Comparison of Bioluminescent Dinoflagellate (QwikLite) and Bacterial (Microtox) Rapid Bioassays for the Detection of Metal and Ammonia Toxicity

Abstract

This study compared the sensitivity of two rapid toxicity tests, QwikLite and Microtox, to seven metals and ammonia. Both of these tests measure a reduction in light production from bioluminescent microorganisms (dinoflagellates and marine bacteria, respectively) as a means of toxicity detection and are simple and inexpensive to conduct compared to many standardized acute toxicity tests. For QwikLite tests, three marine dinoflagellate species (Lingulodinium polyedrum, Ceratocorys horrida, and Pyrocystis noctiluca) were separately evaluated following a 24-h exposure period. The marine bacterium, Vibrio fischeri, was used in the Microtox tests, in 15-min exposures to the same metal preparations as those used for the QwikLite tests. The QwikLite tests were generally one to two orders of magnitude more sensitive than the Microtox tests, as indicated by lower median effects concentrations (EC(50)). Both QwikLite and Microtox, however, resulted in similar toxicity rankings for the metals tested. The dinoflagellate species used in the QwikLite tests responded similarly for most compounds tested, with L. polyedrum appearing to be somewhat more sensitive than the other two species for most metals evaluated. QwikLite was also more comparable in sensitivity to several commonly used standardized toxicity tests. As with all toxicity tests, species selection for QwikLite should take into account study-specific factors, including the potential for sensitivity to confounding factors, such as ammonia.