Search publications of the members of the Royal Belgian institute of natural Sciences
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Sea cucumbers (Echinodermata, Holothuroidea) from the JR275 expedition to the eastern Weddell Sea, Antarctica
- Thirty-seven holothuroid species, including six potentially new, are reported from the eastern Weddell Sea in Antarctica. Information regarding sea cucumbers in this dataset is based on Agassiz Trawl (AGT) samples collected during the British Antarctic Survey cruise JR275 on the RRS James Clark Ross in the austral summer of 2012. Species presence by site and an appendix of holothuroid identifications with registrations are included as supplementary material. Species occurrence in the Weddell Sea is updated to include new holothuroids from this expedition.
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Species distribution models describe spatial variability in mesopelagic fish abundance in the Southern Ocean
- Introduction Mesopelagic fishes play a central role in the transfer of energy through open-ocean food webs, particularly in the Southern Ocean where they are both important predators of zooplankton and a key prey group for many higher predators. However, they are notoriously difficult to sample, which has limited our understanding of the bio-physical predictors of their abundance and spatiotemporal variability. Species distribution models can be used to help understand species’ ecological requirements by relating records of their presence or abundance to environmental data. Methods Here, we used data from Myctobase – a new circumpolar database of mesopelagic fishes – to model patterns in abundance of eight key myctophid species (family Myctophidae) and the genus Bathylagus in the Southern Ocean south of 45°S. We developed species-specific boosted regression tree models to obtain circumpolar predictions of abundance. Average daytime and night-time summer predictions for the period 1997 to 2011 at 0 to 200m depths were generated for each species. Results Depth and solar position were important predictors and species were stratified in their depth distribution. For all species, except for G. nicholsi , there was an interaction between depth of capture and solar position, reflecting diel vertical migration. Other important variables included sea surface temperature, dissolved oxygen at 200 m, chlorophyll a , and sea surface height, indicating an association with water mass properties. Circumpolar patterns of abundance varied between species with some displaying affinities for oceanic regions at Antarctic latitudes (e.g., E. antarctica and Bathylagus spp.) or sub-Antarctic latitudes (e.g., K. anderssoni and P. tenisoni ); and affinities for shelf regions (e.g., P. bolini and G. nicholsi ). Discussion Our findings suggest that the abundance of mesopelagic fish is influenced by diel vertical migration and meso- and sub-mesoscale oceanographic features, with the Polar Front being a major delimiting feature. Our study showed contrasting patterns in community composition with higher species diversity north of the Polar Front that might be indicative of latitudinal variability in food web structure. Our spatial analysis is an important step toward resolving what determines important habitat for mesopelagic fishes, providing foundational information for understanding shifting food web dynamics into the future.
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articlereference.hernandezetal.2018.newfrontiers
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Measuring Performances, Skill and Accuracy in Operational Oceanography: New Challenges and Approaches
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Three new species of Muricidae (Ocenebrinae, Pagodulinae) from the Gulf of California, Mexico and update of the living muricids from the area
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Description of a remarkable and huge new species of Zacatrophon (Muricidae: Ocenebrinae) from the Gulf of California
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Mixing of magmatic-hydrothermal and metamorphic fluids and the origin of peribatholitic Sn vein-type deposits in Rwanda
- The fluid sources of granite-related Sn-quartz vein deposits are commonly obscured by fluid mixing or fluid-rock interactions. As a result, fluid inclusions, minerals and isotopes in these veins indicate an intermediate composition between magmatic and metamorphic, but the degree of mixing between these endmembers is currently unquantified. This study presents a novel quantitative approach to assess the degree of mixing between magmatic-hydrothermal and external metamorphic fluids in the formation of peribatholitic Sn-quartz veins. In particular, fluid mixing in the Sn-mineralized Rwamagana-Musha-Ntunga pegmatite-quartz vein field in East Rwanda has been evaluated by the following four methods: quartz stable isotopes, muscovite geochemistry, fluid inclusion microthermometry and LA-ICP-MS, and geochemical modelling. The quartz stable isotope data (δ18O: +13.1 to +15.8‰ V-SMOW; δD: −27.6 to −59.7‰ V-SMOW) cannot uniquely differentiate between a metamorphic fluid origin or an initial magmatic hydrothermal fluid origin with subsequent metamorphic fluid mixing or host-rock interaction. However, granitophile element concentrations in magmatic muscovite from pegmatites and hydrothermal muscovite from associated Sn-quartz veins are equally high, indicating a close genetic link (Rb: 530–8740 ppm, Li: 110–1990 ppm, Sn: 87–810 ppm, Cs: 62–420 ppm). Primary H2O-CO2-N2-NaCl medium saline magmatic fluid inclusions in quartz of pegmatites (∼12.7 wt% NaCleq) and H2O-CO2-(N2)-NaCl low saline fluid inclusions in barren metamorphic quartz veins (∼4.9 wt% NaCleq) were analyzed by LA-ICP-MS. These results show an enrichment in Li, Rb, Sn and Cs for the magmatic fluid, while the metamorphic fluid is characterized by low granitophile element concentrations and high Sr and Ba contents. The expected Rb-Cs and Rb-Sn signature of the Sn-quartz vein muscovite was modelled using the measured fluid endmember compositions, confirming mixing between magmatic and metamorphic fluids in the formation of the veins. The quantification suggests that the hydrothermal Sn-quartz vein fluid contains 5–80% of an external metamorphic fluid component.
