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  • 2020-2022  (4)
  • 2010-2014  (15)
  • 1985-1989  (12)
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  • 1
    Publikationsdatum: 2024-03-20
    Beschreibung: Ocean acidification, caused by rising concentrations of carbon dioxide (CO2), is widely considered to be a major global threat to marine ecosystems. To investigate the potential effects of ocean acidification on the early life stages of a commercially important fish species, European sea bass (Dicentrarchus labrax), 12 000 larvae were incubated from hatch through metamorphosis under a matrix of two temperatures (17 and 19 °C) and two seawater pCO2 levels (ambient and 1,000 µatm) and sampled regularly for 42 days. Calculated daily mortality was significantly affected by both temperature and pCO2, with both increased temperature and elevated pCO2 associated with lower daily mortality and a significant interaction between these two factors. There was no significant pCO2 effect noted on larval morphology during this period but larvae raised at 19 °C possessed significantly larger eyes and lower carbon:nitrogen ratios at the end of the study compared to those raised under 17 °C. Similarly, when the incubation was continued to post-metamorphic (juvenile) animals (day 67-69), fish raised under a combination of 19 °C and 1000 µatm pCO2 were significantly heavier. However, juvenile D. labrax raised under this combination of 19 °C and 1000 µatm pCO2 also exhibited lower aerobic scopes than those incubated at 19 °C and ambient pCO2. Most studies investigating the effects of near-future oceanic conditions on the early life stages of marine fish have used incubations of relatively short durations and suggested that these animals are resilient to ocean acidification. Whilst the increased survival and growth observed in this study supports this view, we conclude that more work is required to investigate whether the differences in juvenile physiology observed in this study manifest as negative impacts in adult fish.
    Schlagwort(e): Alkalinity, total; Alkalinity, total, standard deviation; Animalia; Aragonite saturation state; Bicarbonate ion; Calcite saturation state; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbon, total; Carbon/Nitrogen ratio; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Chordata; Coast and continental shelf; Code; Containers and aquaria (20-1000 L or 〈 1 m**2); DATE/TIME; Diameter; Dicentrarchus labrax; Dry mass; Duration, number of days; Figure; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Growth/Morphology; Height; Identification; Individuals; Laboratory experiment; Larvae; Larvae, dead; Length; Length, standard; Length, total; Metabolic rate, maximum; Metabolic rate, routine; Mortality; Mortality/Survival; Nekton; Nitrogen, total; Not applicable; OA-ICC; Ocean Acidification International Coordination Centre; Oxygen; Partial pressure of carbon dioxide, standard deviation; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; pH; pH, standard deviation; Potentiometric; Potentiometric titration; Reproduction; Salinity; Salinity, standard deviation; Sample ID; Single species; Species; Temperate; Temperature; Temperature, water; Temperature, water, standard deviation; Treatment; UKOA; United Kingdom Ocean Acidification research programme; Wet mass
    Materialart: Dataset
    Format: text/tab-separated-values, 26641 data points
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Publikationsdatum: 2010-06-21
    Beschreibung: The post-Caledonian development of the West Orkney Basin is regularly cited as a classic example of basement-influenced rifting. This paper presents the first detailed multidisciplinary analysis of the three-dimensional (3D) geometries and distribution of post-Caledonian faults in onshore northernmost Scotland, examining their relationships to basement fabrics and comparing them to rift-related structures developed offshore in the West Orkney Basin. Two phases of rift-related faulting are distinguished: 1) Devonian ENE-WSW extension localized in the east of the basin and related to regional sinistral transtension along the Great Glen Fault; and 2) Permo-Triassic NW-SE extension focused to the west of the basin and probably contemporaneous with movements along the Minch Fault. A complex North Coast Transfer Zone is developed along the northern Scottish coast linking Mesozoic rifts that reactivated Caledonian structures in the West Orkney Basin (Naver Thrust) to those bounding the North Minch Basin (Outer Hebrides Fault Zone). Polymodal faulting patterns are widespread in onshore exposures. Fault patterns vary due to changes in the obliquity between regional rifting vectors and variably orientated pre-existing structures in each basement terrane. The geometric complexity and spatial variations in fault patterns onshore can be correlated with changes in basement structures, despite limited direct reactivation of pre-existing fabrics.
