δ13C and δ15N in yellow and silver eels (Anguilla anguilla, 1758) from different Mediterranean local stocks and their variation with body size and growth
F. Capoccioni
A E , C. Leone B , F. Giustini C , M. Brilli C , L. Buttazzoni A , R. Hanel D and E. Ciccotti B
+ Author Affiliations
- Author Affiliations
A Consiglio per la Ricerca in Agricoltura e l’Analisi dell’Economia Agraria, Centro di Ricerca ‘Zootecnia e Acquacoltura’, Via Salaria 31, I-00015 Monterotondo, Roma, Italy.
B Università degli Studi di Roma ‘Tor Vergata’, Dipartimento di Biologia, Via della Ricerca Scientifica snc, I-00173 Roma, Italy.
C Consiglio Nazionale delle Ricerche, Istituto di Geologia Ambientale e Geoingegneria, Area della Ricerca di Roma1, Via Salaria chilometro 29.300, I-00015 Monterotondo Stazione, Roma, Italy.
D Johann Heinrich von Thünen-Institut Federal Research Institute for Rural Areas Forestry and Fisheries, Institute of Fisheries Ecology, Herwigstraße 31, D-27572 Bremerhaven, Germany.
E Corresponding author. Email: fabrizio.capoccioni@crea.gov.it
Marine and Freshwater Research 72(8) 1208-1219 https://doi.org/10.1071/MF20144
Submitted: 10 May 2020 Accepted: 27 January 2021 Published: 22 March 2021
Abstract
The European eel, a catadromous endangered species, displays plasticity in phenotypic traits and in trophic behaviour, features that can eventually affect growth. The aim of this study was to compare variation in carbon (δ13C) and nitrogen (δ15N) stable isotopes in muscle tissue of the adult eel life stages (i.e. yellow and silver eel), as function of growth. Eel samples were obtained from nine sites across the Mediterranean region, that included seven coastal lagoons of different size and ecological structure, and two freshwater habitats corresponding to one river and one lake. A large variability was found in both δ13C and δ15N values, suggesting that eels fed over a broad range of potential food sources. Eels from each location showed specific range values of δ13C, in most sites irrespective of stage, reflecting lagoon- or freshwater-specific carbon sources. A positive correlation was found between individual δ15N values and annual growth rates, suggesting that eels generally seem to feed on prey of higher δ15N values among the trophic resources available in each foraging habitat. This allows individuals to grow faster and to attain earlier the pre-spawning phase (i.e. the silver stage). A better understanding of eel trophic ecology across different life stages and different habitats is one of the prerequisites for the effective management of local stocks.
Keywords: European eel, stable isotopes, coastal lagoons, freshwater habitats, feeding plasticity.
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