Abstract Summary
The ability to monitor the growth and survival of a restored coral is vital for assessing the success of a restoration program as a whole. Information on outplant performance is useful to restoration managers to direct future operations as well as to scientists using such coral to understand ecological and evolutionary processes of the reefs. Current non-intrusive methods for monitoring coral are limited to total linear extension or indirect estimates of surface area which can be difficult to obtain in the field, especially when dealing with structurally complex corals. 3D photogrammetry provides a way to digitally reconstruct a coral and quantify morphometric characteristics outside of the water. Within the timespan of a routine monitoring survey, Acropora cervicornis fragments were photographed with a standard underwater camera from an array of angles to produce 50 to 100 images; a process that required roughly 90 seconds per fragment. Images of each coral were entered into the Agisoft Photoscan software which then generated the 3D models. Using the scaling targets photographed into the models, we calculated linear extension, surface area, and volume of 270 corals outplanted by Mote Marine Laboratory’s Staghorn Restoration Project. In order to ground-truth the methodology, we compared photogrammetry-based measures to in situ measurements of total linear extension. To assess bleaching, analysis of color cards included in photographs provided quantification of fragment color with no additional effort on the part of the surveyors. Long-term data on outplant survival will enable determination of the utility of 3D photogrammetry for assessing the performance of coral outplants. By obtaining direct total linear extension, surface area, volume, and color measurements, 3D photogrammetry can provide a more comprehensive method of monitoring outplant success when compared to traditional methods without adding substantial effort to current restoration practices.
