sea.
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  • 22
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    Elsevier
    In:  Advances in Marine Biology, 25 . pp. 85-115.
    Publication Date: 2019-02-19
    Description: Cephalopods are exclusively marine molluscs and should be included among the organisms that are of general interest to marine biologists. As to experimental embryology, Naef has already stressed the suitability of cephalopod embryos for experimental work. The whole body of information accumulated in this field during the past half century since Naef published his monograph was reviewed by Marthy. This field of research is clearly underrated by many developmental biologists who could profit by the topological simplicity of the blastulation pattern in cephalopods, which contrasts with the spiralian mode of other molluscs. Questions raised by comparative/evolutionary embryology, following the tradition of descriptive developmental morphology, are truly stimulating to the field of experimental embryology, and vice versa. However, experimental studies are generally possible with only a limited number of models, which, in the case of cephalopods, appear to be embryos of medium to small size. On the other hand, some of the most intriguing questions in cephalopod biology are related to those forms that produce eggs of extremely large size. This chapter gives a brief overview of these recent studies placing them in the chronological sequence of embryogenesis. Studies covering early stages of embryonic development as well as later ones will be cited at least once in the section dealing with the earliest stage considered. Most of these investigations ultimately rest on the basic work by Naef.
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  • 23
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    AMS (American Meteorological Society)
    In:  Journal of Physical Oceanography, 19 . pp. 77-97.
    Publication Date: 2018-04-05
    Description: We report a study of a coastal frontal zone of the southeastern United States based on a field experiment and numerical modeling. The study was conducted in the spring of 1985 during weak to moderate wind stress and strong input of buoyancy from solar radiation and river discharge. The study confirms that the structure and slope of the frontal zone depends on a combination of wind stress and cross-shelf advection of buoyancy. A cross-shelf/depth two-dimensional (x, y), time-dependent numerical model illustrated the response of the frontal zone to the local wind stress regimes. A comparison of model results with field data showed that the model successfully predicted onsets of stratification and mixing. When alongshore wind stress was negative (southward), isopycnals in the frontal zone steepened due to a combination of horizontal advection and vertical convection. When stress was positive (northward), the offshore advection of low density water flattened the isopycnals and potential energy decreased, demonstrating that horizontal advection terms are important in the equation of conservation of buoyancy. The model predicts die offshore advection of lenses of less dense water during upwelling-favorable wind stress. These lenses are of the order of 20 km in cross-shelf scale and represent an efficient mechanism to export nearshore water. The lenses consist of a mixture of low-salinity coastal water and continental shelf water originating further offshore and advected onshore along the bottom. The mean flow inside the frontal zone opposed the mean alongshore wind stress. Part of the alongshore flow was in geostrophy with the cross-shore pressure gradient; the other part was due to an alongshore pressure gradient force (kinematic) of about 1 × 10−6 m s−2 (equivalent sea surface slope = 1 × 10−7), which was trapped along the coast with an offshore width scale of O(10 km). It is likely that the alongshore extent of this pressure gradient was governed by the scale at which freshwater is injected to the continental shelf, i.e., 20–30 km. The pressure gradient force immediately outside of the frontal zone was about −5 × 10−7 m s−2 in the direction of the mean alongshore wind stress. It is hypothesized that, as a result of wind setup and freshwater influx, the northward pressure gradient forced over outer shelf/slope by the Gulf Stream decreases in magnitude onshore, and can even change sign across a nearshore frontal zone of O(10 km). The implied flow field near the frontal zone is therefore highly three-dimensional with |∂v/∂y|≈|∂u/∂x|, where (u, v) are velocities in the cross-shore (x) and alongshore (y) directions, respectively.
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  • 24
    Publication Date: 2019-05-06
    Description: Sediment fluxes were highest in the Norwegian Sea during late glacial/early deglacial periods, i.e., at oxygen isotope transition 43, below transition 65, at various levels within stage 6, and below stage 9. Dark diamictons deposited at these times reflect intense iceberg rafting in surface waters fed by surges along the front of the marine-based parts of the continental ice sheets in the southeastern sector of the Norwegian Sea. The high organic carbon content (0.5–1.3%) in these layers reflects input from erosion of terrigenious matter-rich sediments outcropping on the shelves. Partial oxidation of organic matter and decreased deep-water renewal may explain the strong carbonate dissolution observed during these periods. Interglacial environments were strongly variable throughout the last 350 ka. Circulation patterns of stage 5e best resemble modern conditions, while stage 7 and 9 sediments record a much weaker Norwegian Current.
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  • 25
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    Elsevier
    In:  Journal of Experimental Marine Biology and Ecology, 126 (3). pp. 231-241.
    Publication Date: 2016-11-29
    Description: 19 samples (1189 individuals) of the commercially fished Patagonian squid Loligo gahi d'Orbigny were collected from Falkland waters between March 1987 and April 1988 and subjected to starch gel electrophoresis. 41 enzyme-coding loci were screened for polymorphism. Clearly resolved enzyme phenotypes were obtained at 21 loci of which six exhibited polymorphism (glutamate oxaloacetate transaminase, GOT-II, E.C. 2.6.1.1.; α-glycerophosphate dehydrogenase, α-GPDH, E.G. 1.1.1.8; isocitrate dehydrogenase, ICD, E.C. 1.1.1.42; malate dehydrogenase, MDH-II, E.G. 1.1.1.37; phosphogluconate dehydrogenase, PGD, E.C. 1.1.1.44; and phosphoglucose mutase, PGM, E.G. 2.7.5.1). Routine scoring at the 21 loci revealed moderate levels of genetic variability, with the proportion of polymorphic loci, P = 0.273, mean heterozygosities per locus = 0.0693, and the effective number of alleles, Ne, with values of 1.13–1.83.
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  • 26
    Publication Date: 2016-11-29
    Description: Genetic population structure of the commercially fished Patagonian squid Loligo gahi d'Orbigny was examined by collecting 19 samples (1189 individuals) from Falkland waters between March 1987 and April 1988 and subjecting individuals to electrophoretic and morphometric analysis. Morphological features (dorsal mantle length, fin length oblique, fin width, interorbital width, tentacle length, length of arms I and II, and mid-mantle circumference), sex and stage of reproductive maturity (Lipinski's universal scale) were recorded prior to electrophoresis. Analyses of allele frequencies at six polymorphic loci provided no evidence of stock separation, and the frequency distribution of genotypic classes almost exclusively fitted Hardy-Weinberg expectations for a randomly interbreeding population. Nei's mean genetic distances and identities between samples ranged from 0.000–0.002 and 0.997–1.00, respectively, supporting the contention of a genetically homogeneous breeding unit. Multivariate analyses revealed significant differences in the morphometrics among certain samples collected at approximately the same time, especially of interorbital width, first arm length and fin width. This morphological differentiation was not correlated with differences at the genetic level. The frequency distribution of dorsal mantle length and stages of reproductive maturity through the year were compatible with two alternative interpretations of population structure: (i) the existence of two temporally distinct separate spawning populations, one autumn- and the other spring-spawning, or, (ii) that slow-growing or late spawned individuals spawn at 18 months old while most squid spawn at 1 yr old in the austral spring and summer. Although it is not possible to discount either interpretation unequivocally, the latter hypothesis of population structure is more congruent with existing genetic evidence.
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  • 27
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    AMS (American Meteorological Society)
    In:  Journal of the Atmospheric Sciences, 46 (5). pp. 661-686.
    Publication Date: 2018-04-16
    Description: The sensitivity of the global climate system to interannual variability of he Eurasian snow cover has been investigated with numerical models. It was found that heavier than normal Eurasian snow cover in spring leads to a “poor” monsoon over Southeast Asia thereby verifying an idea over 100 years old. The poor monsoon was characterized by reduced rainfall over India and Burma, reduced wind stress over the Indian Ocean, lower than normal temperatures on the Asian land mass and in the overlying atmospheric column, reduced tropical jet, increased soil moisture, and other features associated with poor monsoons. Lighter than normal snow cover led to a “good” monsoon with atmospheric anomalies like those described above but of opposite sign. Remote responses from the snow field perturbation include readjustment of the Northern Hemispheric mass field in midlatitude, an equatorially symmetric response of the tropical geopotential height and temperature field and weak, but significant, perturbations in the surface wind stress and heat flux in the tropical Pacific. The physics responsible for the regional response involves all elements of both the surface heat budget and heat budget of the full atmospheric column. In essence, the snow, soil and atmospheric moisture all act to keep the land and overlying atmospheric column colder than normal during a heavy snow simulation thus reducing the land–ocean temperature contrast needed to initiate the monsoon. The remote responses are driven by heating anomalies associated with both large scale air-sea interactions and precipitation events. The model winds from the heavy snow experiment were used to drive an ocean model. The SST field in that model developed a weak El Niño in the equatorial Pacific. A coupled ocean-atmosphere model simulation perturbed only by anomalous Eurasian snow cover was also run and it developed a much stranger El Niño in the Pacific. The coupled system clearly amplified the wind stress anomaly associated with the poor monsoon. These results show the important role of an evolving (not specified) sea surface temperature in numerical experiments and the real climate system. Our general results also demonstrate the importance of land processes in global climate dynamics and their possible role as one of the factors that could trigger ENSO events.
