[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 effluents (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).