2006 Volume 9 Issue 2 Pages 115-131
We present the results of a test run done for protocols drafted to evaluate the toxicity of different bioremediation agents against spilled-oil using marine organisms and crude oil. The aim of the study was to evaluate experimentally the change in toxicity of oil when mixed with bioremediation agents and fertilizers used on oiled shores to enhance oil biodegradation under actual environmental conditions prevailing at the oiled site before considering any large-scale application. The protocols were designed to use three marine species at different trophic levels, i.e. diatoms Skeletonema costatum, rotifers Brachionus plicatilis, and red sea bream Pagrus major, and to carry out algal growth inhibition, zooplankton acute immobilization, and fish acute toxicity tests. The agents tested are: Inipol EAP22™, oleophilic fertilizer; Terrazyme™, bioaugmentation agent; and Super IB™/Linstar™, slow-release fertilizer.
While Super IB™/Linstar™ did not enhance the toxicity of oil, clear suppression of diatom cell growth was observed when 100 ppm of Inipol EAP22™ was added to oil. The concentration is estimated to be of the same range as that of the interstitial water at the Exxon Valdez remediation site after the spraying of Inipol EAP22™. This suggests that the toxic effect of the agent on some marine microalgae could be greater than the harm done by the oil itself.
Effective test methods for evaluating the ecotoxicity of bioremediation agents, therefore, need to allow comparison of the toxicity of the agent with the coexistence of contaminants and their biodegraded products, reproducing the actual conditions at oiled seashores.
