Search publications of the members of the Royal Belgian institute of natural Sciences
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Canyons of the Eastern Shore of Southern Baikal: Morphology and Genesis
- We present new data on canyons and other morphological features of the underwater slope on the eastern coast of the southern basin of Lake Baikal obtained during high-resolution bathymetric surveys of the bottom using multibeam echo-sounders ELAC SeaBeam 1050 and Kongsberg EM710S. Based on the array of bathymetric data generated, we have constructed a digital elevation model for which we used at once several software products responsible for individual tasks. Analysis of the digital elevation model has indicated that tectonic processes played the leading role in the creation of the main, most noticeable forms of relief on the underwater slope. These processes formed a graben-like depression to the south of the Posol’skaya Bank and tectogenic scarps at the foot of the southern slope of the depression as well as canyon-shaped valleys along the entire coast. We have determined that the unusual direction of the Posol’skii canyon across the coastal slope and the relatively small size of the fan in this canyon are due to the history of the tectonic development of this part of the shoreline: in the past, the canyon valley skirted the continental slope of the Selenga river paleodelta from the southeast, and after the formation of a younger graben-like depression it preserved the old direction of its channel. We have suggested that underwater erosion processes initiated tectonic lowering of the floor of the basin. Ultimately, this resulted in the destruction and erosion of the ancient geomorphological surfaces and formation of the ridge and hollow relief and canyon valleys that are currently at different stages of development. Landslide forms resulting from paleoseismic dislocations play a secondary, yet a significant role in the relief of the slope, which undoubtedly complicated the geomorphological surface. It is assumed that the fans created by the activities of the canyons, the ancient channels of canyons and landslide bodies may be promising for the search for hydrate-bearing structures in this part of the lake.
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Fungi in raw insect and arachnid taxa containing species used in human entomophagy: a review
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New fossils from Tadkeshwar Mine (Gujarat, India) increase primate diversity from the early Eocene Cambay Shale
- Several new fossil specimens from the Cambay Shale Formation at Tadkeshwar Lignite Mine in Gujarat document the presence of two previously unknown early Eocene primate species from India. A new species of Asiadapis is named based on a jaw fragment preserving premolars similar in morphology to those of A. cambayensis but substantially larger. Also described is an exceptionally preserved edentulous dentary (designated cf. Asiadapis, unnamed sp. nov.) that is slightly larger and much more robust than previously known Cambay Shale primates. Its anatomy most closely resembles that of Eocene adapoids, and the dental formula is the same as in A. cambayensis. A femur and calcaneus are tentatively allocated to the same taxon. Although the dentition is unknown, exquisite preservation of the dentary of cf. Asiadapis sp. nov. enables an assessment of masticatory musculature, function, and gape adaptations, as well as comparison with an equally well-preserved dentary of the asiadapid Marcgodinotius indicus, also from Tadkeshwar. The new M. indicus specimen shows significant gape adaptations but was probably capable of only weak bite force, whereas cf. Asiadapis sp. nov. probably used relatively smaller gapes but could generate relatively greater bite forces.
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Mastication and enamel microstructure in Cambaytherium, a perissodactyl‑like ungulate from the early Eocene of India
- The dentition of Cambaytherium was investigated in terms of dental wear, tooth replacement and enamel microstructure. The postcanine tooth row shows a significant wear gradient, with flattened premolars and anterior molars at a time when the last molars are only little worn. This wear gradient, which is more intensive in Cambaytherium thewissi than in Cambaytherium gracilis, and the resulting flattened occlusal surfaces, may indicate a preference for a durophagous diet. The tooth replacement (known only in C. thewissi) shows an early eruption of the permanent premolars. They are in function before the third molars are fully erupted. During the dominant phase I of the chewing cycle the jaw movement is very steep, almost orthal, with a slight mesiolingual direction and changes into a horizontal movement during phase II. The enamel microstructure shows Hunter-Schreger-bands (HSB) in the inner zone of the enamel. In some teeth the transverse orientation of the HSB is modified into a zig-zag pattern, possibly an additional indicator of a durophagous diet.