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Description of a new species of the genus Prionus Geoffroy, 1762 from northern Vietnam (Coleoptera: Cerambycidae: Prioninae)
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Calcardea junnei Gingerich, 1987 from the late Paleocene of North America is not a heron, but resembles the early Eocene Indian taxon Vastanavis Mayr et al., 2007
- We revisit the holotype of Calcardea junnei Gingerich, 1987 from the latest Paleocene (Clarkforkian) of the Willwood Formation (Wyoming, USA). The species is based on a partial skeleton and was originally assigned to the Ardeidae (herons). As we show, this classification cannot be upheld and Calcardea Gingerich, 1987 more closely resembles the taxon Vastanavis Mayr et al., 2007 (Vastanavidae), a parrot-like bird from the early Eocene of India. Even though C. junnei is a large bird, its long wings and short tarsometatarsus argue against a predominantly terrestrial way of living, and the morphology of the tarsometatarsus and pedal phalanges instead suggest strong grasping feet.We conclude that an assignment of Calcardea to the landbird clade (Telluraves) is better supported than its classification into the waterbird clade (Aequornithes), which includes Ardeidae and other ‘ciconiiform’ and ‘pelecaniform’ taxa. Calcardea junnei is one of the oldest known representatives of Telluraves and its morphology shows plesiomorphic features, which contributed to its previous misidentification as a heron. Calcardea exhibits a distinctive osteology and affords a glimpse of a previously unknown late Paleocene avian morphotype.
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New fossils, systematics, and biogeography of the oldest known crown primate Teilhardina from the earliest Eocene of Asia, Europe, and North America
- Omomyiform primates are among the most basal fossil haplorhines, with the oldest classified in the genus Teilhardina and known contemporaneously from Asia, Europe, and North America during the PaleoceneeEocene Thermal Maximum (PETM) ~56 mya. Characterization of morphology in this genus has been limited by small sample sizes and fragmentary fossils. A new dental sample (n ¼ 163) of the North American species Teilhardina brandti from PETM strata of the Bighorn Basin, Wyoming, documents previously unknown morphology and variation, prompting the need for a systematic revision of the genus. The P4 of T. brandti expresses a range of variation that encompasses that of the recently named, slightly younger North American species ‘Teilhardina gingerichi,’ which is here synonymized with T. brandti. A new partial dentary preserving the alveoli for P1-2 demonstrates that T. brandti variably expresses an unreduced, centrally-located P1, and in this regard is similar to that of T. asiatica from China. This observation, coupled with further documentation of variability in P1 alveolar size, position, and presence in the European type species T. belgica, indicates that the original diagnosis of T. asiatica is insufficient at distinguishing this species from either T. belgica or T. brandti. Likewise, the basal omomyiform ‘Archicebus achilles’ requires revision to be distinguished from Teilhardina. Results from a phylogenetic analysis of 1890 characters scored for omomyiforms, adapiforms, and other euarchontan mammals produces a novel clade including T. magnoliana, T. brandti, T. asiatica, and T. belgica to the exclusion of two species previously referred to Teilhardina, which are here classified in a new genus (Bownomomys americanus and Bownomomys crassidens). While hypotheses of relationships and inferred biogeographic patterns among species of Teilhardina could change with the discovery of more complete fossils, the results of these analyses indicate a similar probability that the genus originated in either Asia or North America.
