32181 research outputs found
Sort by
Paleoenvironments, δ13C and δ18O signatures in the Neoproterozoic carbonates of the Comba Basin, Republic of Congo: Implications for regional correlations and Marinoan event
Get PDFThe Ediacaran Schisto-Calcaire Group is a similar to 1300 m-thick succession belonging to the West Congo Supergroup in Central Africa. In the Comba Basin, it consists of three carbonate-dominated units defined as formations (SCI to SCIII) that are unconformably overlain by clastic deposits (Mpioka Group) interpreted as a molassic formation associated with the Panafrican Orogen. The underlying Upper Tillite and Cap Carbonate (SCIa) units, considered as markers of the Snowball Earth event were studied in three sections. We investigated the carbonates of the Schisto-Calcaire Group by defining new microfacies (MF1-MF7) and we performed C and O isotopic analyses in order to constraint the depositional and diagenetic events directly after the Marinoan interval. Stratigraphic variations of the stable isotopes are important in the series with lighter delta O-18 values (>1.5 parts per thousand) than those of the Neoproterozoic ocean in the SCIc unit. According to regional stratigraphy a temperature effect can be dismissed and a freshwater surface layer is the origin of such negative delta O-18 values in this unit. The negative delta C-13 anomaly (-3.5 parts per thousand on average) of the Cap Carbonate is similarly to the delta O-18 values (-6.4 parts per thousand on average) in the range of the marine domain during postglacial sea level rise. The sample suite as a whole (SCII and SCIII formations) displays heavier delta O-18 and delta C-13 than those of the lower part (SCI unit) of the Schisto-Calcaire Group. The comparison with the Lower Congo (Democratic Republic of Congo) and Nyanga (Gabon) basins shows that the meteoric flushing in SCIc unit of the Schisto-Calcaire Group was regional and not local, and could be derived from a climatic evolution. Although an overall overprint is present, our isotopic relationships argue against overall diagenetic resetting of primary compositions and suggest that with careful examination combined with detailed petrographic analysis general depositional and diagenetic controls can be discerned in oxygen and carbon isotopic data in the Schisto-Calcaire Group
Privateers, merchant ships and their crews between the Mediterranean and the North Sea during the War of the Spanish Succession (1702-1714): new insights from Southern-Netherlandish Prize Papers
Get PDFOptimized plankton imaging, clustering and visualization workflows through integrative data management and application of artificial intelligence
Get PDFPhytoplankton is a diverse group of photosynthesizing organisms which account for approximately fifty percent of the primary production on Earth. Increasing our knowledge on phytoplankton dynamics (and plankton in general) is therefore of major importance. In the present research, we aimed to reveal the spatiotemporal dynamics of the phyto- and zooplankton community in the Eastern English Channel, Southern Bight of the North Sea and the Thames estuary. To do so, we organized a JERICO-NEXT Lifewatch cruise in May 2017 on board of the RV Simon Stevin and sampled 44 stations, involving five research institutions from France (CNRS-LOG,), The Netherlands (RWS, NIOZ) and Belgium (UGENT, VLIZ). To quantify the biomass of the phytoplankton community we used a unique combination of three flow cytometers and two Fast Repetition Rate Fluorometerss that were coupled to the underway ferrybox system. These observations were complemented with Water Insight Spectrometer and water profile data (by means of a CTD) and samples for zooplankton, pigment and nutrient analysis. A dedicated data workshop was organized with all partners to conduct a joint analysis on both the biotic and abiotic data. A first exploration of the data, by means of regression-based models and multivariate statistics, suggested that mainly nutrient discharges from the rivers influence the plankton structure. Furthermore, water turbidity is controlling photosynthetic activity and horizontal and vertical variations of photosynthetic properties can be discriminated
BERMS, ERMS and WORMS: Community tools to facilitate our knowledge of marine biodiversity
Get PDFThe World Register of Marine Species (WoRMS) celebrated its 10th anniversary in 2017. Over thepast ten years, the content of WoRMS has grown steadily, currently containing more than 242,000accepted marine species names. WoRMS is therefore unique: there is no comparable globaldatabase for marine species, which is driven by a large, global expert community, supported by aData Management Team and can rely on a permanent host institute, dedicated to keeping WoRMSonline. The system has seen several user applications, including facilitating local and regionalmarine species data management and data analysis, but also answering big scientific questions forexample about the estimated number exiting marine species, providing a metric for how much wedo and do not know about life in the oceans.One of the unique features of WoRMS is that it is containing and integrating over 100 global, 12regional and 4 thematic species databases integrated within a common taxonomy. This allowsregional, thematic or ecological expert groups to focus on specific contents of the database,providing additional information and creating community ownership of a specific subcomponentof WoRMS.A regional example of WoRMS is BeRMS, the Belgian Register of Marine Species. Published in 2010,this register enabled to provide an inventory of all marine species encountered within the BelgianExclusive Economic Zone, including the intertidal zone.Now, a major update of the Belgian Census has started. A major literature review, dataminingactivities of marine biogeographic databases such as the European Biogeographic InformationSystem (EurOBIS) and additional species surveys are planned in order to complete this register,allowing to provide a nearly complete assessment of the Belgian marine biodiversity
The effects of biological diversity on marine ecosystem functions
Get PDFThe biological diversity found back in natural systems is an important determinant of the functioning of ecosystems and their stability in changing environments. However, biodiversity can be defined at various hierarchical levels, going from the within-species to the community and landscape level. In addition, biodiversity at a fixed hierarchical level can affect ecosystem functions and their stability through various mechanisms. I will illustrate this using a theoretical framework, and translate this framework to a simple trait-based model for competitive communities. Next, I will turn to practical examples of how trait diversity at various hierarchical levels can affect marine ecosystem functions and discuss some challenges for future research, including the up-scaling to complex multi-trophic systems (‘food webs’). Lastly, I will present a new collaborative research project that will start end 2018, where we plan to study the effect of intraspecific trait diversity on the resistance of species diversity and ecosystem productivity to multiple stressors
