Sensitivity of water flea daphnia carinata and freshwater microalgae scenedesmus from Viet Nam to Cadmium

In South-eastern region of Viet Nam, Sai Gon river not only provides drinking water for million people, but also supports biodiversity of local freshwater ecosystem. However, due to development of industry and agriculture, the river is continuously loaded with xenobiotics released by anthropogenic activities. Among pollutants, heavy metals are considered as the most toxic elements to aquatic living organisms and human health. The aim of this study is to assess the sensibility of freshwater microalgae Scenedesmus and water flea Daphnia carinata, two fresh water species from Viet Nam to cadmium (Cd). After physical and chemical characterization, field water samples from upstream of Sai Gon River was used as dilution water in toxicity tests. With water flea D.carinata, the EC50 value of 48h immobilization experiment was 7.62 µg/Lfor Cd. Growth inhibition of the algae cells was determined following exposure for 72 h, and EC50 values of Cd was 328.5 µg/L. The results showed that Cd is highly toxic to both species, and water flea D.carinata was much more sensitive than freshwater algae Scenedesmus. Based on the observed high sensitivity with Cd, D.carinata is a potential bioindicator for the assessment of Cd pollution in fresh water ofSai Gon river. While Cd-tolerance algae Scenedesmus calls for further investigation on metal uptake capacity and utilization in Cd contaminated water treatment.