CHANGES IN MACROINVERTEBRATE ASSEMBLAGES IN STREAMS UNDER ANTHROPOGENIC IMPACT

摘要

The anthropogenic impact on the distribution and biodiversity of benthic macroinvertebrates and water quality in four Lithuanian streams was studied. A total of 88 macro-invertebrate taxa (including 76 identified species) belonging to 47 families were identified in the investigated streams. The greatest species richness was recorded for the groups Trichoptera (20 species/1 taxa) and Chironomidae (18 species). The data obtained showed that reference streams differed from urban ones in the dominance of individual taxa. Significant differences were found in the abundance of pollution-tolerant Asellus aquaticus among the studied streams. These isopods were dominant in urban streams, while their abundance in the small reference stream was very low, and in the reference medium-sized stream, they were not found. Pollution sensitive Plecoptera were absent in urban streams, and Ephemeroptera also had lower abundance in urban streams compared to that in reference ones. Except for macroinvertebrate taxa richness (SR), % Trichoptera, % Chironomidae, % Scrapers, % Shredders, % Filterers, all other investigated metrics had at least one significant correlation with water quality variables. The Hilsen-hoff s biotic index (HBI) and % Isopoda were positively correlated with all water quality variables, (except PO_4-P).