Indexed on: 01 Dec '07Published on: 01 Dec '07Published in: Moscow University Biological Sciences Bulletin
The main ways of reaction of a green chlorococcal alga Scenedesmus quadricauda (Turp.) Breb. model population to the toxic action of different chemicals (the fungicide imazalil sulfate and heavy metal Cr6+ as a potassium bichromate) are analyzed. Regularities of the change in the size-age and functional population characteristics are considered, and four types of universal microalgal response to the toxic action are demonstrated. In the presence of low concentrations (0.001 mg/l), the slowdown of the culture growth was caused by the long stop of cell division in part of the algal population rather than by cell death or a decrease in their growth. The lack of effect (or even culture growth stimulation under medium concentrations (0.1 mg/l)) is related to the cell division proliferation after a temporary stop. After increasing the toxicant concentration up to 1.0 mg/l, we observed a long cell division inhibition; however, the cell death was under high toxicant concentrations of 5.0–10.0 mg/l). A significant inhibition of functional cell parameters (photosynthetic intensity) took place only under high toxicant concentrations (5.0 mg/l and higher). It is shown that the microalgal population state can be estimated on the basis of an analysis of its structural and functional parameters.