Formation and ecological features of the parasite communities of redfish of the genus Sebastes (Perciformes: Sebastidae) in the Arctic Ocean

Thе study presents the ecological, zoogeographic, biotopic, ontogenetic, and phylogenetic features that contribute to the formation of diverse parasite communities in redfish of the genus Sebastes, which inhabit the Arctic Ocean. The study was conducted by performing a complete parasitological dissection on 956 individuals of redfish from three species. The detected parasites were identified and subjected to taxonomic, hostal, age-specific, eco-geographical, and quantitative analyses to understand the specific characteristics of the parasite fauna in these fishes. The study determined that parasite species belonging to the epicontinental, mesobenthic, and polyzonal ecological complexes were dominant, with a predominance of arctoboreal species. The species diversity of parasite communities in the ontogeny of redfish is influenced by their species, biotopical, and age-related trophic peculiarities. The variation in parasite communities’ structure among various species suggests that the ecological differentiation of redfish in the Sebastes species is influenced by the processes and sequence of their speciation in the incompletely spatially isolated biotopes. This sequence resulted in the offshore shift of distribution to deeper shelf, bathypelagic, and mesopelagic areas in the succession of redfish species: Sebastes viviparus → S. norvegicus → S. mentella. The opinion is provided regarding the species structure of the researched part of their ranges, based on the findings of analyzing the geographical features of their parasite communities. Life strategy of beaked redfish S. mentella as the phylogenetically youngest species of the genus Sebastes aiming at the extension of the distribution range and colonization of new biotopes induced the formation of the pelagic and demersal intrapopulation groupings.