Water level fluctuations as a major determinant of chironomid community structure in the inshore zone of a large temperate river
Reckendorfer, W.; Keckeis, H.; Winkler, G.; Schiemer, F.
The chironomid communities of two gravel banks in the free-flowing section of the River Danube were investigated from May to August 1994. The two sites differed significantly in grain size composition, current velocity, chironomid abundance and species richness. Seventy-four species of larval chironomids could be identified, most of them belonging to the subfamily Orthocladiinae. Sampling sites were characterized through an index that incorporates duration and intensity of dessication. This index is considered to express the level of disturbance. Chironomid densities were negatively correlated to index values. Species richness and diversity were highest at intermediate values as predicted by ecological theory. Evenness was positively related to the index, suggesting dominance of a few species in undisturbed, permanently flooded sites.