When we survey a reef, we take measurements just like a doctor does. We count and measure the size of corals, sponges, sea urchins and fishes to see if they are growing big and strong. We check each coral for diseases which can harm the coral, and look to see if each coral head looks pale due to overheating or overexposure to the sun.
By mapping these factors across large areas from year to year we are able to provide an "annual check-up" on the ecological health of our coral reefs - which then guides the management and research activities of government agencies and local scientists.
Lots of fish, corals and gorgonians make for a healthy reef!