Changes in the morphostructure of Scenedesmus acutus and culture growth rate induced by the exudate of primary consumer Daphnia magna

摘要

It is shown that growth of the Scenedesmus acutus Meyen. culture is epigenetically modified by components released from the lake zooplankton species Daphnia magna, an algavorous primary consumer. Multicellular colonies of Scenedesmus were effectively formed in the deficient mineral medium, even in the absence of a substance released by the grazer (consumer-released factor). When an enriched mineral medium was used for culturing, the consumer-released factor had little effect on the formation of coenobia. The partial effects of nutrient components and doses of the consumer-released factor, as well as interactions of these variables, were assessed with regard to morphometric and growth parameters of the Scenedesmus culture. The agedependent dynamics of the response surface for these parameters was revealed and explained as being due to the depletion of a certain nutrient during culturing. The interaction of this nutrient with a consumer-released factor is supposed to be crucial for the induction of changes in the growth rate and morphometric characteristics of the algal culture.