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Fresh faeces of dormice found in nestboxes along the permanent transect in Białowieża Forest were analysed. The study area was a managed forest of diverse biotopes. In total, 196 samples of faeces of the forest dormouse (Dryomys nitedula) and 62 of edible dormouse (Glis glis) were examined. In the faeces analysed, the following categories of food remains were distinguished: chitin carapaces, calcareous shells, feathers, seeds, plant fibres. In the forest dormouse, chitin carapaces were found in 100% of samples, but in only 8% of the edible dormouse samples. Feathers were noted in 36% of samples of forest dormouse faeces, but only in 12% of samples from the edible dormouse. Calcareous shells were found in 14% of forest dormouse samples and 1.6% of edible dormouse faeces. Remains of animal food were found in 100% of samples of forest dormouse excrements, but only in 29% of samples from the edible dormouse. The highest percent of faecal samples with animal remains was found in the edible dormouse in July, while in the forest dormouse seasonal variation occurred only in some types of animal remains. Most of the chitin carapaces identified in forest dormouse faeces came from Chilopoda (45%), Hemiptera (33%) and Coleoptera (22%). In faeces of the edible dormouse the majority were remains of butterflies (55%). The results presented here suggest an almost total separation of the food niches of the two dormouse species.
Hydroacoustical methods due to their very high resolution in time and space can be used to register subtle changes in fish distribution and behaviour, thus enabling observation of the effect of habitat modification upon the fish. A number of examples have been presented which show dependence between fish parameters measured acoustically (such as depth, density, degree of aggregation, length frequency distribution), and different environmental parameters characterising the habitat quality (trophic levels, presence of chemicals, littoral coverage, predation pressure, temperature and oxygen gradients). This suggest that by performing hydroacoustical monitoring one can measure fish reactions to the habitat changes on a scale and with an accuracy not available with other methods.
The results of hydroacoustical monitoring in three water ecosystems exposed to anthropogenic pressure are presented. One is Żarnowieckie Lake, where a hydroelectric power station is operating, the second is a system of three lakes that are periodically included in the cooling system of the Konin-Pątnów power plant, and the third, the Solina Reservoir, is a typical dam reservoir situated in a recreational, mountainous area. In all three ecosystems, the fish distribution, biomass and migrations showed different patterns dependent on the environmental conditions and their changes due to human activity. In Żarnowieckie Lake, fish abundance increased during summer about four-fold as the probable result of fish migration from littoral to pelagic water, while in the Konin lakes it decreased 2.7 times as the result of fish migration to the lakes affected by the power plant's operation. In the Solina Reservoir, fish abundance was 20 times lower than in the other two ecosystems, which was probably due to high fluctuations in the water level. This prevented the development of the littoral and affected fish breeding grounds.
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