Gauthier SCHAAL

Marine biology and ecology, trophic ecology, stable isotopes, fatty acids

Senior Lecturer
Université de Bretagne Occidentale


LEMAR Laboratory



I have been a teacher-researcher at the University of Western Brittany since 2012, after a PhD at the Roscoff Biological Station (Sorbonne Universities), and a post-doctorate in South Africa, at Rhodes University (Grahamstown).

My research activity focuses on the understanding of trophic interactions within ecosystems, from benthic primary consumers to large pelagic predators. I use different approaches, in particular those based on trophic biomarkers such as stable isotopes (C, N, S, Hg), lipids (fatty acids, sterols) or metallic trace elements. My activity also leads me to be interested in other aspects of ecosystem functioning, such as the structure and composition of communities, in connection with a strong personal interest in the taxonomy of benthic invertebrates.

My main geographical areas of interest are the coastal environments of Western Europe, Mediterranean lagoons, the Pacific coast of Mexico (Baja California), Gabon and Mayotte.

I am currently co-supervising the theses of:

  • Anthony Voisin: Biodiversity under rapid environmental changes: food web structure, trophic interactions, and commmunity response in benthic Antarctic ecosystems
  • Rémi Brosse: Factors influencing the distribution of the gastropod Terebralia palustris in the magroves of Mayotte
  • Alice Guillot: The diversity of nutritional and toxicological profiles in Western and Central African marine resources
  • Johann Ludovic Happi: Mangrove-associated benthic macrofauna in Gabon: impact of human activities and the development of pollution indicators
  • Youri Ivann Mvomo Minko: The functional role of gabonese coastal waters for two shark species: Sphyrna lewini and Carcharhinus limbatus


