| Abstract: | Estimates for the production of calcium carbonate by Halimeda spp. have been based on limited measures in small areas or over short periods, subsequently extrapolated over larger temporal and spatial scales. The accuracy of these extrapolations depends on the variations in time and space of the parameters used for the derivations of the production, which were evaluated in the present study for Halimeda incrassata (J. Ellis) J. V. Lamour. in the Puerto Morelos reef lagoon, Mexican Caribbean. Growth, biomass, and CaCO3 content of the branches of the thalli were determined at 1–3 monthly intervals from November 1997 until June 1999, using the marking technique with the coloring agent Alizarin Red‐S. Biomass exhibited great variability (V=25.4%), and fluctuations were closely related to changes in thallus density. Growth and CaCO3‐content changes were related to the solar cycle, having coefficients of 15.4% and 2.5%, respectively. Additionally, calcified biomasses of the thalli were determined over a large spatial (31 stations in ～7 km2 area) and time (6 y) scale. Spatial variability in calcified biomass was 59%, and the coefficient of variation attained its highest value (69%) for the samples collected over a 6 y period, from 1990 to 1996 (except 1995). Based on overall average values, branches of H. incrassata in the study area had a mean turnover of 30 d, with an annual production of 815 g CaCO3 per square meter. |
