Search publications of the members of the Royal Belgian institute of natural Sciences
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Contrasting saltmarsh vegetation impacts under increasing sea level rise rates
- The resilience of saltmarshes mainly depends on their ability to gain elevation by sediment accretion to keep pace with sea level rise. While vegetation is known to facilitate sediment accretion at the plant scale by trapping mineral sediments and producing organic matter, the long-term impact at the landscape scale is still poorly understood. Here we use the biogeomorphic model Demeter to reveal contrasting vegetation impacts on spatial patterns of sediment accretion under different sea level rise regimes. Under contemporary sea level rise rates (2-10 mm/yr), vegetation inhibits sediment transport from tidal channels to platform interiors and creates levee-depression patterns. Hence, intertidal platforms accrete slower with vegetation than without, but this trend attenuates with increasing sea level rise rate, as water depth increases, and vegetation drag decreases. Under extreme sea level rise rate (20 mm/yr), platform interiors don’t keep up and turn into open water, while vegetation allows to preserve intertidal levees. Our results help to better understand some basic biophysical mechanisms that will control the fate of coastal wetlands under global climate change.
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Observations of tidal attenuation and amplification in a mangrove forest: channels as conduits
- Mangroves are increasingly recognized as an effective nature-based coastal defence strategy. Mangrove trees are proven to reduce the height of propagating long-period waves such as storm tides and extreme sea levels. Existing empirical studies, however, are limited to small scales (~10²-10³ m) or only cover continuous belts of mangroves. Here we present water level measurements along a 20 km channel and in the surrounding mangrove forests for regular neap- and spring tides in a natural mangrove forest in the Guayas Delta, Ecuador. For tides with peak water levels which are high enough to flood the surrounding mangroves, inundation levels reached 45 cm with attenuation rates up to 40 cm/km. Along the entire 20 km channel, however, no attenuation occurred. Instead, we measured amplification with rates varying between 4.3 and 4.6 cm/km. Amplification rates increased with peak water level until water levels were high enough to flood the surrounding mangroves, upon which amplification rates decreased with peak water level. The latter implies that with higher peak levels, such as during an extreme sea level event, the capacity of mangroves to dampen amplification or even attenuate increases.
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Revision of the Eurybrachidae (XV). The Oriental genus Purusha Distant, 1906 with two new species and a key to the genera of Eurybrachini (Hemiptera: Fulgoromorpha: Eurybrachidae)
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Grasping ecological opportunities: not one but five paedophagous species of Haplochromis (Teleostei: Cichlidae) in the Lake Edward system
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Paropeas achatinaceum (Pfeiffer, 1846) and other alien Subuline and Opeatine land snails in European greenhouses (Gastropoda, Achatinidae)
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Extension of the phasmid genus Presbistus to Cambodia with a new species and notes on genitalia and captive breeding (Phasmida, Aschiphasmatidae, Aschiphasmatinae)
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Brain evolution of early placental mammals: the impact of the end-Cretaceous mass extinction on the the neurosensory system of our distant relatives
- The end-Cretaceous mass extinction, 66 million years ago, profoundly reshaped the biodiversity of our planet. After likely originating in the Cretaceous, placental mammals (species giving live birth to well-developed young) survived the extinction and quickly diversified in the ensuing Paleocene. Compared to Mesozoic species, extant placentals have advanced neurosensory abilities, enabled by a proportionally large brain with an expanded neocortex. This brain construction was acquired by the Eocene, but its origins, and how its evolution relates to extinction survivorship and recovery, are unclear, because little is known about the neurosensory systems of Paleocene species. We used high-resolution computed tomography (CT) scanning to build digital brain models in 29 extinct placentals (including 23 from the Paleocene). We added these to data from the literature to construct a database of 98 taxa, from the Jurassic to the Eocene, which we assessed in a phylogenetic context. We find that the Phylogenetic Encephalization Quotient (PEQ), a measure of relative brain size, increased in the Cretaceous along branches leading to Placentalia, but then decreased in Paleocene clades (taeniodonts, phenacodontids, pantodonts, periptychids, and arctocyonids). Later, during the Eocene, the PEQ increased independently in all crown groups (e.g., euarchontoglirans and laurasiatherians). The Paleocene decline in PEQ was driven by body mass increasing much more rapidly after the extinction than brain volume. The neocortex remained small, relative to the rest of the brain, in Paleocene taxa and expanded independently in Eocene crown groups. The relative size of the olfactory bulbs, however, remained relatively stable over time, except for a major decrease in Euarchontoglires and some Eocene artiodactyls, while the petrosal lobules (associated with eye movement coordination) decreased in size in Laurasiatheria but increased in Euarchontoglires. Our results indicate that an enlarged, modern-style brain was not instrumental to the survival of placental mammal ancestors at the end-Cretaceous, nor to their radiation in the Paleocene. Instead, opening of new ecological niches post-extinction promoted the diversification of larger body sizes, while brain and neocortex sizes lagged behind. The independent increase in PEQ in Eocene crown groups is related to the expansion of the neocortex, possibly a response to ecological specialization as environments changed, long after the extinction. Funding Sources Marie Sklodowska-Curie Actions, European Research Council Starting Grant, National Science Foundation, Belgian Science Policy Office, DMNS No Walls Community Initiative.
