Three-dimensional laser scanning as an efficient tool for coral surface area measurements

Michal Raz-Bahat, Hanny Faibish, Tali Mass, Baruch Rinkevich

Limnol. Oceanogr. Methods 7:657-663 (2009) | DOI: 10.4319/lom.2009.7.657

ABSTRACT: In scleractinian corals, as in many sessile colonial organisms, surface area serves as the prime descriptor for standardization and quantification of physiological and biochemical parameters. The complexity of colonial architecture, however, complicates measurement of surface area, yielding less than satisfactory results for the established methodologies. Here, we used a 3D desktop laser scanner for accurate measurements of skeletal surface area of various coral fragments. The original 127-µm accuracy of the scanner was tested on modules with increasing complexity. It showed a linear (R2 = 0.912), but relatively small, increase of up to 9.67% accuracy error in complex modules. The scanner’s maximum credibility error in repeated measurements was only 1.67%, representing an average error of 0.87 ± 0.66%. We compared the scanner’s measured surface area results with those of four established methods: wax coating, foil paper wrapping, methylene blue dipping, and caliper measurements. In all methods, credibility and accuracy errors pointed to the superiority of the new method. Laser scanning is rapid (minimum 10 min per scan), efficient, easy to operate, and economically feasible as a common bench tool.