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Inproceedings Reference A model of diffuse attenuation of downwelling irradiance for ecosystem models
Estimation of the underwater attenuation of light is important to ecosystem modellers, who require information on Photosynthetically Available Radiation (PAR), and on the euphotic depth for calculation of primary production. Characterisation of these processes can be achieved by determining the diffuse attenuation coefficient of PAR, KPAR. A review of bio-optical models of the spectral diffuse attenuation coefficient for downwelling irradiance, K-d, is presented and stresses the necessity for a better knowledge and parameterization of these coefficients. In the second part of this work, radiative transfer simulations were carried out to model K-dZ1\% the spectral diffuse attenuation of downwelling irradiance averaged over the euphotic depth Z(1\%) (depth where the downwelling irradiance is 1\% of its surface value). This model takes into account the effects of varying sun zenith angle and cloud cover and needs absorption and backscattering coefficients (the inherent optical properties, IOPs) as input. It provides average and maximum relative errors of 1\% and 5\% respectively, for sun zenith angles [0 degrees-50 degrees] and of 1.7\% and 12\% respectively at higher sun zenith angles. A relationship was established between K-dZ1\% at a single wavelength (590nm) and KPAR at Z(PAR1\%) (where PAR is 1\% of its value at the surface) which allows for a direct expression of KPAR(ZPAR1\%) in terms of inherent optical properties, sun angle and cloudiness. This model provides estimates of KPAR within 25\% (respectively 40\%) relative errors respectively with a mean relative error less than 7\% (respectively 9\%) for sun zenith angles ranging from 0 degrees to 50 degrees (respectively higher than 50 degrees). A similar method is applied to derive a model for the diffuse attenuation of photosynthetically usable radiation, KPURZPUR1\%, with similar performance.
Located in Library / RBINS Staff Publications
Conference Reference A modelling approach to trace the origin of jellyfish swarms in the Southern North Sea.
The life cycle, the phenology and the interannual variability of jellyfish (i.e. cnidaria medusozoa scyphozoa) are under study across the world as there is debate on their increasing occurrence under human pressure (overfishing, eutrophication, climate change) (Condon et al. 2012). Beside interference in human activities, jellyfish swarms affect the marine food web as these organisms feed on fish eggs and larvae, and compete for food with adult fish (Lynam et al. 2005, Pauly et al. 2009). Whether jellyfish nuisance can be mitigated remains unclear and depends on our understanding of the causes of outbreaks. Most North Sea jellyfish species have a sessile polyp stage as part of their life cycle, and therefore need solid substrate to fix. While A. aurita polyps are visible along the Belgian and Dutch coasts, the location of other species polyps (e.g. Cyanea, Chrysaora) remains largely unknown. Tracing back the origin of an observed jellyfish swarm in the North Sea could help identifying the potential location of polyps and the timing and temperature of strobilation. A Lagrangian particle tracking model parameterized for jellyfish in the English Channel and the southern North Sea is used in backtracking (15 days) and forecast (3 days; forced by UKMO forecast) modes to study the potential origin and fate of jellyfish swarms. A backtracking simulation was applied on a jellyfish swarm observed in 2013 in the Belgian coastal zone . It allowed identifying potential areas of origin for the outbreak, raising new scientific questions. A first sensitivity study illustrates the wind influence on the backtracking simulation.
Located in Library / RBINS Staff Publications
Proceedings Reference A modelling tool to assess dispersal abilities of Antarctica species
Located in Library / RBINS Staff Publications 2017
Proceedings Reference A molecular eye on Nipponarion (Stylommatophora: Arionidae)
Located in Library / RBINS Staff Publications
Proceedings Reference A new approach to locating Slender-billed Curlew breeding grounds.
Located in Library / RBINS Staff Publications
Inproceedings Reference A new archaeonycterid bat from the early Eocene of southern Europe
Recent research on early bats has shown that diversification began early in the Early Eocene. The diversity was the highest in Europe and India and composed of the families Onychonycteridae, Icaronycteridae, Archaeonycteridae, Palaeochiropterygidae, and Hassianycteridae. However, in Europe, the oldest species have all been described from Northern Europe with the exception of Archaeonycteris? praecursor from Silveirinha (MP7, Portugal). Here we present a new bat from La Borie (MP8+9, South France). It is the first early Eocene species from Southern Europe identified on a relatively complete dentition: about 40 isolated teeth and dentary fragments. The teeth are nyctalodont and characterized by: moderate sized canines; middle sized p4 with well-developed metaconid; wide m1-2 with very lingual hypoconulid and high entoconid; middle sized P4; M1-2 with deep ectoflexus, weak paraconule, weak to absent metaconule, centrocrista not joining the labial border; m3/M3 smaller than m1-2/M1-2. These characters indicate that this species belongs to the Archaeonycteridae and is close to Archaeonycteris. It differs from Archaeonycteris trigonodon from Messel (MP11, Germany), A. brailloni from Mutigny and Avenay (MP8+9, France), and Protonycteris gunnelli from Vastan (India) by being about 25 % smaller. It is similar in size to Archaeonycteris? praecursor, A? storchi from Vastan, and the new archaeonycterid from Meudon (MP7, France). It differs from A? storchi by smaller p4 and shallower dentary, and from the Meudon species by more lingual hypoconulid, higher entoconid, and longer postcristid. In fact, it is very similar to A? praecursor by the m2 with relatively high entoconid and long postcristid; the main difference being the hypoconulid that is a little more lingual. The latter character suggests a more advanced dilambdodonty than A? praecursor, which is in agreement with the ages of the two localities. Both species seem to belong to the same evolutionary lineage geographically restricted to Southern Europe.
