Bioassays: Use and Misuse in Marine Pollution Studies

In the past decade, laboratory bioassay tests have been abused by marine monitoring and regulatory programs. Present state-of-the-art precludes using bioassays to predict or measure the impact of a particular contaminant on a marine ecosystem or population. The poor predictive power of bioassay tests stems from their extreme sensitivity to a host of confounding factors that accrue in laboratory and other nonnatural situations. Over 200 primary papers published after 1975 have been reviewed to categorize such confounding factors. These categories include, but are not limited to, the age, gender, acclimation, and marine environmental history of the test organism; the length of the test exposure; and a large number of experimental artifacts. Variation in bioassay test results arising from each of these factors ranges from one to five orders of magnitude. In the future, practitioners of bioassay testing must be more responsible than to extrapolate indiscriminately from their controlled, simplistic test regimes to the uncontrolled, complex, and highly interactive marine ecosystem.