Quantifying Growth and Calcium Carbonate Deposition of Calliarthron Cheilosporioides (corallinales, Rhodophyta) in the Field Using a Persistent Vital Stain

Growth and calcium carbonate deposition rates of the coralline alga Calliarthron cheilosporioides Manza were quantified by monitoring fronds in the intertidal zone that had been chemically labeled with the nontoxic fluorescent brightener Calcofluor white. This vital stain effectively labeled apical meristems of coralline thalli in the field: fronds exposed for only 5 min had detectable chemical marks at least 1.5 years later. By distinguishing portions of thalli that developed before and after exposure, this methodology permitted accurate measurement of growth and calcium carbonate deposition at each meristem. In Calliarthron, meristematic activity declined with increasing frond size. However, because growing fronds dichotomize, the total number of meristems and the deposition rate of new calcified tissue both increased with frond size. Growth rates reported here suggest that large fronds may not be as old as previously estimated. The Calcofluor white method may improve demographic studies of corallines by resolving growth and age of fronds in the field and may facilitate studies of climate change on calcium carbonate deposition in these ecologically important, calcifying algae.