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  • 28
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    Elsevier
    In:  Palaeogeography, Palaeoclimatology, Palaeoecology, 71 (1-2). pp. 119-136.
    Publication Date: 2020-08-07
    Description: Pore fluids extracted from near-surface sediments of the deformation front along the Oregon subduction zone have, in general, the dissolved nutrient pattern characteristic of bacterial sulfate reduction. However, in certain locations there are peculiar ammonium distributions and anomalously 13C-depleted dissolved ΣCO2. These carbon isotope and nutrient patterns are attributed to the concurrent microbially-mediated oxidation of sedimentary organic matter (POC) and methane (CH4) originating from depth. In contrast to the oxidation of sedimentary organic matter in the sulfate zone, utilization of methane as the carbon source by sulfate-reducing bacteria would generate only half as much total carbon dioxide for each mole of sulfate consumed and would not generate any dissolved ammonium. The isotopically light ΣCO2 released from methane oxidation depletes the total metabolic carbon dioxide pool. Therefore, NH4+, ΣCO2 and δ13C of interstitial carbon dioxide in these pore fluids distintcly reflect the combined contributions of each of the two carbon substrates undergoing mineralization; i.e. methane and sedimentary organic matter. By appropriately partitioning the nutrient and substrate relationships, we calculate that in the area of the marginal ridge of the Oregon subduction zone as much as 30% of the ΣCO2 in pore fluids may result from methane oxidation. The calculation also predicts that the carbon isotope signature of the carbon dioxide derived from methane is between −35‰ and −63‰ PDB. Such an isotopically light gas generated from within the accretionary complex could be the residue of a biogenic methane pool. Fluid advection is required to carry such methane from depth to the present near-surface sediments. This mechanism is consistent with large-scale, tectonically-induced fluid transport envisioned for accreted sediments of the world's convergent plate boundaries.
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  • 29
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    Institut für Polarökologie Kiel
    In:  Mitteilungen zur Kieler Polarforschung, 3 . pp. 15-18.
    Publication Date: 2017-08-08
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  • 30
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    Institut für Polarökologie Kiel
    In:  Mitteilungen zur Kieler Polarforschung, 3 . pp. 19-27.
    Publication Date: 2017-08-08
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  • 31
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    Institut für Polarökologie Kiel
    In:  Mitteilungen zur Kieler Polarforschung, 3 . pp. 28-33.
    Publication Date: 2017-08-08
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  • 32
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    Institut für Polarökologie Kiel
    In:  Mitteilungen zur Kieler Polarforschung, 3 . pp. 38-43.
    Publication Date: 2017-09-11
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  • 33
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    Institut für Polarökologie Kiel
    In:  Mitteilungen zur Kieler Polarforschung, 3 . pp. 44-45.
    Publication Date: 2017-09-11
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  • 34
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    Institut für Polarökologie Kiel
    In:  Mitteilungen zur Kieler Polarforschung, 3 . pp. 34-37.
    Publication Date: 2017-09-11
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  • 35
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    Institut für Polarökologie Kiel
    In:  Mitteilungen zur Kieler Polarforschung, 3 . pp. 5-14.
    Publication Date: 2017-08-08
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  • 36
    Publication Date: 2017-11-08
    Description: Marine geophysical surveys employing Seabeam, multi- and single-channel seismic reflection, gravity and magnetic instruments were conducted at two locations along the continental slope of the Peru Trench during the Seaperc cruise of the R/V “Jean Charcot” in July 1986. These areas are centered around 5°30′S and 9°30′S off the coastal towns of Paita and Chimbote respectively. These data indicate that (1) the continental slope off Peru consists of three distinct morpho-structural domains (from west to east are the lower, middle and upper slopes) instead of just two as previously reported; (2) the middle slope has the characteristics of a zone of tectonic collapse at the front of a gently flexured upper slope; (3) the upper half of the lower slope appears to represent the product of mass wasting; (4) thrusting at the foot of the margin produces a continuous morphologic feature representing a deformation front where the products of mass-wasting are overprinted by a compressional tectonic fabric; (5) a change in the tectonic regime from tensional to compressional occurs at the mid-slope-lower slope boundary, the accretionary prism being restricted to the very base of the lower slope in the Paita area. The Andean margin off Peru is an “extensional active margin” or a “collapsing active margin” developing a subordinated accretionary complex induced by massive collapse of the middle slope area.
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  • 37
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    AMS (American Meteorological Society)
    In:  Journal of Physical Oceanography, 18 . pp. 320-338.
    Publication Date: 2018-04-05
    Description: We examine the diffusive behavior of the flow field in an eddy-resolving, primitive equation circulation model. Analysis of fluid particle trajectories illustrates the transport mechanisms, which are leading to uniform tracer and potential vorticity distributions in the interior of the subtropical thermocline. In contrast to the assumption of weak mixing in recent analytical theories, the numerical model indicates the alternative of tracer and potential vorticity homogenization on isopycnal surfaces taking place in a nonideal fluid with strong, along-isopycnal eddy mixing. The eastern, ventilated portion of the gyre appears to be sufficiently homogeneous to allow the concept of an eddy diffusivity to apply. A break in a random walk behavior of particle statistics occurs after about 100 days when along-flow dispersion sharply increases, indicative of mean shear effects. During the first months of particle spreading, eddy dispersal and mean advection are of similar magnitude. Eddy kinetic energy is of O(60–80 cm2 s−2) in the model thermocline, comparable to the pool of weak eddy intensity found in the eastern parts of the subtropical oceans. Eddy diffusivity in the model thermocline (Kxx = 8 × 107, Kyy = 3 × 107 cm2 s−1) seems to be higher by a factor of about 3 than oceanic values estimated for these area. Below the thermocline, model diffusivity decreases substantially and becomes much more anisotropic, with particle dispersal preferentially in the zonal direction. The strong nonisotropic behavior, prominent also in all other areas of water eddy intensity, appears as the major discrepancy when compared with the observed behavior of SOFAR floats and surface drifters in the ocean.
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  • 38
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    Elsevier
    In:  Journal of Experimental Marine Biology and Ecology, 117 (3). pp. 271-278.
    Publication Date: 2018-03-21
    Description: In ecological studies, especially in those dealing with energy circulation in nature, determinations of the energy content of organisms are inevitable. Energy determinations are, however, laborious and time-consuming. Average conversion factors based on different species form various areas and seasons may often be a shortcut for overcoming this problem. To establish general energy conversion factors for aquatic invertebrate groups, we used 376 values of J · mg−1 DW and 255 values of J · mg−1 AFDW, representing 308 and 229 species, respectively. The dry-weight-to-energy factors were highly variable both within and between taxonomic groups, e.g.: Porifera, 6.1 J · mg−1 DW; insect larvae, 22.4 J · mg−1 DW (median values). The energy-conversion factors related to AFDW showed a much smaller dispersion with a minimum median value of 19.7 J · mg−1 AFDW (Ascidiacea) and a maximum of 23.8 J · mg−1 AFDW (insect larvae). Within taxonomic groups, the 95% confidence intervals (AFDW) were only a few percent of the median values. The use of energy-conversion factors based on AFDW is preferable due to their lower dispersion. For aquatic macrobenthic invertebrates, a general conversion factor of 23 J · mg−1 AFDW can be used.
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  • 39
    Publication Date: 2016-09-05
    Description: Paleoceanographic and stratigraphic methods, based on high-resolution compressional wave (p-wave) velocity measurements, have been applied to the studies of late Quaternary deep-sea carbonates in the western and eastern equatorial Atlantic. The measurements provide sonostratigraphic records in which changes in p-wave velocity parallel the changes from a glacial to an interglacial climate: Maxima in p-wave velocity (greater than 1540 m/s) occur during interglacial oxygen isotope stages 1, 5 and 7. Minima (1490 m/s) occur during glacial oxygen isotope stages 2, 4 and 6. Changes in p-wave velocity parallel past changes in carbonate accumulation and sediment coarse fraction, and allow a detailed core to core correlation. From these results two main patterns emerge: (1) In cores from shallower than 4300 m and from well above the present lysocline, large temporal changes in p-wave velocity parallel the production of planktonic foraminifera and the climatic history recorded in the sediments, and (2) below 4300 m, the position of the foraminiferal lysocline in the western equatorial Atlantic, large downcore p-wave velocity fluctuations gradually disappear due to dissolution of carbonate sediments. Dissolution also causes a distinct decrease in p-wave velocity and acoustic reflectivity in surface sediments across the present foraminiferal lysocline. Thus, past changes in the position of the foraminiferal lysocline or calcite compensation depth that caused distinct changes in reflectivity of sediments should lead to distinct reflectors within sediment columns. Their distribution can be utilized to map paleowater masses with different degrees of carbonate saturation.
