Search publications of the members of the Royal Belgian institute of natural Sciences
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A 365-Million-Year-Old Freshwater Community Reveals Morphological and Ecological Stasis in Branchiopod Crustaceans
- Branchiopod crustaceans are represented by fairy, tadpole, and clam shrimps (Anostraca, Notostraca, Laevicaudata, Spinicaudata), which typically inhabit temporary freshwater bodies, and water fleas (Cladoceromorpha), which live in all kinds of freshwater and occasionally marine environments. The earliest branchiopods occur in the Cambrian, where they are represented by complete body fossils from Sweden such as Rehbachiella kinnekullensis and isolated mandibles preserved as small carbonaceous fossils from Canada. The earliest known continental branchiopods are associated with hot spring environments represented by the Early Devonian Rhynie Chert of Scotland (410 million years ago) and include possible stem-group or crown-group Anostraca, Notostraca, and clam shrimps or Cladoceromorpha, which differ morphologically from their modern counterparts. Here we report the discovery of an ephemeral pool branchiopod community from the 365-million-year-old Strud locality of Belgium. It is characterized by new anostracans and spinicaudatans, closely resembling extant species, and the earliest notostracan, Strudops goldenbergi. These branchiopods released resting eggs into the sediment in a manner similar to their modern representatives. We infer that this reproductive strategy was critical to overcoming environmental constraints such as seasonal desiccation imposed by living on land. The pioneer colonization of ephemeral freshwater pools by branchiopods in the Devonian was followed by remarkable ecological and morphological stasis that persists to the present day.
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Nouvelle contribution à l'étude du genre Autocrates Thomson, 1860 avec la description d'une nouvelle espèce du Vietnam: A. ivanovi n.sp. (Coleoptera: Trictenotomidae).
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Description de Patellapis (Chaetalictus- mpalaensis sp.nov. et redescription de P. (C.) virungae Timmerman, 2009 de l'Afrique orientale et centrale (Hymenoptera: Apoidea: Halictidae)
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Updating laternflies biodiversity knowledge in Cambodia (Hemiptera: Fulgoromorpha: Fulgoridae) by optimizing field work surveys with citizen science involvement through Facebook networking and data access in FLOW website
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Building a transnationally harmonised marine geological database
- Within the framework of marine resource management, a common knowledge base is being developed on the distribution, composition and dynamics of various geological resources. Focus is on data from the Belgian part of the North Sea, being representative of a typical sandbank sedimentary system. To ensure harmonised seabed mapping over large, supraregional areas and to facilitate the exchange of information, special attention was paid to compatibility with marine geodatabases from the adjacent Netherlands territory. With reference to the seabed and its subsurface, two main databases are being compiled: one comprising all available lithological descriptions and one with all numerical grain-size information. To enable standardisation of the data and make them easily query-able, non-numerical descriptions are being coded to an international standard (EU FP7 Geo-Seas; www.geoseas.eu), of which the Udden-Wentworth scale is the main classifier. Several other parameters were derived, such as percentages mud, sand, gravel, shells and organic material. For the sediment database, cumulative grain-size-distribution curves were compiled, enabling calculations of any desired granulometry parameter, such as percentages of the grain-size fractions (fine, medium, coarse sand) and percentiles that are relevant in seabed-habitat mapping or sediment-transport modelling (D35, D50, D84). For both databases, the completeness and accuracy of the metadata were considered highly important. Information about sampling and coring techniques, analytical methods, horizontal and vertical positioning accuracy, and the exact timing of data acquisition is pivotal in uncertainty analyses, which are an increasingly important element of seabed mapping. The time of seabed mapping is critical to convert measured water depths to a common datum such as TAW in Belgium, facilitating integration of sample data in bathymetry data and thus their incorporation in 4D-modelling studies on morphodynamic change. For Belgium, the geological databases will be imbedded in the data infrastructure of the Belgian Marine Data Centre (www.bmdc.be), ensuring compatibility with international standards and providing easy access to a wide user community. Following processing to generate data products such as resource-related subsurface models, visualisation is foreseen through Subsurface Viewer (GmbH INSIGHT). Applied maps and models thus disseminated are crucial in decision making, and invaluable for outreach and educational purposes. The newly developed database and its associated data products will contribute to the objectives of the projects TILES (Belspo Brain-be), EMODnet-Geology (EU DG MARE), and ZAGRI (private revenues from the marine-aggregate industry).
