Response of grazer-induced colony formation of Scenedesmus obliquus in relation to grazer's size
Zhu, Xuexia; Wu, Xinyan; Zhang, Lu; Zhu, Chen; Yang, Zhou
published: May 1, 2015
ArtNo. ESP141018603004, Price: 29.00 €
Colony formation in Scenedesmus can be induced by infochemicals released by various herbivorous zooplankton species, such as cladocerans and rotifers. Natural Daphnia populations have a complex age structure, and different sizes of Daphnia play a different degree of ecological roles in the system. Thus, we hypothesized that the response of grazer-induced colony formation of Scenedesmus may be related to the grazer's size. In this study, to examine this hypothesis, we used filtered test water containing infochemicals released by different sizes of Daphnia magna to stimulate the inducible colony formation in Scenedesmus obliquus. The results showed that induced colony formation occurred in S. obliquus after exposure to infochemicals released from D. magna, regardless of their body size. However, the proportions of large colonies in the treatments with oversized D. magna were higher. The number of cells per particle increased significantly with increasing body size of D. magna in the cultures from which the added filtrate was derived. The influence of D. magna body size on the number of cells per particle followed a rectangular hyperbolic function during the effective induction period. Such results suggest that strengthening of grazer-induced colony formation in Scenedesmus is closely related to the grazer's size.