Photo tow: a new method for estimating coral reef status and changes at large spatial scale. A coral bleaching event case study

Refering to a coral bleaching event that took place in French Polynesia in 2002, and in order to document the health of the coral reef outer slope at a scale of several tens of kilometers of coastline, we developed a new method on the island of Moorea. This method consists of monitoring the reef at constant depth by towing, behind a boat, a scuba diver operating a photographic camera. This method enables precise and fast scanning of the reef at regular intervals along a great distance. In the case of the study presented here, geographical differences were found around the island: healthy coral cover was greater on the north coast, and bleaching intensity was greatest on the north-west coast.