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Sclerochronological evidence of pronounced seasonality from the Pliocene of the southern North Sea Basin, and its implication
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RBINS Staff Publications 2021
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Sclerochronological evidence of pronounced seasonality from the late Pliocene of the southern North Sea Basin, and its wider implications
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RBINS Staff Publications 2022
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Sclerochronological evidence of pronounced seasonality from the late Pliocene of the southern North Sea Basin, and its implications
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RBINS Staff Publications 2021
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Sea Cucumbers of the Comoros Archipelago
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Sea cucumbers have been harvested for centuries in the Far East. Overexploitation, coupled with increasing demand has led to local depletion of certain standing stocks. De novo investigation at Grande Comore (one of the four main islands of the Comoros Archipelago) allows reappraisal of local holothuroid biodi- versity. Comparison with neighbouring areas allows extrapolation of holothuroid species richness to the rest of the archipelago. The current exploitation of holothuroids has been documented and there are definite signs of overexploitation. Conservation measures are urgently needed if exploitation of sea cucumbers in this area is to become sustainable in the near future.
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RBINS Staff Publications
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Seasonality only works in certain parts of the year: The reconstruction of fishing seasons through otolith analysis
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Seasonality estimations using incremental data usually suffer from small sample sizes and from the lack of comparison with sufficiently large modern samples. The present contribution reports on incremental studies carried out on large assemblages of plaice (Pleuronectes platessa) and haddock (Melanogrammus aeglefinus) from a late medieval fishing village (Raversijde, Belgium) on the North Sea coast. In an attempt to refine previous seasonality estimates made for this site, and to expand conclusions concerning general methodology, extensive monthly samples of modern otoliths of these species, caught within the North Sea, have also been investigated. The modern material shows that the timing of the seasonal changes in the edge type (hyaline or opaque) of the otoliths is extremely variable and that it is dependent on the fishing ground, the year considered, and the age of the fish. It also appears that the increase of the marginal increment thickness is highly variable, to such an extent that the thickness of the last increment of a single otolith is mostly useless for seasonality estimation. Where large archaeological otolith assemblages can be studied, preferably from single depositional events, seasonality determination becomes possible on the condition, however, that the archaeological assemblage corresponds to fish that were captured during their period of fast growth. The growth ring study on the otoliths from Raversijde shows that plaice fishing took place in spring and that it was preceded by a haddock fishing season, probably in late winter/early spring.
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RBINS Staff Publications
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Secondary sex estimation using morphological traits from the cranium and mandible: application to two Merovingian populations from Belgium
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It is generally accepted that the coxal bone is the most reliable bone for estimating the sex of adult subjects. When the coxal bone is not usable, researchers generally turn to methods based on the skull (cranium and mandible). However, these methods are less reliable, because they are largely based on an estimate of the robusticity, which can be influenced by characteristics independent of the sex of the subject. In the context of primary sex estimation, skull-based methods should therefore be avoided. However, by using morphological traits of the cranium and the mandible as part of a secondary sex estimation, we were able to estimate the sex of a relatively large number of individuals with a minimum reliability of 95%. Our study thus illustrates the value of using morphological characteristics of the skull for a secondary sex estimation conducted with a reliable statistical method.
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RBINS Staff Publications 2024
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Secrets of de Selys Longchamps archives: one watercolour and two records of nineteenth century observations of the grasshopper species Psophus stridulus (Linnaeus, 1758) and Locusta migratoria (Linnaeus, 1758) in Belgium (Orthoptera: Acrididae)
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Next to voucher specimens in entomological collections, also historical archives and historical illustrations can contain valuable taxonomical as well as ecological and faunistic data. We report here faunistic data for two currently extinct Belgian grasshopper species from the year 1862, deduced from a letter accompanied by a watercolour. The letter and watercolour are stored in the archives of Edmond de Selys Longchamps at the Royal Belgian Institute for Natural Sciences (RBINS). Both the watercolour and the letter are discussed, focusing on the observations of Psophus stridulus (Linnaeus, 1758) and Locusta migratoria (Linnaeus, 1758) (Orthoptera) at Lanaken in 1862. Two voucher specimens of these observations and their original labels, that are stored in the RBINS collections, were studied. We can conclude that Egide Fologne was the first to observe P. stridulus in Belgium. He reported this in a letter to Edmond de Selys Longchamps and supplied the watercolour depicting the specimen he collected and donated to Selys for his collection.
