Search publications of the members of the Royal Belgian institute of natural Sciences
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First report of monogenean flatworms from Lake Tana, Ethiopia: gill parasites of the commercially important Clarias gariepinus (Teleostei: Clariidae) and Oreochromis niloticus tana (Teleostei: Cichlidae)
- Background: Lake Tana is the largest lake in Ethiopia and the source of the Blue Nile. The lake harbours unique endemic cyprinid fish species, as well as the commercially important endemic Nile tilapia subspecies Oreochromis niloticus tana and the North African catfish Clarias gariepinus. Its endemicity, especially within the Labeobarbus radiation, its conservation importance and its economic indispensability attract scientific interest to the lake’s ichthyofauna. Fish parasites of Lake Tana, however, are hitherto poorly known, and no formal report exists on its monogenean flatworms. For sustainable aquaculture and fisheries development, it is essential to study monogenean fish parasites in these economically most important fish species. Moreover, it remains to be verified whether this unique ecosystem and its endemicity gave rise to a distinct parasite fauna as well. Results: Nile tilapia and North African catfish hosts were collected from Lake Tana in 2013. Nine species of monogenean parasites of two orders, Gyrodactylidea Bychowsky, 1937 and Dactylogyridea Bychowsky, 1937, were recovered. Gyrodactylus gelnari Přikrylová, Blažek & Vanhove, 2012, Macrogyrodactylus clarii Gussev, 1961, Quadriacanthus aegypticus El-Naggar & Serag, 1986 and two undescribed Quadriacanthus species were recovered from C. gariepinus. Oreochromis niloticus tana hosted Cichlidogyrus cirratus Paperna, 1964, C. halli (Price & Kirk, 1967), C. thurstonae Ergens, 1981 and Scutogyrus longicornis (Paperna & Thurston, 1969). Conclusions: Except for M. clarii, all species represent new records for Ethiopia. This first study on the monogenean fauna of Lake Tana revealed that the lake’s North African catfish, as well as its endemic Nile tilapia subspecies, harbour parasites that are known from these host species elsewhere in Africa.
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Cichlids: a host of opportunities for evolutionary parasitology
- Thanks to high species diversity and a broad range of speciation mechanisms, cichlid fishes represent a textbook model in evolutionary biology. They are also of substantial economic value. Despite this importance, cichlid parasites remain understudied, although some are more diverse than their hosts. They may offer important insights into cichlid evolution and the evolution of host–parasite interactions. We review five major lines of research conducted on cichlid para- sites so far: the study of parasite diversity and speciation; the role of parasites in cichlid diversification; the evolutionary ecology of host specificity; historical biogeography; and biological invasions. We call for more research in these areas and suggest approaches to valorise the potential that cichlid parasites hold for the study of evolutionary parasitology.
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Weak link between dispersal and parasite community differentiation or immunogenetic divergence in two sympatric cichlid fishes
- Geographical isolation, habitat variation and trophic specialization have contributed to a large extent to the astonishing diversity of cichlid fishes in the Great East African lakes. Because parasite communities often vary across space and environments, parasites can accompany and potentially enhance cichlid species diversification. However, host dispersal may reduce opportunities for parasite-driven evolution by homogenizing parasite communities and allele frequencies of immunity genes. To test for the relationships between parasite community variation, host dispersal and parasiteinduced host evolution, we studied two sympatric cichlid species with contrasting dispersal capacities along the shores of southern Lake Tanganyika. Whereas the philopatric Tropheus moorii evolved into several genetically differentiated colour morphs, Simochromis diagramma is phenotypically rather uniform across its distribution range and shows only weak population structure. Populations of both species were infected with divergent parasite communities and harbour differentiated variant pools of an important set of immune genes, the major histocompatibility complex (MHC). The overall extent of geographical variation of parasites and MHC genes was similar between host species. This indicates that immunogenetic divergence among populations of Lake Tanganyika cichlids can occur even in species that are strongly dispersing. However, because this also includes species that are phenotypically uniform, parasite-induced evolution may not represent a key factor underlying species diversification in this system.
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Collection valorisation and stakeholder involvement for the sustainable management of African aquatic ecosystems as best practices in capacity building
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Haemogregarine parasites parasitizing frogs of the Hyperoliidae (sedge and bush frogs) from South Africa
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Former Katanga Province in the Democratic Republic of Congo – rich in diversity and life! Preliminary results on freshwater fish parasite diversity
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Capacity building for an assessment of the impact of mining in Katanga (D.R.Congo) on fishes and their aquatic habitats
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Pelagic freshwater fish parasites in Lake Tanganyika: do the monogeneans mirror host origin?
