MEPS prepress abstract  -  DOI: https://doi.org/10.3354/meps12332

Assessing trophic interactions of the jellyfish Pelagia noctiluca in the NW Mediterranean: evidence from stable isotope signatures and fatty acid composition

Uxue Tilves*, Verónica L. Fuentes, Giacomo Milisenda, Christopher C. Parrish, Salvatrice Vizzini, Ana Sabatés

*Email: tilves@icm.csic.es

ABSTRACT: We investigated the trophic interactions of one of the most abundant and conspicuous jellyfish, Pelagia noctiluca (medusae and ephyrae), on the Catalan coast located in the NW Mediterranean. A combination of stable isotope and fatty acid analyses was used to obtain a broad picture of the feeding habits of the jellyfish in order to understand their potential interactions with the most abundant fish species (larvae and adults) during summer in the area. The results suggested that, in addition to the predation of fish larvae by P. noctiluca, this jellyfish had similar feeding requirements to those of most fish larvae, suggesting a potential competition. The trophic niche of medusae and ephyrae overlapped highly with that of larvae of Engraulis. encrasicolus, Trachurus mediterraneus, Sardinella aurita and to a lesser extent with that of Serranus hepatus, Sparus pagrus and Mullus barbatus. Nevertheless no overlap was observed with Arnoglossus sp. larvae and adult E. encrasicolus, Sardina pilchardus, T. mediterraneus and S. aurita. Our findings demonstrated that P. noctiluca could be an important predator and competitor for fish larvae, but not for adult fish. Moreover, salps were found to be a significant food source for P. noctiluca.