Invasive fish species in ichthioecosystems of Western Polissya of Ukraine

Purpose. To study ichthyocenoses, species composition and the current state of fish populations in water bodies of the Western Polissya of Ukraine by focusing on their changes under the effect of invasive fish species. Methodology. Ichthyological studies were carried out in natural and artificial water bodies for various purposes in the Western Polissya of Ukraine during 2007-2017. In particular, fish surveys were carried out using beach seins and gill nets with different mesh sizes in the karst lakes Svityaz and Pischane from the Shatskiy National Nature Park, channel lakes Lyubyaz and Nobel from the Pripyat River basin, right-bank tributaries of the Pripyat Rivers including Styr and Goryn Rivers, Khrinnitske reservoir from the Styr River basin, fish ponds of Bochanitsa village and Progress LLC (Goryn River basin). The material for the study were both the populations of native and invasive fish species. Findings. The results of our own studies and data of other authors highlighted the issue of the spread of invasive fish species in water bodies of the river-lake network of Western Polissya of Ukraine, presented the diagrams of the distribution of these fish in different water bodies of different origins of the above-mentioned region. Originality. The greatest threat to the abundance of aboriginal fish species in this region was found to be self-reproducing populations of the brown bullhead (Ictalurus nebulosus), Amur sleeper (Percсottus glenіi), stone moroko or topmouth gudgeon (Pseudorasbora parva), three-spined (Gasterosteus aculeatus) and nine-spined (Punguitius punguitius) sticklebacks. In particular, the composition of their gut content during the spawning period included 95% of eggs of fish species, which spawned in spring, as shown in the diagrams presented in this paper. Practical Value. The proposed measures to be carried out at the national and regional levels will help prevent the ingress of new invasions and mitigate the impact of the existing ones on the ichthyocenoses of the reservoirs of Western Polissya of Ukraine. Key words: ichthyocenoses, invasive fish species, aboriginal ichthyofauna, Western Polissya.

HEMATOLOGICAL PARAMETERS AND PARASITE FAUNA OF AMUR SLEEPER PERCCOTTUS GLENII IN A SINGLE-SPECIES ICHTHYOCENOSIS OF A SMALL URBAN RESVOIR

The article presents the results of hematological and parasitological studies of Amur sleeper Perccottus glenii of a small reservoir of artificial origin located in the vicinity of Perm. In this reservoir, Amur sleep-er is the only representative of the ichthyofauna. The collection of material was carried out in the spring-summer period of 2019. A total of 55 specimens of Amur sleeper were studied (30 specimens on May 8 and 25 specimens on July 12). Significant differences were found in the majority of quantitative indicators of fish blood cells in the spring and summer periods: in summer, the number of hematopoietic cells is higher (except for lymphocytes and monocytes), and in general, the content of mature leukocytes in the blood microliter in summer is lower. The parasite fauna of Amur sleeper in the studied reservoir is ex-tremely impoverished and is represented by the infusoria Trichodina nigra, cestode Nippotaenia mogurndae and nematodes, the latter were not recorded in Amur sleeper in this reservoir previously. The relationship between hematological parameters and the extent of parasite invasion was revealed: in more infected fish the number of immature erythrocytes, protoleukocytes, as well as neutrophils and eosinophils is significantly higher. The large numbers of Amur sleeper in the studied reservoir, the absence of devel-opmental anomalies in all the studied specimens, and the low proportion of fish with blood cell patholo-gies indicate the relative well-being of the studied part of the Amur sleeper population.