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The response of four categories of the fish Lebistes reticulatus (young fishes, females with embryos and without embryos, and males) to 24-h exposure in stream waters that differed in pH: water I, pH = 6.01-6.25, water II, pH = 4.36-4.55, and water III, pH = 4.11-4.39 was examined. Tap water - water 0 (pH = 7.54-8.26) was considered as control. In strongly acidified water, the metabolism of L. reticulatus was modified. Mainly proteins were digested, and lipids were cumulated in faeces, increasing their energy content by 4-36% per mg dry weight as compared with the energy content of food. The excretion of ammonium considerably increased, implying that the oxidisation of proteins increased in the process of respiration. Oxygen consumption increased with acidification only in young fishes.
The effect of methylene chloride, chloroform, and carbon tertrachloride on the following aquatic organisms: Pseudomonas fluorescens, Scenedesmus quadricauda, Lemna minor, Daphnia magna, and Lebistes reticulatus, was investigated. Pseudomonas fluorescens bacteria were found to be most sensitive test organisms, and a toxic effect towards them was observed just at the concentration of 100 µg/l of each agent. Studies on degradation in distilled water, river-water, and aqueous ecosystem revealed moderate stability in aqueous medium of compounds under investigation. Chloroform and carbon tetrachloride were detecable in river-water still after 40 days in concentrations toxic to aqueous ecosystem. More rapid degradation of methane halogen derivatives in river-water than in distilled water indicated the presence of microorganisms living in water from natural source, and being accessory to the decomposition of these agents. Degradation in the presence of adapted microflora took, as a general rule, a slower cource. Decrease of temperature to 6°C inhibited considerably the degradation rate of the investigated contaminants. The reduction of methane halogen derivatives content during 21-day exposure in aqueous ecosystem came up to 73%. Moreover, these compounds were found not to have biocumulative properties, and not to be toxic - in concentrations up to 300 µg/l - to aqueous biocenosis homing the experimental ecosystem.
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