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Publikationsdatum: 2011-02-22
    Print ISSN: 0027-8424
    Digitale ISSN: 1091-6490
    Thema: Biologie , Medizin , Allgemeine Naturwissenschaft
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Publikationsdatum: 2011-03-09
    Beschreibung: Carbonate mud is a major constituent of recent marine carbonate sediments and of ancient limestones, which contain unique records of changes in ocean chemistry and climate shifts in the geological past. However, the origin of carbonate mud is controversial and often problematic to resolve. Here we show that tropical marine fish produce and excrete various forms of precipitated (nonskeletal) calcium carbonate from their guts (“low” and “high” Mg-calcite and aragonite), but that very fine-grained (mostly
    Print ISSN: 0027-8424
    Digitale ISSN: 1091-6490
    Thema: Biologie , Medizin , Allgemeine Naturwissenschaft
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Publikationsdatum: 2013-10-08
    Beschreibung: We present z ' -band secondary eclipse photometry of the highly irradiated hot Jupiter WASP-12b using ULTRACAM on the 4.2 m William Herschel Telescope. We measure a decrease in flux of  = 0.130 ± 0.013 per cent during the passage of the planet behind the star, which is significantly deeper than the previous measurement at this wavelength (0.082 ± 0.015 per cent). Our secondary eclipse is best fitted with a mid-eclipse phase, , that is compatible with a circular orbit  = 0.501 ± 0.002, in agreement with previous results. In combination with existing data, our eclipse depth measurement allows us to constrain the characteristics of the planet's atmosphere, which is consistent with a carbon-rich model, with no evidence for a strong thermal inversion. If the difference in eclipse depth reported here compared to that of López-Morales et al. is of physical origin, as opposed to due to systematics, it may be caused by temporal variability in the flux, due to atmospheric dynamics.
    Print ISSN: 0035-8711
    Digitale ISSN: 1365-2966
    Thema: Physik
    Publiziert von Oxford University Press
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Publikationsdatum: 2013-04-26
    Beschreibung: We present time-resolved J -band spectroscopy of the short-period cataclysmic variable SDSS J143317.78+101123.3. We detect absorption lines from the sub-stellar donor star in this system, which contributes 38 ± 5 per cent to the J -band light. From the relative strengths of the absorption lines in the J band, we estimate the spectral type of the donor star to be L2 ± 1. These data are the first spectroscopic detection of a donor with a confirmed sub-stellar mass in a cataclysmic variable, and the spectral type is consistent with that expected from semi-empirical evolutionary models. Using skew mapping, we have been able to derive an estimate for the radial velocity of the donor of K d = 520 ± 60 km s –1 . This value is consistent with, though much less precise than, predictions from mass determinations found via photometric fitting of the eclipse light curves.
    Print ISSN: 0035-8711
    Digitale ISSN: 1365-2966
    Thema: Physik
    Publiziert von Oxford University Press
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Publikationsdatum: 2013-10-29
    Beschreibung: We present results from the first year of a campaign to characterize and monitor the optical turbulence profile at the South African Astronomical Observatory's Sutherland observing station in South Africa. A Multi Aperture Scintillation Sensor Differential Image Motion Monitor (MASS-DIMM) was commissioned in 2010 March to provide continuous monitoring of the seeing conditions. Over the first month of the campaign, a Slope Detection And Ranging (SLODAR) from Durham University was also installed, allowing an independent verification of the performance of the MASS-DIMM device. After the first year of data collection, the overall median seeing value is found to be 1.32 arcsec as measured at ground level. The ground layer which includes all layers below 1 km accounts for 84 per cent of the turbulence, while the free atmosphere above 1 km accounts for 16 per cent with a median value of 0.41 arcsec. The median isoplanatic angle value is 1.92 arcsec, which is similar to other major astronomical sites. The median coherence time, calculated from corrected MASS measurements, is 2.85 ms. The seeing conditions at the site do show a strong correlation with wind direction, with bad seeing conditions being associated with winds from the south-east.
