engleski

Trophic ecology shapes gastrointestinal helminth communities of two sympatric mesopredatory sharks in the Adriatic Sea

We investigated and compared the structure of parasite communities in two sympatric, commercially exploited sharks. We analysed 188 gastrointestinal tracts from a crustacean- feeder Mustelus punctulatus and 157 gastrointestinal tracts from a piscivorous Squalus acanthias. The overall prevalence of helminth parasites was very high (84.0%) for M. punctulatus with nematode Cucullanus micropapillatus as the most abundant species (mean abundance 13.96) and Anisakis spp. larvae as the most prevalent taxa (47.9%). In contrast, only 21.7% of S. acanthias specimens were infected, showing Anisakis spp. larvae as the most prevalent (17.8%) and abundant taxa (mean abundance 0.39). The subsample of Anisakis spp. larvae, isolated from both hosts, was molecularly identified at ITS locus as A. pegreffii. Significant variations among size classes were recorded for M. punctulatus, mainly as a consequence of higher C. micropapillatus loads in larger sharks. Seasonal patterns in prevalence and abundance of C. micropapillatus were recorded for M. punctulatus, with peaks in autumn, while Anisakis spp. larvae prevailed during spring, for both sharks. Sex contributed little to the observed parasite abundances, although female spiny dogfish were more prone to infections than males, and higher helminth diversity was recorded in females in both shark species. The differences in infection parameters between the two shark species likely reflect the variations in foraging strategies and availability of intermediate hosts. Our findings suggest that crustacean feeder M. punctulatus is more susceptible to helminth infections in the Adriatic Sea, which may affect the health status of local shark populations.

Squalus acanthias; Mustelus punctulatus; parasite prevalence; mean abundance; Brillouin’s diversity index; Adriatic Sea

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