pH-associated changes in induced colony formation and growth of Scenedesmus obliquus
Yang, Jingwen; Li, Bangping; Zhang, Chaowei; Luo, Hongxuan; Yang, Zhou
published: Feb 1, 2016
published online: Feb 16, 2016
manuscript accepted: Dec 10, 2015
manuscript received: Aug 10, 2015
ArtNo. ESP141018703006, Price: 29.00 €
As one of the most important environmental variables, water pH affects not only the growth but also the inducible morphological defenses in phytoplankton. Water pH in some lakes is currently decreasing because of contamination and increased carbon dioxide concentration. To investigate the response of induced colony formation and growth of phytoplankton to decreasing pH, we cultured Scenedesmus obliquus in a medium with Daphnia magna infochemicals at different pH values ranging from 5 to 9. Results revealed that the cells per particle of S. obliquus increased with time and then decreased after they reached a plateau. A four-parameter Modified Gauss- ian model provided an accurate fit for the changes in the cells per particle with time under any pH conditions. In general, the maximum number of cells per particle was reached at either day 3 or day 4, depending on pH. The maximum number of cells per particle significantly decreased as pH decreased, which can be fitted by using a three-parameter Sigmoid model. Specific growth rates significantly decreased at low pH. Therefore, the induced colony formation and growth of S. obliquus are higher in neutral to weakly alkaline water environment and will be impaired under acidic water conditions.