CENTRAL MEDITERRANEAN ECOSYSTEMS Trophic relationships between anchovy (Engraulis encrasicolus) and zooplankton in the Strait of Sicily (Central Mediterranean sea): a stable isotope approach Paola Rumolo . Emanuela Fanelli . Marco Barra . Gualtiero Basilone . Simona Genovese . Serena Gherardi . Rosalia Ferreri . Antonella Gargano . Salvatore Mazzola . Angelo Bonanno Received: 16 February 2017 / Revised: 27 July 2017 / Accepted: 1 August 2017 Ó Springer International Publishing AG 2017 Abstract The study of the relationships among environmental factors, primary production, zooplank- ton community, and feeding behavior of fish species represents a key aspect to obtain a deeper knowledge of biological processes acting at ecosystem level. In this context, oceanographic data and biological sam- ples were collected in two different surveys, carried out during late June 2011 and early July 2015 in the Strait of Sicily (Central Mediterranean Sea). Differ- ences in abundance, biomass, and assemblage struc- ture of zooplankton and anchovy (Engraulis encrasicolus Linnaeus, 1758) population were observed between the two surveys. Still, zooplankton biomass was significantly correlated to longitude, chlorophyll a recorded during the surveys (as a proxy of primary production), and oxygen concentrations. Such differences affected the isotopic composition of anchovy, which showed changes in d 15 N and d 13 C values between the two surveys. Mixing models identified different contributions of food sources in the two sampling periods, i.e., major consumption on large copepods and euphausiids in 2015 with respect to 2011, which was consistent with a greater avail- ability of these preys in the environment in 2015. The obtained results evidenced that E. encrasicolus may be affected by any environmental change that influences the plankton community, which is the basis of the diet of these fishes. Such findings highlighted the impor- tance to further investigate the trophic relationships among different compartments of the food web, as well as the possible environmental influences, in order to obtain a more complete picture of ecosystem functioning and also in the light of an ecosystem- based approach to fisheries management. Keywords Zooplankton Á Small pelagic fish Á Bayesian mixing models Á Environmental drivers Á Mediterranean Sea Introduction The European anchovy (Engraulis encrasicolus Lin- naeus, 1758) is the most important small pelagic fish in the Mediterranean Sea both in terms of biomass and Guest editors: Angelo Bonanno, Othman Jarboui, Salem Wniss Zgozi, Roberta Mifsud & Luca Ceriola / Marine Ecosystems and Living Resources in the Central Mediterranean Sea P. Rumolo (&) Á M. Barra Á S. Gherardi IAMC-CNR Sede di Napoli, Calata Porta di Massa, 80100 Naples, Italy e-mail: paola.rumolo@iamc.cnr.it E. Fanelli ENEA, Marine Environment Research Centre, Santa Teresa Pozzuolo di Lerici, 19100 La Spezia, Italy G. Basilone Á S. Genovese Á R. Ferreri Á A. Gargano Á S. Mazzola Á A. Bonanno IAMC-CNR UOS di Capo Granitola, Via del Mare, 3 Torretta Granitola, 91021 Campobello di Mazara, Italy 123 Hydrobiologia DOI 10.1007/s10750-017-3334-9