Fatty acids released by Daphnia: do they induce colony formation in Scenedesmus acutus?

摘要: There is lirde information on grazer-mediated inducrion of defenses in phytoplankton. Only recendy in rhe phenorypically plasric green alga Scenedesmus a grazer-mediated increase in colony (coenobia) size was shown (HESSEN & VAN DONK 1993) which leads to protection against grazing (LüRLING & VAN DoNK 1996). The same coenobiainducing activiry occurs under natural conditions when grazers are highly abundant (LüRLING & VAN DoNK 1997, VAN DoNK et al. 1998). Since starving Daphnia produced less coenobia-inducing activiry rhan actively feeding ones (LAMPERT er al. 1994) it was concluded that the infochemical is produced by digestion of the algae by the grazer (LüRLING & VAN OONK 1997). Alternatively, it can be hypothesized that the cue originates from zooplankton metabolism and is thus only indirecdy linked to rhe digestion of food. Release of the infochemical by digestion might be …