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Transcription, signaling receptor activity, oxidative phosphorylation and fatty acid metabolism mediate the presence of closely-related cryptic species in distinct intertidal and cold-seep habitats
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Dynamics of very-large dunes in sandbank areas subjected to marine aggregate extraction, Belgian continental shelf
- Dynamics of very-large dunes were investigated over sandbanks subdued to marine aggregate extraction in the Belgian continental shelf. In the Flemish Banks, six areas were regularly monitored with a multibeam echosounder (MBES) providing high resolution bathymetric data. An optimization procedure was set up to estimate the dune migration distance and direction between successive campaigns. These dune migration data were compared to simulated hydrodynamic forces and indicated that dune migration was mostly driven by tidal currents, with the direction and magnitude of migration being dependent on the relative position of the dunes on the sandbanks. Closer investigation in a heavily extracted area suggested a local reorganization of sediments in the area: an accretional trend in the extraction pit is observed at the expense of the surrounding very-large dunes which presented an erosive and flattening pattern.
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Taxonomic challenges in freshwater fishes: a mismatch between morphology and DNA barcoding in fish of the north-eastern part of the Congo basin
- This study evaluates the utility of DNA barcoding to traditional morphology-based species identifications for the fish fauna of the north-eastern Congo basin. We compared DNA sequences (COI) of 821 samples from 206 morphologically identified species. Best match, best close match and all species barcoding analyses resulted in a rather low identification success of 87.5%, 84.5% and 64.1%, respectively. The ratio ‘nearest-neighbour distance/maximum intraspecific divergence’ was lower than 1 for 26.1% of the samples, indicating possible taxonomic problems. In ten genera, belonging to six families, the number of species inferred from mtDNA data exceeded the number of species identified using morphological features; and in four cases indications of possible synonymy were detected. Finally, the DNA barcodes confirmed previously known identification problems within certain genera of the Clariidae, Cyprinidae and Mormyridae. Our results underscore the large number of taxonomic problems lingering in the taxonomy of the fish fauna of the Congo basin and illustrate why DNA barcodes will contribute to future efforts to compile a reliable taxonomic inventory of the Congo basin fish fauna. Therefore, the obtained barcodes were deposited in the reference barcode library of the Barcode of Life Initiative.
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A new early Pliocene species of Mesoplodon: a calibration mark for the radiation of this species-rich beaked whale genus
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Comparative phylogeographies of six species of hinged terrapins (Pelusios spp.) reveal discordant patterns and unexpected differentiation in the P. castaneus/P. chapini complex and P. rhodesianus
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The new Oriental lanternfly genus £Bhaskaraena gen.nov. with two new species (Hemiptera: Fulgoromorpha: Fulgoridae)
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Fossil marine vertebrates of Cerro Los Quesos: Distribution of cetaceans, seals, crocodiles, seabirds, sharks, and bony fish in a late Miocene locality of the Pisco Basin, Peru
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Towards a revision of the Neotropical soldierless termites (Isoptera: Termitidae): redescription of the genus <i>Grigiotermes</i> Mathews and description of five new genera
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Is TNT leaking to the North Sea?