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  • 40
    Publication Date: 2016-05-18
    Description: Silica chimneys were discovered in 1985 at 86°W in the rift valley of the Galapagos Spreading Center at 2600 m depth (“Cauliflower Garden”). The inactive chimneys lack any sulfides and consist almost entirely of amorphous silica (up to 96 wt.% SiO2, opal-A); Fe and Mn oxides are minor constituents. Oxygen isotope data show that formation of the silica chimneys took place at temperatures between 32°C (+29.9‰ δ18O) and 42°C (+27.8‰ δ18O).Th/Udating reveals a maximum age of 1440 ± 300y. Amorphous silica solubility relations indicate that the silica chimneys were formed by conductive cooling of pure hydrothermal fluids or by conductive cooling of a fluid/seawater mixture. Assuming equilibrium with quartz at 500 bars, initial fluid temperatures of more than 175°C (i.e., a concentration of 〉 182 ppm SiO2) were required to achieve sufficient supersaturation for the deposition of amorphous silica at 40°C and 260 bars. If the silica chimneys originate from the same or a similar fluid as higher-temperature ( 〈 300°C) sulfide-silica precipitates found nearby (i.e., 2.5 km away), then subsurface deposition of sulfides may have occurred.
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  • 41
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    Elsevier
    In:  Chemical Geology, 70 (4). pp. 359-371.
    Publication Date: 2016-07-19
    Description: The release of exchangeable Mg in marine sediments from displacement by ammonium ions was estimated by way of experimentally determining the parameters that govern this ion-exchange equilibrium on solid geochemical phases: smectite, humic acid, illite and opal. We showed that: (a) both the conditional selectivity constant as well as the solid concentration are important parameters in determining the relative contribution of ammonium-exchangeable Mg from smectite, organic matter, illite and opal; and (b) that, except in the cases where opal or organic matter concentrations are very high, the clays are the dominant carrier phases for labile Mg which is exchangeable by ammonium. A model, based on the sum of the contributions from the major geochemical phases present in the sediment reliably predicts the amount of Mg released by exchange with ammonium in marine sediments.
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  • 42
    Publication Date: 2016-07-19
    Description: A radiotracer technique, employing 27Mg, is used to determine the Mg released by ammonium exchange on undis-solved humic acid in a seawater medium. This new method allows for the measurement of exchangeable Mg on the solid phase surface, which eliminates the problem caused by the high-Mg background in the seawater matrix. The precision calculated from the counting statistics is better than ±2%; the reproducibility among repeated counts ranged from ±1% to ±3%. The higher sensitivity of the method allows for monitoring the MgNH4 exchange at concentrations as low as 30 mM NH4. This is a major improvement relative to the data obtained with the analytical methods used so far, which allow detection of exchangeable Mg only at NH4 concentrations higher than 1 M. The lower experimental concentrations are more in accordance with the natural ammonium levels found in anoxic marine sediments. For the undissolved humic acid used in this experiment, the amount of exchangeable Mg in apparent equilibrium with an ammonium-free seawater matrix was found to be 96.6 ± 0.4 meq/100g. The Mg-NH4 exchange on humic acid in seawater comes to a steady-state value in 〈 18 min. The conditional equilibrium constant obtained for this reaction, Kcond = 0.039 ± 0.001 M−1. The technique can be expanded to other geochemical solid phases in seawater and it can be modified to study the behavior of the major cations by using 24Na, 42K and 49Ca.
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  • 43
    Publication Date: 2016-06-15
    Description: Sharp jumps in climate punctuate the records from borings in the Greenland ice cap during the time interval 60,000 to about 20,000 yr ago. Rapid fluctuations are also seen in foraminifera records for cores from the northern Atlantic and in a pollen record from a core from a bog in the Vosges Mountains in France. In this paper we present a new radiocarbon chronology for northern Atlantic deep-sea core V23-81 which permits comparison with the radiocarbon-dated Vosges Mountains pollen record. Because of the lack of a 14C chronology for the Greenland ice record and of distortions peculiar to each of the three records, it is not yet possible to say whether or not the events are genetically related.
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  • 44
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    Elsevier
    In:  Journal of Experimental Marine Biology and Ecology, 116 (2). pp. 177-190.
    Publication Date: 2019-02-22
    Description: Age and growth were estimated on two brood stocks of a loliginid squid, Photololigo edulis (Hoyle), by examining growth increments within the statoliths from 773 specimens. Samples were collected from the northwestern coast of Kyushu, Japan, and the southwestern coast of the Sea of Japan between January 1983 and June 1984. Length and age data were fitted to logistic growth curves for each sex and brood, under the assumption that increments formed daily. Relationships between age and mantle length and the modelled growth curves showed that: the posthatch life span may be 〈 1 yr; growth rates vary considerably between individuals, especially in the second half of life; the average growth rate of the male was higher than that of the female in the warm-season brood, but almost the same in the cold-season brood. Because of the wide variation in the individual growth rate, it was presumed that warm- and cold-season broods were not genetically discrete populations.
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  • 45
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    AMS (American Meteorological Society)
    In:  Journal of the Atmospheric Sciences, 45 (6). pp. 964-979.
    Publication Date: 2018-04-16
    Description: A coupled ocean-atmosphere general circulation model has been developed for TOGA related problems. The coupled model consists of an ocean model of the tropical Pacific and a global low-order spectral atmosphere model. The two models interact via wind stress and sea surface temperature. In order to avoid a climate drift within the coupled model, a flux correction method is applied.Experiments were performed by introducing a westerly wind stress burst over the western equatorial Pacific for one month. Thereafter, the wind burst is turned off and the response of the coupled model to the initial disturbance is investigated. The results are compared with the response of the ocean model run with the same disturbance in an uncoupled mode.It is shown that the coupling leads to a significant increase of the duration of anomalous conditions in the ocean. SST anomalies persist for about 12 months in the coupled run, while they have already disappeared after 4 months in the uncoupled case. The increase in persistence is due to the feedback of the atmosphere, which responds with an eastward shift of the ascending branch of the Walker Circulation.In a second experiment with the coupled model the initial disturbance was introduced within another season. The results show no basic differences to the results of the first experiment.An interesting result of the coupled model runs is the occurrence of spontaneous westerly wind bursts over the western Pacific, which developed by internal dynamics. Location and duration of these spontaneous wind bursts show some correspondence with the time-space structure of observed westerly wind stress episodes over the western Pacific.
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  • 46
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    Institut für Polarökologie Kiel
    In:  Mitteilungen zur Kieler Polarforschung, 2 . pp. 12-21.
    Publication Date: 2017-08-08
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  • 47
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    Institut für Polarökologie Kiel
    In:  Mitteilungen zur Kieler Polarforschung (2). pp. 22-29.
    Publication Date: 2017-07-25
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    Institut für Polarökologie Kiel
    In:  Mitteilungen zur Kieler Polarforschung (2). pp. 40-44.
    Publication Date: 2017-07-25
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  • 49
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    Institut für Polarökologie Kiel
    In:  Mitteilungen zur Kieler Polarforschung (2). pp. 5-11.
    Publication Date: 2017-07-25
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  • 50
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    Institut für Polarökologie Kiel
    In:  Mitteilungen zur Kieler Polarforschung (2). pp. 45-51.
    Publication Date: 2017-07-25
    Description: Auf der Basis wirtschaftlicher und politischer Interessen haben ähnlich wie in der Antarktis auch in der Arktis die Forschungsaktivitäten in den letzten 10 Jahren sehr stark zugenommen. Im Vordergrund stehen die Prospektion und Ausbeutung von fossilen Brennstoffen, vor allem von Öl, aber auch der Ausbau der militärischen Sicherheit. Denn in der Arktis stehen sich die beiden großen Machtblöcke, USA und Sowjetunion, am nächsten gegenüber. Man hat wohl auch bald erkannt, daß die sogenannte angewandte Forschung in diesem nur unzureichend bekannten Terrain einer massiven Unterstützung durch die Grundlagenforschung bedurfte.
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  • 51
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    Institut für Polarökologie Kiel
    In:  Mitteilungen zur Kieler Polarforschung (2). pp. 30-39.
    Publication Date: 2017-07-25
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  • 52
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    Elsevier
    In:  Quaternary Science Reviews, 6 (3-4). pp. 231-243.
