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(M/EH024) Comparison of heavy metal toxicity observed in two rapid bioluminescent tests: QwikLite and Microtox®. Rosen, Gunther1, Robayo, Maria2, Rivera-Duarte, Ignacio1, Lapota, David1, 1 2 ABSTRACT- This study compared the toxic response of two rapid acute toxicity bioassays, QwikLite and Microtox®, to seven heavy metals. Both of these tests measure a reduction in light output from bioluminescent microorganisms as a means of toxicity detection, and are relatively simple and inexpensive to set up. For QwikLite tests, two marine dinoflagellate species, Gonyaulax polyedra and Ceratocorys horrida, were separately evaluated following a 24 h exposure period. The marine bacterium, Vibrio fischeri, was exposed for 15 min in the Microtox tests. Although both QwikLite and Microtox data resulted in similar toxicity rankings for the chemicals tested (i.e. copper was more toxic than zinc), the dinoflagellates were generally 1 to 2 orders of magnitude more sensitive than the bacteria, as indicated by lower EC50 values. The two dinoflagellate species used in the QwikLite assays responded similarly for most compounds tested, with G. polyedra appearing to be somewhat more sensitive than C. horrida for all metals evaluated. The observed difference in sensitivity between the two QwikLite species, however, was only statistically significant (P<0.05) in two of the metals tested (Hg2+ and Cu2+). Although both QwikLite and Microtox appear to be effective tools for rapid screening of aquatic pollutants for their toxicity, this study suggests that QwikLite is much more responsive. Key words: metal toxicity, bioluminescence, QwikLite, Microtox |
