Seasonal variation of parasite infection of three-spined stickleback [Gasterosteus aculeatus L.] in the Southern Baltic

Seasonal changes of infection were observed in the case of some species of ectoparasites: Trichodina domerguei domerguei, T. tenuidens, Gyrodactylus arcuatus, and Thersitina gasterostei, as well as for endoparasites: Glugea anomala, Schistocephalus solidus, Diphyllobothrium ditremum, and Proteocephalus filicollis. Same seasonal changes in frequency of developmental stages were observed in the case of females T. gasterostei. The highest level of infection with ectoparasites was observed in spring and summer and was probably an effect of increase of the reproductive activity with increase of temperature. Infection with tapeworms was generally low and was a result of feeding activity and fish diet.