355235 ACL schaal apa 50 desc 1 Schaal, G. 199792
Solsona, N., Sturbois, A., Desroy, N., Ponsero, A., Schaal, G., & Le Pape, O. (2024). How trophic impasses structure coastal food webs? Insights from ECOPATH modelling. ESTUARINE COASTAL AND SHELF SCIENCE, 299, 108691. Cite
Beauvais, S. M. S., Martinez-Rincon, R. O., Ketchum, J. T., Schaal, G., Lluch-Cota, S. E., & Hoyos-Padilla, M. (2024). Movement patterns and residency of silvertip sharks (Carcharhinus albimarginatus) in a remote archipelago of the Eastern Tropical Pacific. ENVIRONMENTAL BIOLOGY OF FISHES. Cite
Serre, S., Jung, A., Cherel, Y., Gamblin, C., Hennache, C., Le Loc’h, F., Lorrain, A., Priac, A., Schaal, G., & Stephan, E. (2024). Stable isotopes reveal intrapopulation heterogeneity of porbeagle shark (Lamna nasus). REGIONAL STUDIES IN MARINE SCIENCE, 69, 103340. Cite
Sturbois, A., De Caceres, M., Bifolchi, A., Bioret, F., Boye, A., Gauthier, O., Grall, J., Gremare, A., Labrune, C., Robert, A., Schaal, G., & Desroy, N. (2023). Ecological quality assessment: A framework to report ecosystems quality and their dynamics from reference conditions. ECOSPHERE, 14(12), e4726. Cite
Le Croizier, G., Lorrain, A., Hoyos-Padilla, M., Ketchum, J. T., Amezcua-Martinez, F., Le Loc’h, F., Munaron, J.-M., Schaal, G., & Point, D. (2023). Do marine protected areas influence mercury exposure? Insights from a shark community in the tropical Northeast Pacific. ENVIRONMENTAL POLLUTION, 336, 122352. Cite
Besnard, L., Lucca, B. M. M., Shipley, O. N. N., Le Croizier, G., Martinez-Rincon, R. O., Sonke, J. E. E., Point, D., Galvan-Magana, F., Kraffe, E., Kwon, S. Y., & Schaal, G. (2023). Mercury isotope clocks predict coastal residency and migration timing of hammerhead sharks. Journal of Applied Ecology. Cite
Sturbois, A., Cozic, A., Schaal, G., Desroy, N., Riera, P., Le Pape, O., Le Mao, P., Ponsero, A., & Carpentier, A. (2022). Stomach content and stable isotope analyses provide complementary insights into the trophic ecology of coastal temperate bentho-demersal assemblages under environmental and anthropogenic pressures. Marine Environmental Research, 182, 105770. Cite
Burel, T., Schaal, G., Grall, J., Le Duff, M., & Gall, E. A. (2022). Clear-cut wave height thresholds reveal dominance shifts in assemblage patterns on rocky shores. Marine Ecology Progress Series, 683, 21–36. Cite
Besnard, L., Duchatelet, L., Bird, C. S., Le Croizier, G., Michel, L., Pinte, N., Lepoint, G., Schaal, G., Vieira, R. P., Goncalves, J. M. S., Martin, U., & Mallefet, J. (2022). Diet consistency but large-scale isotopic variations in a deep-sea shark: The case of the velvet belly lantern shark, Etmopterus spinax, in the northeastern Atlantic region and Mediterranean Sea. Deep-Sea Research Part I-Oceanographic Research Papers, 182, 103708. Cite
Sturbois, A., Riera, P., Desroy, N., Brebant, T., Carpentier, A., Ponsero, A., & Schaal, G. (2022). Spatio-temporal patterns in stable isotope composition of a benthic intertidal food web reveal limited influence from salt marsh vegetation and green tide. Marine Environmental Research, 175, 105572. Cite
Burel, T., Schaal, G., Grall, J., Le Duff, M., Chapalain, G., Schmitt, B., Gemin, M., Boucher, O., & Ar Gall, E. (2019). Small-scale effects of hydrodynamics on the structure of intertidal macroalgal communities: A novel approach. Estuarine Coastal and Shelf Science, 226, UNSP 106290. Cite
Sturbois, A., Cucherousset, J., De Cáceres, M., Desroy, N., Riera, P., Carpentier, A., Quillien, N., Grall, J., Espinasse, B., Cherel, Y., & Schaal, G. (2022). Stable Isotope Trajectory Analysis (SITA): A new approach to quantify and visualize dynamics in stable isotope studies. Ecological Monographs. Cite
Sturbois, A., Cormy, G., Schaal, G., Gauthier, O., Ponsero, A., Le Mao, P., Riera, P., & Desroy, N. (2021). Characterizing spatio-temporal changes in benthic communities: Taxonomic and functional trajectories of intertidal assemblages in the bay of Saint-Brieuc (English Channel). Estuarine Coastal and Shelf Science, 262, 107603. Cite
