Trophic web and coastal ecosystem under anthropic pressure
  • Timeframe : 2011 - 2014
  • Local Budget: 0 €
  • Coordinator: ESE research unit, Hervé Le Bris
  • Contact: Hervé LE BRIS
  • Keywords : Bay of Biscay, Bays, Coastal margins, Isotopes, Terrestrial influence


Context and Issues
The main objective of Retrocan is to understand terrestrial vs offshore influences on marine coastal ecosystem functioning. It is focused on the northern part of the Bay of Biscay and based on a two-scale transect approach using trophic markers (C and N isotopes and fatty acids) measured at various levels of the benthic food web. The first scale concerns the bays (3-40 m deep) sheltered by islands and shoals. The second scale concerns gradients from inshore to the continental margin (3-170 m deep).
  • Isotopic spatio-temporal trends from primary producers to secondary consumers give evidence of a clear contrast in the functioning of the Bay of Brest compared to the Bay of Vilaine, where freshwater inputs are much larger.
  • Isotopic N of benthic consumers (invertebrates and fish) shows a general decreasing trend across the continental shelf. Questions arise about N isotopic fractionation and food sources at greater depths, where, according to fatty acid analysis, the latter are more characterised by detrital material.

Publications issued from the project

MORTILLARO, J.-M. SCHAAL, G. GRALL, J. NEROT, C. BRIND'AMOUR, A. MARCHAIS, V. PERDRIAU, M. LE BRIS, H. (2014) .Comparative study of isotopic trends in two coastal ecosystems of North Biscay: a multitrophic spatial gradient approach

NEROT, C. (2011) .Invertebres benthiques et biomarqueurs: temoins du fonctionnement trophique des ecosystemes cotiers

People involved

LE BERRE Thomas, Technician
Phone : +33 2 23 48 59 23
Email :
LE BRIS Hervé, Scientist
Phone : +33 2 23 48 59 28
Email :


IFREMER, Ecologie et Modèles pour l'Halieutique research unit, Nantes, France, Anik Brind'Amour
Institut Universitaire Européen de la Mer, Université de Bretagne Occidentale (UBO), Jacques Grall
UMR UBO-CNRS-IRD-IFREMER, LEMAR, Brest : Caroline Nérot, Gauthier Schall, Fabrice Pernet

Funding and Support

IFREMER (Oceanographic Vessel Gwen Drez)
CNRS-Insu and Ifremer (support Ecosphère Continentale et Côtière “Retrocan”)
Council of Bretagne (grant Stratégie d’Attractivité Durable “Recomab”)
Université Européenne de Bretagne (grant Equipes Projets Transversaux “Moresca”)