Studies on heterotrophic nitrification in a lake. [Translation from: Z.allg.Mikrobiol. 12 567-574, 1973. ]

In a lake the nitrogen compounds are liable to regular cycling in which nitrate is reduced and ammonium oxidised. As a nitrate maximum is regularly established in the upper part of the hypolimnion of a stratified summer lake, the authors have dealt in particular with the oxidising side of the nitrogen cycle. Described here are partial results of the nitrification in Plusssee. The Plusssee was chosen, since it is almost entirely without inflows, and, lying in a wooded basin, is well protected from the wind, and therefore stably stratified. In order to determine the number of autotrophic nitrificants the distribution of the Nitrosomonas and Nitrobacter spores in the lake were analysed. From the estimates on the determination of spore numbers of the heterotrophic nitrificants, 14 species in the pure culture were isolated and examined from morphological, biochemical and taxonomic viewpoints.

Fundamental aspects of the feeding of the amphipod Gammarus (R.) balcanicus (Crustacea, Amphipoda). [Translation from: Nauchn.Dokl.vyssh.Shkoly (Biol.Nauk) 1970(7) 12-16, 1970]

The amphipods are major food items for many commercial fishes, and they are used as protein food for agricultural animals. In the present paper are presented the results of four-year observations on the feeding of Gammarus balcanicus in nature and in an aquarium. Among the studied aspects were the dependence of daily food ration on sex and physiological state (with and without eggs) and feeding on different kinds of plant food. The study concludes that Gammarus balcanicus willingly feed on soft half-decayed plant residues; into their ration also enters food of animal origin. In contrast to other amphipods, G. balcanicus eats representatives of its own species very rarely, and only dead or immobile ones.

On the diel rhythm of motor activity in perch [Translation from: Informatsionnyi Byulleten Biologiya Vnutrennikh Vod No.30, 12-14, 1976]

The river perch (Perca fluviatilis L.) is most active in the daytime hours, and displays seasonal changes of diel rhythm with a break of the rhythm in spring and autumn. In the present work data were obtained on the motor activity of 3 perch measuring l8-20 cm, caught by net in the littoral of a reservoir and spawned under laboratory conditions. The degree of intensity of movement of perch was judged by special experiments. The results are summarised in this short paper.

A study of the nutrition of the Rotifer Asplanchna, with the help of Carbon 14 [Translation from: Byulleten ' Instituta Biologii Vodokhranilishch, No. 12, pp.17-20, 1962]

Laboratory research was done in order to study the feeding of larval Cricotopus silvestris F. in relation to characters of structure of oral apparatus. Results of the experiments are summarised and the oral apparatus morhologically described.

The efficiency of plankton in the utilization of the sun radiation [Translation from: Briroda, 12, 29-35, 1948]

The efficiency of utilisation of the sun's radiation by natural communities has not been properly demonstrated with what so far has been obtained of reliable values, and it represents a great interest in many respects. A systematic study of the biotic balance of lakes was done in the course of a succession of summers starting in 1932, extensive material was obtained, which permitted to compute a value fear the utilisation of the sun's radiation by plankton in lakes, and to compare this with corresponding values for marine plankton and terrestrial vegetation.