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Detection of shipwrecks in ocean colour satellite imagery
- Waterborne swath acoustic and airborne laser systems are the main methods used to detect and investigate fully submerged shipwreck sites. In the nearshore, waterborne techniques are compromised as search tools as their effective swath is a function of water depth, necessitating very close survey line spacing in shallow water, increasing cost accordingly. Additionally, in turbid coastal waters bathymetric LiDAR is ineffective as it relies on clear non-turbid water. Therefore, the nearshore turbid zone represents a challenging area for archaeologists in the search for fully submerged archaeological sites. In this study, we describe a new methodology to detect the presence of submerged shipwrecks using ocean colour satellite imagery in turbid waters. We demonstrate that wrecks generate Suspended Particulate Matter (SPM) concentration signals that can be detected by high-resolution ocean colour satellite data such as Landsat-8. Surface SPM plumes extend downstream for up to 4 km from wrecks, with measured concentrations ranging between 15 and 95 mg/l. The overall ratio between the plume and background SPM concentrations is about 1.4. During slack tidal phases sediments in suspension settle to create fluffy mud deposits near the seabed. Scour pits developed around wrecks act as sinks where fine-grained suspended material is preferentially deposited at slacks. The scour pits subsequently act as sources for suspended material when the bottom current increases after slacks. SPM plumes develop immediately before maximum ebb or flood current is reached, during maximum current and immediately after. Particulate matter is suspended in sufficient concentrations to be detected in ocean colour data. The ability to detect submerged shipwrecks from satellite remote sensors is of benefit to archaeological scientists and resource managers interesting in locating wrecks and investigating processes driving their evolution.
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Habitat association and coexistence of endemic and introduced ant species in Galapagos Islands
- 1. We investigated ant communities in all main vegetation zones of the model island of Santa Cruz in the Galápagos archipelago (155 collection points, spread over 21 sites; 28 ant species collected), and evaluated the distribution, coexistence, and effect of environmental factors in a community composed of endemic, probably endemic, and introduced ants of the New World and exotic origin. 2. Introduced species were the most frequent, occurring in 98% of the samples, yet endemic and probably endemic species still occurred in 54% of the samples, and constituted one of three most common species. The present study revealed that the habitat type along with altitude and the tree cover are the primary factors shaping ant community composition. Little evidence was found for a competitively structured assemblage of ant species. 3. The present study confirmed the predominance of two dominant invasive species, Solenopsis geminata Fabricius and Wasmannia auropunctata Roger, whose abundances are negatively correlated. The abundance of S. geminata is positively correlated with the overall species richness, and with the proportion of other introduced species. The presence of both invasive ants is associated with a low evenness of ant communities. 4. The present study (i) stresses the dominance of introduced species and the relative resistance of endemic species, (ii) highlights the on-going processes of species introductions and (iii) points out the need for adequate monitoring and conservation of the pristine and threatened environments that constitute the Galápagos Islands.
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Belgian Biodiversity Platform, Annual Report 2015
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Predator effects on the feeding and bioirrigation activity of ecosystem-engineered Lanice conchilega reefs
- Ecosystem engineers can considerably affect the community composition, abundance and species richness of their environment. This study investigates the existence of positive or negative feedbacks of species that compose the community in intertidal biogenic reefs constructed by the ecosystem engineer Lanice conchilega. This tubeworm creates attractive nursery and feeding grounds for the predatory brown shrimp Crangon crangon, while at the same time is preyed upon by C. crangon. The effect of the predation pressure exerted by C. crangon on the bioirrigation and feeding activity of the tubeworm is up until now unknown and it is hypothesised that these activities are affected by the high densities of C. crangon in the reefs. A mesocosm experiment was set up to investigate the effects of predation pressure on the bioirrigation and feeding activity of L. conchilega in the i) absence; ii) restricted presence; and iii) unrestricted presence of C. crangon. Bioirrigation was quantified by the decrease of an artificially introduced bromide (Br−) tracer, while feeding activity was measured from the incorporation of 13C via stable isotope analysis. The bioirrigation rate of the L. conchilega reef equalled about 30 L·m−2·d−1 andwas not affected by the presence of the predator. The food uptake of the tubewormwas however about three times lower in the unrestricted presence of C. crangon, presumably due to the retraction of the worm's body and tentacles in its tube induced by physical contact with the predator. Notwithstanding the impacted food uptake of L. conchilega, the tubeworm maintains its functional role in the presence of predators in soft-bottom intertidal areas.
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Assessment of soil metal distribution and environmental impact of mining in Katanga (Democratic Republic of Congo).
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Environment and subsistence in north-western Europe during the Younger Dryas: An isotopic study of the human of Rhünda (Germany)