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A hitchhiker’s guide to tilapia: How parasites take a ride on introduced Nile tilapia in the DR Congo
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Decline in parasite diversity promoted by lower host densities in Lake Tanganyika
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Quantification of hydrodynamic changes induced by an offshore mussel aquaculture farm using COHERENS (Part 2)
- The goal of this numerical study is the quantification of hydrodynamic changes (especially sea currents) induced by an offshore aquaculture farm similar to that of the industrial project “Westdiep Sea Farm”. To do that, a parameterization of the impact of longlines and droppers on hydrodynamics has been included in the 3D COHERENS hydrodynamic model and the impact of several configurations of the aquaculture farm on currents and bottom shear stress has been estimated in a simplified test case. In this previous internship project, a numerical study to quantify the impacts of an offshore aquaculture farm on hydrodynamics processes has been performed. To do so, a new module has been developed in the COHERENS model to compute the drag forces exerted by the droppers and then this module has been applied on a simplified case study, i.e. a modest farm with up to 40 longlines of 104 droppers and located in a straight open channel of 500 m width and 2 km length. The simulations show that, in all configurations tested, the presence of droppers significantly changes the hydrodynamics of the channel. Particularly, analysis of the bottom shear stress variations allowed to conclude that the presence of a modest offshore aquaculture farm could modify the erosion/sedimentation pattern around the farm, leading, for example, to a risk of destabilization of the neighbouring sandbanks, which would justify the implementation of an environmental monitoring program. Nevertheless, this previous work remains a preliminary study and many simplifications have been applied in order to obtain results in the given time. This second work (Part 2) will allow to refine the physics of the test channel in order to make it more realistic and to obtain results more faithful to the hydrodynamic reality in the North Sea. In this report, different sensitivity studies will be carried out mainly for the first phase of the project. Several metrics will be illustrated. Then, comparisons between the different phases will be made.
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D4.2 Improving the prediction of HNS concentration in the atmosphere
- Responding to maritime accidents can be extremely challenging when involving HNS that behave as evaporators. Due to their potential to form toxic or combustible clouds, evidence-based decisions are needed to protect the crew, responders, the coastal population and the environment. However, when an emergency is declared, key information is not always available for all the needs of responders. A case in point is the lack of knowledge and data to assess the risks that responders or rescue teams could take when intervening, or those that could impact coastal communities when allowing a shipping casualty to dock at a place of refuge. The MANIFESTS project aims to address these uncertainties and improve response and training capacities through the development of an operational decision-support system (DSS) for volatile HNS spills. Besides management and communication, the project includes four other work packages: WP2 on collecting new data on evaporators, WP3 on table top exercises and field training, WP4 on improving modelling tools and WP5 on the development of the DSS. Key expected outcomes include: · Operational guidance; · Desktop and field exercises; · In situ training; · Experimental data on gas cloud fate; · A brand-new fire and explosion modelling module; · Improved HNS database with new experimental data on evaporation/dissolution kinetics. This report presents the developments realized in the framework of the task 4.2. This task gave the opportunity to the MANIFESTS consortium to improve one or several features of their models allowing to better simulate the HNS concentration in the atmosphere. Only RBINS seizes this opportunity and has implemented in OSERIT some improvements in order to better simulate the HNS concentration at the sea surface, evaporation processes and finally has implemented a new atmosphere transport and dispersion model. OSERIT (Oil Spill Evaluation and Response Integrated Tool) is a model which describes the drift of a pollutant at sea using Lagrangian particle. It can be used in case of an accident with release of oil or chemical, to obtain an estimation of the pollution trajectory as well as some basic information about its behavior and fate at sea. In the framework of the MANIFESTS project, a new atmospheric dispersion module fully coupled to OSERIT has been developed and several marine processes have been improved. In this report, the improved processes are described and their actual implementation in OSERIT is explained.
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D4.3 - Models intercomparison
- Maritime transport represents more than 80% of the international trade volume (UNCTAD, 2017). Apart from crude oil, tanker trades of refined petroleum products, chemicals and gas have increased by 4% over the 2019-2021 period, with a 5.6% growth in Liquefied Natural Gas (LNG) trade (UNCTAD, 2022). The volume of hazardous and noxious substances (HNS) is thus constantly rising with an increased risk of accidental spillages potentially associated with marine pollutions, whether in ports or in the open sea. In the event of an incident and a spill in the environment, information on the fate of the chemical(s) involved is essential to better anticipate the risks incurred by responders and populations, the impacts on the environment as well as the appropriate response techniques (Mamaca et al., 2009). Chemicals accidentally spilled into the marine or aquatic environment generally undergo physical-chemical modifications that will characterize their behaviour and fate. As observed by Mamaca et al. (2004) and Le Floch et al. (2011), these modifications are dependent on the intrinsic parameters of the product involved, the in situ environmental parameters (temperature, density and salinity of the water) and the met-ocean conditions (e.g. sea state, wind speed, marine currents). A few hours following the spill short-term effects may thus occur such as spreading, natural dispersion in the water column (dissolution, emulsification) and evaporation into the atmosphere. Longer term degradation (e.g. polymerisation, biodegradation) and sedimentation processes can then follow, depending on the persistence and the nature of the substance. One of the main concerns is that around 2,000 different types of HNS are regularly shipped in bulk or package forms (Purnell, 2009) which thus make difficult to capture their behaviour if accidentally released in the environment. Of the wide variety of HNS traded, volatile and gaseous substances are particularly problematic for marine pollution response authorities. The release of such substances at sea can indeed lead to the formation of toxic, flammable, or explosive gas plumes – sometimes invisible to the naked eye – that can travel large distances and pose risks over a wide area in relatively short timescales. Yet, key information on the risks that responders or rescue teams could take when intervening, or those that could impact coastal communities and the environment when allowing a shipping casualty to dock at a place of refuge remain poorly known. The MANIFESTS EU-project is part of this context.
