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In this study, the chronic effects of Ampicillin on survival, reproduction and growth of Daphnia magna was monitored during 21 days exposure test. The results showed that Ampicillin strongly affected on life history traits of Daphnia magna, i.e. 47% reduction of survival proportion, lower 68% reproduction than the control, and reduction in body length and in the intrinsic population rate, especially at its highest concentration. The antibiotics especially Ampicillin should be included int the Vietnam guidelines for environmental and ecological protection.

Cyanobacterial blooms often consist of mixtures of microcystin-producing and microcystin-free species and both of them can cause unpredictable effects on aquatic organisms. In this work, the subchronic effects of the cyanobacterial crude extracts (CCEs) from microcystin-producing and microcystin-free cyanobacteria, with different microcystin concentrations (1, 10, and 50 µg L −1) on Daphnia magna (D. magna) were investigated. The life-history trait responses of D. magna to CCEs were determined based on survival, reproduction, and somatic growth. In addition, the physiological response represented by the feeding rate of D. magna on green algae (Scenedesmus sp.) after exposure to both type of crude extracts was also estimated. Our results showed that both microcystin-containing (MCCE) and microcystin-free (NCCE) crude extracts insignificantly reduced survival but strongly enhanced reproduction and somatic growth of organisms. However, the degradation of eggs and neonates of the gravid females exposed to the CCEs was observed. Besides, the feeding rate of D. magna exposed to MCCE has been increased significantly whereas no change in the feeding rate was observed for NCCE-exposed D. magna. In general, new and interesting aspects of the toxicity of MCCE and NCCE were obtained from this study and our study contributed to the understanding of the toxicity of Pseudanabaena sp. extract on D. magna under bioassays.

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