Fatty acids and stable isotopes as tracers of food assimilation in fish-oyster-macroalgae integrated multitrophic aquaculture ponds

• Main Authors: Nahon, Sarah, Villa de Brito, Goncalo, Quental-Ferreira, Hugo, Aubin, Joël, Cunha, Maria Emilia
• Other Authors: Nutrition, Métabolisme, Aquaculture (NuMéA), Institut National de la Recherche Agronomique (INRA)-Université de Pau et des Pays de l'Adour (UPPA), Instituto Português de Investigação do Mar e da Atmosfera (IPMA), Sol Agro et hydrosystème Spatialisation (SAS), Institut National de la Recherche Agronomique (INRA)-AGROCAMPUS OUEST, European Aquaculture Society (EAS).
• Format: Conference Object
• Language: English
• Published: HAL CCSD 2018
• Subjects: food intake; fish; stable isotopes; interaction trophique; alimentation; aquaculture; système aquacole; poisson; huître; macroalgue; isotope stable; [SDV.BA]Life Sciences [q-bio]/Animal biology; [SDV.OT]Life Sciences [q-bio]/Other [q-bio.OT]; Imta; Crassostrea gigas
• Online Access: https://hal.science/hal-01913008; https://hal.science/hal-01913008/document; https://hal.science/hal-01913008/file/2018_Nahon_Aqua18_1.pdf

Résumé Résumé Integrated MultiTrophic Aquaculture (IMTA) is based on the production of fed species (e.g., finfish) along with extractive species which re-use the inorganic (e.g., seaweeds) and organic (e.g., suspension-feeders) nutrients excess. To increase the development of IMTA practices, it is important to understand the trophic relationship within the system. In Mediterranean earthen ponds, meagre (Argyrosomus regius), white seabream (Diplodus sargus) and mullet (Mugil chepalus) are three fish species of different trophic levels that are good candidates to be cultured with oysters (Crassostrea gigas) and sea lettuce (Ulva flexuosa) but their trophic behavior are not well known under polyculture. The aim of this study was to identify the food sources used by fish and oysters using fatty acids (FA) as well as carbon (δ13C) and nitrogen (δ15N) stable isotopes. Within the Era Net COFASP project IMTA-Effect, experiments were conducted in 6 earthen ponds at IPMA´s Estação de Piscicultura de Olhão, south of Portugal. Similar biomass and proportions of meagre, white seabream and mullet were introduced in each pond and three different combinations of organisms were tested: fish-oysters, fish-macroalgae, fishoysters-macroalgae. According to the combination, oyster spats were introduced while autochthonous macroalgae were let grown or removed from the ponds. Fish were fed daily with a commercial diet. At the end of the experiment, fish and oyster tissues were collected as well as all potential food sources present in ponds: commercial pellet, macroalgae, suspended particulate organic matter (SPOM) and polychetes. FA composition as well as δ13C and δ15N values of samples were determined. The combinations of organisms had no effect on FA composition of fish and oysters. FA composition of fish were significantly different between species. FA composition of meagre and white seabream was close to those of feed. FA composition of mullet was farther than those of feed with lower proportion of C18:1ꞷ9 and C18:2ꞷ6 and higher ...