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The investigations of the microflora and some groups of microfauna in the protected ecosystem of Zasavica [Serbia, Yugoslavia]
1998
Ratajac, R. (Poljoprivredni fakultet, Novi Sad (Yugoslavia)) | Rajkovic, D. | Stojkovic, S. | Bobic, M.
The protected natural goods of the swamp Zasavica is situated in the north part of Macva (Serbia, Yugoslavia). It is parallel to the flow of the Sava river, which leads to the fact that it used to be the riverbed of the Sava and also of the Drina river. It is interesting for its variety of the plant and animal species. The investigations have been done during autumn period 1997, when the investigated groups were the most heterogeneous. It included algae, Rotatoria,Cladocera, Copepoda and Hydracarina. Among algae, Bacillariophyta were dominant. Among all the investigated groups Rotatoria were the most heterogenous, with great number of the species that are rarely present. Also, some Cladocera species were rare. The estimation of the water quality is given according to the bioindicator species.
Afficher plus [+] Moins [-]The establishing of ichthyological status of the Nisava river (Serbia, Yugoslavia) with special review of fishes' hematology
1998
Brankovic, S. (Fakultet zastite na radu, Nis (Yugoslavia)) | Ciric, B. | Stankovic, M.
Biosystematic research of fish population from the river Nisava (Serbia, Yugoslavia) is placed from the mouth of Jerma river and Nisava river to the mouth of Nisava river and Juzna Morava river (Serbia, Yugoslavia). The next part of the research is about determining the methodology for counting of particular fish species in the river Nisava. Hematological analyses of some species were done at the same time in order to establish the relation between water quality and number of erythrocytes, leucocytes and quantity of haemoglobin. Two autochthonous and allochthonous species were analyzed. The method used in this research are explained as well.
Afficher plus [+] Moins [-]Biomanipulation in eutrophication process control
1998
Maletin, S. (Univerzitet u Novom Sadu, Novi Sad (Yugoslavia). Poljoprivredni fakultet) | Djukic, N. | Miljanovic, B. | Teodorovic, I.
Amplified and accelerated eutrophication process is a characteritic of a whole variety of small and medium-sized water-bodies, such as channel systems, microreservoirs, ponds, lakes and bank regions of many even bigger ecosystems. During the process, in relatively short period of time, the upper capacity limit of a certain biotop is far too exceeded, which leads to reduced ability of ecosystem's autopurification. As a consequence of such degradation, ecosystem faces a serious discrepancy between members of a biocenosis e.g. in ration producers/consumers/decomposers, which, in the end, causes destruction, e.g. dystrophy of the hydroecosystem. The introduction of diverse fish communities, can, therefore, be one of the basic measures for enabling a sustainable trophic stability, in a sense of keeping a dynamic balance. This measure includes carefully planed fish community - it should consist of three basic components of a trophic food web (planktivore and macrophytovore, bentivore and carnivore). Apart from enabling certain biodiversity considering particular fish species (both quantitative and qualitative), care must be inevitably taken of age structure, as well as fish stock and fishing dynamic, concerning the number, quantity and age.
Afficher plus [+] Moins [-]Water quality modeling and controlled successions of ichthyofauna
1998
Djordjevic, B. | Milanovic, T. (Univerzitet u Beogradu, Beograd (Yugoslavia). Gradjevinski fakultet)
Mathematical modles and adequate investigation works enables successful water quality modeling. These models includes all relevant abiotic components (concentration of dissolved oxygen, temperature regimes and temperature stratification, concentration of organic and inorganic components of physical-chemical water conditions), while the biotic components are present only with phyto- and zooplankton. In new water reservoir, ichthyofauna mostly undergo mancontrolled successions, starting with planned stocking a water reservoir with fish. The paper presents analytical approach for mathematical modeling of ichthyofauna and application of Lotka - Volterr's equations.
Afficher plus [+] Moins [-]Effects of Afforestation on Acidity and Invertebrates in Danish Streams and Implications for Freshwater Communities in Denmark
1998
Friberg, Nikolai | Rebsdrof, Aage | Larsen, Søren
The relationship between acidity and benthic invertebrate communities was investigated in two small streams in coniferous forests in central Jutland, Denmark, during 1992 and 1993. Stream pH was acid (mean pH 4.8 and 5.4) and alkalinity fluctuated greatly with mean values around zero. During rain events, water from springfed reaches upstream were mixed downstream with brown humic acid water with high aluminium content, and pH declined from circumneutral near the springs down to pH below 4 over a very short distance (0.5–1.5 km). The benthic invertebrate communities in the most acidic downstream reaches of both streams were dominated by filipalpian stoneflies, mainly Leuctra nigra (Olv.). Community composition remained very similar throughout the sampling period despite variations in pH. In the upper (neutral) reaches invertebrates intolerant of low pH such as Gammarus pulex L. were found. The concentrations of chloride and sulphate in the streams were more than double the concentrations in a nearby moorland stream indicating a strong impact of acidifying atmospheric deposition on the two forest streams. Results of this study indicate that afforestation with conifers on sandy Danish soils with low buffering capacity (about 25% of the total Danish land area) may lead to an increased acidification of surface waters and thereby also to an impoverished aquatic fauna.
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