Parasites of sculpins (Teleostei: Agonidae, Cottidae, Psychrolutidae) in the Barents Sea

Abstract Little information is available on the parasite faunas of marine sculpins. These small fish play an important role in ecosystem function by transferring energy through the food web, in which they fill an intermediate position. Fish were collected during research vessel cruises in the Barents Sea between 2015 and 2021. Ten different sculpin species, totalling 267 fish, were examined for protozoan and metazoan parasites. All parasites were identified morphologically, and some ascaridoid nematode larvae were also identified molecularly. Twenty-seven different parasite taxa were recorded, of which 15 were identified to species level, and 28 new host records were reported. The most frequently occurring of the major taxonomic groups were adult trematodes and larval nematodes. The use of parasite data on trophically transmitted parasites as indicators of host diet suggests mainly demersal feeding with little evidence of feeding on pelagic organisms. The main difference between the parasite faunas of freshwater and marine sculpins is in their trematode faunas: freshwater sculpins tend to have more larval forms and marine sculpins more adults. The frequent occurrence of larvae of the nematode genera Contracaecum and Phocanema suggests an important role for sculpins, particularly Triglops murrayi , as transmitters of these nematodes to their pinniped definitive hosts. Evidence from the spatial distribution of a monogenean with a direct single-host life cycle suggests a sedentary lifestyle which makes sculpins and their parasites potentially useful sentinel species in studies of marine pollution.