Search publications of the members of the Royal Belgian institute of natural Sciences
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Monitoring organic microcontaminants in the marine environment: Principles, programmes and progress
- Monitoring trace organic microcontaminants in the marine environment has been on-going for several decades. However, the compounds considered in most programmes are still mainly the 'old' organochlorines, the polynuclear aromatic hydrocarbons, several metals and metal-containing compounds. However, the marine environment is threatened by a much larger suite of organic microcontaminants. In recent years, European and other international organisations have been moving towards extending their lists of priority hazardous substances. Simultaneously, there have become available novel analytical techniques that offer new possibilities for monitoring in the marine environment. © 2005 Elsevier Ltd. All rights reserved.
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Polychlorinated biphenyls in marine sediments from the southern North Sea and Scheldt estuary: A ten-year study of concentrations, patterns and trends
- The paper reports the concentrations and patterns of CBs in sediments of the Belgian part of the southern North Sea and the Scheldt estuary for the period 1991-2001. The long-term analytical performance was well within the quality assurance boundaries set at the outset of the study and is consistent with the state of the art for this type of analysis. The CB concentrations (given as the median of the sum of IUPAC Nos 28, 52, 101, 118, 138, 153 and 180) vary between 0.1 μg kg-1 and 50 μg kg-1 dry weight in the total sediment and it could be demonstrated that CB patterns in the fine fraction of the sediment were closely similar throughout the investigated area. Isolation of the fine fraction (<63 μm) by sieving can be regarded as a physical normalisation to reduce the differences in sediment granulometric composition. It allows for a better understanding of CB distribution and patterns and improves the trend analysis. A significant downward trend could not be found at any of the stations, which suggests that CB levels have not been changing in the area of interest in the past decade. © The Royal Society of Chemistry 2005.
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Use of the near infrared similarity reflectance spectrum for the quality control of remote sensing data
- The shape of water-leaving reflectance spectra in the near infrared range 700-900nm is almost invariant for turbid waters and has been analysed and tabulated as a similarity spectrum by normalisation at 780nm. This similarity spectrum is used here for the quality control of seaborne reflectance measurements and for the improvement of sky glint correction. Estimates of the reflectance measurement error associated with imperfect sky glint correction from two different wavelength pairs are shown to be nearly identical. A demonstration of residual reflectance correction for data collected in cloudy, high wave conditions has shown that this correction removes a large source of variability associated with temporal variation of the wave field. The error estimate applied here to seaborne measurements has wide-ranging generality and is appropriate for any water-leaving reflectance spectra derived from seaborne, airborne or satellite borne sensors provided suitable near infrared bands are available.
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Rotifers from Kalasin Province, Northeast Thailand, with notes on new and rare species
- We report on a survey of rotifers from 30 habitats in Kalasin Province, Northeast Thailand, collected during Dec. 2001. One hundred and fifty species were identified. One of them, Lecane lungae sp. nov. is new to science, and two, L. opias (Harring and Myers), and L. stichoclysta Segers are new to the Oriental region and Thailand; the record of L. stichoclysta is the second record ever of the species after its description from Nigeria (Africa). In addition, we illustrate a remarkable morphological variant of Keratella cochlearis. These records, together with the new occurrences of other endemic rotifer species illustrate the remarkable diversity of the Thai rotifer fauna, and add to our knowledge of rotifer chorology.
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The use of mathematical models for estimating oil pollution damage at sea description of the system developed in the frame of the mare-dasm project
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The future of freshwater biodiversity research: An introduction to the target review
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Tale of a sleeping beauty: A new and easily cultured model organism for experimental studies on bdelloid rotifers
- We present the description of a new species of bdelloid rotifer, Adineta ricciae n. sp., which emerged from dry mud of Ryan's billabong, Victoria, Australia. Its conspicuous frontal eyes easily diagnose the species; it differs from A. oculata (Milne) by the position of the eyes and its general habitus. The animal came to our attention because it is exceptionally easy to culture, so that the species already is being used in diverse experimental studies utilising bdelloid rotifers as model organisms. © Springer 2005.
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Two new species of the genus Chersodromia Walker (Diptera: Hybotidae) from Southeast Asia
- Two new species of the genus Chersodromia Walker are described from mangroves of Singapore: C. nigripennis sp.n. and C. singaporensis sp.n. Palpal sensory pits are recorded for the first time in the genus and Tachydromiinae as a whole. They are present in both species. Some aspects of the male terminalia in Chersodromia are shortly discussed. Copyright © 2005 Magnolia Press.