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Plesiadapid mammals from the latest Paleocene of France offer new insights on the evolution of Plesiadapis during the Paleocene-Eocene transition
- Plesiadapidae are among the most successful mammal families of the Paleocene, but in North America they disappear abruptly around the Paleocene-Eocene boundary. In contrast, in Europe, they survive a few million years into the Eocene, although only as the genus Platychoerops. The latest Paleocene deposits of Petit-P^atis (Paris Basin, France) have produced three new plesiadapid species, one of each genus known in Europe: Plesiadapis ploegi, sp. nov., Platychoerops boyeri, sp. nov., and Chiromyoides mauberti, sp. nov. Each of these new species is represented by the very characteristic upper incisor, thus ascertaining their concomitant presence and in particular the spatial and temporal coexistence of Plesiadapis and Platychoerops. Plesiadapis ploegi, sp. nov., is morphologically intermediate between Plesiadapis tricuspidens and Platychoerops russelli, with a tricuspid I1 typical of Plesiadapis and a semimolariform p4 closer to Platychoerops. Its relatively high morphological variability is illustrated. Platychoerops boyeri, sp. nov., has the simple derived I1 of all Platychoerops and a p4 slightly more molariform than that of Ples. ploegi. Chiromyoides mauberti, sp. nov., is closest to Chiromyoides campanicus, but it is smaller and has a particular I1 with multiple posterocones. The systematic position of ‘Platychoerops’ georgei is discussed; this taxon is considered a chimera, and its type I1 belongs to either Chiromyoides or Plesiadapis. Cladistic analysis highlights the paraphyly or polyphyly of all genera of Plesiadapidae. Finally, there is some indication of morphological convergences between European and North American plesiadapids, which may be the result of similar environmental changes on both continents just before the Paleocene-Eocene boundary.
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First eurhinodelphinid dolphin from the Paratethys reveals a new family of specialised echolocators
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Is ‘everything everywhere’? Unprecedented cryptic diversity in the cosmopolitan flatworm Gyratrix hermaphroditus
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Southern Ocean Action Plan (2021-2030) in support of the United Nations Decade of Ocean Science for Sustainable Development.
- In 2017, the United Nations proclaimed a Decade of Ocean Science for Sustainable Development (hereafter referred to as the UN Ocean Decade) from 2021 until 2030 to support efforts to reverse the cycle of decline in ocean health. To achieve this ambitious goal, this initiative aims to gather ocean stakeholders worldwide behind a common framework that will ensure ocean science can fully support countries in creating improved conditions for sustainable development of the world’s oceans. The initiative strives to strengthen the international cooperation needed to develop the scientific research and innovative technologies that can connect ocean science with the needs of society at the global scale. Based on the recommendations in the Implementation Plan of the United Nations Decade of Ocean Science for Sustainable Development (Version 2.0, July 2021), the Southern Ocean community engaged in a stakeholder- oriented process to develop the Southern Ocean Action Plan. The Southern Ocean process engaged a broad community, which includes the scientific research community, the business and industry sector, and governance and management bodies. As part of this global effort, the Southern Ocean Task Force identified the needs of the Southern Ocean community to address the challenges related to the unique environmental characteristics and governance structure of the Southern Ocean. Through this community-driven process, we identified synergies within the Southern Ocean community and beyond in order to elaborate an Action Plan that provides a framework for Southern Ocean stakeholders to formulate and develop tangible actions and deliverables that support the UN Ocean Decade vision. Through the publication of this Action Plan, the Southern Ocean Task Force aims to mobilise the Southernbr Ocean community and inspire all stakeholders to seek engagement and leverage opportunities to deliver innovative solutions that maintain and foster the unique conditions of the Southern Ocean. This framework provides an initial roadmap to strengthen links between science, industry and policy, as well as to encourage internationally collaborative activities in order to address existing gaps in our knowledge and data coverage.
