Dynamics and distribution of macrozoobenthos in the Toplica river, a tributary of the Kolubara

Abstract

Hydrobiological investigations of the macrozoobenthos were carried out at eight localities in the Toplica river (a right-hand tributary of the Kolubara river) from April 2000 to January 2001. The bottom fauna was composed of 19 groups of macroinvertebrates with 85 determined taxa (61 identified to the species level, 24 to the generic level). The most varying groups were the insect orders Trichoptera (20 taxa), Ephemeroptera (15), and Diptera (13), while Isopoda, Decapoda, and insects belonging to orders Collembola, Heteroptera, Megaloptera, and Planipennia were the most uniform. The species Gammarus pulex fossarum Koch and Dugesia gonocephala Duges were the most abundant forms at the river source, and representatives of Ephemeroptera and Gammaridae were the most numerous in its upper course (at the second, third, and fourth locality). The Mollusca and Chironomidae larvae were the most abundant forms at the fifth locality (in the middle course), but no constant dominance of any animal group was recorded at the sixth one, where the dominance alternated among Chironomidae larvae (April, July 2000), Oligochaeta (October 2000) and Mollusca (January 2001). The lower course of the river (the seventh and eighth locality) was characterized by the dominance of the species of the phylum Mollusca (Amphimelania holandri Ferussac, Fagotia esperi Ferussac and Theodoxus transversalis Pfeiffer).