Coral weight increment in situ. A new method to determine coral growth

An underwater weighing apparatus is described. This consits basically of a float, the buoyancy of which is neutralized by a known amount of lead weights. The standard error of the method is ±0.1g. The entire weighing procedure takes place on the reef using SCUBA diving gear. The advantages are that the animals are not harmed by experimental treatment, and that the pure calcium-carbonate increment is registrated. Some results obtained by this method show growth of Montastrea annularis and Madracis mirabilis.