Search publications of the members of the Royal Belgian institute of natural Sciences
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The rise of sea-fish consumption in inland Flanders, Belgium
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Vers of bewerkt? Archeologisch onderzoek naar de bewaarvormen van vis
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Detrital paramagnetic (clays) minerals controlling the magnetic susceptibility signal and detection of detrital ferromagnetic minerals during Danian and Selandian time (Loubieng quarry, France).
- The abandoned Loubieng quarry located close to Pau (France) encompasses the Danian/Selandian boundary (DSb). The section could be subdivided into three parts:i) the basal part of the section consists mostly of Danian whitish carbonate beds withonly scarce and thin marly layers, ii) several limestone/marl alternations at theuppermost part of the Danian, and iii) the Selandian marls. The transitions between those divisions are linked to the Late Danian Event (LDE) and the DSb interval respectively. The three parts are clearly distinguishable in the low-field magnetic susceptibility curve established on 272 samples collected every 10 cm along the section up to 23 m (including the first three meters of the Selandian) and then every 25 cm in the marls. The low-field magnetic susceptibility (XLF) curve could be subdivided into eight major trends (orange arrows noted from 0 to 7) as highlighted in figure 1. The lithology has clearly an influence on the XLF values as the marls have always higher XLF values compared to the Danian limestones and the Selandian sandstones. Moreover, some specific carbonate beds have very low XLF values, sometimes even negative suggesting a diamagnetic behaviour. Some of these beds clearly corresponds to mass-gravity deposits (probably debris flows) as confirmed by microfacies (thin sections) analysis. To better constrain the XLF fluctuations, hysteresis data have been obtained with a Jcoercivity magnetometer on 55 samples selected along the section including all the different lithologies and the whole range of XLF values. A very strong correlation (r = 0.93) is highlighted between XLF and XHF values suggesting that the paramagnetic particles (i.e. the clay minerals) are clearly controlling the signal. Nevertheless, ferrimagnetic particles are also detected indicating a clear contribution of these minerals on the XLF curve. The magnetic viscosity (Sd), the remanence coercive force (Hcr) and the contribution (\%) to the high-field remanence parameters have generally good correlations between them. These parameters reveal two specific intervals where their values are higher: i) around the LDE in an interval displaying yellowish colours and ii) during the DSb interval characterized by reddish marls and limestones. The behaviour of the remanent magnetization was determined in eight samples during cooling and warming cycles on a MPMS3 – VSM (vibrating sample magnetometer). These analyses confirm the presence of goethite and hematite minerals present essentially during LDE and DSb time interval, respectively. We suggest that the paramagnetic (clay minerals, i.e. illite, kaolinite and smectite) and the ferromagnetic minerals are essentially primary minerals (detrital) deriving probably from extensive soils developed on the surrounding continental areas bordering the marine realm.
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The year of the monkey and of global understanding
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De verborgen pracht van nautilussen uit het Boven Jura van Madagascar
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Kleine heremietkreeft aan onze kust
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Re-identification of an exotic bee introduced to the Hunter Valley region, New South Wales – <i>Seladonia hotoni</i> (vachal, 1903) (hymenoptera: halictidae)
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A new Miocene baleen whale from the Peruvian desert
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A new whale barnacle from the early Pleistocene of Italy suggests an ancient right whale breeding ground in the Mediterranean
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Jumping from turtles to whales: a Pliocene fossil record depicts an ancient dispersal of Chelonibia on mysticetes
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A new species of Metopocetus (Cetacea, Mysticeti, Cetotheriidae) from the Late Miocene of the Netherlands
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Structure and growth pattern of the bizarre hemispheric prominence on the rostrum of the fossil beaked whale Globicetus hiberus (Mammalia, Cetacea, Ziphiidae)
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New beaked whales from the late Miocene of Peru and evidence for convergent evolution in stem and crown Ziphiidae (Cetacea, Odontoceti)
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Sawflies (Hymenoptera: Argidae, Pergidae, Tenthredidinidae) from southern Ecuador, with a new record for the country and some ecological data.
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Straks walvistoerisme voor onze kust?
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Zeezoogdieren in België in 2015 [Marine mammals in Belgium in 2015]
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Seasonal habitat-based density models for a marine top predator, the harbor porpoise, in a dynamic environment
- Effective species conservation and management requires information on species distribution patterns, which is challenging for highly mobile and cryptic species that may be subject to multiple anthropogenic stressors across international boundaries. Understanding species– habitat relationships can improve the assessment of trends and distribution by explicitly allowing high- resolution data on habitats to inform abundance estimation and the identification of protected areas. In this study, we aggregated an unprecedented set of survey data of a marine top predator, the harbor porpoise (Phocoena phocoena), collected in the UK (SCANS II, Dogger Bank), Belgium, the Netherlands, Germany, and Denmark, to develop seasonal habitat- based density models for the central and southern North Sea. Visual survey data were collected over 9 yr (2005–2013) by means of dedicated line- transect surveys, taking into account the proportion of missed sightings. Generalized additive models of porpoise density were fitted to 156,630 km of on- effort survey data with 14,356 sightings of porpoise groups. Selected predictors included static and dynamic variables, such as depth, distance to shore and to sandeel (Ammodytes spp.) grounds, sea surface temperature (SST), proxies for fronts, and day length. Day length and the spatial distribution of daily SST proved to be good proxies for “season,” allowing predictions in both space and time. The density models captured seasonal distribution shifts of porpoises across international boundaries. By combining the large- scale international SCANS II survey with the more frequent, small- scale national surveys, it has been possible to provide seasonal maps that will be used to assist the EU Habitats and Marine Strategy Framework Directives in effectively assessing the conservation status of harbor porpoises. Moreover, our results can facilitate the identification of regions where human activities and disturbances are likely to impact the population and are especially relevant for marine spatial planning, which requires accurate fine- scale maps of species distribution to assess risks of increasing human activities at sea.
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Bacterial and eukaryotic biodiversity patterns in terrestrial and aquatic habitats in the Sør Rondane Mountains, Dronning Maud Land, East Antarctica
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How useful are volunteers for visual biodiversity surveys? An evaluation of skill level and group size during a conservation expedition
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Newly discovered populations of the Ethiopian endemic and endangered Afrixalus clarkei Largen, implications for conservation
