StatusThe thesis was presented on the 23 December, 2016
Approved by NCAA on the 16 February, 2017
Abstract– 1.63 Mb / in romanian
3.29 Mb /
Field of study: ichthyology, hydrobiology.
Aim of the thesis: to research in a complex manner the dynamics of migration and the role of biogenic macroelements (compounds of N, P, Si) and nutritive microelements (Se, Co, Mn, Fe) in the Dniester and Prut rivers under the influence of natural and anthropic factors.
Objectives: to research the migration of compounds of N (N-NH4+, N-NO2-, N-NO3-), P (Pmin, Porg), and Si in the Dniester and Prut rivers; to reveal the Se, Co, Mn, Fe regularities and level of accumulation in hydrobionts and to determine their importance in increasingthe fish culture productivity; to determine the microelementaccumulation coefficient and the role of some hydrobiont species in their migration process; to assess the role of different factors in the migration of biogenic elementcompounds; to appreciate the water quality; to elaborate recommendations on monitoring and sustainable use of aquatic resources.
Scientific novelty and originality. For the first time there was carried out a complex study of multiannual, spatial and seasonal dynamics of N, P, Si compounds in the Dniester and Prut rivers; established the functional dependence between the Ptot content and saprophytic bacteria number, the Si content and diatomic algae biomass, the P accumulation level and some molluscs body length; quantitatively described the regularities of Se, Co, Mn, Fe accumulation in hydrobionts; specified the Se, Co, Co+Mn, Co+Fe, Mn+Fe influence on the fish development in early ontogenesis and elaborated a procedure of intensification of the development of natural trophic basis in ponds.
Important scientific problem solved: scientific substantiation of nutritive macro- and microelement migration, their transformation and role in the aquatic ecosystem functioning, which conducted to the underlining of importance of these substances in the aquatic ecosystem eutrophication, establishing the stimulating and suppressing effects of nutritive microelements, determining the tolerance of aquatic organisms, for their later use at the elaboration of scientific proposals on increasing the fish culture productivity and rational exploitation of aquatic ecosystems.
Theoretical significance. Knowledge on the migration of nutritive macro- and microelements in dependence of the natural and anthropic factors, and their role in the water quality formation and eutrophication of Dniester and Prut ecosystems is enlarge. Established regularities on accumulation and influence of some nutritive elements on hydrobionts ground the determination of aquatic organism tolerance, description of aquatic ecosystem functioning and hydrobiocenosis productivity management.
Applicative significance. The results were included in reports on institutional, international (MIS ETC 1150, MIS ETC 1676) projects, grant from World Federation of Scientists; monitoring methodology is part of 2 guidelines; a patent was elaborated and obtained.
Implementation. The results are of high interest for the Ministry of Environment in ful filling the Strategy on biodiversity preservation and management of the district of hydrographic basin Danube-Prut and Black Sea; patented procedure was appreciated with gold medal and implemented in a private fish farm.