Study of pH Changes of Culture Medium of Green Microalgae (Scenedesmus quadricauda) under Chemical Stresses

Biological, chemical and physical factors influence on physiology of aquatic microalgae. Changes in these factors effect and disturb the life cycle of microalgae as well as their physiological parameters.In this study the changes of pH in the culture medium of green algae Scenedesmus quadricauda (Turp.)‌Bréb. In three different culture media under chemical stresses using herbicideMetribuzin and water hardness, was investigated. The experiment was conducted in a completely randomized design for a period of 21 days. Change in acidityof culture media A and B had direct relationship with water hardness and presence of herbicide. Results of pH changes in medium A suggest a direct correlation with the amount of chlorophyll a,‌ b and carotenoid. According to the results of analysis of variance, there are also significant differences (P < 0.05) in some treatments in different media. The greatest amount of carotenoid was observed at 150 mg/L CaCO3. In general, it can be said that the green algae, Scenedesmus quadricauda species, had high tolerance to changes in the acidity of the medium, along with chemical stresses caused by water hardness and presence of herbicide Metribuzin.