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Occurrence of parasitic Metazoa of bream (Abramis brama) in the natural and artificial reservoirs in Poland. The occurrence of parasitic Metazoa of bream in Poland was analyzed. Three types of reservoirs were studied - lakes, lakes heated with thermal effluents and artificial reservoirs. The estimated model S = 3.367 * ln(N) - 1.192 described relationship between sample size and richness of the component community of bream parasites in lakes. On the basis of this model the confidence intervals for each artificial reservoir and thermally affected lake were computed. The richness of the component communitites of bream did not depend on the type of reservoir (natural vs. Artificial). It was affected by the thermal eftluents (richer communities in heated lakes), geographical isolation of the reservoir, and young age of the reservoir. Most spectacular influence of the artificial origin of the reservoir was found in Monogenea (group missing in 5-year old reservoir) and Acanthocephalus anguillae (present in 1 out of 4 artificial reservoirs).
A total of 183 eel, Anguilla anguilla (L.), individuals (measuring 34-84 cm l.t.) caught from five areas of the Szczecin Lagoon and the River Odra mouth area were examined. They were found to house 13 parasitic species, three of which (Bothriocephalus claviceps, Proteocephalus macrocephalus, and Ergasilus sieboldi) being frequent. Acanthocephalus lucii was a relatively frequent parasite, too. The remaining 9 species, i.e., Azygia lucii, Deropristis inflata, Ichthyocotylurs platycephalus (metacercariae), Raphidascaris acus, Camallanus lacustris, Eustrongylides excisus (larva), Acanthocephalus anguillae, Ergasilus gibbus, and Argulus foliaceus were rather rare. The areas the fish were obtained from differed to some extent in the degree of infection. The lowest number of parasites was found off Lubin (5 species) and in the Odra mouth area (6 species), while fishing grounds off Trzebież yielded the highest number of parasitic species (12). The differences are related to environmental conditions being different in the individual areas.
Comparative study of microfossils from two kinds of sediments: chert intercalations (studied in thin section) and phosphorite/phosphatic carbonate (in thin section and maceration), from the upper Neoproterozoic Doushantuo phosphorites in the Weng’an area, Guizhou Province, South China, shows that the phosphatized Megasphaera ornata and the chert−preserved Tianzhushania tuberifera should be regarded as representing the same taxon preserved by different mineralization processes. In phosphatized specimens the outer wall is often peeled off, exposing the ornamented middle wall. Some phosphatized specimens isolated from the rock matrix and specimens seen in thin sections of phosphorites show a partly preserved outer wall with spines, which can be compared to the thin−sectioned specimens from the chert beds. The small pits usually seen on the surface of the ornamented middle wall of phosphatized specimens correspond to the attachment spots of the spines in the outer wall. The presence of a spiny outer wall is a characteristic of Tianzhushania Yin and Li, 1978. Tianzhushania ornata (Xiao and Knoll, 2000) comb. nov. is here proposed as the valid name for the species. The proposed resting−egg nature of T. ornata, mainly based on the ornament type of the middle wall, cannot be excluded. The presence of a spiny outer wall, however, suggests that it is a pelagic rather than a benthic form.
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