The Physiology Respond Of Several Microalgae To Water Acidification

With the CO₂ concentration of the atmosphere increasing,the absorption of oceans and lakes make its pH value gradually reduced,resulting in the change of carbon dioxide in the water carbonate system.Nannochloropsis oceanica and Chlorella vulgaris and Chaetoceros muelleri are not only the important primary productivity and the basis of the flow of the food chain link,but also bait algae with economic value.And they have the good development prospect in areas of energy and medicine.In this study,CO₂ concentration could be divided into five gradients:400ppm,700ppm,1000ppm,1500ppm and 2000ppm.They represent the CO₂ concentration at different times of the current and future,respectively.Physiological responses of these microalgae with the water acidification were detected by physiological and biochemical means.The results showed that the cell density,photosynthesis and most of the biochemical composition contents of Nannochloropsis oceanica and Chlorella vulgaris short-term acidification were increased with the CO₂ concentration increasing.And when the CO₂ concentration was 1500 ppm or 2000 ppm,the promoting effect began to weak.In addition,the cell density,pigments contents and total oil content of Chaetoceros muelleri appeared the same rise trend between the response to short-term acidification and long-term acidification.In the change of other physiological indexes,Chaetoceros muelleri in dealing with the short-term acidificationand long-term acidification occurred on the the opposite trend.Therefore,the physiological responses of different microalgae to the water acidification are different,and even the same microalga also has different responses in different physiological aspects.In addition,the physiological changes are diffierent between long-term acidification and short-term acidification of microalgae.Therefore,when studying the physiological response of microalgae to water acidification,it should not only take into account the difference of species metabolism,but also should conduct long-term acidification verification.