Don Olavides, a scientist at the Marine Science Institute, University of the Philippines Diliman, recently shared this fascinating short video outlining the Geophysical Coral Mapping (GCM) project. Dr. Fernando Sirigan conceptualized and leads the project, whose goal is to map the sea floor within the Coral Triangle to depths of 200 meters and identify the processes that influence the morphology of reefs, as well as document the continuity of reefs below 20 meters. They employ acoustic doppler current profilers (ADCP) and conductivity temperature and depth profilers (CTD) to gather detailed information about the water column, as well as single beam, multibeam, and sidescan ecosounders to create 3-D maps of the reefs and to locate mesophotic reefs.

The team is concentrating their efforts on three areas in particular: Apo Reef (which is the largest reef in the Philippines), the Verde Island Passage, and Patnanungan, Quezon, and is especially interested in the “twilight zone”, or mesophotic reefs, which is the zone between 30 and 150 meters, and until recently, was a mystery to scientists. Since starting the project, which is funded by the Department of Science and Technology-Philippine Council for Agriculture, Aquatic, and Natural Resources Research and Development (DOST-PCAARRD), they have identified over 50 coral genera, and have discovered that instead of the massive and branching corals found in shallow reefs, the twilight zone reefs are mainly made up of plate-like and encrusting corals, which create less shade and are able to capture more of the sunlight that trickles down to such depths. This work is crucial in our understanding of our oceans’ reef systems, and I look forward to hearing about the many more discoveries and insights this team will surely find.