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An integrated risk-based assessment of the North Sea to guide ecosystem-based management
- This study provides an integrated perspective to ecosystem based management (EBM) by considering a diverse array of societal goals, i.e. sustainable food supply, clean energy and a healthy marine ecosystem, and a selection of management measures to achieve them. The primary aim of this exercise is to provide guidance for (more) integrated EBM in the North Sea based on an evaluation of the effectiveness of those management measures in contributing to the conservation of marine biodiversity. A secondary aim is to identify the requirements of the knowledge base to guide such future EBM initiatives. Starting from the societal goals we performed a scoping exercise to identify a “focal social-ecological system” which is a subset of the full social-ecological system but considered adequate to guide EBM towards the achievement of those societal goals. A semi-quantitative risk assessment including all the relevant human activities, their pressures and the impacted ecosystem components was then applied to identify the main threats to the North Sea biodiversity and evaluate the effectiveness of the management measures to mitigate those threats. This exercise revealed the need for such risk-based approaches in providing a more integrated perspective but also the trade-off between being comprehensive but qualitative versus quantitative but limited in terms of the “focal” part of the SES that can be covered. The findings in this paper provide direction to the (further) development of EBM and its knowledge base that should ultimately allow an integrated perspective while maintaining its capacity to deliver the accuracy and detail needed for decision-making.
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Reassessment of historical sections from the Paleogene marine margin of the Congo Basin reveals an almost complete absence of Danian deposits
- The early Paleogene is critical for understanding global biodiversity patterns in modern ecosystems. During this interval, Southern Hemisphere continents were largely characterized by isolation and faunal endemism following the breakup of Gondwana. Africa has been proposed as an important source area for the origin of several marine vertebrate groups but its Paleogene record is poorly sampled, especially from sub-Saharan Africa. To document the early Paleogene marine ecosystems of Central Africa, we revised the stratigraphic context of sedimentary deposits from three fossil-rich vertebrate localities: the Landana section in the Cabinda exclave (Angola), and the Manzadi and Bololo localities in western Democratic Republic of Congo. We provide more refined age constraints for these three localities based on invertebrate and vertebrate faunas, foraminiferal and dinoflagellate cyst assemblages, and carbon isotope records. We find an almost complete absence of Danian-aged rocks in the Landana section, contrary to prevailing interpretations over the last half a century (only the layer 1, at the base of the section, seems to be Danian). Refining the age of these Paleocene layers is crucial for analyzing fish evolution in a global framework, with implications for the early appearance of Scombridae (tunas and mackerels) and Tetraodontiformes (puffer fishes). The combination of vertebrate fossil records from Manzadi and Landana sections suggests important environmental changes around the K/Pg transition characterized by an important modification of the ichthyofauna. A small faunal shift may have occurred during the Selandian. More dramatic is the distinct decrease in overall richness that lasts from the Selandian to the Ypresian. The Lutetian ofWest Central Africa is characterized by the first appearance of numerous cartilaginous and bony fishes. Our analysis of the ichthyofauna moreover indicates two periods of faunal exchanges: one during the Paleocene, where Central Africa appears to have been a source for the European marine fauna, and another during the Eocene when Europe was the source of the Central Africa fauna. These data indicate that Central Africa has had connections with the Tethyian realm.
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Inside baleen: Exceptional microstructure preservation in a late Miocene whale skeleton from Peru
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Berries from Belgium: archaeobotanical finds of redcurrant, blackcurrant and gooseberry
- Recently medieval and post-medieval carpological data from Belgium were collected in an ArboDat© database. The dataset obtained shows a diversification of fruit species during the late medieval period, which can be related to the development of horticulture. Blackcurrant (Ribes nigrum), redcurrant (Ribes rubrum) and gooseberry (Ribes uva-crispa) belong to this new fruit species group occurrence. In the Low Countries Ribes sp. pollen and macrobotanical remains dating to the Atlantic period were recently recorded, suggesting that at least some species are autochthonous. However, it is striking that the earliest records after prehistoric times date to the medieval period. In Northwestern Europe archaeobotanical finds become more frequent from the end of the medieval period and the beginning of the early modern period onwards. Likewise, the oldest historical sources date to the 15th and 16th centuries. This poster gives an overview of the Belgian archaeobotanical records of Ribes species. We will discuss the species status and use during the late medieval and post-medieval period in Belgium based on archaeobotanical finds and information from iconographical and written sources.