    Publication Date: 2016-04-08
    Description: Piston cores from fiords, shelf troughs, and the deep-sea off eastern Baffin Island, N.W.T., Canada, have been sampled for texture and detrital carbonate in the 〈2 mm fraction. The sediments consist primarily of silty clays usually containing 〈5% sand. Estimates are made for sediment accumulation (kg/m**2/ka) over the last ca. 10 ka. Three sets, of two cores each, lie on a fiord-shelf transect and thus define variations in sediment accumulation gradients. These continental margin data are compared with cruder estimates of Holocene sediment accumulation at three sites farther offshore in Baffin Bay, Davis Strait and the northern Labrador Sea. Minimum accumulation in a 2 ka interval was 200 kg/m2 with a maximum estimate of 8,800 kg/m2. Detrital carbonate accumulation varies between 0 and 1,300 kg/m**2. Median accumulation for a typical fiord-shelf-deep-sea transect over the last 10 ka have been 10,340, 3493 and 820 kg/m**2. At DSDP Leg, site 645 in central Baffin Bay, the sedimentation rate ranged between 40 and 130 m/Ma (ca. 400 and 1200 kg/m**2/2ka); that is, comparable with the Late Quaternary input into Baffin Bay.
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  • 53
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    AMS (American Meteorological Society)
    In:  Journal of Physical Oceanography, 17 (1). pp. 158-163.
    Publication Date: 2020-08-04
    Description: The existence of energetic anticyclonic mid-depth vortices of Mediterranean Water (meddies) questions the validity of a conventional advective–diffusive balance in the eastern Atlantic subtropical gyre. A mesoscale experiment in the Azores–Madeira region reveals a link of these meddies to large-scale subsurface meanders. For the first time it is shown that meddies may have strong surface vorticity, indicative of a generation process involving the Azores Current—a deep reaching near-surface jet.
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  • 54
    Publication Date: 2017-12-11
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  • 55
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    Elsevier
    In:  Ocean Modelling, 74 . pp. 5-9.
    Publication Date: 2018-01-24
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  • 56
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    Elsevier
    In:  Environment International, 13 (1). pp. 37-45.
    Publication Date: 2020-07-31
    Description: Of about 20,000 modern fish species, only about 200 are found south of the Antarctic Convergence. The ichthyofauna is dominated by small species up to 40 cm long. The majority are bottom dwelling forms which belong mostly to the suborder Notothenioidei. Antarctic pelagic fishes are descendants from several faunal groups of different origins: bathypelagic and mesopelagic species, and species originating from demersal families which are secondarily adapted to temporary or permanent midwater life. More than 30 species of squid are so far known from the Southern Ocean. The majority are obviously meso-and bathy-pelagic dwellers. Several adaptations, including stenothermy, freezing resistance, aglomerular kidneys, and neutral buoyancy, enable Antarctic coastal fish to live successfully in the harsh environment. Growth rates of coastal fish are comparable to those found in Newfoundland cod. Most coastal fish do not spawn until they are 5 year old. Three reproductive strategies occur in coastal fish: autumn/early winter spawners with few, but yolky, eggs of 3–6 mm diameter; late winter/spring spawners with many, but smaller, eggs of 1.5–2 mm diameter; and species which guard their nests. Based on their food spectra, fish species can roughly be divided into three groups: fish and krill feeders, plankton feeders, and benthos feeders. Krill consumption by coastal fish around South Georgia and in West Antarctic waters was probably in the order of 5–6 × 106 tonnes before the onset of exploitation. Overall euphausiid consumption may have been about 20 × 106 tonnes. Fish, particularly mesopelagic fish, appear to be more important krill predators than squid. The role of squid as krill predators may have been overestimated in the past. Squid seem to be more important as a food resource for top level predators, particularly sperm whales and birds, than fish appear to be. All estimates of food consumption—krill as well as fish—are still subject to many uncertainties, and so it can be expected that increasing knowledge in the future may alter the given figures quite substantially. Exploitation of Antarctic finfish started at the end of the 1960s. The main fishing grounds are South Georgia and Kerguelen Islands. So far about 2.3 × 106 tonnes have been harvested from the Southern Ocean and the stocks particularly around South Georgia are heavily depleted. Conservation measures adopted by the Commission for the Conservation of Antarctic Marine Living Resources in 1984 and 1985 are probably not sufficient to support the recovery of the stocks.
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  • 57
    Publication Date: 2016-11-14
    Description: The upper part of the Deccan Traps sequence (Bushe to Mahabaleshwar Formations) shows a statistically significant tendency for the most mafic lavas to be the most contaminated by crustal materials. This is the reverse of the relationship shown by suites evolving by contamination accompanied by fractional crystallisation (AFC). The observed correlations (e.g. between Mg-number and Sr isotope initial ratios) are partly an accidental consequence of the fact that the most mafic lavas are more abundant in the lower part of the sequence, while contaminant availability declines in the upper part. It is probable, however, that the correlations are augmented by increased contamination of hotter magma batches during ascent through dykes, a process during which fractional crystallisation is suppressed by magmatic turbulence. The absence of AFC relationships suggests that most of the contamination took place during the ascent stage rather than in a magma chamber. Other continental flood basalt provinces such as the Parana and Etendeka do show AFC relationships, and it is speculated that this may be a result of magma chamber contamination coupled with flow rates which prevent contamination during ascent.
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  • 58
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    AMS (American Meteorological Society)
    In:  Journal of Physical Oceanography, 17 (10). pp. 1561-1570.
    Publication Date: 2020-08-04
    Description: Quasi-homogeneous layers in vertical profiles of temperature and salinity in the eastern North Atlantic near Madeira indicate the existence of a subtropical Mode Water in the Eastern Basin. Temperature sections show a maximum horizontal extent of at least 500 km. The frequency distribution analysis of homogeneous layers in a historical XBT dataset shows a Mode Water formation region near and to the north of Madeira. This Mode Water is found at increasing depths and displaced to the west and southwest during the course of the year after its formation by wintertime convection. It disappears almost completely, due to mixing, before the next winter. Volume estimates suggest that this Madeira Mode Water in the eastern Atlantic accounts for 15–20% of the total Central Water formation in the corresponding density range as obtained from tracer studies in the North Atlantic gyre.
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  • 59
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    AMS (American Meteorological Society)
    In:  Journal of Physical Oceanography, 17 (2). pp. 246-263.
    Publication Date: 2018-04-04
    Description: A primitive equation model of the equatorial Pacific Ocean was forced by realistic wind stress distributions over decades. Results were presented for a set of two experiments. In the first experiment the model was forced by an objectively analyzed wind field, while for the second experiment a subjectively analyzed wind field was used. The results indicate a strong sensitivity of the model to the choice of the wind fields. Especially, model results in the eastern Pacific show big differences between the two model runs. Taking the results of the second model run the performance of the model with respect to interannual variability is investigated. Sea level, temperature and zonal currents show pronounced interannual variations within the equatorial belt from 10°N to 10°S. Special attention is given to the simulation of the 1982/83 El Niño event. The model reproduces most of the basic features, which were observed during this El Niño event. In particular the deceleration of the equatorial undercurrent, the evolution of eastward surface currents and the zonal redistribution of heat associated with an eastward propagation of warm water are simulated by the model.
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  • 60
    Publication Date: 2016-10-07
    Description: The planktonic foraminifer Globigerinoides sacculifer (Brady) was maintained in the laboratory under different temperature (19.5-29.5°C) and salinity (33 and 36‰) regimes. The light and feeding conditions were adjusted to the open ocean environment. The light intensity and quality corresponded to a water depth of 10-30 m and the specimens were fed daily. Specimens were raised from a mean initial size of approximately 220-240 μm to the reproductive mean size ranging from 521 μm to 657 μm according to the different temperature and salinity regimes. The survival time decreased with increasing temperature relatively independent of salinity. The growth rate decreased with decreasing temperatures but significantly only at the lowermost temperature range. The general vitality increased with increasing salinity, partially indicated by more chamber formations of specimens of the 36‰ salinity group in comparison to those of the 33‰ salinity group. The different phenotypes of the final chamber and the different morphologies of G. sacculifer are discussed.
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  • 61
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    Elsevier
    In:  Comparative Biochemistry and Physiology Part C: Comparative Pharmacology, 87 (2). pp. 251-258.
    Publication Date: 2021-06-11
    Description: 1. Effects of noradrenaline and the related compounds adrenaline, dopamine, octopamine, tryamine, clonidine and isoprenaline were studied in isolated heart preparations from the cuttlefish Sepia officinalis L. 2. All analogues produced a positive inotropic affect, with noradrenaline being the most potent substance. The chronotropic effects of the tested compounds differed widely. 3. The action of substances of the phenylethanolamine group were not antagonized by propanolol but were partly antagonized by phentolamine. 4. Serotonin and its analogues also produced cardio-excitation. These effects were blocked by cyproheptadine but not by methysergide. 5. These results indicate the presence of two different receptors in the Sepia myocardium: one type reacting with noradrenaline most effectively and a second type being stimulated by serotonin.
