DEVELOPMENT AND APPLICATION OF A SIMPLE PROCEDURE FOR TOXICITY TESTING USING IMMOBILIZED ALGAE

A simple microplate technique was adopted for toxicity assessment of a number of pesticides including six herbicides (Atrazine, Dichloroprop , Glyphosphate, Chlorsulfuron, MCPA, and Simazine), an insecticide (Di methoate) and a fungicide (Propiconazol). Growth response of free and immobilized cultures of the green chlorococcal algae Selenastrum capro com to different treatments of these pesticides was tested and compare d. The biotests were carried out under conditions optimal for the grow th of the test alga. Algal growth was exposed in terms of dry weight, and was employed as the toxicity-response parameter. Dose-response cur ves were used to calculate the toxicity of the tested compounds in ter ms of EC(50) Based on EC(50) values, the responses of both immmobilize d and free cultures were quite similar for almost all the treatments. The technique facilitated the visual detection of the lowest toxic con centration giving no detectable algal growth (EC(100)) The technique i s quite simple, rapid, practical, accurate, and space saving. It sugge sted that batteries of immobilized algae could replace free cultures i n studies of toxicity testing. Copyright (C) 1996 IAWQ.