Interspecific, ontogenetic and temporal variations in stable isotopes of small tuna species in the northeast Atlantic Ocean

• Published in: Isotopes in Environmental and Health Studies
• Main Authors: Muñoz-Lechuga, Rubén, Lino, Pedro G., González-Ortegón, Enrique
• Other Authors: Instituto Português do Mar e da Atmosfera
• Format: Article in Journal/Newspaper
• Language: English
• Published: Taylor & Francis 2024
• Subjects: Body-size; Carbon-13; Food web; Isotope ecology; Nitrogen-15; Scombridae fish family; Trophic discrimination factor; Trophic overlap; Northeast Atlantic
• Online Access: http://hdl.handle.net/10261/355489; https://doi.org/10.1080/10256016.2023.2289956

In order to study the trophic level of small tuna species and their contribution to the carbon flow in pelagic food webs, an analysis of carbon and nitrogen stable isotopes was carried out. The investigation was focused on four small tuna species (Auxis rochei, Auxis thazard, Euthynnus alletteratus and Sarda sarda) commonly harvested in the northeast Atlantic Ocean. The isotope analysis showed how the results for S. sarda are different from the rest of the species analysed, with a higher trophic level, similar to other major tuna species. The greatest niche overlap in δ13C and δ15N occurs among A. rochei, A. thazard and E. alletteratus. Auxis rochei and E. alletteratus showed a size-dependent variability in δ15N, and in δ13C for S. sarda. The small tuna S. sarda exhibits the highest migration rates among various geographical areas in comparison to other small pelagic tunas, and the seasonal variability of isotope values in the area studied can be attributed to the incorporation of larger individuals with a higher lipid content. The results of this work provide new information on the ecological role played by small tuna in food webs, which is more complex and varied than currently thought. This knowledge is essential for a more effective management of fisheries. Biological sampling for this study was conducted by the Portuguese Institute for the Ocean and Atmosphere (IPMA), within the scope of the EU Data Collection Framework (DCF/PNAB – Programa Nacional de Amostragem Biológica). Peer reviewed