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On a new Seison Grube, 1861 from coastal waters of Kenya, with a reappraisal of the classification of the Seisonida (Rotifera)
- On occasion of the discovery of a new species of a marine epizoic rotifer of the enigmatic Seisonidae, from Gazi Bay in Kenya, we reassessed the classification of the group. The taxon was until now known to contain only 2 species, viz. Seison nebaliae and S. annulatus, both of which live attached to Crustacea of the genus Nebalia. The new species, Seison africanus sp. nov., was diagnosed by its species-specific trophi morphology and relatively small size. A comparison with the 2 other known seisonid species reveals a sister group relationship between S. africanus sp. nov. and S. nebaliae, based on similarities in trophi structure and, accordingly, an assumed feeding mode and relationship with their hosts. The fundamental differences between these 2 commensal sister taxa and the ectoparasitic S. annulatus prompted a reevaluation of the generic classification of these animals. Accordingly, we propose to reestablish the genus Paraseison Plate, 1887 in order to accommodate P. annulatus (Claus, 1876) (comb. nov.).
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Multiple origins of tetraploid taxa in the Eurasian Bufo viridis subgroup
- We used Q-banding and analyzed nucleolar organizing regions (NORs) to study the cytogenetic evolution of tetraploids within the Palearctic Bufo viridis subgroup, the only known amphibian complex comprising di-, tri- and tetraploid bisexually reproducing taxa. We examined three diploid (2n) nominal taxa (Bufo viridis viridis, B. v. turanensis, B. v. kermanensis) from five Eurasian localities and six tetraploid (4n) nominal taxa (B. oblongus, B. o. danatensis, B. pewzowi pewzowi, B. p. taxkorensis, B. p. unicolor, B. p. strauchi) from eight Central Asian localities. Homeologous chromosomes of 2n and 4n toads exhibit a similar morphology. Silver-staining and in situ hybridization revealed terminal NORs in the long arms of chromosomes 6 in all 2n but in only two out of four chromosomes 6 in all 4n taxa. Q-banding and a rapidly evolving mitochondrial marker suggest at least two origination events for Asian 4n toads: "Western Central Asian tetraploids" (B. oblongus Nikolsky, 1896) exhibit distinct differences within some chromosome quartets, which are divisible into pairs of chromosomes and may be allopolyploid. In contrast, "Central Asian tetraploids" (B. pewzowi Bedriaga, 1898) showed homogenous Q-banding patterns within each quartet, suggesting autopolyploidy. In Northeastern Iran, we discovered a zone of either common ancestry or hybridization of 2n and Western Central Asian 4n toads. This raises intriguing questions about how diploid and tetraploid taxa may evolve by exchanging genetic material. © Springer 2005.
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Total suspended matter maps from chris imagery of a small inland water body in oostende (Belgium)
- It has been already established that total suspended matter (TSM) can be retrieved from CHRIS imagery for turbid coastal waters, but what about inland waters? Because of the high resolution of CHRIS/PROBA images, inland waters not visible by sensors like SeaWiFS, MERIS and MODIS become detectable and are expected to become a key new application domain for optical remote sensing. In the Oostende test site there is a small (800m* 1400m) inland water body with an average depth of 1.5m called the Spuikom. On 6 July 2004, a cloud free CHRIS acquisition of the Oostende test site occurred with simultaneous in situ measurements. The reprocessed dataset is evaluated and analyzed. Data from CHRIS show abnormally high near infrared (NIR) reflectance in the lake, especially near the borders. This does not significantly affect TSM maps but does contaminate the chlorophyll maps deduced from CHRIS imagery. This high NIR reflectance is probably caused by adjacency effects, although the possibility of bottom reflection must also be assessed. In the summer of 2005 a measurement campaign is planned to investigate further the influence of nearby land and bottom reflection in order to provide a benchmark dataset for testing of algorithms to detect and correct for such effects. CHRIS images will be an important component of this dataset.
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Molecular systematics of the endemic Leptaxini (Gastropoda: Pulmonata) on the Azores islands
- The Azorean representatives of the Leptaxini (Pulmonata) are single island endemics, where a high-spired shell distinguishes the monotypic genus Helixena from two slightly different low-spired forms within Leptaxis (azorica and caldeirarum type). We studied the evolutionary history of putative taxa and the three shell-types using 12 allozyme loci and sequences of nuclear (ITS-1 and ITS-2) and mitochondrial DNA (COI and 16S rRNA). While little variation was found in both ITS genes, allozyme and mtDNA divergence was among the highest reported for pulmonate land snails. Generally, phylogeographic patterns are indicative of allopatric differentiation via the successive colonization of (younger) islands, while a major role for adaptive evolution is not supported. The azorica shell-type is monophyletic and has no common history with other sympatric shell-types on the same islands. The (ambiguous) position of Helixena sanctaemariae makes Leptaxis paraphyletic on the Azores and possibly also the caldeirarum shell-type. Helixena can therefore not be distinguished as a separate genus on the Azores. Following a lineage-based concept, representatives on all (ancient) islands should be considered distinct species. © 2005 Elsevier Inc. All rights reserved.
