Characterization of the association between fish juveniles and jellyfish in the Catalan coast (NW Mediterranean)

Abstract

Aquatic Sciences Meeting, Aquatic Sciences: Global And Regional Perspectives - North Meets South, 22-27 February 2015, Granada, SpainFish-jellyfish association is described as a temporary symbiosis believed to protect the fishes from predators and to provide them of food. Such biological interactions were studied close to Barcelona (Spain) during the summer period from 2011 to 2014. Jellyfish and their associated fishes were collected, counted, identified and measured; fish juvenile¿s behaviour was described by visual observations and videotaping; biomarkers were also analysed to determine both groups diet. Juveniles of Trachurus mediterraneus, Trachurus trachurus, and Caranx rhonchus were found associated to the scyphomedusae Rhizostoma pulmo and Cotylorhiza tuberculata. In both jellyfish species, the size of T. mediterraneus ranged between 8 and 56 mm, being small size classes (12-32 mm) predominant in C. tuberculata. No clear pattern was found between the number of fish and the medusa size but they were more abundant when swimming with C. tuberculata. Observations on juvenile behaviour showed they swam around jellyfish and they got into their oral arms when they scared. The study of these associations will help to understand the potential effect of jellyfish blooms in the survival and recruitment of some fish speciesPeer Reviewe