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D4.4 - Model validation
- The transportation of hazardous and noxious substances (HNS) on ships has been on the rise in recent years, posing a significant threat to both human health and the environment. The spill of these chemicals can have far-reaching consequences, particularly when dealing with highly volatile substances that can spread rapidly and unpredictably. The MANIFESTS project has been established with the goal of better understanding the behaviour of these substances to improve response capabilities in the event of a spill. Through research and analysis, the project aims to improve already existing models for predicting the behaviour of HNS in various environments, and to validate these models through a series of experiments and real-world scenarios. Models are essential tools to understand and predict the behaviour of HNS in the event of a spill. However, they are not perfect and have limitations in terms of accuracy, which must be considered by the users. During the MANIFESTS project, the models CHEMMAP, OpenDrift, OSERIT, and MOHID, have been utilized and compared against separate sets of data. These models will be introduced briefly in the next section. This report consists of three validation sections. The first section compares a small-scale laboratory experiment that visualizes the competition between evaporation, dissolution, and volatilization, and assesses the model's ability to simulate these processes. The second section investigates the impact of wind on the evaporation rate and provides as much environmental data as possible to the model, using a wind tunnel. The two last section of this report compares the models' simulation with the sea trials that took place at the end of May 2022. These sections compare both the drift in the water and the air dispersion against field data. By analysing these different experiments, we can understand the capabilities and limitations of the models used in this project.
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D5.2 - MANIFESTS DSS - Installation guides
- This technical deliverable explains the installation details of the decision support tools developped during the MANIFESTS project "MANaging risks and Impacts From Evaporating and gaseous Substances To population Safety". These tools includes: - The MANIFESTS Common Operational Picture and its viewer (COP tool) - The MANIFESTS models web application
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D5.3 - MANIFESTS DSS - User guides
- This technical deliverable explains the utilisation of the decision support tools developped during the MANIFESTS project "MANaging risks and Impacts From Evaporating and gaseous Substances To population Safety". These tools includes: - The MANIFESTS Common Operational Picture and its viewer (COP tool) - The MANIFESTS models web application for the fire module, explosion module and for OSERIT HNS - The HNS database
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D5.4 - Proof of concept of MANIFESTS DSS
- This technical report is a proof of the availability of the service developed and improved during the MANIFESTS project "MANaging risks and Impacts From Evaporating and gaseous Substances To population Safety". It include the models for the fire, explosion, OSERIT object, OSERIT HNS and OSERIT OIL
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Preliminary report on weathering
- This is a list of several parametrizations related to the weathering of oil. This is mainly a work document with references.
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New insights into cave hyena ethology and the implications for territorial competition with hominins in Late Pleistocene north-west Europe: the case of Caverne Marie-Jeanne (Belgium)
- Megacarnivore behaviours shape ecological dynamics between their prey and competitors and therefore play a key role in structuring ecosystems. In Late Pleistocene Eurasia, hominins and hyenas were sympatric predators. Since the first discoveries of Crocuta c. spelaea in the 19th century, this ‘bone-crushing’ species has been identified at most Palaeolithic sites and has inspired many taphonomic studies. Nonetheless, there is still very little known about its reproductive, social and spatial behaviours. We believe that exploring the complexity of the cave hyena's ethology is a way to better understand spatial relationships and niche sharing/partitioning between hominins and other top predators in Pleistocene ecosystems. This paper focuses on the study of Caverne Marie-Jeanne Layer 4 (Hastière, Belgium), one of the best-preserved palaeontological sites in the region. The exceptional number of hyena neonates in this assemblage (minimum number of individuals 300) has led us to describe, for the first time, a Late Pleistocene hyena birth den that was reused over a long period of time around 47.6–43k a bp. By bridging the gap between archaeology and palaeontology, we explore the potential of carnivore socio-spatial organisation and denning habits as an ecological proxy and discuss how these new unique data could help us further understand hominins’ spatial strategy in southern Belgium.
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Description of Aspella lorenzi n. sp. (Gastropoda: Muricidae: Aspellinae) from the Northern Red Sea