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EKLIPSE: engaging knowledge holders and networks for evidence-informed European policy on biodiversity and ecosystem services
- The aim of EKLIPSE is to develop a mechanism to inform European-scale policy on biodiversity and related environmental challenges. This paper considers two fundamental aspects of the decision-support mechanism being developed by EKLIPSE: 1) the engagement of relevant actors from science, policy and society to jointly identify evidence for decision making; and 2) the networking of scientists and other holders of knowledge on biodiversity and other relevant evidence. The mechanism being developed has the potential not only to build communities of knowledge holders but to build informal networks among those with similar interests in evidence, be they those that seek to use evidence or those who are building evidence, or both. EKLIPSE has been successful in linking these people and in contributing to building informal networks of requesters of evidence, and experts of evidence and its synthesis. We have yet to see, however, significant engagement of formal networks of knowledge holders. Future success, however, relies on the continued involvement with and engagement of networks, a high degree of transparency within the processes and a high flexibility of structures to adapt to different requirements that arise with the broad range of requests to and activities of EKLIPSE. key messages EKLIPSE develops a mechanism to inform policy on biodiversity and related environmental challenges. EKLIPSE operates at a European scale, bringing together policy-makers and knowledge holders from both science and society. EKLIPSE promotes the networking of scientists and other holders of knowledge on biodiversity and other relevant evidence.
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Extant diversity and estimated number of Gracillariidae (Lepidoptera) species yet to be discorverd in the Neotropical region
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In situ incubations with the Gothenburg benthic chamber landers: Applications and quality control
- In situ incubations of sediment with overlying water provide valuable and consistent information about benthic fluxes and processes at the sediment-water interface. In this paper, we describe our experiences and a variety of applications from the last 14 years and 308 deployments with the Gothenburg benthic chamber lander systems. We give examples of how we use sensor measurements for chamber leakage control, in situ chamber volume determination, control of syringe sampling times, sediment resuspension and stirring quality. We present examples of incubation data for in situ measurements of benthic fluxes of oxygen, dissolved inorganic carbon, nutrients, metals and gases made with our chamber landers, as well as manipulative injection experiments to study nitrogen cycling (injections of 15N nitrate), phosphate retention (injections of marl suspension) and targeted sediment resuspension. Our main goal is to demonstrate the possibilities that benthic chamber lander systems offer to measure solute fluxes and study processes at the sediment-water interface. Based on our experience, we recommend procedures to be used in order to obtain high quality data with benthic chamber landers.
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Bioturbation has a limited effect on phosphorus burial in salt marsh sediments
- It has been hypothesized that the evolution of animals during the Ediacaran–Cambrian transition stimulated the burial of phosphorus in marine sediments. This assumption is centrally based on data compilations from marine sediments deposited under oxic and anoxic bottom waters. Since anoxia excludes the presence of infauna and sediment reworking, the observed differences in P burial are assumed to be driven by the presence of bioturbators. This reasoning however ignores the potentially confounding impact of bottom-water oxygenation on phosphorus burial. Here, our goal is to test the idea that bioturbation increases the burial of organic and inorganic phosphorus (Porg and Pinorg, respectively) while accounting for bottom-water oxygenation. We present solid-phase phosphorus speciation data from salt marsh ponds with and without bioturbation (Blakeney salt marsh, Norfolk, UK). In both cases, the pond sediments are exposed to oxygenated bottom waters, and so the only difference is the presence or absence of bioturbating macrofauna. Our data reveal that the rate of Porg and Pinorg burial are indistinguishable between bioturbated and non-bioturbated sediments. A large terrestrial fraction of organic matter and higher sedimentation velocity than generally found in marine sediments (0.3 +/- 0.1 cm yr-1) may partially impact these results. However, the absence of a clear effect of bioturbation on total P burial puts into question the presumed importance of bioturbation for phosphorus burial.
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Deep-water inflow event increases sedimentary phosphorus release on a multi-year scale
- Phosphorus fertilisation (eutrophication) is expanding oxygen depletion in coastal systems worldwide. Under low-oxygen bottom water conditions, phosphorus release from the sediment is elevated, which further stimulates primary production. It is commonly assumed that reoxygenation could break this “vicious cycle” by increasing the sedimentary phosphorus retention. Recently, a deepwater inflow into the Baltic Sea created a natural in situ experiment that allowed us to investigate if temporary reoxygenation stimulates sedimentary retention of dissolved inorganic phosphorus (DIP). Surprisingly, during this 3-year study, we observed a transient but considerable increase, rather than a decrease, in the sediment efflux of DIP and other dissolved biogenic compounds. This suggested that the oxygenated inflow elevated the organic matter degradation in the sediment, likely due to an increase in organic matter supply to the deeper basins, potentially combined with a transient stimulation of the mineralisation efficiency. As a result, the net sedimentary DIP release per m2 was 56 %–112% higher over the years following the re-oxygenation than before. In contrast to previous assumptions, our results show that inflows of oxygenated water to anoxic bottom waters can increase the sedimentary phosphorus release.
