Physiological interaction of Daphnia and Microcystis with regard to cyanobacterial secondary metabolites.

摘要: Abstract Cyanobacterial blooms in freshwater ecosystems are a matter of high concern with respect to human health and ecosystem services. Investigations on the role cyanobacterial secondary metabolites have largely been confined microcystins, although cyanobacteria produce huge variety toxic or inhibitory metabolites. Mass occurrences strongly impact zooplankton communities; especially unselective filter feeder Daphnia. Daphnids shown successfully suppress bloom formation. However, opposite situation, i.e. suppression Daphnia populations by can be observed as well. To understand these contradictory findings elucidation underlying physiological mechanisms that help daphnids cope cyanotoxins is crucial. We fed magna cyanobacterium Microcystis aeruginosa PCC7806 for 24 h used high-resolution LCMS analytics analyze cells, tissue surrounding medium order investigate fate seven investigated compounds (cyanopeptolins A–C, microcyclamide 7806A aerucyclamides B–D). For none bioactive evidence biotransformation biodegradation were found. Instead feeding subsequent release experiments point at importance transport regard cyanopeptolins A C 7806A. In addition we found hints new inducible defense mechanism against predation These putative include elevated production other than could demonstrated here aerucyclamide B D, cyanopoeptolin Moreover, our data demonstrate active export least one compound (microcyclamide 7806A) into response grazer presence, which might constitute an entirely not yet described mechanism.