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  • 62
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    Elsevier
    In:  Geochimica et Cosmochimica Acta, 51 (7). pp. 1861-1866.
    Publication Date: 2020-04-08
    Description: Samples of foraminiferal ooze from two North Atlantic cores were cleaned and progressively dissolved. Most of the P, Fe, and Mn was released during the first of two reductive cleaning steps. Most of the remainder of these elements and most of the Ca were released during the final acid dissolution step. The P in these samples is present largely in Fe- and Mn-rich coatings, not as a constituent of the foraminiferal shells themselves. Our results are consistent with those of earlier studies. The concentration of P in carbonate oozes in which it is clearly associated with coatings is similar to that of modern calcareous sediments in general, and with that of reasonably pure limestones of all ages. Phosphorus is apparently associated with (Fe, Mn)-oxide coatings in many carbonate sediments. The rate of removal of P from the oceans as a constituent of such sediments depends on the rate of formation of (Fe, Mn) coatings, not on the rate of incorporation of P into calcium carbonate.
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  • 63
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    Elsevier
    In:  Chemical Engineering Science, 42 (7). pp. 1645-1653.
    Publication Date: 2021-11-03
    Description: The kinetics of methane hydrate decomposition was studied using a semibatch stirred-tank reactor. The decomposition was accomplished by reducing the pressure on a hydrate slurry in water to a value below the three-phase equilibrium pressure at the reactor temperature. The data were obtained at temperatures from 274 to 283 K and pressures from 0.17 to 6.97 MPa. The stirring rates were high enough to eliminate mass-transfer effects. Analysis of the data indicated that the decomposition rate was proportional to the particle surface area and to the difference in the fugacity of methane at the equilibrium pressure and the decomposition pressure. The proportionality constant showed an Arrhenius temperature dependence. An estimate of the hydrate particle diameters in the experiments permitted the development of an intrinsic model for the kinetics of hydrate decomposition.
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  • 64
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    Institut für Polarökologie Kiel
    In:  Mitteilungen zur Kieler Polarforschung, 1 . pp. 18-20.
    Publication Date: 2017-08-08
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  • 65
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    Institut für Polarökologie Kiel
    In:  Mitteilungen zur Kieler Polarforschung (1). pp. 11-13.
    Publication Date: 2017-07-25
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  • 66
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    Institut für Polarökologie Kiel
    In:  Mitteilungen zur Kieler Polarforschung (1). pp. 14-17.
    Publication Date: 2017-07-25
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  • 67
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    Institut für Polarökologie Kiel
    In:  Mitteilungen zur Kieler Polarforschung (1). pp. 21-25.
    Publication Date: 2017-07-25
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  • 68
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    Institut für Polarökologie Kiel
    In:  Mitteilungen zur Kieler Polarforschung (1). pp. 4-10.
    Publication Date: 2017-07-25
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  • 69
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    Institut für Polarökologie Kiel
    In:  Mitteilungen zur Kieler Polarforschung (1). pp. 26-29.
    Publication Date: 2017-07-25
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  • 70
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    AMS (American Meteorological Society)
    In:  Journal of Physical Oceanography, 16 (5). pp. 827-837.
    Publication Date: 2016-04-19
    Description: Data from a surface mooring located in the Sargasso Sea at 34°N, 70°W between May 1982 and May 1984 were compared with satellite data to investigate large diurnal sea surface temperature changes. Mooring and satellite measurements are in excellent agreement for those days on which no clouds covered the site at the time of the satellite pass. During the summer half-year at this site, there is a 20% charm of diurnal warming of more than 0.5°C, with values of up to 3.5°C observed in the two-year period. Diurnal warming observed at the mooring has been simulated well by a one-dimensional model driven by local beat and momentum fluxes. Under the conditions of very light wind and strong insolation that produce the Largest surface warming, the surface mixed-layer depth reduces to the convection depth, and wind-mixing becomes unimportant. The thermal response is then limited to depths between 1 and 2 m, making it likely that such events have been underreported in routine ship observations. In all cases observed, the spatial extent of warming events as determined by satellite data are well correlated with the corresponding atmospheric pressure patterns. Conditions giving rise to the largest diurnal warming events are often associated with a westward-extending ridge of the Bermuda high. In the region studied, 57°–75°W and 29°–43°N, diurnal warming of more than 1°C was found on occasion to cover areas in excess of 300 000 km2, with warming of more than 2°C coveting areas in excess of 130 000 km2.
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  • 71
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    AMS (American Meteorological Society)
    In:  Journal of Atmospheric and Oceanic Technology, 3 (1). pp. 75-83.
    Publication Date: 2016-05-10
    Description: An XBT interface is described for use with Commodore and other 6502 based microprocessors. This interface takes the form of a single circuit board mounted inside the microcomputer and is completely software controlled. The application of this digital XBT system to the real-time computation of density and dynamic height, using historical or recent temperature-salinity relationships, is also described. Comparison between XBT and CTD measured temperatures from the Northeast Atlantic yield a mean temperature difference of −0.08°C and an rms temperature difference of 0.33°C for the upper 800 m. Examples of dynamic topography maps and a temperature section computed using this technique are also presented and comparison between objectively analyzed XBT and CTD dynamic topographies demonstrates the reliability of the method for mapping the baroclinic flow.
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  • 72
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    Elsevier
    In:  Aquatic Toxicology, 8 . pp. 129-137.
    Publication Date: 2015-06-24
    Description: The primary purpose of this study was to determine the toxicity of nitrite to several species of freshwater fishes and to investigate the underlying physiological mechanisms which account for differential toxicity among species. Green sunfish (Lepornis cyanellus) was the most resistant species studied while the channel catfish (Ictaluruspunctatus) was the least resistant. Ninety-six hour median lethal concentrations correlated significantly with both the percentage of hemoglobin in the methemoglobin form and plasma nitrite concentrations among species. Plasma nitrite levels also correlated significantly with percent methemoglobin. Environmental chloride did not increase the tolerance of largemouth bass (Micropterus salmoides) to nitrite toxicity as it did for channel catfish. These results indicate that plasma nitrite concentrations are the primary determinant of the toxicity of nitrite to fishes. Further, plasma nitrite concentrations in various species depend on the discriminatory ability of the active transport system in fish gills which ordinarily transports chloride ions.
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  • 73
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    Elsevier
    In:  Advances in Space Research, 6 (12). pp. 299-306.
    Publication Date: 2016-01-22
    Description: Halophilic representatives are found in all main lines of evolutionary descendence of microbes: in archaebacteria, Gram-negative and Gram-positive eubacteria, and also in eucaryotes. In principe all halophilic microorganisms have to adapt their surface and membrane structures to their highly ionic environments. Concerning their intracellular compartment two different strategies have been developed: Inorganic ions are largely excluded in some microorganisms while such ions are actively accumulated in others. In particular the second group of organisms has to adapt the whole metabolic machinery to the highly ionic conditions of several molar salts, whereas in the first group only the outer surface of the cytoplasmic membrane and the extracytoplasmic structures are in contact with high concentrations of inorganic ions. In this latter group, a variety of organic solutes is accumulated in response to increases of the salinity of the environment.
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  • 74
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    AMS (American Meteorological Society)
    In:  Journal of Atmospheric and Oceanic Technology, 3 (2). pp. 255-264.
    Publication Date: 2020-08-04
    Description: The inclination of oceanographic mooring lines due to current drag causes errors in time series observations of currents and temperatures. The prediction of this effect requires knowledge of the drag coefficients for the mooring components. Drag coefficients, known for simple geometric shapes such as spheres or cylinders, are commonly used for mooring response computations. Selected mooring components (buoyancy elements and instruments) were tested in a tow tank to determine their actual drag coefficients. Over the Reynolds Number range, typical of oceanic conditions, deviations of the drag coefficient up to 50% are found when compared with the appropriate simple geometric shape coefficients. A set of model moorings and model current profiles is used to determine the resulting changes in component depth level and displacement. The changes in horizontal displacement of the upper part of the mooring are on the order of 10% in extreme cases and 1% under typical conditions. Their effects on current measurements will usually be negligible. However, the related vertical displacements are on the order 100 to 10 m. Such vertical displacements may carry instruments to depth levels where currents and particularly thermocline temperatures are sufficiently different from the intended level to cause errors in the time series observations.
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  • 75
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    AMS (American Meteorological Society)
    In:  Journal of Physical Oceanography, 16 (5). pp. 814-826.
