The impact of the spatial structure of hydromacrophytes on the similarity of rotifera communities (Budzynskie Lake, Poland)

The hydrobiological research was carried out on the shallow and macrophyte-dominated Lake Budzynskie (Wielkopolski National Park, Poland). Biometric parameters (such as length of stems and dry weight) of particular plant associations (Charetum tomentosae, Myriophylletum verticillati, Potametum natantis, and Typhetum angustifoliae) were analysed. Additionally, the dry biomass of periphyton obtained from the rinsing of each type of plant was estimated, in order to compare the content of periphyton adequate to I litre of water in each particular phytocoenosis. Macrophyte beds with Myriophyllum verticillatum and Chara tomentosa were characterised by significantly higher scale values of periphyton, contrary to the macrophyte beds represented by Typha angustifolia and Potamogeton natans. These results were connected with the differences in the density and the morphological build of particular plant species. However, the analysis of the mean value of the similarity of rotifer community between particular macrophyte stations revealed that the stands of floating and emerged macrophytes, which were of the 'sparse' spatial structure and low values of chemical variables obtained from periphyton, were of the highest similarity. A second group, consisting of both species of submerged macrophytes, which was characterised by 'dense' spatial structure and high values of chemical variables, was distinguished but the level of similarity of the rotifera community was lower.