Communication Dans Un Congrès Année : 2024

Mesoscale organization and trophic functioning of the benthic shelf ecosystem in the Bay of Biscay

Organisation méso-échelle et fonctionnement trophique du l'écosystème benthique du Golfe de Gascogne

Résumé

Marine shelves are highly productive ecosystems where benthic communities play an important role in food webs, particularly in the Bay of Biscay (BoB). Knowledge of the structural and functional characteristics of these communities can facilitate the understanding of the functioning of this ecosystem in response to environmental forcings. Previous works in the 60s on the northern part of the BoB have already shown the role of sediment and thermal depth gradient on the spatial organization of the macrobenthic component. The recurrent EVHOE survey of the French part of the shelf provides data on epibenthic megainvertebrates and bentho-demersal fish, two other biological components of this ecosystem. The study of their characteristics can account for environmental forcings and ecological processes operating at the mesoscale (10 to 100 km). This was accomplished in this work using taxonomic and functional approaches over a 12y dataset (2008-2020 data), and also by the assessment of epibenthic megainvertebrates production. Based on species composition, structural parameters and the high significant correlation (68%) between the respective spatial organizations of the two biological components (fish and invertebrates), seven distinct benthic areas, referred to as "benthiscapes”, were recognized. They were distributed from the coast to the shelf break and extending from the north to the south of the BoB. The spatial organization of both components were mainly correlated to meso-scale environmental forcings such as river plumes and bottom current velocities. The epibenthic megainvertebrates revealed distinct functional differences between benthiscapes, with a prevalent carnivorous dominance observed in disturbed areas affected by fishing activity or estuarine influence, contrasted with an increased deposit feeding activity near shelf break upwellings. Productions were notably higher in the former areas. This indicates that primary production, stimulated by nutrients supplies from rivers or deep waters, plays a key role in the spatial organisation of the observed benthic trophic dynamics and functioning.

IsobayV4.pdf (7.5 Mo) Télécharger le fichier
Origine Fichiers produits par l'(les) auteur(s)
Licence

Dates et versions

hal-04825576 , version 1 (08-12-2024)

Identifiants

  • HAL Id : hal-04825576 , version 1

Citer

Thomas Outrequin, Pascal Laffargue, Jacques Grall, Hervé Le Bris. Mesoscale organization and trophic functioning of the benthic shelf ecosystem in the Bay of Biscay. International Symposium on the Oceanography of the Bay of Biscay (ISOBAY 18), Jun 2024, La Rochelle (France), France. ⟨hal-04825576⟩
93 Consultations
71 Téléchargements

Partager

  • More