Decline of cold-water fish species in the Bay of Somme (English Channel, France) in response to ocean warming

• Published in: Estuarine, Coastal and Shelf Science
• Main Authors: Auber, Arnaud, Gohin, Francis, Goascoz, Nicolas, Schlaich, Ivan
• Other Authors: Laboratoire Ressources halieutiques Boulogne sur mer (LRHBL), Halieutique Manche Mer du Nord (HMMN), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Laboratoire d'Ecologie Pélagique (PELAGOS), Dynamiques des Écosystèmes Côtiers (DYNECO), Laboratoire Ressources Halieutiques de Port-en-Bessin (LRHPB)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2017
• Subjects: [SDU]Sciences of the Universe [physics]; [SDV]Life Sciences [q-bio]; Northeast Atlantic
• Online Access: https://hal.science/hal-04201846; https://doi.org/10.1016/j.ecss.2017.03.010

A growing number of studies have documented increasing dominance of warm-water fish species (“tropicalisation”) in response to ocean warming. Such reorganization of communities is starting to occur in a multitude of local ecosystems, implying that tropicalisation of marine communities could become a global phenomenon. Using 32 years of trawl surveys in the Bay of Somme (English Channel, France), we aimed to investigate the existence of a tropicalisation in the fish community at the local scale of the estuary during the mid-1990s, a period where an exceptional temperature rise occurred in Northeast Atlantic. A long-term response occurred (with a major transition over 6 years) that was characterized by a marked diminution in the abundance of cold-water species in parallel to a temperature rise generated by the ocean-scale phenomenon, the Atlantic Multidecadal Oscillation, which switched from a cool to a warm phase during the late 1990s. Despite finding no significant increase in the dominance of warm-water species, the long-term diminution of cold-water species suggests that the restructuring of the fish community was mainly influenced by global-scale environmental conditions rather than local ones and that indirect effects may also occurred through biological interactions.