The Use of Aniline Blue for the Determination of Dead Phytoplankton, Zooplankton and Meroplankton in LC₅₀ Testings After 96 Hours: A Re-Evaluation of the US Environmental Protection Agency Methodology

There is a need for a reliable staining technique to distinguish between live and dead organisms following LC₅₀ tests. This is especially so in cases where organisms can be stressed or even become unconscious and appear dead to the aided or naked eyes. Visual observations under such conditions can result in an LC₅₀ value shifting to the lower concentration thereby imposing stiffer guidelines for compliance. Aniline blue can only stain individuals which are physiologically dead imposing an accurate live-dead evaluation and producing a true LC₅₀ value. Guidelines imposed using such data will facilitate compliance and provide an accurate value for an LC₅₀.