    Print ISSN: 0035-8711
    Digitale ISSN: 1365-2966
    Thema: Physik
    Publiziert von Oxford University Press
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Publikationsdatum: 2013-12-27
    Beschreibung: The next generation of adaptive optics systems will require tomographic reconstruction techniques to map the optical refractive index fluctuations, generated by the atmospheric turbulence, along the line of sight to the astronomical target. These systems can be enhanced with data from an external atmospheric profiler. This is important for Extremely Large Telescope scale tomography. Here we propose a new instrument which utilizes the generalized Scintillation Detection And Ranging (SCIDAR) technique to allow high sensitivity vertical profiles of the atmospheric optical turbulence and wind velocity profile above astronomical observatories. The new approach, which we refer to as ‘stereo-SCIDAR’, uses a stereoscopic system with the scintillation pattern from each star of a double-star target incident on a separate detector. Separating the pupil images for each star has several advantages including increased magnitude difference tolerance for the target stars; negating the need for re-calibration due to the normalization errors usually associated with SCIDAR; an increase of at least a factor of 2 in the signal-to-noise ratio of the cross-covariance function and hence the profile for equal magnitude target stars and up to a factor of 16 improvement for targets of 3 mag difference and easier real-time reconstruction of the wind-velocity profile. Theoretical response functions are calculated for the instrument, and the performance is investigated using a Monte Carlo simulation. The technique is demonstrated using data recorded at the 2.5-m Nordic Optical Telescope and the 1.0-m Jacobus Kapteyn Telescope, both on La Palma.
    Print ISSN: 0035-8711
    Digitale ISSN: 1365-2966
    Thema: Physik
    Publiziert von Oxford University Press
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Publikationsdatum: 2020-01-01
    Beschreibung: Gaia16aye was a binary microlensing event discovered in the direction towards the northern Galactic disc and was one of the first microlensing events detected and alerted to by the Gaia space mission. Its light curve exhibited five distinct brightening episodes, reaching up to I = 12 mag, and it was covered in great detail with almost 25 000 data points gathered by a network of telescopes. We present the photometric and spectroscopic follow-up covering 500 days of the event evolution. We employed a full Keplerian binary orbit microlensing model combined with the motion of Earth and Gaia around the Sun to reproduce the complex light curve. The photometric data allowed us to solve the microlensing event entirely and to derive the complete and unique set of orbital parameters of the binary lensing system. We also report on the detection of the first-ever microlensing space-parallax between the Earth and Gaia located at L2. The properties of the binary system were derived from microlensing parameters, and we found that the system is composed of two main-sequence stars with masses 0.57 ± 0.05 M⊙ and 0.36 ± 0.03 M⊙ at 780 pc, with an orbital period of 2.88 years and an eccentricity of 0.30. We also predict the astrometric microlensing signal for this binary lens as it will be seen by Gaia as well as the radial velocity curve for the binary system. Events such as Gaia16aye indicate the potential for the microlensing method of probing the mass function of dark objects, including black holes, in directions other than that of the Galactic bulge. This case also emphasises the importance of long-term time-domain coordinated observations that can be made with a network of heterogeneous telescopes.
    Print ISSN: 0004-6361
    Digitale ISSN: 1432-0746
    Thema: Physik
    Publiziert von EDP Sciences
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Publikationsdatum: 2020-01-01
    Print ISSN: 0305-8719
    Digitale ISSN: 2041-4927
    Thema: Geologie und Paläontologie
    Standort Signatur Erwartet Verfügbarkeit
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