Helminths in Leuciscus cephalus from the river Adda, Lombardy, Northern Italy

Chubs (Leuciscus cephalus) were caught at various locations along the river Adda and from Lake of Como (Lombardy, Northern Italy) and endoparasitic helminths were studied in order to integrate the knowledge on distribution of helminth fauna of chubs in Lombardy and to investigate on the structure of its parasite infracommunities with respect to different habitat typologies. The following species of parasites were isolated: Pomphorynchus laevis, Allocreadium markewitschi, Parasymphylodora markewitschi, Raphidascaris acus, Hysterothylacium aduncum and Molnaria intestinalis. P laevis resulted the most common species (P = 56.52%). The mean abundances and the prevalence of helminths were different in chubs according to the sampling site. The mean abundances were lower in chubs sampled in the lake than those sampled in the river. Particularly, P. laevis showed the highest prevalences in fish captured in the river sites. The trematodes (P. markewitschi and A. markewitschi) seem to be more related with "lake" typology. These results are discussed and related to differences in life cycle of these parasites and to other factors like sampling period and the conditions of the aquatic sites that could influence the richness of parasite species.