During the 1981-1996 period, qualitative and quantitative structure of oligachaeta communities as indicator of the eutrophication process was investigated in the lake Palic (the 2nd oxidation lake), Serbia (Yugoslavia). The mean annual number of oligochaetes was related to nutrient concentration (total nitrogen and total phosphorus). The analysed data for both oligochaete community and nutrients, leads to the conclusion that the second oxidation lake Palic can be classified as an highly eutrophic environment, with tendency towards dystrophic, particularly in past two years.

During the period from 11th May, 1991 to 5th March, 1994, seasonal study of the river Jablanica (Serbia, Yugoslavia) macrozoobenthos was carried out. Investigations were done of three sectors: in the upper, middle and down reach of the river, with the aim to estimate water quality changes by the changes in bottom fauna composition. Bottom fauna community was composed of 17 invertebrate groups with 100 taxa determined. The most diverse Oligochaeta (21 taxa) and Ephemeroptera (19 taxa). Macroinvertebrates diversity decreased downstream the river as a result of the pollutional degree increase. Saprobic indices were from 1.51 (sector 2) to 1.8 (sector 3).

In Yugoslavia, application of macrozoobenthos for the purpose of bioindication has been relatively limited. This communities has been used in conjugation with saprobiological methods, while biotic indexes have been unjustifiable used to a small extent. This paper shows the most significant biotic indexes used in the World and possibility of their application in Yugoslavia, as well as the necessity for their modification and elaboration of new ones specific to Yugoslav conditions.