Effects of fixatives on ciliates as related to cell size

Abstract
Abundances of ciliate size classes and of phototrophic ciliates were compared between 2% formaldehyde and 1% Lugol’s preserved samples collected over 1 year at a coastal Mediterranean site. Large cells and Mesodinuim rubrum were poorly preserved in formaldehyde. A correction factor for ciliate numbers in formaldehyde samples of 1.6 for M. rubrum and of 1.3 for other naked ciliates was found at our study site, where most ciliates were <30 µm equivalent spherical diameter (ESD). Commercially produced Lugol’s appears inferior to laboratory prepared solutions.