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Iron and sulfur cycling in the cGENIE.muffin Earth system model (v0.9.21)
- The coupled biogeochemical cycles of iron and sulfur are central to the long-term biogeochemical evolution of Earth’s oceans. For instance, before the development of a persistently oxygenated deep ocean, the ocean interior likely alternated between states buffered by reduced sulfur (“euxinic”) and buffered by reduced iron (“ferruginous”), with important implications for the cycles and hence bioavailability of dissolved iron (and phosphate). Even after atmospheric oxygen concentrations rose to modern-like values, the ocean episodically continued to develop regions of euxinic or ferruginous conditions, such as those associated with past key intervals of organic carbon deposition (e.g. during the Cretaceous)and extinction events (e.g. at the Permian–Triassic boundary). A better understanding of the cycling of iron and sulfur in an anoxic ocean, how geochemical patterns in the ocean relate to the available spatially heterogeneous geological observations, and quantification of the feedback strengths between nutrient cycling, biological productivity, and ocean redox requires a spatially resolved representation of ocean circulation together with an extended set of (bio)geochemical reactions. Here, we extend the “muffin” release of the intermediate complexity Earth system model cGENIE to now include an anoxic iron and sulfur cycle (expanding the existing oxic iron and sulfur cycles), enabling the model to simulate ferruginous and euxinic redox states as well as the precipitation of reduced iron and sulfur minerals (pyrite, siderite, greenalite) and attendant iron and sulfur isotope signatures, which we describe in full. Because tests against present-day (oxic) ocean iron cycling exercises only a small part of the new code, we use an idealized ocean configuration to explore model sensitivity across a selection of key parameters. We also present the spatial patterns of concentrations and d56Fe and d34S isotope signatures of both dissolved and solid-phase Fe and S species in an anoxic ocean as an example application. Our sensitivity analyses show that the first-order results of the model are relatively robust against the choice of kinetic parameter values within the Fe–S system and that simulated concentrations and reaction rates are comparable to those observed in process analogues for ancient oceans (i.e. anoxic lakes). Future model developments will address sedimentary recycling and benthic iron fluxes back to the water column, together with the coupling of nutrient (in particular phosphate) cycling to the iron cycle.
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End-Permian marine extinction due to temperature-driven nutrient recycling and euxinia
- Extreme warming at the end-Permian induced profound changes in marine biogeochemical cycling and animal habitability, leading to the largest metazoan extinction in Earth’s history. However, a causal mechanism for the extinction that is consistent with various proxy records of geochemical conditions through the interval has yet to be determined. Here we combine an Earth system model with global and local redox interpretations from the Permian/Triassic in an attempt to identify this causal mechanism. Our results show that a temperature-driven increase in microbial respiration can reconcile reconstructions of the spatial distribution of euxinia and seafloor anoxia spanning the Permian–Triassic transition. We illustrate how enhanced metabolic rates would have strengthened upper-ocean nutrient (phosphate) recycling, and thus shoaled and intensified the oxygen minimum zones, eventually causing euxinic waters to expand onto continental shelves and poison benthic habitats. Taken together, our findings demonstrate the sensitive interconnections between temperature, microbial metabolism, ocean redox state and carbon cycling during the end-Permian mass extinction. As enhanced microbial activity in the ocean interior also lowers subsurface dissolved inorganic carbon isotopic values, the carbon release as inferred from isotope changes in shallow subsurface carbonates is likely overestimated, not only for this event, but perhaps for many other carbon cycle and climate perturbations through Earth’s history.