    Publication Date: 2018-04-04
    Description: Simulated transient-tracer distributions (tritium, 3H3, freons) on the isopycnal horizons σ0=26.5 and 26.8 kg m−3 are presented for the East Atlantic, 10° −40°N. Tracer transport is modeled by employing a baroclinic flow field based on empirical data in a kinematic isopycnal advection-diffusion numerical model, in which winter convection is taken as the mechanism of communication with the ocean surface layer, and the isopycnal diffusivity is a free parameter. Diapucnic transport is ignored. The simulations employ time-dependent tracer boundary conditions, which are constructed on the basis of available observations. Simulations are compared to data obtained on a meridional section in 1981 (F/S Meteor, cruise 56/5). Best simulations were obtained by means of a subjective optimization procedure. On both levels, the observed distributions and the best simulated distributions agree well. The fact that the surface boundary conditions and interior distributions of the tracers are distinctly different leads us to the conclusion that our model provides a consistent description of upper main-thermocline ventilation and interior transport Surface-water densities in February are found to represent adequately the winter outcrop boundaries with an uncertainty of about ±300 km across. The required isopycnal diffusivity south of 29°N is 1700 m2 s−1, and 2900 m2 s−1 further north (+70/−40%). Interior transport is found to be predominantly advective. Advective ventilation across 30.5°N east of 33°W amounts to only 12% and 40% for the 26.5 and 26.8 horizons of the total ventilation rates reported by Sarmiento. The North Atlantic/South Atlantic Central Water boundary near 15°N is found to be predominantly determined by advection.
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  • 76
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    Elsevier
    In:  Quaternary Research, 26 (1). pp. 121-134.
    Publication Date: 2016-06-16
    Description: Published oxygen isotope results from benthic and planktonic foraminifera are used to constrain the extent to which surface ocean temperatures in the tropics changed between glacial and interglacial time. The possible impacts of bioturbation and of the redistribution of 18O16O ratios within the sea, putting aside the oxygen isotope results, are consistent with the CLIMAP project conclusion that tropical ocean temperatures remained within ±2°C of their present value.
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  • 77
    Publication Date: 2016-09-02
    Description: Marine molluscan shells from para-type and other loclities of the Holsteinian interglaciation were dated by ThU and the electron spin resonance (ESR) method to more than 350,000 and 370,000 yr B.P., beyond the limit of ThU dating. The high age estimate is corroborated by a KAr age of 420,000 yr B.P. determined from volcanic ash near the base of the Ariendorf paleosol in the Middle Rhine valley believed to be a pedostratigraphic equivalent of the Holsteinian. Shells from the Herzeele marine unit III, an equivalent of the Wacken (Dömnitz) warm stage in northern France and subsequent to the Holsteinian, revealed ages between 300,000 and 350,000 yr B.P. A correlation of these two warm stages with marine oxygen-isotope stages 11 and 9 on the SPECMAP and CARTUNE time scales is suggested. From the benthic oxygen-isotope record one may infer that no exceptionally high global sea-level rise corresponds to the large transgressions of the Holstein Sea in northern Germany. Therefore, a significant proportion of the transgression was probably the result of an unusually large local glacial-isostatic depression caused by the extreme buildup of ice during the preceding Elster glaciation (stage 12). According to the deep-sea record, it lasted approximately 50% longer than the subsequent cold stage 10. The outstanding soil formation with Braunlehm and the well-developed thermal optimum of the Holsteinian are tentatively related to a phase of minimum sea-ice cover in the Norwegian-Greenland Sea, as deduced from long benthic carbon-isotope records from the central Atlantic.
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  • 78
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    Elsevier
    In:  Marine Geology, 71 (3-4). pp. 341-362.
    Publication Date: 2016-06-23
    Description: Dissolution of biogenic shallow-water carbonates exposed on deep-sea moorings indicates that skeletal structure is important for the rate of disintegration of biogenic carbonates, besides mineralogy and grain size of particles. The aragonites and high Mg-calcites used represent a wide spectrum of mineralogies and types of skeletal framework. The particles were deployed at different water depths on a mooring in the Drake Passage for 52 days. Weight loss curves for the various types of particles show the relative importance of the different structural factors for the disintegration of these biogenic carbonates. Organic coatings, intraskeletal pore spaces, and sizes and shapes of individual crystallites in the skeletons may be more important than carbonate mineralogy and particle size in cases. The presence of internal sediments, cement aggregates and natural contaminations and of diatoms incorporated during growth into carbonate skeletons, strongly influence the disintegration of the skeletal materials. The first step of particle disintegration is the selective removal of impurities. This step is analogous to a “cleaning” of specimens. It is succeeded by initial dissolution, by strong dissolution and finally by disintegration.
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  • 79
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    Elsevier
    In:  Dynamics of Atmospheres and Oceans, 10 (1). pp. 63-92.
    Publication Date: 2018-01-24
    Description: In a series of numerical experiments the wind-driven ocean circulation is studied in an idealized, rectangular model ocean, which is forced by steady zonal winds and damped by lateral and/or bottom friction. The problem as described by the barotropic vorticity equation is characterized by a Rossby number (R) and horizontal and/or vertical Ekman numbers (EL, EB) only. With free-slip conditions at the boundaries steady solutions for all chosen values of R are obtained, provided the diffusivity is sufficiently large. For both the forms of frictional parameterization a northern boundary current emerges with an eastward penetration scale depending on R. The recirculation pattern in the oceanically relevant ‘intermediate’ range of R is strongly affected by the type of friction. If lateral diffusion dominates bottom friction, a strong recirculating sub-gyre emerges in the northwestern corner of the basin. Its shape resembles the vertically integrated transport fields in recent eddy resolving model (EGCM) studies. The maximum transport is increased to values several times larger than the Sverdrup transport. The increase in transport is coupled with a development of closed contours of potential vorticity, enabling a nearly free inertial flow. This behaviour provides a sharp contrast to the bottom friction case (Veronis) where inertial recirculation only takes place with values of R so large that the eastward jet reaches the eastern boundary. It is shown that the linear friction law puts a strong constraint on the flow by preventing an intense recirculation in a small part of the basin. A reduction of the diffusivity (EL) in the lateral friction case leads to quasi-steady solutions. The interaction with eddies becomes an integral part of the time mean energetics but does not influence the recirculation character of the flow. The main conclusion of the study is that the horizontal structure of the EGCM-transport fields can be explained in terms of a steady barotropic model where lateral friction represents the dominant dissipation mechanism
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  • 80
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    Elsevier
    In:  Journal of Experimental Marine Biology and Ecology, 104 . pp. 23-30.
    Publication Date: 2021-01-19
    Description: The octopus Eledone cirrhosa (Lamarck 1798), enclosed in a small chamber of flowing sea water, was tested for responses to water-borne chemicals. Incidence of body movements and change in ventilation rate were recorded by a non-invasive technique- At concentrations no more than 1x10 -4M at the animal, the octopuses responded to betaine, proline, alanine, lactic acid, and serine (order of decreasing sensitivity)- Glutamic acid and trimethylamine oxide were considerably less stimulatory, arginine and taurine were hardly more effective than sea-water controls.
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  • 81
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    Elsevier
    In:  Organic Geochemistry, 10 (4-6). pp. 759-768.
    Publication Date: 2018-09-04
    Description: Microbial anaerobic oxidation of methane in sediments is a kinetic process associated with a carbon isotope effect which enriches the remaining methane in 13C. Three, models: % residual methane, higher hydrocarbon enrichment, and CO2-CH4 coexisting pairs are used to independently calculate fractionation factors (αc) in the range of 1.002–1.014, which overlap the range determined by culture studies, αc is smaller than that associated with methanogenesis by CO2 reduction or by acetate-type fermentation, and comparison of the coexisting CO2-CH4 pairs can distinguish between the formation and consumption processes. Methane oxidation in sediments continues to a threshold concentration of ca. 0.2 mM; the residual methane is either unavailable or unattractive to consumption. Minor amounts of methane may also be produced simultaneously in the methane consumption zone, influencing the apparent fractionation factor in this zone.
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  • 82
    Publication Date: 2017-07-10
    Description: A total of 131 current meter records of between 6 and 24 month duration are analysed to describe the deep flow field of the eastern North Atlantic from 19° to 54°N and from the Continental Slope to the Mid Atlantic Ridge. Mean flows are weak and may be statistically indeterminate in some records and locations, but appear to indicate cyclonic circulations around the Iberia and Porcupine abyssal plains with a generally southward flow along the Mid Atlantic ridge and a deep northward slope current (where measurements exist) along the eastern boundary. The deepest inflow to the north-eastern basin that has been identified to date takes place through the Discovery Gap of 〉4,700 m sill-depth at 37° 25′N 15° 45′W in the Azores-Portugal ridge. South of that ridge, observations are sparse and no systematic circulation is yet evident. These observations are discussed in relation to recent geostrophic estimates of the deep circulation.
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  • 83
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    Elsevier
    In:  Quaternary Science Reviews, 4 (4). pp. 215-278.
