COMPARISON OF BIOLOGICAL INDICES FOR THE ASSESSMENT OF THE STATUS OF LITHUANIAN MEDIUM-SIZED STREAMS

摘要

The status of three Lithuanian medium-sized streams: a forested natural stream, an agricultural natural stream and a straightened stream, receiving diffused pollution from agricultural lands, was evaluated in spring, summer and autumn 2008 using selected physicochemical variables and macroinvertebrate analysis. Taxonomic composition of invertebrate macrofauna was used for calculation of the following biotic indices: the Danish Stream Fauna Index (DSFI), Hilsenhoff Biotic Index (HBI), Biological Monitoring Working Party (BMWP), Average Score per Taxon (ASPT), Belgian Biotic Index (BBI) and Extended Biotic Index (IBE). The data obtained show that water quality was of class 1 in the forested natural stream, of class 3 in the agricultural natural stream and of class 4 in the agricultural channelized stream (on a five-class scale), according to NO3-N and N total values. It was concluded that BMWP, ASPT, BBI and IBE indices tend to assign stream water to a higher water quality class than DSFI and HBI do. According to BMWP, BBI and IBE indices, good water quality was found even in the agricultural natural stream, where water quality was moderate according to NO3-N and NT values.