Intertidal are undergoing changes influenced by hydrodynamic processes. Saint-Brieuc (English Channel, France) is a bay composed of salt marshes (sheltered) and sandy habitats (exposed), influenced by mega tidal regimes. The benthic assemblages face biotic and abiotic stresses revealing several gradients. Cerastoderma edule’s physiological regulation (seasonal/spatial variations) will be investigated by integrating the lipid classes compositions. Fatty acids will unravel the food webs of C.edule, S.plana, P.ulvae. This study aims to define the trophic ecology, (1) main food sources, and (2) physiological regulations, of C. edule and associated invertebrates, at Saint-Brieuc.
(1) Linoleic acid (terrestrial plant biomarker) concentrations decreased from coastal to downstream as opposed to docosahexaenoic acid (dinoflagellate/phytoplankton biomarker) which increased. The first stations demonstrate an influence by sea purslane found in the salt marshes, while the last stations were more influenced by planktonic primary producers (i.e. dinoflagellates).
(2) C.edule’s lipid classes ceramide aminoethylphosphonate and free sterols showed a high concentration in January which could indicate their need to strengthen the immune system, while Triglycerides (storage lipid) were present in April most likely for gametogenesis. A gradient of increasing in plasmalogens far from the coast prevents stresses by increasing the immune response.
