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The aim of the study was to determine the contribution of pikeperch aged 0 + (Lt <10 cm) to the ichthyofauna structure as an indicator of the reproductive success of this species in Lake Miejskie where biomanipulation was performed. The treatment was carried out in late summer 2006, and comprised stocking the lake with the predatory fish species pike, pikeperch, European catfish, and eel. Gillnet monitoring catches were performed in the lake three times before biomanipulation in 2006, and then three times throughout 2007 after it. Overall, 14 fish species were noted, including four species of predatory fish. After biomanipulation, the share of predatory fish in the ichthyofauna abundance structure increased from 3.2% to 8.9%. Before biomanipulation, pikeperch accounted for more than half of the share of predators, approximately 23% of which was 0 + pikeperch juveniles (TL10 cm). Because of the fourfold increase in the number of 0 + pikeperch individuals one year after biomanipulation, the overall share of pikeperch among predators had increased to over 91%.
This study aimed to determine the species spectrum and abundance of zoopleuston in five small water bodies in different types of peatlands in Roztocze National Park in 2012. The highest number of taxa and density occurred in transitional bogs. The results of DCA analysis showed distinct grouping of zoopleuston communities, depending on bog type. The studied group of organisms had a strong gradient depending on the bog type correlated with the concentration of chlorophyll-a, suspension, and concentrations of inorganic nutrients in the habitat.
The knowledge on the ichthyofauna community in forest complexes in our country is mainly limited to few information on fish species found in rivers and reservoirs located in the protected areas. Hence, the aim of present study was to evaluate the importance of forested and non−forested areas, which include small rivers, on the occurrence of fish communities. The main criteria of evaluation were species richness, biodiversity and density of fish from rivers located in forested and non−forested areas in Roztocze and Puszcza Solska (south−eastern of Poland). The 12 study sites in the two groups of small rivers located on forested and non−forested areas were chosen (tab. 1). The control fishing was performed by electrofishing using IUP−12 gear. The total of 779 individuals of fish and lamprey belonging to 22 species were caught during the study. In the sections of rivers located in non−forested areas we noted 18 species, while in the rivers in forested areas – 16 ones. The analysis of the abundance domination showed that the dominant species in the rivers sections on non−forested areas were perch, roach and gudgeon, while in rivers located in forested areas: gudgeon, dace and brown trout. Simultaneously, in abundance of fish fauna from rivers in forested area a significant share of eastern sculpin, burbot and European brook lamprey were noted. The fish communities from both habitats showed similar values of biological diversity indices, but slightly higher density was observed in the rivers located in non−forested areas. The fish species composition was highly dependent on the close surroundings of the watercourse and the type of riparian zone. For the habitats from river located in non−forested areas the common, associated with aquaculture and also invasive fish species were characteristic. However, in the rivers in wooded areas, the typical for small streams and the rheophilic fish species were more frequent. The results of present study showed, that the largest differences in the dominance in fish structure and indicators of fidelity to the habitat preferences between the groups of rivers were determined.
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