The effect of epiphytic macroinvertebrates on microbial communities in different types of macrophyte-dominated shallow lakes

Complex interactions between epiphytic fauna and microbial food webs in periphyton are vital to the ecosystem ecology of shallow lakes. However, little is known about how different types of macrophyte dominated lakes may influence microbial and metazoan communities. The goal of the present study was to examine the impact of metazoan on microbial food web in three different types of lakes (Stratiotes-dominated,Ceratophyllum-dominated andPotamogeton-dominated). The results of this study suggest a strong correlations between chironomid larvae, small Metazoa and microbial communities in the periphyton of macrophyte-dominated lakes. Weak relations between food web components were found in thePotamogeton-dominated andCeratophyllum-dominated lakes, where environmental variables explained the bulk of the total variance in periphyton abundance, whereas strong predator-prey relations were noted in theStratiotes-dominated lake, where environmental variables had a minor role in the total variance in periphyton abundance. Our study contributes to knowledge of the functioning of eutrophic lakes in the current era of increasing eutrophication caused by climate change and human activity.

Comparison of gastrotrich fauna on elodeids and in bottom sediments of lakes of different trophic status (the region Polesie Lubelskie, Eastern Poland)

Species diversity of gastrotrich communities on elodeids and in bottom sediments of lakes of different trophic status was compared. Thirty-eight species of Gastrotricha (34 in bottom sediment and 21 on elodeids) were found, which belong to the only family of Chaetonotidae Zelinka, 1889. Species diversity of both habitats was reflected in the diversity indices ranging from 2.02 (a dystrophic lake) to 2.67 (a strongly eutrophic lake) for bottom sediment, and from 2.01 (a mesotrophic lake) to 2.54 (a strongly eutrophic lake) for elodeids. The similarity of gastrotrich fauna from the two habitats was low, and varied from 17% (a mesotrophic lake) to 38% (a strongly eutrophic lake). Low similarity of elodeid fauna from lakes of different trophic status was also found, in spite of similar plant species composition. The lowest similarity in elodeid fauna (23%) was recorded for dystrophic and mesotrophic lakes, whereas the highest one (68%) was observed for eutrophic and strongly eutrophic lakes. That allows to conclude that the diversity of epiphytic fauna is affected by trophic status rather than by vegetation type. The comparison of the gastrotrich fauna from elodeids and bottom sediments in lakes of different trophic status provides additional autoecological characteristics of Heterolepidoderma ocellatum (Mečnikow, 1865) and allows to recognize this species as belonging to a group of species closely related to macrophytes.

The food preferences of three-spined stickleback, Gasterosteus aculeatus L., downstream from a dam reservoir

The food preferences of three-spined stickleback,Submersed plants appeared in the impounded section of the Warta River as a consequence of low discharge in summer and were colonized by epiphytic fauna dominated by