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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.
A total of 142 individuals of Gasterosteus aculeatus L. and 22 individuals of Pungitius pungitius (L.) from several areas of the coastal waters of the Gdańsk Bay both brackish- and freshwater were examined for parasites. The survey was carried out within 1988-1991. Six parasite species, namely: Gyrodactylus arcuatus, Apatemon gracilis, Sphaerostomum bramae, Phyllodistomum folium, Neoechinorhynchus rutili, and Argulus foliaceus were recovered from sticklebacks caught in freshwater habitats; while the other 4 parasites: Apatemon annuligerum, Bothriocephalus sp., Schistocephalus solidus, Proteocephalus percae occurred only in fish from brackish-water areas. Additional 5 parasites: Trichodina domerguei, Diplostomum pungitii, Diplostomum spathaceum, Rhaphidascaris acus, and Thersitina gasterostei were recorded in fishes from both habitats.
Anisakis simplex stage 3 larvae found in herring were used to experimentally infect 155 sticklebacks and 6 nine-spined sticklebacks, caught in the Gdynia marina (Gulf of Gdańsk). The larvae were observed in the fish body cavity as early as 24 h after infection, only the sticklebacks being affected. Altogether, 50 live and 2 dead larvae were found in the stickleback body cavity. The infection prevalence and mean intensity were 13.6% and 2.4 larvae, respectively, from 1 to 8 larvae per fish being recorded. It is concluded that the stickleback may serve as a paratenic host for Anisakis simplex.
This paper analyses the changes in the level of infection with the freshwater parasite Schistocephalus solidus of the three-spined stickleback from the Gdynia Marina. Environmental factors such as salinity, pollution and eutrophication or the presence of other species affect the transmission of parasites. Infection indices have been increasing since the 1990s. Differences in the infection level of morphological forms were also found: this may be due to their environmental preferences.
Four species, one subspecies and one parasite marked to the genus were collected from the nine-spined stickleback Pungitius pungitius L. from the Gulf of Gdańsk and the mouth of Dead Vistula. Nine - spined stickleback was noted as a new host in Polish coastal water for five parasites: Glugea anomala (Microsporidia), Diplostomum spathaceum (Digenea – metacercariae) and Apatemon sp. (Digenea - incysted metacercariae), Hysterothylacium aduncum (Nematoda - third stage larvae) and Thersitina gasterostci (Copepoda). Earlier in this area have been obserwed only ciliates Tnchodina domerguei.
The annual reproductive cycle in two wild populations of three-spined stickleback was studied. Sticklebacks from the Dead Vistula River (Martwa Wisła) (brackish water) and the Oliva Stream (Potok Oliwski) (freshwater) were exposed to annual environmental changes in their natural habitats. Ovaries and livers (females), and testes and kidneys (males) were collected during 1–2 years. The gonadosomatic IG, hepatosomatic IH, nephrosomatic IN indices, kidney epithelium height (KEH) and size of oocytes were calculated. The number of mature oocytes and percentage of ovulating females were determined during the spawning season. Histological changes in the ovaries and testes were described throughout a year. Annual reproductive cycles were similar in both populations of sticklebacks. This is the first histological and morphological study carried out throughout a year, simultaneously in two wild populations of three-spined sticklebacks inhabiting different environments. An improved scale of gonadal development in conjunction with the determined indices and fecundity give a comprehensive description of the reproductive cycle. These newobserv ations, in combination with previously reported features, provide a universal scale that can be successfully used to distinguish all phases of gametogenesis in sticklebacks in different habitats.
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