    Publication Date: 2020-06-04
    Description: Molluscan fossils collected from shallow water marine sediment across NW Europe and nearby Arctic regions have been analysed for the extent of isoleucine epimerization (DL ratio) in indigenous protein residues. The DL ratios confirm that essentially all ‘classical’ Eemian sites from NW Europe are of the same age, and are correlative with the type locality near Amersfoort in the Netherlands; shells from interglacial marine sediment beneath the type Weichselian till in Poland also correlate with the type Eemian site. DL ratios in Holsteinian marine shells (0.29) are substantially higher than in their Eemian counterparts (0.17); ‘Late Cromerian’ shells yield even higher ratios (0.46). DL ratios in late glacial shells (0.06) and Middle Weichselian shells (0.09) permit differentiation from modern (0.01) and last interglacial material. Based on the position of the Matuyama-Brunhes boundary and the differences in DL ratios, the Eemian must correlate with isotope substage 5e, whereas the Holsteinian is most likely substage 7c, possibly stage 9 but certainly younger than stage 11. Intra-Saalian warm periods may be terrestrial equivalents of the younger substages of stage 7. Extensive pre-Eemian marine sediments along the SW coast of Denmark previously correlated with the Holsteinian are shown to be of ‘Late Cromerian’ age. The underlying till there is the first widespread evidence of a pre-Elsterian till in NW Europe. DL ratios in molluscs from last interglacial sites along the Arctic coast of the USSR, the Arctic Islands and eastern Greenland are substantially lower than in their European counterparts due to their low thermal histories. The combined mid- and high-latitude data are used to develop a predictive model for the expected DL ratio in any of several moderate epimerization-rate taxa for last interglacial sites with mean temperatures between −20 and +15°C. Not all sites could be unambiguously assigned to an established interglacial. The Fjøsanger (Norway) and Margareteberg (Sweden) sites previously thought to be Eemian, yield DL ratios higher than in secure nearby Eemian material. It is yet unresolved whether these are aberrant sites or if they predate the last interglacial. In situ shoreline deposits encountered in borings in SW Belgium and in exposures on the Belgium coastal plain contain molluscs that yield DL ratios intermediate between secure Eemian and Late Weichselian ratios, raising the possibility that a late stage 5 high-sea-level event attained near-modern levels in the southern North Sea basin. Resolution of these uncertainties is the focus of future work.
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  • 84
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    Elsevier
    In:  Elsevier, Amsterdam, 294 pp. ISBN 0-444-42471-7
    Publication Date: 2019-08-28
    Type: Book , NonPeerReviewed
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  • 85
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    Elsevier
    In:  Journal of Volcanology and Geothermal Research, 25 . pp. 193-224.
    Publication Date: 2017-07-19
    Description: Small-volume (ca. 0.6 km3) pyroclastic flow deposits at Laacher See contain lithic breccias and two types of ground layers that differ significantly in their structure and composition from the main body of flow units. Lithic breccia bodies, up to 3.5 m thick, containing up to 85 weight% lithic blocks, occur locally at various distances from the vent. The deposition of these breccias was apparently governed by the strong influence of paleomorphology on the dynamics of the pyroclastic flows. The breccias were deposited at three main changes in bottom gradient along the path of the pyroclastic flows. The accumulation of large lithics is explained: (a) by compression of flows on the rising bottom close to the vent; (b) by thinning of flows accelerating over a steep incline; (c) by deceleration of the pre-concentrated lower part of flows in hydraulic jumps; and (d) possibly by a stationary vortex at the inner bend of a valley curvature. Poorly sorted lithic-rich ground layers, laterally highly variable in internal structure and composition, are restricted to marginal regions of the pyroclastic flow deposits within deep and narrow valleys. They are interpreted as having formed due to the extreme roughness of the valley walls, enforcing irregular turbulent flow and intense fluidization of the flow head, in which density-dominated segregation of lithics occurred. Wellsorted lapilli-rich ground layers of constant lateral thickness were probably generated by a more regularly moving, less intensely fluidized head of pyroclastic flows in which size-dominated segregation was effective but density-segregation was minor. A model of the temporal and longitudinal evolution of a flow head is proposed. Close to the vent, the head is exclusively erosive. With increasing distance, erosive power declines and erosion is paralleled by ground layer formation under strong fluidization. Further from the vent, the head ceases to erode while fluidization is still sufficient for ground layer formation. When fluidization declines to a level ineffective for segregation, ground layers terminate while the head advances and only terminates when plug-flow dominates.
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  • 86
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    AMS (American Meteorological Society)
    In:  Journal of Physical Oceanography, 15 (7). pp. 885-897.
    Publication Date: 2020-08-04
    Description: Long-term temperature and current-meter records from moorings in the northern Canary Basin display strong current events with time scales between one and three months and large vertical scales of several thousand meters. The data are compared to hydrographic surveys in the area that show a meandering subtropical front. The strong current events are found to be related to the passage of the front through the mooring positions. An analysis of composite time series, for selected depths, indicates cases of westward and of eastward propagation of frontal meanders. The frontal pattern is also found in geopotential anomalies inferred from historical XBT data sets, suggesting that the front is a persistent feature of the density field. In two cases strong current events appear to be related to a Mediterranean Water lens.
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  • 87
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    Elsevier
    In:  Tectonophysics, 115 (1-2). pp. 101-129.
    Publication Date: 2018-01-17
    Description: Plastically deformed quartzites from the Betic Movement Zone (Betic Cordilleras, Spain) exhibit microstructures indicative of crystal plasticity on a mineral grain scale. Quartzites with dynamically recrystallized grain sizes larger than 10 μm have strong crystallographic preferred orientations, narrow grain boundaries, little creep damage, and an inverse proportionality of dislocation density and grain size. Mylonites with grain sizes smaller than 10 μm have low crystallographic preferred orientations, wide grain boundaries (up to 1000 Å), abundant creep damage, and decreasing dislocation density with diminishing grain size. This is thought to reflect a clear-cut shift in deformational regimes from dislocation creep to superplastic flow at 10 μm grain size. Superplasticity can be acquired by quartzites which suffer dynamic recrystallization to grain sizes smaller than 10 μm during an initial dislocation creep stage. Dislocation motion is the major accomodating mechanism for strain incompatibilities that arise during grain-boundary sliding in the mylonites.It seems reasonable to estimate flow stresses from unbound dislocation densities and dynamically recrystallized grain sizes in the tectonite specimens. In the mylonites, dynamically recrystallized grain size probably reflects the stress magnitude before the shift in deformational mechanisms, and an estimate for late stage stresses is provided by unbound dislocation densities. In both deformational regimes the flow strength appears to depend on the extent of dynamic recrystallization.
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  • 88
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    Elsevier
    In:  Progress in Oceanography, 14 . pp. 231-257.
    Publication Date: 2016-05-10
    Description: Hydrographic data from two cruises in the Canary Basin (Meteor 57, July 1981; Poseidon 86, April 1982) are analysed with respect to current distribution and lateral heat flux in the Azores-Madeira region. The first part of the data base consists of long transects of XBT and G.E.K. measurements between Cape Finisterre (North West Spain) and the northern Canary Basin, where several year-long current meter records exist. Further information is obtained by thermosalinograph surface data and by expendable current profilers (XCP). Geostrophic currents are derived from XBT profiles, using the tight temperature-salinity relationship in the depth range of the Warmwassersphäre. The results compare well with the G.E.K. and XCP current observations. The second part consists of CTD data from an eddy resolving, box-shaped CTD survey (500 × 500 km2) centered at the mooring location (33°N, 22°W), The observations are supplemented by satellite-buoy trajectories. Horizontal parameter distribution is shown in terms of objectively contoured maps. Bands of spatially enhanced energetic structures, seen in the long transects are further resolved by the box survey as a deep jet-like current system cross the Canary Basin in a west-east direction. Associated with this Azores Current is a frontal zone with near-surface temperature and salinity steps of order 2 K and 0.3 practical salinity units. The dynamic topography field can be decomposed into a linear background field, a Rossby wave and a mesoscale eddy field. We find that major contributions to the meridional eddy heat flux are confined to the vicinity of the Azores current frontal zone. It is shown that the principal balance in the temperature equation is between heating by the mean horizontal advection terms and cooling by the eddy flux divergence.
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  • 89
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    Elsevier
    In:  In: Coupled Ocean-Atmosphere Models. , ed. by Nihoul, J. C. Elsevier Oceanography Series, 40 . Elsevier, Amsterdam, pp. 63-81.
    Publication Date: 2019-08-08
    Description: A primitive equation equatorial model has been developed to study climate variability due to wind and thermodynamic forcing in an equatorial region. The model basin extends from 30° S to 30° N and zonally over 140°, has a variable horizontal resolution (50–800 km) and 13 vertical levels. Experiments are performed with observed annual cycle as well as 32 years of observed bimonthly wind data. A preliminary analysis of these experiments shows that the model is capable of simulating the basic pattern of annual as well as interannual variability of the Pacific Ocean. In particular, the model response shows evidence of the major El Niños which occurred between 1947 and 1978.