Masia, P., Mateo, J. L., Arias, A., Bartolome, M., Blanco, C., Erzini, K., Le Loc’h, F., Mve Beh, J. H., Power, D., Rodriguez, N., Schaal, G., Machado-Schiaffino, G., & Garcia-Vazquez, E. (2022). Potential microplastics impacts on African fishing resources. Science of the Total Environment, 806, 150671. Cite
Sturbois, A., Cormy, G., Le Moal, A., Schaal, G., Broudin, C., Thiebaut, E., Ponsero, A., Le Mao, P., Jones, A., Riera, P., Gauthier, O., & Desroy, N. (2021). Using ecological trajectories to track long-term taxonomic and functional changes in benthic shallow soft-bottom communities (Bay of Saint-Brieuc, English Channel). Aquatic Conservation-Marine and Freshwater Ecosystems. Cite
Besnard, L., Le Croizier, G., Galvan-Magana, F., Point, D., Kraffe, E., Ketchum, J., Martinez Rincon, R. O., & Schaal, G. (2021). Foraging depth depicts resource partitioning and contamination level in a pelagic shark assemblage: Insights from mercury stable isotopes. Environmental Pollution, 283, 117066. Cite
Burel, T., Grall, J., Schaal, G., Le Duff, M., & Ar Gall, E. (2020). Wave height vs. elevation effect on macroalgal dominated shores: an intercommunity study. Journal of Applied Phycology, 32(4), 2523–2534. Cite
Mathieu-Resuge, M., Le Grand, F., Schaal, G., Lluch-Cota, S. E., Racotta, I. S., & Kraffe, E. (2020). Specific regulations of gill membrane fatty acids in response to environmental variability reveal fitness differences between two suspension-feeding bivalves (Nodipecten subnodosus and Spondylus crassisquama). Conservation Physiology, 8, coaa079. Cite
Le Croizier, G., Lorrain, A., Schaal, G., Ketchum, J., Hoyos-Padilla, M., Besnard, L., Munaron, J.-M., Le Loc’h, F., & Point, D. (2020). Trophic resources and mercury exposure of two silvertip shark populations in the Northeast Pacific Ocean. Chemosphere, 253, 126645. Cite
Le Croizier, G., Lorrain, A., Sonke, J. E., Jaquemet, S., Schaal, G., Renedo, M., Besnard, L., Cherel, Y., & Point, D. (2020). Mercury isotopes as tracers of ecology and metabolism in two sympatric shark species. Environmental Pollution, 265(PT B), 114931. Cite
Jones, A. G., Quillien, N., Fabvre, A., Grall, J., Schaal, G., & Le Bris, H. (2020). Green macroalgae blooms (Ulva spp.) influence trophic ecology of juvenile flatfish differently in sandy beach nurseries. Marine Environmental Research, 154, UNSP 104843. Cite
Mathieu-Resuge, M., Le Grand, F., Schaal, G., Kraffe, E., Lorrain, A., Letourneur, Y., Lemonnier, H., Benoit, J., & Hochard, S. (2020). Assimilation of shrimp farm sediment by Holothuria scabra: a coupled fatty acid and stable isotope approach. Aquatic Living Resources, 33, 3. Cite
Le Croizier, G., Lorrain, A., Sonke, J. E., Hoyos-Padilla, E. M., Galvan-Magana, F., Santana-Morales, O., Aquino-Baleyto, M., Becerril-Garcia, E. E., Muntaner-Lopez, G., Ketchum, J., Block, B., Carlisle, A., Jorgensen, S. J., Besnard, L., Jung, A., Schaal, G., & Point, D. (2020). The Twilight Zone as a Major Foraging Habitat and Mercury Source for the Great White Shark. Environmental Science & Technology, 54(24), 15872–15882. Cite
Sturbois, A., De Caceres, M., Sanchez-Pinillos, M., Schaal, G., Gauthier, O., Le Mao, P., Ponsero, A., & Desroy, N. (2021). Extending community trajectory analysis: New metrics and representation. Ecological Modelling, 440, 109400. Cite
Le Croizier, G., Schaal, G., Point, D., Le Loc’h, F., Machu, E., Fall, M., Munaron, J.-M., Boye, A., Walter, P., Lae, R., & Tito-de-Morais, L. (2019). Stable isotope analyses revealed the influence of foraging habitat on mercury accumulation in tropical coastal marine fish. Science of the Total Environment, 650, 2129–2140. fdi:010074333 ; Cite
Mathieu-Resuge, M., Kraffe, E., Le Grand, F., Boens, A., Bideau, A., Lluch-Cota, S. E., Racotta, I. S., & Schaal, G. (2019). Trophic ecology of suspension-feeding bivalves inhabiting a north-eastern Pacific coastal lagoon: Comparison of different biomarkers. Marine Environmental Research, 145, 155–163. Cite
Mathieu-Resuge, M., Schaal, G., Kraffe, E., Corvaisier, R., Lebeau, O., Lluch-Cota, S. E., Salgado Garcia, R. L., Kainz, M. J., & Le Grand, F. (2019). Different particle sources in a bivalve species of a coastal lagoon: evidence from stable isotopes, fatty acids, and compound-specific stable isotopes. Marine Biology, 166(7), 89. Cite