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A micro- and macrobotanical study of two Middle Weichselian, fluviatile deposits in the loam area of middle Belgium
- A palynological study of Middle Weichselian fluviatile deposits, lying at the base of a bipartite loam cover at Soignies and Courcelles, revealed an open landscape with some scattered trees or shrubs of Pinus, Betula and Salix except for the lowermost channel at Soignies, where a boreal forest composed of Alnus, Pinus, Betula and Salix could be reconstructed. The diaspores appear to have been derived from plant communities representing a diversity of habitats, i.e., fully aquatic communities (Charetea, Potametea), swamps and mires (Phragmitetea, Parvocaricetea, Molinio-Arrhenatheretea) and pioneers of bare ground (Bidentetea). The abundance of leaves from Salix herbacea, retrieved from both sites, confirms the arctic climatic conditions. © Royal Botanical Society of Belgium.
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The Middle Holocene shell mound of El Gouna on the Red Sea (Egypt)
- In the El Gouna (Hurghada) area on the Red Sea of Egypt, a Middle Holocene shell mound from around 5800 B.P. (uncalibrated radiocarbon years before A.D. 1950) has been tested by a restricted excavation. Collection of shellfish on the Red Sea shore provided subsistence opportunities for Middle Holocene groups coeval with the Early Predynastic Tasian of the Nile Valley. The El Gouna site demonstrates for the first time that prehistoric shell mounds exist near the Egyptian Red Sea shore.
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Identification of a member of the “Palaeochelys s.l. – Mauremys group” (Testudines) in the early Oligocene of Boutersem (Belgium)
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Molecular phylogenetics of Haustrinae and Pagodulinae (Neogastropoda: Muricidae) with a focus on New Zealand species
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Van heinde en verre: gebruik en herkomst van polychrome marmers in Romeins Tongeren - een eerste stand van zaken.
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Graan en stenen in het hart van de civitas Tungrorum . Resultaten van recent maalsteenonderzoek
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Stratigraphic context and dating of the Middle and Late Eocene vertebrate localities of the Fayum.
- The Fayum Oasis and surrounding areas in Egypt include a number of exceptionally rich and important fossil vertebrate sites. These include the Wadi Al-Hitan World Heritage Site, made famous by the abundance of archaeocete whale remains, and the site BQ-2 with its diverse terrestrial mammals, including primates. Despite the importance of this area, the stratigrapby is poorly understood and there has be little agreement in the dating of the fossiliferous units. This is in large part due to the extreme diachroneity of some of the rock units and paucity of biostratigraphically useful fossils within the shallow water facies. Platform carbonates are overlain by condensed open marine mudstones of the Gebannam Formation. These span the Bartonian-Priabonian boundary, with a diverse offhore marine fauna being present throughout, including marine mammals. Four units of shoreface sandstone of the Birkel Qarun Formation overlie and partly pass into the Gehannam Formation. The lowest of these sandstone units is dated to nannofossil zone NP19/20, and hence 'mid' Priabonian, and contains the oldest archaeocetes described from the region. Diverse fossils, including abundant whales, are present throughout the Birket Qarun Formation, but these are especially concentrated at the top of the lowest sandstone (lowstand systems tract) and in the transgressive lower part of the third sandstone and its lateral equivalent within the Gehannam Formation (transgressive systems tract). The overlying Qasr el Sagha Formation is a very rapidly deposited deltaic/lagoonal complex. Tidal channels from two to over 40 metres deep are present throughout. The lower part of this formation is still in nannofossil zone NP19/20. INterchannel deposits contain a fully marine, but probably shallow water, assemblage. Larger channels also include deeper water elements near the base, with transported terrestrial and quasimarine elements being present within the uppermost part of a small channel fill at quarry BQ-2. The transition to the non-marine units above is sharp but conformable and coincides with the base of the Oligocene. The clastic succession indicates the initiation of Nile-type drainage and coincides with the uplift of East Africa, preventing drainage to the east. It is likely that clastic successions in the Qattara Depression and Libya can be related to the same sedimentological episodes. This is largely based on, and dedicated to, the work of Chris King, who passed away earlier this year.
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Le site d'habitat romain à enclos fossoyé de Silly "Tramasure" (Silly, province de Hainaut)