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  • 90
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    Elsevier
    In:  In: Coupled ocean-atmosphere models. Elsevier Oceanography Series, 40 . Elsevier, Amsterdam, The Netherlands, pp. 543-590. ISBN 0-444-42486-5
    Publication Date: 2020-08-03
    Description: The potential vorticity profile in the seasonal pycnocline can be predicted from the surface buoyancy and momentum fluxes by means of the Lagrangian correlation of seasonally varying mixed-layer depth and density. Water flows geostrophically from the seasonal pycnocline into the permanent pycnocline, through the sloping surface of depth D defined by the annual maximum depth of the mixed layer. Potential vorticity flows into the permanent pycnocline where U(D)· ∇D ≤W(D) and vice versa. A theory is given for the regional variation of D, and methods of determining D from hydrographic data are reviewed. This physical understanding of potential vorticity sources and sinks makes it possible to reformulate ventilated thermocline models in terms of flux rather than density boundary conditions, and guides the design of coupled models of ocean—atmosphere circulation. It leads to formulae for water-mass formation and the nutrient balance in the seasonal boundary layer.
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  • 91
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    Elsevier
    In:  Marine Geology, 64 (1-2). pp. 157-177.
    Publication Date: 2019-04-16
    Description: Water samples and suspended matter taken in the Atlantis-II Deep area (Red Sea) during the expedition SO-2 (with RV “Sonne”) in November 1977 were investigated for chemical composition. Only slight changes have been found for most components since 1966. A strong decrease of the Cu content (from 100–500 μg kg−1 according to Brooks et al., 1969, to values below 1 μg kg−1) has, however, become evident. Comparison between theoretical concentrations in the intermediate brine layers (resulting when using the lower or the upper homothermal layers, respectively, as end members of mixing processes with Red Sea deep water) and the concentrations measured prove that precipitation and resolution processes have considerable influence on the concentrations found in solution. Components strongly involved in such processes are: iron, manganese, copper, oxygen, sulfate, and silica, as could be shown from comparison of theoretical and measured concentration profiles along the water column. Investigations of the metals suspended in the brine confirm these processes. Compared to 1971/1972, the Cu and Zn values in suspension (preferring the southwestern basin at that time) are clearly reduced — thus being in agreement with the recently lowered hydrothermal activity. Remarks on the hypothetical composition of the unknown hydrothermal brine discharging into the deepest basin are also included.
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  • 92
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    Elsevier
    In:  Earth and Planetary Science Letters, 73 (2-4). pp. 285-298.
    Publication Date: 2020-04-08
    Description: The concentrations of nine rare earth elements (REE) La, Ce, Nd, Sm, Eu, Gd, Dy, Er and Yb, have been determined in mixed species assemblages of foraminifera tests taken from Atlantic Ocean sediment core tops. Reductive cleaning techniques have revealed that REE are present in three phases in foraminifera tests collected from sea floor sediments; REE included in the foraminiferal calcite matrix (termed lattice REE), REE associated with an authigenic FeMn-rich phase adsorbed onto the surface of the test following the death of the organism (termed coating REE) and REE associated with alumino-silicate detritus (termed detrital REE) which commonly infills the test chambers after burial in the sediment. The concentrations of REE in the nondetrital (lattice plus coating) and lattice phases have been measured in this study. Approximately 90% of the REE measured in the non-detrital phase reside in the coating phase, the remainder being present in the lattice phase. These data have been used to investigate the relationship between the distribution of dissolved REE in the ocean and in the coating and lattice phases. In addition to the REE the concentrations of Mn, Fe, Cu, Al and PO4 have been measured as an aid to characterisation of the various phases.
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  • 93
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    Elsevier
    In:  Deep Sea Research and Oceanographic Abstracts, 11 (1). pp. 113-126.
    Publication Date: 2017-05-12
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  • 94
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    Elsevier
    In:  Deep Sea Research and Oceanographic Abstracts, 11 (6). pp. 881-890.
    Publication Date: 2016-09-22
    Description: Observations of temperature and electrical conductivity by a recording in situ salinometer are discussed in respect oo the physical processes connected with the renewal of North Atlantic deep water. The measured fine structure of the layering suggests that the downward movement of cooled surface water is combined with horizontal mixing down to more than 1000 m depth. This is confirmed by the existence of water elements which have slightly different temperature and salinity. Curves of temperature, conductivity, and salinity and T-S diagrams are shown.
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  • 95
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    Elsevier
    In:  Progress in Oceanography, 2 . pp. 1-52.
    Publication Date: 2016-10-07
    Description: Reviews the major deep-sea expeditions from that of HMS Challenger in 1873 to 1960. Emphasis is on the increasing sophistication of vessels and equipment used, the growth of international cooperation and the proliferation of branches of oceanographic studies. Arctic work by Nansen, Sverdrup, recent Soviet scientists, the Scripps Institution and the Norpac program are mentioned (maps). Vessels used during the period and their activities are tabulated. Two maps show cruises of the Atlantic Polar Front Program Jan-Dec 1958 in the Greenland and Barents Seas
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  • 96
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    Elsevier
    In:  Advances in Marine Biology, 2 . pp. 171-260.
    Publication Date: 2019-09-13
    Description: This chapter throws the attention on the methods of sampling the benthos, which has been directed mainly to the operation of the gear at sea and to such other factors as may influence sampling methods. This chapter briefly traces the history of benthos investigations, and then considers how far the instruments now available provide with the quantitative samples. It also shows how advances in other fields, such as radio-position finding, sonar and electronic equipment have increased the precision of our sampling methods. Moreover, sorting and sieving on board ship can be considered and brief mention made of methods of soil analysis and biomass determination. This chapter discusses the two possible approaches for the development of satisfactory quantitative collecting methods. First the improvement of the grab-type of instrument, with particular reference to increasing penetration and the perfection of release gear for the open sea, and second; the development of a wide-core sampler, like the Knudsen sampler, which works satisfactorily in the open sea. Moreover, statistics need to be even more fully applied, where collecting methods justify them, to such problems as the degree and scale of dispersion of individuals.
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  • 97
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    Elsevier
    In:  The Journal of Laboratory and Clinical Medicine , 64 (1). pp. 29-41.
    Publication Date: 2022-01-06
    Description: Fecal excretion of calcium of endogenous origin has been measured in 52 studies in 33 adult human subjects, under full metabolic balance conditions. Endogenous fecal calcium averaged .130 ± .047 Gm. per day, was positively correlated with both fecal calcium and dietary calcium and was inversely correlated with fractional calcium absorption. The regression line relating endogenous fecal calcium with fractional absorption allowed estimates for total intestinal calcium secretion at both zero and 100 per cent absorption; from these estimates it was calculated that approximately 15 per cent of the total intestinal calcium secretion was nonabsorbable even under conditions when dietary calcium was completely absorbed (presumably because it enters the gut caudad of the absorption sites). Total intestinal calcium secretion, calculated so as to allow for this nonabsorbable fraction, averaged .194 ± .073 Gm. per day, and could not be correlated with age, sex, dietary calcium intake, caloric intake, urine calcium, or plasma calcium. A weak correlation with body size (weight, surface area) was observed. The conditions studied were principally disorders of bone, calcium, and parathyroid metabolism, and in most of them total intestinal calcium secretion appeared identical. The sole exception was seen in two studies on a patient with acromegaly, in which total intestinal calcium secretion was over twice the mean value for the remainder of the group.
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  • 98
    Publication Date: 2023-01-16
    Description: The coagulation of hydrosols was investigated theoretically and experimentally. A reduced form of the particle size distribution function, designated “self-preserving,” was found to satisfy Smoluchowski's equations of coagulation by Brownian motion and shear flow. Brownian motion coagulation experiments with two heterogeneous hydrosols showed that the distributions were self-preserving. The rate of coagulation for heterogeneous systems was found to be second order in total particle concentration, consistent with the self-preserving form of the distribution function. Coagulation experiments were carried out in a simple laminar shear field using a homogeneous Dow polystyrene latex dispersion. Smoluchowski's shear flow theory was confirmed for shear rates ranging from 1 to 80 sec.−1 The shear coagulation of a heterogeneous emulsion was studied at several shear rates, and the size distributions were self-preserving.
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  • 99
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    Elsevier
    In:  Deep Sea Research and Oceanographic Abstracts, 10 (3). pp. 269-277.
    Publication Date: 2016-09-22
    Description: After some brief comments on the measurement of temperature and electrical conductivity in oceanography, the measuring probes suitable for in situ measurements are reviewed. Then the method of measurement is described using an improved model of the so-called bathysonde. This makes possible a continuous recording of temperature, conductivity, and pressure with high accuracy in great depths. Measurements from the Skagerrak and from the Mediterranean are considered. Finally, problems are discussed which arise when evaluating electrical conductivity and temperature from in situ measurements.
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