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

A 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.