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The three-spined stickleback (Gasterosteus aculeatus) infection with Schistocephalus solidus in Hel marina (Puck Bay, Baltic Sea, Poland)

Abstract Parasitic relations between animals are very common in wild nature. In this paper, we studied levels of infection in three-spined stickleback with plerocercoids of Schistocephalus solidus from Puck Bay (Baltic Sea, Poland). The total prevalence of infection was 54.2%, while proportion of infected individuals was significantly higher for females than for males. The body width was found to be significantly positively correlated with the number and the weight of parasites. In spite of the increasing deterioration of the Baltic Sea ecosystem by excessive eutrophication and hypoxia, lower prevalence of infection compared to previous published data indicates that there are likely other factors than pollution affecting the life cycle of parasites and the level of parasitism.