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RBINS Staff Publications 2017
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Self-domestication or human control? The Upper Palaeolithic domestication of the wolf
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RBINS Staff Publications 2018
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Sensitivity analysis of the dark spectrum fitting atmospheric correction for metre- and decametre-scale satellite imagery using autonomous hyperspectral radiometry
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The performance of the dark spectrum fitting (DSF) atmospheric correction algorithm is evaluated using matchups between metre- and decametre-scale satellite imagery as processed with ACOLITE and measurements from autonomous PANTHYR hyperspectral radiometer systems deployed in the Adriatic and North Sea. Imagery from the operational land imager (OLI) on Landsat 8, the multispectral instrument (MSI) on Sentinel-2 A and B, and the PlanetScope CubeSat constellation was processed for both sites using a fixed atmospheric path reflectance in a small region of interest around the system&\#x2019;s deployment location, using a number of processing settings, including a new sky reflectance correction. The mean absolute relative differences (MARD) between in situ and satellite measured reflectances reach <20&\#x0025; in the Blue and 11&\#x0025; in the Green bands around 490 and 560 nm for the best performing configuration for MSI and OLI. Higher relative errors are found for the shortest Blue bands around 440 nm (30&\#x2013;100&\#x0025; MARD), and in the Red-Edge and near-infrared bands (35&\#x2013;100&\#x0025; MARD), largely influenced by the lower absolute data range in the observations. Root mean squared differences (RMSD) increase from 0.005 in the NIR to about 0.015&\#x2013;0.020 in the Blue band, consistent with increasing atmospheric path reflectance. Validation of the Red-Edge and NIR bands on Sentinel-2 is presented, as well as for the first time, the Panchromatic band (17&\#x2013;26&\#x0025; MARD) on Landsat 8, and the derived Orange contra-band (8&\#x2013;33&\#x0025; MARD for waters in the algorithm domain, and around 40&\#x2013;80&\#x0025; MARD overall). For Sentinel-2, excluding the SWIR bands from the DSF gave better performances, likely due to calibration issues of MSI at longer wavelengths. Excluding the SWIR on Landsat 8 gave good performance as well, indicating robustness of the DSF to the available band set. The DSF performance was found to be rather insensitive to (1) the wavelength spacing in the lookup tables used for the atmospheric correction, (2) the use of default or ancillary information on gas concentration and atmospheric pressure, and (3) the size of the ROI over which the path reflectance is estimated. The performance of the PlanetScope constellation is found to be similar to previously published results, with the standard DSF giving the best results in the visible bands in terms of MARD (24&\#x2013;40&\#x0025; overall, and 18&\#x2013;29&\#x0025; for the turbid site). The new sky reflectance correction gave mixed results, although it reduced the mean biases for certain configurations and improved results for the processing excluding the SWIR bands, giving lower RMSD and MARD especially at longer wavelengths (>600 nm). The results presented in this article should serve as guidelines for general use of ACOLITE and the DSF.
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RBINS Staff Publications 2020
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Serial population extinctions in a small mammal indicate Late Pleistocene ecosystem instability
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The Late Pleistocene global extinction of many terrestrial mammal species has been a subject of intensive scientific study for over a century, yet the relative contributions of environmental changes and the global expansion of humans remain unresolved. A defining component of these extinctions is a bias toward large species, with the majority of small-mammal taxa apparently surviving into the present. Here, we investigate the population-level history of a key tundra-specialist small mammal, the collared lemming (Dicrostonyx torquatus), to explore whether events during the Late Pleistocene had a discernible effect beyond the large mammal fauna. Using ancient DNA techniques to sample across three sites in North-West Europe, we observe a dramatic reduction in genetic diversity in this species over the last 50,000 y. We further identify a series of extinction-recolonization events, indicating a previously unrecognized instability in Late Pleistocene small-mammal populations, which we link with climatic fluctuations. Our results reveal climate-associated, repeated regional extinctions in a keystone prey species across the Late Pleistocene, a pattern likely to have had an impact on the wider steppe-tundra community, and one that is concordant with environmental change as a major force in structuring Late Pleistocene biodiversity.
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RBINS Staff Publications