Utilisation de la microchimie de l'otolithe pour discriminer les populations de chabots au sein du bassin de la Meuse walonne

peer reviewedA recent study revealed the presence of 0+ bullhead (Cottus gobio) in a deeply modified (canalized) stretch of the Belgian River Meuse in Tihange (Huy), in which suitable spawning grounds for bullheads are absent. We suggested that these 0+ bullheads might reveal dispersion from local upstream tributaries. To assess this hypothesis, we used otolith microchemistry to compare element fingerprints between bullheads samples originating from four rivers of the Meuse basin with a sample of bullhead of the River Meuse in Tihange. Some elements detected by ICPMS analysis revealed anthropogenic disturbance, like metallurgic industries outlet (Fe, Cr, Mn). Among other elements, Sr was the most appropriate to discriminate bullhead stocks. We observed that the Meuse sample was not linked with the populations of two upstream tributaries (Hoyoux and Samson), nor with the two other rivers considered (Ambleve and Aisne). These results confirm that otolith microchemistry allows bullhead stocks discrimination within a small part of the River Meuse basin. Moreover, our hypothesis of tributaries contribution to explain the presence of bullheads in the River Meuse in Tihange is inferred, consequently bullheads are probably able to spawn on alternative spawning grounds in the River Meuse itself

Arithmetic and Memorial Practices by and around Sophie Germain in the 19th Century

International audienceSophie Germain (1776-1831) is an emblematic example of a woman who produced mathematics in the first third of the nineteenth century. Self-taught, she was recognised for her work in the theory of elasticity and number theory. After some biographical elements, I will focus on her contribution to number theory in the context of the mathematical practices and social positions of the mathematicians of her time. I will then analyse some receptions and uses of Germain's life and scientific work under the French Third Republic