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Evolution of plant economy in Medieval and Post-Medieval Belgium, a review of the Archaeobotanical Data
- The first archaeobotanical studies on medieval and early modern sites in Belgium were published in the eighties of last century. Since then hundreds of samples from rescue excavations have been analysed and the increasing amount of data permits a first review. In this presentation we will give a synthesis of the carpological records of cultivated and collected plants of economic importance from medieval and post-medieval sites in Belgium. It will comprise published data from Flanders (the northern part of Belgium) and published and unpublished data from the Brussels region and the Walloon region (the southern part of Belgium), recently collected by the archaeobotanical team of the Royal Belgian Institute of Natural Sciences. After evaluating the potential and limits of this rich archaeobotanical dataset, diachronic trends related to intensification of crop cultivation, developments in horticulture and fruit cultivation, introductions of non-indigenous species, changing trade networks and changes in food consumption patterns of medieval and post-medieval populations will be discussed. The data will be confronted with information from historical sources and archaeobotanical records from the wider region. Finally we will define some research questions for future studies.
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Notes on Latest Cretaceous Cirripedes (Crustacea, Thoracica) from Tunisia - Part 1. A new species of Pachyscalpellum Buckeridge, 1991
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An update of the lithostratigraphy of the Ieper Group.
- The objective of the present revision is to complement the lithostratigraphy of the Ieper Group published in 2001 (Laga et al., 2001). This last publication reflected the activities in the Tertiary Subcommission at that time. The review published in 2001 framed in an initiative of the National Stratigraphic Commission and was limited to the lithostratigraphy at formation level. The Laga et al (2001) reference document has been the basis for the NCS website until now. The Ieper Group is characterised by clay−dominated sediments overlying, in most situations, the Landen Group strata and, if not outcropping, underlying the sand−dominated Zenne Group sediments. According to Laga et al. (2001) in their reference document for Paleogene and Neogene lithostratigraphy, the Ieper Group consists of the Kortrijk, Tielt and Gentbrugge Formations and ,members in these Formations are only listed. These subdivisions are also used on the 1:50 000 geological maps of Flanders, edited in the last decades of the 20th century. Especially the additional description of the members, and where possible, horizons, identified in the Formations, made the present review necessary and also modifications at the formation level itself arisen since 2001 needed to be integrated in a new synthesis. The present update is based on the earlier description of members in Maréchal & Laga (1988), Geets et al. (2000) and Steurbaut (1998) as far as appropriate. All modifications, discussions and additions are supported by the relevant literature references.
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Macroraptorial sperm whales (Cetacea, Odontoceti, Physeteroidea) from the Miocene of Peru
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The Holocene occurrence of Acipenser spp. in the southern North Sea: the archaeological record
- Archaeological sturgeon remains from the southern North Sea basin used to be automatically attributed to Acipenser sturio, since this was the only acipenserid species believed to occur there. These species identifications, however, were in need of revision after a growing number of indications were found for the historical presence of Acipenser oxyrinchus in western Europe. In this study, morphological and genetic data on sturgeon remains from archaeological sites along the southern North Sea are revised. A large number of Dutch, Belgian, British and some French archaeological sturgeon remains, dating from theMesolithic up to Late Modern times, are morphologically examined and fish sizes are reconstructed. This study of >7000 acipenserid bones proves the sympatric occurrence of European sturgeon A. sturio and Atlantic sturgeon A. oxyrinchus in the southern North Sea at least since the Neolithic (fourth millennium BC onwards), with A. oxyrinchus remains always outnumbering those of A. sturio. Human influence is documented by the decrease in finds through time, but no clear evidence was found for a diachronic change in fish lengths that could possibly be related to fishing pressure.
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Fluorapatite in carbonatite-related phosphate deposits: the case of the Matongo carbonatite (Burundi)
