Cell shrinkage of Isochrysis galbana (Prymneshiophyceae) during storage with preservatives

Abstract

Cell volume of Isochrysis galbana (Prymneshiophyceae) was determined with a microscope before and after fixation during storage at 4 and 25°C. The shrinkage effect at 4°C was not detectable but at 25°C. It was described by the exponential equation; Y=0.797+0.224 exp (−0.074 X) for 2% formaldehyde and Y=0.849+0.150 exp (−0.87 X) for 1.6% Lugol's solution where X is hours and Y is the ratio of fixed volume to live volume. Lugol's solution provides 6.5% less shrinkage than formaldehyde (p<0.05). We recommend Lugol's solution as a preservative at 25°C with a shrinkage correction or refrigeration for storage at 4°C, otherwise a species–specific correction should be made for estimating live volume from fixed material.