Surfactant (Genapol OX-80) toxicity to Selenastrum capricornutum

A non-ionic surfactant (Genapol OX-80) was proposed as a means of reducing destructive crayfish activity in rice. In order to study the toxicity of th is product on algae, a test in accordance to the ISO 8692 protocol (1989) w as performed. The growth inhibiting effect of the pure formulation of Genap ol OX-80 was studied on Selenastrum capricornutum in the concentration rang e of 0.01-1.0 mg/l. The result indicated a 72 h EC50-value of 0.5 mg/l. The suggested field concentration of approximately 50 mg/l is therefore two or ders of magnitude above the algal EC50-value. From our findings it is expec ted that the impact on the rice field algae will not be negligible. (C) 200 0 Elsevier Science Ltd. All rights reserved.