Development of tolerance against toxic Microcystis aeruginosa in three cladocerans and the ecological implications.
This is the first experimental study to compare difference in the development of tolerance against toxic Microcystis among multi-species of cladocerans (Daphnia, Moina and Ceriodaphnia) pre-exposed to two M. aeruginosa PCC7820 strains (MC-containing and MC-free). Zooplankton were divided into S population (fed Scenedesmus), M-F population (fed Scenedesmus+MC-free Microcystis), and M-C population (fed Scenedesmus+MC-containing Microcystis). M-F and M-C populations were pre-exposed to Microcystis strains for 4 weeks, and their newborns were collected for experiments. A pre-exposure to MC-containing or MC-free Microcystis increased tolerance against toxic Microcystis. The marked increases in survival rate and median lethal time (LT(50), 100-194% increase) in the M-C population of Ceriodaphnia suggest that small-sized cladocerans may develop stronger tolerance against Microcystis than large-sized ones when both groups are exposed to toxic Microcystis. This may explain why dominant Daphnia is usually replaced by small-sized cladocerans when cyanobacteria bloomed in summer in eutrophic lakes.
Guo
Nichun
N
Donghu Experimental Station of Lake Ecosystems, State Key Laboratory of Freshwater Ecology and Biotechnology of China, Institute of Hydrobiology, Chinese Academy of Sciences, Donghu South Road 7, Wuhan 430072, PR China.
Xie
Ping
P
D000818:Animals; D033361:Cladocera / Q000187:drug effects / Q000254:growth & development*; D005068:Eutrophication; D005247:Feeding Behavior; D005618:Fresh Water; D008018:Life Cycle Stages; D046931:Microcystis / Q000145:classification / Q000378:metabolism*; D010456:Peptides, Cyclic / Q000633:toxicity*; D018675:Toxicity Tests
D010456:Peptides, Cyclic