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Phylogenetic position of Olbitherium (Mammalia, Perissodactyla) based on new material from the early Eocene Wutu Formation
- The genus Olbitherium was originally described in 2004 from the early Eocene of the Wutu Formation in China as a ‘perissodactyl-like’ archaic ungulate. Described material of Olbitherium consists of partial dentaries with lower cheek teeth, isolated upper molars, and an isolated upper premolar. Subsequent collaborative fieldwork by Belgian and Chinese researchers discovered new material including a partial skull, the anterior portion of the dentary, and associated postcrania. In their general form, the skull and postcrania are similar to those of early perissodactyls. The new material provides a more complete picture of the upper dentition, and the anterior dentary demonstrates the presence of three lower incisors and a large canine, both ancestral features for perissodactyls. A phylogenetic analysis was conducted to test the affinities of Olbitherium, using a matrix of 321 characters and 72 taxa of placental mammals emphasizing perissodactyls and other ungulates. The results produced four shortest trees of 1981 steps. In all four trees, Olbitherium is the sister-taxon to all perissodactyls except Ghazijhippus. In contrast, when scoring was restricted to the originally described material, the results produced 16 shortest trees of 1970 steps, and Olbitherium nests well within Perissodactyla as sister-taxon to a clade including Lambdotherium and the brontotheriids Eotitanops and Palaeosyops. The new material not only supports the identification of Olbitherium as a perissodactyl, but it also suggests that it is significant for understanding the ancestral perissodactyl morphotype. Funding Sources U.S. National Science Foundation (DEB1456826), Chinese Ministry of Science and Technology (2009DFA32210), and Belgian Science Policy Office (BL/36/C54).
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A new genus and species of Cicada from Vietnam: Cochloeopsaltria duffelsi gen. et. sp. nov. (Hemiptera: Cicadomorpha: Cicadidae)
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Is the vertical distribution of meiofauna similar in two contrasting microhabitats? A case study of a macrotidal sandy beach
- Tides are an important forcing factor of macrotidal sandy beaches because they are directly responsible for the local morphodynamic conditions. Macrotidal beaches may harbor different microhabitats such as sandbars and runnels. We evaluated the influence of tides on the vertical distribution of meiofaunal organisms, particularly nematodes, in these two microhabitats at De Panne Beach, on the North Sea coast of Belgium. The 11 meiofaunal groups found were Acari, Amphipoda, Copepoda, Gastrotricha, Nematoda, Oligochaeta, Ostracoda, Polychaeta, Rotifera, Tardigrada and Turbellaria. The nematodes were identified to species level; the 147 species found included 112 in the sandbar and 117 in the runnel. Only turbellarians and nematodes migrated upward during low tide in the sandbar. The response of the nematodes was species-specific; during low tide, they migrated upward in the sandbar and downward toward deeper layers of the sediment in the runnel. These migration patterns were attributed to the feeding strategies in the sandbar (i.e. possible increase of diatom biomass in the surface layer due to high solar incidence), while environmental variables best explained the migration patterns in the runnel (i.e. preferred grain size and amount of total organic carbon). These results suggest a dissimilar vertical migration of the meiofauna over the tidal cycle in the two microhabitats. We attribute the vertical distribution of nematode species and some other meiofaunal groups to active migration toward preferred sites with more food or better environmental conditions. This study also indicated that other variables such as predation and competition, rather than the commonly studied physical variables should be included in future sampling designs of sandy-beach meiofauna assessments, since the environmental variables measured here could not fully explain the vertical distributions of the major meiofaunal groups or the community as a whole.
