Abstract: | The study has been made concerning the composition of and the relationships among: physico-chemical factors, abundance, number of species, biomass, heterotrophic and photoautotrophic components, and functional groups with regard to the feeding patterns of a river-reservoir system. The most outstanding results concerning the system as a whole are: 1, a relationship exists between the biomass of protozoa and the biomass of ciliates; 2, the most important functional groups, in terms of the number of species, are group III (ciliate “downstream” filter feeders) and group IV (ciliate “upxtream” filter feeders), and in terms of the abundance of specimens, the most important ones are groups III and V (raptorial feeders); 3, the division into functional groups according to feeding modes is similar in the river and the reservoir studied. This correlation is quite significant with regard to the number of species, the abundance of specimens, and between the samples taken from the two areas. |