Lelievre, Y., Sarrazin, J., Marticorena, J., Schaal, G., Day, T., Legendre, P., Hourdez, S., & Matabos, M. (2018). Biodiversity and trophic ecology of hydrothermal vent fauna associated with tubeworm assemblages on the Juan de Fuca Ridge. Biogeosciences, 15(9), 2629–2647. Cite
Liénart, C., Savoye, N., Bozec, Y., Breton, E., Conan, P., David, V., Feunteun, E., Grangeré, K., Kerhervé, P., Lebreton, B., Lefebvre, S., L’Helguen, S., Mousseau, L., Raimbault, P., Richard, P., Riera, P., Sauriau, P.-G., Schaal, G., Aubert, F., … Sultan, E. (2017). Dynamics of particulate organic matter composition in coastal systems: A spatio-temporal study at multi-systems scale. Progress in Oceanography, 156, 221–239. Cite
Gasmi, S., Bernard, I., Pouvreau, S., Maurer, D., Schaal, G., Ganthy, F., Cominassi, L., Allain, G., Sautour, B., & David, V. (2017). Spatial patterns in the condition index of the wild Pacific oyster Crassostrea gigas in a macrotidal coastal ecosystem: Influence of tidal processes and beyond. Journal of Sea Research, 119, 28–36. Cite
Quillien, N., Nordstrom, M. C., Schaal, G., Bonsdorff, E., & Grall, J. (2016). Opportunistic basal resource simplifies food web structure and functioning of a highly dynamic marine environment. Journal of Experimental Marine Biology and Ecology, 477, 92–102. Cite
Schaal, G., Nerot, C., Grall, J., Chouvelon, T., Lorrain, A., Mortillaro, J.-M., Savoye, N., Brind’Amour, A., Paulet, Y.-M., & Le Bris, H. (2016). Stable isotope ratios in bentho-demersal biota along a depth gradient in the Bay of Biscay: A multitrophic study. Estuarine Coastal and Shelf Science, 179, 201–206. fdi:010068095. Cite
Schaal, G., Leclerc, J.-C., Droual, G., Leroux, C., & Riera, P. (2016). Biodiversity and trophic structure of invertebrate assemblages associated with understorey red algae in a Laminaria digitata bed. Marine Biology Research, 12(5), 513–523. Cite
Le Croizier, G., Schaal, G., Gallon, R., Fall, M., Le Grand, F., Munaron, J.-M., Rouget, M.-L., Machu, E., Le Loc’h, F., Laë, R., & Tito-de-Morais, L. (2016). Trophic ecology influence on metal bioaccumulation in marine fish: Inference from stable isotope and fatty acid analyses. Science of the Total Environment, 573, 83–95. fdi:010068793. Cite
Chouvelon, T., Schaal, G., Grall, J., Pernet, F., Perdriau, M., A-Pernet, E. J., & Le Bris, H. (2015). Isotope and fatty acid trends along continental shelf depth gradients: Inshore versus offshore hydrological influences on benthic trophic functioning. Progress in Oceanography, 138, 158–175. Cite
Nerot, C., Meziane, T., Schaal, G., Grall, J., Lorrain, A., Paulet, Y.-M., & Kraffe, E. (2015). Spatial changes in fatty acids signatures of the great scallop Pecten maximus across the Bay of Biscay continental shelf. Continental Shelf Research, 109, 1–9. fdi:010065445. Cite
Schaal, G., & Grall, J. (2015). Microscale aspects in the diet of the limpet Patella vulgata L. Journal of the Marine Biological Association of the United Kingdom, 95(6), 1155–1162. Cite
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. Estuarine, Coastal and Shelf Science, 136, 149–156. Cite
Leclerc, J.-C., Riera, P., Leroux, C., Lévêque, L., Laurans, M., Schaal, G., & Davoult, D. (2013). Trophic significance of kelps in kelp communities in Brittany (France) inferred from isotopic comparisons. Marine Biology, 160(12), 3249–3258. Cite
Marchais, V., Schaal, G., Grall, J., Lorrain, A., Nerot, C., Richard, P., & Chauvaud, L. (2013). Spatial variability of stable isotope ratios in oysters (Crassostrea gigas) and primary producers along an estuarine gradient (Bay of Brest, France). Estuaries and Coasts, 36(4), 808–819. Cite
Schaal, G., Riera, P., & Leroux, C. (2012). Food web structure within kelp holdfasts (Laminaria): a stable isotope study. Marine Ecology, 33(3), 370–376. Cite
Schaal, G., Riera, P., Leroux, C., & Grall, J. (2010). A seasonal stable isotope survey of the food web associated to a peri-urban rocky shore. Marine Biology, 157(2), 283–294. Cite