Abstract
Studies on the role of Ceratophyllum demersum L. as a substratum for epiphytic midges in relation to lake status were conducted within two shallow polymictic lakes of Polesie Lubelskie. Lake Skomielno is classified as macrophyte dominated (MD), clear water state and Lake Syczyńskie represents phytoplankton dominated (PD), turbid water state. The results demonstrated that lake status is a determinant of community composition of epiphytic chironomids. Both species richness and abundance showed significantly higher values in the macrophyte dominated lake. The studied ecosystems differ in the composition of dominant chironomid taxa. In the clear state lake, the group of dominants included four taxa: Psectrocladius sp. (gr. sordidellus), Glyptotendipes sp., Ablabesmyia phatta and Paratanytarsus austriacus, the contribution of which changed during the studied months. In the turbid state lake two midge taxa dominated: Cricotopus sp. (gr. sylvestris) and Endochironomus albipennis. The CCA ordination showed the important differences between the studied lake types. In the MD lake, four environmental factors (temperature, chlorophyll-a, total P, P-PO4) influenced mostly the distribution and composition of epiphytic chironomids. In the MD lake, five variables (periphyton biomass, total suspension, N-NH4, total P, pH) affected the structure of midges.