COPPER TOXICITY FOR GREEN ALGAE CULTURE SCENEDESMUS QUADRICAUDA UNDER FLUCTUATIONS IN PH VALUE
PH value (pH) of water is a strictly normalized parameter in the preparation of culture media and aquaculture. However, the pH is very labile and depends on the properties of the water (buffering, hardness), external factors (acid rain, wastewater), as well as vital activity of photosynthetic organisms. In this regard, physiological state of aquatic organisms and their resistance to stress, including toxicity may vary. Changes in pH was examined during growth of laboratory culture Sc. quadricauda normally and when exposed to toxic concentrations of copper (0.3 mg / l), and the impact of pH fluctuations on the stability of the algae exposed to copper. During growth intact algal culture pH value increased from 7.8 to 10.8 for 8 days. By adding copper to fresh culture photosynthetic alkalinization proceeded slowly to the level of 9.6 on the background of the lack of cell division. The artificial alkalinization of culture media to pH 10 led to reduce the toxicity of copper. The increased algal resistance to copper during growth was detected, but it was not only due to the natural alkalinization by photosynthesis. Metabolites accumulation in the culture media and the formation of an integrated population in the process of growth of the culture are contributing to the increase of algae resistance.