Browsing by Author "Schaal, Gauthier"
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- Diet consistency but large-scale isotopic variations in a deep-sea shark: the case of the velvet belly lantern shark, Etmopterus spinax, in the northeastern Atlantic region and Mediterranean SeaPublication . Besnard, Lucien; Duchatelet, Laurent; Bird, Christopher S.; Le Croizier, Gaël; Michel, Loïc; Pinte, Nicolas; Lepoint, Gilles; Schaal, Gauthier; Vieira, Rui P.; Gonçalves, Jorge M. S.; Martin, Ulrich; Mallefet, JérômeDeep-sea elasmobranchs are commonly reported as bycatch of deep-sea fisheries and their subsequent loss has been highlighted as a long-running concern to the ecosystem ecological functioning. To understand the possible consequences of their removal, information on basic ecological traits, such as diet and foraging strategies, is needed. Such aspects have been widely studied through stomach content analysis but the lack of long-term dietary information requires other tools to be used such as stable isotopes. This study examines nitrogen and carbon isotope compositions of the velvet belly lantern shark, Etmopterus spinax, one of the most impacted shark species in northeastern Atlantic fisheries as a result of accidental catches. E. spinax was sampled at four different locations, characterized by contrasting oceanographic and ecological conditions: the western Mediterranean Sea (near the Balearic Islands), the southern Iberian upwelling system, Rockall Trough and southwestern Norwegian fjords. Stomach content analysis revealed similar prey species among sites, with a diet dominated by Euphausiacea (mostly Meganyctiphanes norvegica) and an ontogenetic shift towards small teleost fishes, cephalopods or other crustaceans. Despite these similarities, muscle stable isotope compositions differed across sampled locations. Rather than clear dietary differences, the contrasted isotopic values are likely to reflect differences in environmental settings and biogeochemical processes affecting nutrient dynamics at the base of the food webs.
- Potential microplastics impacts on African fishing resourcesPublication . Masiá, Paula; Mateo, Juan L.; Arias, Andrés; Bartolomé, Marlene; Blanco, Carmen; Erzini, Karim; Le Loc'h, François; Mve Beh, Jean Hervé; Power, Deborah; Rodriguez, Noemi; Schaal, Gauthier; Machado-Schiaffino, Gonzalo; Garcia-Vazquez, EvaMicroplastic (MP) pollution is increasing worldwide and affecting aquatic fauna in different ways, which endangers current aquatic resources in a still unknown extent. MP-induced threats to marine fauna are critical for developing countries, where waste treatment may be not optimal and coastal communities rely heavily on marine resources for dietary protein. In this study, we assess the importance of MP pollution for African fishing resources. A new meta-database was created from published studies, containing 156 samples with more than 6200 individuals analysed for microplastic content from African and adjacent waters. A combination of research landscape analysis and rank analysis served to identify main research targets and to determine regional fishing resources especially affected by MP. A network of relevant terms showed fish health as a concern in Mediterranean waters, environmental pollution in freshwater and an emphasis on plastic items in South Africa. MP contents in fishing resources from Nile countries and the Gulf of Guinea, followed by Tunisia, are significantly higher than in other regions. Some of the most exploited species are among the most polluted ones, highlighting the threat of MP pollution in valuable but already compromised African fishing resources. Large geographic gaps with almost absent data about MP in aquatic fauna were revealed, especially in freshwater and in East African coasts. These results emphasize the importance of increasing the coverage of MP pollution in African fishing resources, and improving plastic waste management in the continent.