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Preface. in: Degraer, S. et al. (Eds.) (2017). Environmental impacts of offshore wind farms in the Belgian part of the North Sea: A continued move towards integration and quantification.
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Executive summary. in: Degraer, S. et al. (Eds.) (2017). Environmental impacts of offshore wind farms in the Belgian part of the North Sea: A continued move towards integration and quantification.
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Effects of pile driving on harbour porpoises in the Belgian part of the North Sea
- The harbour porpoise (Phocoena phocoena) is the most common marine mammal in the Belgian part of the North Sea and is protected by both national and EU law. In the North Sea, the harbour porpoise is considered under threat because of high bycatch levels and increasing noise pollution. Impulsive pile driving noise originating from the construction of offshore wind farms has been shown to affect porpoises up to distances of more than 20 km from the noise source. Driven by high porpoise densities in Belgian waters, a pile driving ban is in force from the start of January up to the end of April. However, The Netherlands do not enforce such an embargo for the Borssele offshore wind farm, which is only one kilometer away from Belgian waters. Considering the high mobility of harbour porpoises, there is a need for improved insights into the impact of pile driving noise on porpoises which can serve as a basis for an objective evaluation of the respective legal regimes. From May to September 2016 pile driving was taking place at the Nobelwind wind farm located on the Bligh Bank in Belgium. In this period, porpoise activity was recorded using passive acoustic monitoring (C-PODs), at various distances from the construction site (1 to 45 km). In this study we compare porpoise detections before, during and after pile driving with the focus on the influence of repeated pile driving events. In addition to porpoise monitoring data, noise measurements and noise levels are extrapolated for the different locations. The data for this study were obtained from the RBINS wind farm monitoring programme and the VLIZ Lifewatch observatory.
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The influence of pile driving noise on harbour porpoises
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Effects of Offshore Wind Farms on the Early Life Stages of Dicentrarchus labrax
- Anthropogenically generated underwater noise in the marine environment is ubiquitous, comprising both intense impulse and continuous noise. The installation of offshore wind farms across the North Sea has triggered a range of ecological questions regarding the impact of anthropogenically produced underwater noise on marine wildlife. Our interest is on the impact on the "passive drifters," i.e., the early life stages of fish that form the basis of fish populations and are an important prey for pelagic predators. This study deals with the impact of pile driving and operational noise generated at offshore wind farms on Dicentrarchus labrax (sea bass) larvae.
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Identifying Elusive Prehistoric Land Use by Integrating Electromagnetic and Invasive Survey Approaches
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2500 years of charcoal production in the Low Countries: the chronology and typology of charcoal kilns and their relation with early iron production.
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Early and High Medieval (c. 650 AD - 1250 AD) charcoal production and its impact on woodland composition in the Northwest-European lowland: a study of charcoal pit kilns from Sterrebeek (Central Belgium).
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Review of two Tonnoir moth fly species, overlooked for a century (Diptera: Psychodidae: Psychodinae)
- A lectotype (male) and paralectotypes (male, female) of Pneumia vittata (Tonnoir, 1919) comb. nov. (= Pericoma crispi Freeman, 1953 syn. nov.) from Belgium are designated. The species is redescribed and illustrated, and a diff erential diagnosis is given. The former designation of a holotype, paratypes and paratypoids by Jung is invalid because it was not published. In addition, a problem with Tonnoiriella obtusa (Tonnoir, 1919) comb. nov. (= Tonnoiriella anchoriformis Salamanna, 1975 syn. nov.) from Belgium is resolved. A female specimen is designated as a lectotype, but only the dissected wings from this specimen are in condition suitable for redescription. There is additional non-type material collected later by Tonnoir; this material, including 3 females and 1 male, was the basis for redescription, illustrations and diff erential diagnosis. The unpublished male lectotype designated by Jung is invalid. Two species are added to the last checklist of Psychodidae from Belgium, raising the total number to 94.
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Distribution and habitat preferences of Galápagos ants (Hymenoptera: Formicidae)
- We present the first comprehensive review of the ant taxa of the Galápagos archipelago. The review is based on data gathered during literature searches, field surveys, and the revision of museum specimens, and includes information on the distribution, habitat, and ecology of 47 species. At least nine of these species are assumed to be native or endemic to the islands and at least 32 species have been introduced through human-associated pathways. The status of the remaining six species is unknown. The information compiled in this study will allow us to better understand the ecological role of indigenous species and their potential as indicators of ecosystem health. Baseline information on the distribution of introduced ants will be indispensable for assessing impact and spread within the archipelago.
