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This study compares the present (1991-1993) breeding avifauna from the city of Olsztyn with that in the years 1954- 1968. Habitats changed significantly over the 25-year interval. A rise in the human population was associated with the expansion of residential and industrial districts and a consequent contraction of natural areas. Changes occurred between 1968 and 1993 in the diversity and dominance structure of the breeding avifauna. Chlidonias niger, Tringa totanus, Upupa epops, Luscinia svecica, Galerida cristata and Corvus frugilegus were lost from the city, while an additional 15 species declined. Nine species are currently endangered in the city, and will probably disappear in the near future. Urbanization meanwhile has favored 11 species that inhabit built-up areas or are undergoing synurbization. The appearance of Aythya ferina, Bucephala clangula, Mergus merganser and Columbia livia domestica as new breeding species reflects general trends towards increased populations in both Poland and the continent as a whole.
Results of investigations on the influence of introduction of various fish species to lake biocenosis on the parasite fauna of fishes are presented. Phytophagous fishes: Ctenopharyngodon idella, Hypophthalmichthys molitrix and Aristichthys nobilis, introduced to lakes Warniak and Dgał Wielki (Mazurian Lakeland) caused great changes in biocenoses of these lakes (destruction of aquatic plants followed by impoverishment of invertebrate fauna). An indirect bearing of these changes on the parasite fauna of native fishes was manifested either in a reduction of the quantity of some common parasites (Tylodelphys, Ergasilus) or in their increase (Ichthyocotylurus spp.). Some less common or numerous species of parasites showed a tendency to disappearance (e.g. acanthocephalans). The introduced fishes enriched the parasite fauna with 4 species. They were also susceptible to native parasite infections (Ergasilus, Diplostomum, Apharyngostrigea).
Aura
|
2004
|
nr 04
11-12
Polish agriculture differs from the agriculture in most EU countries as regards the break-up of arable land into small plots and moderately intensive agricultural management. Due to this, agricultural land in a number of Polish regions features a relatively high diversity. However, in lowlands of western, south-western and central Poland the agriculture has been intensified for a long time which has resulted in stronger human pressures on species populations and natural impoverishment. The author discusses these issues using Dezydery Chłapowski Landscape Park located in Turwia area (Wielkopolska region).
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