Physiological responses of Chaetoceros sp. and Nannochloropsis sp. to short-term 2, 4-D, dimethylamine and endosulfan exposure

Author： Hii Yii Siang

Publisher： Taylor & Francis Ltd

ISSN： 1463-4988

Source： Aquatic Ecosystem Health & Management, Vol.12, Iss.4, 2009-10, pp. : 375-389

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Abstract

The effects of two widely used pesticides in paddy fields, 2, 4-D, dimethylamine and endosulfan, on growth, photosynthetic rate and the photosynthetic pigments of Chaetoceros sp. and Nannochloropsis sp. were assessed in this study. The 48 hour 50% inhibitory concentration (IC50) value for 2, 4-D dimethylamine on Chaetoceros sp. and Nannochloropsis sp. were 142.2 mg l-1 and 211.8 mg l-1, respectively, and the 48 hour IC50 value for endosulfan on Chaetoceros sp. and Nannochloropsis sp. were 21.9  g l-1 and 45.8  g l-1, respectively. Endosulfan was much more toxic to the microalgae than 2, 4-D dimethylamine. Both pesticides reduced photosynthetic pigments and oxygen production rate of the microalgae. After 48 hours exposure to the pesticides, the microalgae were transferred to a pesticide-free medium to investigate the post-exposure effect. 2, 4-D dimethylamine and endosulfan did not cause irreversible damage on the microalgae. However, there was a prolonged lag phase and the maximum specific growth rate () of the microalgae was significantly retarded.