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Journal Article

Chemical induction of colony formation in a green alga (Scenedesmus acutus) by grazers (Daphnia)

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http://pubman.mpdl.mpg.de/cone/persons/resource/persons56790

Lampert,  Winfried
Department Ecophysiology, Max Planck Institute for Limnology, Max Planck Institute for Evolutionary Biology, Max Planck Society;

http://pubman.mpdl.mpg.de/cone/persons/resource/persons56890

Rothhaupt,  Karl Otto
Department Ecophysiology, Max Planck Institute for Limnology, Max Planck Institute for Evolutionary Biology, Max Planck Society;

http://pubman.mpdl.mpg.de/cone/persons/resource/persons56660

Von Elert,  Eric
Department Ecophysiology, Max Planck Institute for Limnology, Max Planck Institute for Evolutionary Biology, Max Planck Society;

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Citation

Lampert, W., Rothhaupt, K. O., & Von Elert, E. (1994). Chemical induction of colony formation in a green alga (Scenedesmus acutus) by grazers (Daphnia). Limnology and Oceanography, 39(7), 1543-1550.


Cite as: http://hdl.handle.net/11858/00-001M-0000-000F-E34A-1
Abstract
The green alga, Scenedesmus acutus, grows in culture in unicellular form, but it forms colonies (coenobia) when exposed for 48 h to a chemical released by the grazer Daphnia magna. The colony-forming response can be evoked only in growing cells. The Daphnia factor affects colony size but not algal growth rate. The minimum concentration of Daphnia factor that induces colony formation is equivalent to a Daphnia biomass of 0.5 mg dry wt liter(-1) in the culture medium. Actively feeding daphniids induce a stronger response than starved ones. Homogenized Scenedesmus, homogenized Daphnia, ammonium, and urea are not effective. The Daphnia factor is a nonvolatile, organic substance of small molecular mass (<500 Da). It is moderately lipophilic, heat stable, pH-resistant in a range from 1 to 12, and not affected by treatment with Pronase E. The chemical activity is not lost when the substance is dried but disappears during incineration. Colony formation can be interpreted as a grazing defense mechanism. The phenotypic response may have evolved because of the tradeoff between higher sinking rates and grazing resistance of colonial forms