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A series of two Workshops to develop a suite of management options to reduce the impacts of bottom fishing on seabed habitats and undertake analysis of the trade-offs between overall benefit to seabed habitats and loss of fisheries revenue (WKTRADE3)
- WKTRADE3 developed methods and data flows that allow the assessment of seabed abrasion, economic value, weight of landings and impact on the seabed of mobile bottom-contacting gears in European waters by MSFD broad habitat type and métier. This report provides regional-specific assessments of pressure and impact of bottom-contacting fishing gears on the seabed and of trade-offs between fisheries and seafloor habitat protection. We also present an analysis of spatial and temporal variation in core fishing grounds, and review and evaluate any potential consequences to the ecosystem that could arise, if greater areas of seabed are left undisturbed by bottom fishing. An attempt was made to disaggregate variable costs from the STECF Annual Economic Report out on VMS data. The assessment covers four MSFD (sub)regions, 22 sub-divisions and four countries from Mediterranean and Black Sea. It is spanning from Norway and Finland in the North to Bulgaria in the south. For all areas, the surface abrasion data were avail-able for at least one year. For the Greater North Sea and Baltic Sea, it was possible to perform a complete analysis, while in the other regions data availability was more limited and it was not possible to assess the seabed impact. The impact of mobile bottom-contacting gears (MBCG) on seabed biota was assessed using two different methods and the percentage unfished c-squares was used as an indicator of fishing pressure. The average fishing intensity varies widely between habitat types and regions. Landings per swept area, and landings per unit impact also vary be-tween métiers by an order of magnitude. Effort reductions resulted in different responses between the two impact indicators and the fishing pressure indicator. For PD, the reduction of effort resulted in proportional reductions between benthic impact and fisheries value. For the two other indicators, L1 and percentage area unfished, the relationship between the weight/value and the indicators was not linear, meaning that larger improvements in the indicators could be obtained at small decreases in fisheries landings. There are many other direct and indirect benefits to eco-system and ecosystem services that could result from a reduction in MBCG, but currently the methods and data are not available to quantify these at the required spatial scale. Collectively, ICES expert groups produce many valuable reports each year. Some of these are very long (up to 1000 pp.). As much of the target audience will not have time to read the whole of each document, it is imperative that reports start with a clear, succinct, and factual executive summary that presents the key issues addressed in the main report.
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Subtidal Natural Hard Substrate Quantitative Habitat Mapping: Interlinking Underwater Acoustics and Optical Imagery with Machine Learning
- Subtidal natural hard substrates (SNHS) promote occupancy by rich benthic communities that provide irreplaceable and fundamental ecosystem functions, representing a global priority target for nature conservation and recognised in most European environmental legislation. However, scientifically validated methodologies for their quantitative spatial demarcation, including information on species occupancy and fine-scale environmental drivers (e.g., the effect of stone size on colonisation) are rare. This is, however, crucial information for sound ecological management. In this investigation, high-resolution (1 m) multibeam echosounder (MBES) depth and backscatter data and derivates, underwater imagery (UI) by video drop-frame, and grab sediment samples, all acquired within 32 km2 of seafloor in offshore Belgian waters, were integrated to produce a random forest (RF) spatial model, predicting the continuous distribution of the seafloor areal cover/m2 of the stones’ grain sizes promoting colonisation by sessile epilithic organisms. A semi-automated UI acquisition, processing, and analytical workflow was set up to quantitatively study the colonisation proportion of different grain sizes, identifying the colonisation potential to begin at stones with grain sizes Ø ≥ 2 cm. This parameter (i.e., % areal cover of stones Ø ≥ 2 cm/m2) was selected as the response variable for spatial predictive modelling. The model output is presented along with a protocol of error and uncertainty estimation. RF is confirmed as an accurate, versatile, and transferable mapping methodology, applicable to area-wide mapping of SNHS. UI is confirmed as an essential aid to acoustic seafloor classification, providing spatially representative numerical observations needed to carry out quantitative seafloor modelling of ecologically relevant parameters. This contribution sheds innovative insights into the ecologically relevant delineation of subtidal natural reef habitat, exploiting state-of-the-art underwater remote sensing and acoustic seafloor classification approaches.
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The first lower jaw of a ctenacanthid shark from the Late Devonian (Famennian) of Belgium
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The erroneous chondrichthyan egg case assignments from the Devonian: implications for the knowledge on the evolution of the reproductive strategy within chondrichthyans
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First Detections of Culiseta longiareolata (Diptera: Culicidae) in Belgium and the Netherlands
