Differentiated stable isotopes signatures between pre- and post-flexion larvae of Atlantic bluefin tuna (Thunnus thynnus) and of its associated tuna species of the Balearic Sea (NW Mediterranean). (June 2017)

• Record Type: Journal Article
• Authors: García, Alberto; Laiz-Carrión, Raúl; Uriarte, Amaya; Quintanilla, José M.; Morote, Elvira; Rodríguez, José M.; Alemany, Francisco
• Is Part Of: Deep sea research. Volume 140(2017)
• Page Start: 18
• Page End: 24
• Publication Date: 2017-06
• Subjects: Bluefin larvae -- Stable isotopes -- Trophic ecology -- Balearic Sea; Oceanography -- Periodicals; Ocean bottom -- Periodicals; Marine biology -- Periodicals; 551.46
• DOI: 10.1016/j.dsr2.2017.02.006
• Languages: English
• ISSNs: 0967-0645

Abstract

Abstract: The trophic ecology of bluefin tuna larvae ( Thunnus thynnus ) from the Balearic Sea, together with its co-existing tuna species such as albacore ( T. alalunga ), bullet ( Auxis rochei ) and little tunny ( Euthynnus alletteratus ) were examined by nitrogen and carbon stable isotope analyses. A total of 286 larvae were analyzed for this study, of which 72 larvae corresponded to bluefin, 57 to albacore, 81 to bullet tuna and 76 to little tunny. Tuna larvae were separated into the pre-flexion and post-flexion developmental stages. Within the size 3–9 mm standard length (SL), the stable isotope of nitrogen (δ 15 N) showed significant differences between species where bluefin tuna larvae ranked highest. Pre-flexion bluefin tuna and little tunny larvae showed significantly higher δ 15 N signatures than the post-flexion larvae. This effect is attributed to a biochemical trace of maternal δ 15 N signatures. However, neither albacore nor bullet tuna larvae showed this pattern in δ 15 N signatures, possibly owing to a compensation effect between lower maternal δ 15 N values transmitted to pre-flexion larvae and the early increase of δ 15 N values in post-flexion stages. One way ANOVA showed significant differences between species in the stable isotope ratio of carbon (δ 13 C) values, which suggests specific differences of carbon sources. Furthermore, a similar significant ontogenic effect between δ 13 C signatures of pre-flexion and post-flexion larvae is also evidenced in all four species. At pre-flexion stages, all species except bullet tuna larvae showed significant negative relationships between δ 15 N and larval standard length. At post-flexion stages, a significant linear relationship with larval size was only observed in albacore and bullet tuna larvae indicating a possible trophic shift towards early piscivory. With respect to δ 13 C values with larval size, all four species showed significant linear decreases. It may be explained by the metabolism of growth of somatic mass subject to modification of the relative carbon isotopic sources. In conclusion, the species' signatures of δ 15 N and δ 13 C indicate differentiated early life trophic niches. In addition, it is worth remarking the potential use of transgenerational isotopic transmission in future research applications.