Pergamon 0045-6535(94)00347-5 Chemosphere, Vol. 29, No. 12, pp. 2701-2710, 1994 Copyright © 1994 Elsevier Science Ltd Printed in Great Britain. All rights reserved 0045-6535/94 $7.00+0.00 CYST-BASED TOXICITY TESTS X : COMPARISON OF THE SENSITIVITY OF THE ACUTE DAPHNIA MAGNA TEST AND TWO CRUSTACEAN MICROBIOTESTS FOR CHEMICALS AND WASTES Guido Persoone ', Colin Janssen and Wim De Coen Laboratory for Biological Research in Aquatic Pollution, University of Ghent, J.Plateaustraat 22, B-9000 Ghent, Belgium (Received in USA 29 August 1994; accepted 30 August 1994) ABSTRACT This paper statistically evaluates the sensitivity of the acute Daphnia magna bioassay in comparison to that of two crustacean microbiotests: the Streptoxkit F and Thamnotoxkit F, which make use of larvae of the anostracans Streptocephalus proboscideus and Thamnocephalus platyurus respectively, hatched from cysts. Regression equations were calculated for 146 data pairs, taken from 5 different studies dealing with the acute toxicity of pure chemicals, effluents, river sediments, solid wastes and monitoring wells, and sludges. All comparisons show that there is a significant relationship (p< 0.05) between the acute effects found with the D.magna and the two crustacean microbiotests; correlation coefficients ranged from 0.84 to 0.92. In the majority of cases, effect ratios between the conventional D.magna and the microbiotests were within a factor 2 for both pure chemicals and environmental samples. Variation coefficients for repeated tests on the reference chemical potassium dichromate indicate a good precision and hence a good degree of standardization of the microbiotest procedures. The evidence provided in this paper demonstrates that the new crustacean microbiotests can be used as low cost alternatives to the conventional D. magna acute assay. INTRODUCTION Evaluation of the hazard of pure chemicals to the environment is based on performance of (a restricted number of) toxicity tests, following standard procedures. The same test methods are also applied for determination of the environmental impact of toxic discharges. Because of their dependence on maintenance and culturing of live stocks of test species, application of "conventional" toxicity tests is restricted to specialized laboratories and is quite expensive (Persoone and Van de Vel, 1988). Consequently, determination of the potential impact of toxic discharges on the environment is often approached indirectly through chemical analyses. 2701