Hydrobiological studies on the Tugela river system

Summary A chemical and biological survey of the Tugela river, Natal is described. Some relationships between physical and chemical conditions in the river and the geology and climate of the basin are indicated. The flora and fauna of the main river is described, and the zonation of species in the river, and seasonal variations in the communities at various stations in the zones are delineated.Some relationships between the physical and chemical conditions in the basin, and the distribution and seasonal variations of the biological communities are indicated. Comparisons are made with other rivers. It is concluded that the Tugela river as a type in Southern Africa, falls intermediate between temperate and sub-tropical conditions.     

Hydrobiological studies on the Vaal River in the Vereeniging area

Summary This paper deals with the chemical, bacteriological and faunal studies on the muddy bottom deposits of the Vaal River near Vereeniging, in a 64 kilometre section where it is held back by a barrage. No significant sewage pollution or other forms of organic pollution were found to occur but pollution by copper and mineral oil was found at one sampling station. Attempts to relate chemical, bacteriological and faunal results were largely negative except that high sulphide figures were normally accompanied by higher counts of oligochaetes than usual. The pollution with copper and mineral oil practically eliminated the fauna but had no obvious effects on the bacteriological results. On the whole the bottom fauna was rather sparse and poor in variety. This was attributed mainly to the regular deposition of fine, clayey silt.

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Zusammenfassung Dieser Artikel enthält chemische, bakteriologische und faunale Studien über die schlammigen Bodensedimente des Vaal-Flusses nahe Vereeniging, in einer Entfernung von 64 Kilometern, wo er durch ein Stauwerk zurückgehalten wird. Es wurden keine nennenswerte Abwasserverunreinigung oder andere Formen organischer Verunreinigung angetroffen. Bei einer Stelle der Probenentnahme wurde jedoch Verunreinigung durch Kupfer and Mineralöl angetroffen. Versuche, Beziehungen zwischen den chemischen, bakteriologischen und faunalen Ergebnissen herzustellen, fiel weitgehend negativ aus, mit Ausnahme von dem hohen Sulphidgehalt, der meistens von einer größeren Anzahl Oligochaeten als gewöhnlich begleitet wurde. Die Verunreinigung durch Kupfer and Mineralöl schaltete praktisch die Fauna aus, hatte jedoch keine offensicht-liche Auswirkung auf die bakteriologischen Ergebnisse. Im großen und ganzen war die Bodenfauna ziemlich spärlich und wies keine großen Variationen auf. Dies war hauptsächlich zurückzuführen auf eine regelmäßige Ablagerung von feinem, tonartigem Material.

     

Hydrobiological studies with reference to sudden fish mortality

Summary Hydrobiological investigation of Gandhisagar (Nagpur) was undertaken with a view to finding out the causes of sudden fish mortality. Extensive observations carried out for over a period of several weeks, prior to, during and after mortality, have led us to the conclusion that depletion of dissolved oxygen was the main cause of sudden fish mortality.The depletion of Oxygen was brought about by several factors, viz., the depletion of phytoplankton resulting in the lesser evolution of oxygen, the gradual increase in the zooplankton which reached the maximum on the day of the fish mortality, resulting in the increased consumption of Oxygen for respiratory purposes, and the decomposition of the bottom sludge which also consumed oxygen to a large measure for the purposes of Chemical oxidation.The changes that are normally correlated with the decrease in the phytoplankton, such as, (i) lowering of the pH (from 8.9 to 7.5), (ii) the decrease in the carbonate contents of the water and (iii) the increase in the bottom turbidity were also noticed. Causes of the depletion of phytoplankton have not been ascertained but may be due to the presence ofDaphnia in very large numbers. Other aspect of the problem is under investigation.Published with the permission of the Director.     

Hydrobiological Outline of the Mongolian Lakes

The waters of Mongolia can be classified according to their catchment areas into three hydro-geographic regions: basin of the Arctic Ocean, basin of the Pacific Ocean, Central Asian basin without outlet. After a short historical survey of the exploration of the lakes of the Mongolian People's Republic, the formation and the classification of the lake system is briefly dealt with. Recent hydrobiological findings are presented in addition to hydrological data. As far as possible, statements are made on the size and the depth of the waters, the growth of macrophytes and the trophic level of the lakes. A distinction is made between ultraoligotrophic, oligotrophic, mesotrophic, eutrophic and dystrophic waters. They are characterized by data on the biomass of the plankton and the ichthyofauna. In the zooplankton of the Central Asian basin, 17 copepod, 29 cladoceran and 58 rotatorian species, and in the waters belonging to the drainage basin of the Pacific Ocean 16 copepod, 40 cladoceran and 37 rotatorian species have already been identified. The results represent the basis for an intensification of fishery in the Mongolian People's Republic.     

Environmental studies and recovery actions for sturgeon in the Lower Danube River system

Over the last decade there has been a drastic decline in sturgeon v catches in the Lower Danube River system. The present paper analyses the past and present situation and suggests policies for a sturgeon recovery programme.     

Biophysical studies on the liposome-albumin system

The potential use of liposomes as a delivery system is still limited by the poor understanding of their interaction mechanisms with biological media. In the present work, interaction between bovine albumin (BA) and liposomes was studied using phase transition and dielectric measurements as well as solubilization process using non-ionic detergent octylglucoside (OG). After liposomes were incubated with diluted and concentrated BA, phase transition, characterizing the liposome membrane exhibited a shift towards higher temperatures, together with initiation of multiple phase transitions. The relaxation time of liposome membrane molecules also increased in a concentration-dependent manner. The solubilization profiles of incubated samples also showed remarkable changes, especially in beginning of solubilization stages. Moreover, amount of detergent needed to completely solubilize membrane was also increased. It was concluded that BA significantly altered the physical state of liposome membrane, which may be attributed to BA interaction with liposomes surface and/or by its incorporation within the bilayer membrane.