Methodological precision of in situ and in vitro algal density measurements in the model cnidarian, Exaiptasia diaphana

The objective of this study was to evaluate the precision of <i>in vitro</i> and <i>in situ</i> algal density measurement protocols using light, fluorescent, and confocal microscopy and an automated cell counter. <i>In situ</i> algal density was quantified as algal area fraction (%) using confocal images of tentacle clippings mounted on two types of slides. <i>In vitro</i> algal density of holobiont homogenate was quantified as algal cells/µl of holobiont homogenate using an automated cell counter and a hemocytometer viewed using light and fluorescent microscopy. Triplicate measurements of each method for ten anemones were collected and the coefficient of variation was calculated and compared across the ten anemones within each method.