Seasonality of metazoan ectoparasites in marine European flounderPlatichthys flesus(Teleostei: Pleuronectidae)

Abstract

SUMMARYSeasonal occurrence of metazoan ectoparasites is described for the first time in marine European flounder,Platichthys flesus(L.). The parasitofauna, in this study monitored during 1 year, was found to be similar to that previously recorded for flounder. Moreover, specimens ofCaligussp. Müller, 1785 andLepeophtheirus pectoralis(Copepoda: Caligidae),Acanthochondria cornuta(Copepoda: Chondracanthidae),Holobomolochus confusus(Copepoda: Bomolochidae) andNerocila orbignyi(Isopoda: Cymothoidae), and also, a praniza larva (Isopoda: Gnathiidae), were isolated. From these,L. pectoralisandA. cornutawere the dominant parasites in all samples of flounder, whileCaligussp.,H. confusus,N. orbignyiand the gnathiid praniza seemed to infect the flounder only occasionally. As far as the seasonality of infections is concerned, it differed considerably from that described for estuarine environments. Indeed, both prevalence and abundance ofL. pectoralisandA. cornutareached significant peaks in the summer, whereas the literature identifies the autumn as the season of maximum infection on estuarine flounder. Thus, the former period seems more favourable for the occurrence of epizooties ofL. pectoralisandA. cornutain flounder culturing systems running on seawater and operated in the studied or similar environments.