Located in Library / RBINS Staff Publications 2016
Proceedings Reference A new archaic shark-toothed dolphin from the late Oligocene-early Miocene of Peru
Located in Library / RBINS Staff Publications
Article Reference A new basal neoceratopsian dinosaur from the ‘middle’ Cretaceous of Jilin Province, China
Located in Library / RBINS Staff Publications
Inproceedings Reference A new basal raoellid artiodactyl (Mammalia) from the middle Eocene Subathu Group of Rajouri District, Jammu and Kashmir, northwest Himalaya, India
A new artiodactyl of moderate size is described on the basis of several dentaries and maxillae from the middle Eocene Subathu Group of the Kalakot area, Rajouri District, Jammu and Kashmir, India. Despite its general resemblance with the family Dichobunidae this taxon shares with Raoellidae two unambiguous characters: the presence of a hypoconulid on p4, and an asymmetrical P4. The position of the new taxon within the Cetacea / Raoellidae clade is strongly supported by eight non ambiguous synapomorphies, among which a cristid obliqua on lower molars anteriorly pointing towards the postectoprotocristid, and a P3 with only two roots. The new taxon is characterised by the following characters: a long symphysis; p3 and p4 with small parastylid and metastylid but no metaconid; lower molars with metaconid as the highest cusp, voluminous hypoconid, and absence of ‘hypolophid’; m1 and m2 with small paraconid, basally fused with metaconid, and small bifid tubercle-like hypoconulid; m3 with a crestiform paraconid; P3 and P4 with small protocone and shelf-like cingulae; upper molars with small paraconule and large metaconule (pseudohypocone); M1 and M2 with conical brachydont cusps; M3 with bunodont bulbous cusps; cristae and cingulae distinct and thick, presence of an ectoloph. The presence of a new primitive raoellid in the middle Eocene Subathu Group sheds new light on the phylogeny and paleobiogeography of basal raoellid artiodactyls. This work is partly funded by project BR/121/A3/PALEURAFRICA from the Belgian Science Policy Office.
Located in Library / RBINS Staff Publications 2019
Inproceedings Reference A new Chinese partial skeleton revives questions about the multituberculate mammal Kryptobaatar
Multituberculates are an extinct rodent-like order that lived between Late Jurassic and late Eocene, on almost every continent. Due to their extraordinary longevity, their evolutive history is important to understand. One of the most numerous and best-preserved groups is the superfamily Djadochtatherioidea from the Late Cretaceous of the Gobi Desert. All djadochtatherioid genera are monospecific, except Kryptobaatar. The large number of K. dashzevegi fossils come from Outer Mongolia, while the only two specimens found in Bayan Mandahu, Inner Mongolia, China belong to K. mandahuensis. However, a new particularly well-preserved specimen (IMM 99BM-IV/5) found in Bayan Mandahu during the 1990s Sino-Belgian expeditions seems at first sight very close to K. dashzevegi. IMM 99BM-IV/5 consists of a skull associated with cervical and thoracic vertebrae, ribs, shoulder girdle, broken right humerus and an almost complete left forelimb. It is the first specimen for which the hand is described in detail. Based on micro-CT scan and comparison, it appears that IMM 99BM-IV/5 presents morphological characters of both species of Kryptobaatar, as well as new characters of its own. Phylogenetic analysis suggests that IMM 99BM-IV/5 has an intermediate position between K. dashzevegi and K. mandahuensis and could therefore belong to a new species. However, Kryptobaatar is paraphyletic in the resulting tree, which raises again questions about intraspecific variability in multituberculates. Since only 13 specimens of Kryptobaatar out of the hundreds found have been studied, it is impossible to reliably know if IMM 99BM-IV/5 is included in the variability of K. dashzevegi or not. However, it is crucial to know this variability to define whether the genus is monospecific or not. By comparing K. mandahuensis with published specimens, we concluded that it is a valid species. This work also highlighted the lack of knowledge of the variability of the type species K. dashzevegi, without which it is impossible to clearly assign IMM 99BM-IV/5. Finally, endemism alone is not the cause of this variability, but the role of paleoenvironment or age is currently unknown.
Located in Library / RBINS Staff Publications 2021