Use of Aniline Blue for Distinguishing Between Live and Dead Freshwater Zooplankton

Abstract

It is possible to distinguish between live and dead freshwater zooplankton after 15-min immersion in an aqueous solution of aniline blue. Organisms physiologically dead at the time of staining are dyed blue, whereas living organisms remain unstained. This mortal staining technique has been repeatedly used in evaluating the survival of individuals belonging to all major groups of freshwater zooplankton. It has special application where the survival of large numbers of plankters must be determined either within a short interval, for successive intervals, or where conditions do not permit such evaluations immediately following collection or treatment. Stained samples preserved in formalin showed no evidence of leaching when stored at 4–15 °C for several months. This technique has been used successfully for entrainment studies for power plants with once-through cooling systems. Key words: freshwater plankton, zooplankton, phytoplankton, ichthyoplankton, dead–live determinations, mortal staining, power plant(s) entrainment, industrial monitoring