than a drop of water in the ocean. But when trillions combine in one location they form coral reefs and one of the largest animal colonies on the planet. These same polyps form a mutually beneficial relationship with algae which colors the reef and provides nutrients to polyps through photosynthesis. The polyps in turn deposit calcium carbonate which forms what we see as corals today and in turn provides shelter for thousands of species of fish. If either of these organisms is damaged, the other dies and the reef stops forming. Despite their size and expansive reach across the world, reef building is a painfully slow process. Those large brain corals you see when you dive deep down the coral walls at your local beach, once started from a miniscule speck and only grow millimeters a year. Even basic estimates show that the great mountain corals were here thousands of years before our grandfathers were even born and hopefully will last a few more generations.
Without their symbiotic algae, coral tissues become colorless as they reveal the white of their calcium carbonate skeletons, an event known as coral bleaching.
Even the lightest touch can damage corals let alone seabound vandals who carve into corals.
Cnidarians (corals, soft-corals, sea anemones, gorgonians etc) are the most wellknown organisms containing symbiotic zooxanthellae, but they are also found in other invertebrates such as the Giant Clams (Tridacna) and many nudibranchs. The zooxanthellae (algae) live in a symbiotic relationship with these immobile living creatures, the hard corals, this vital algae helps keep these invertebrates alive and can provide up to 90 percent of a coral’s energy requirement. In return, the coral provides the zooxanthellae with protection, shelter, nutrients and a constant supply of carbon dioxide required for photosynthesis. Reef-building corals largely depend on zooxanthellae limiting the coral growth to the photic zone (light zone); most reefs grow in water 30 m or shallower. Corals provide shelter for other creatures; 25 percent of all marine species live in or around coral reefs; they host the greatest diversity of life in the ocean. They provide nursery grounds for 25 percent of known marine species but coral reefs cover less than 0.2 percent in area of the marine environment. It is a very concentrated resource 50 DESTINATION JEDDAH
Corals grow at a painfully slow pace growing milimeters every decade.
indeed and therefore the slightest damage has a disproportionately large impact on the coral.
Coral Surival 101 Corals need clean water to survive. A major threat is sedimentation, waste and storm water. Trash will block the sunlight reaching the corals causing starvation and suffocation. Under high environmental stress, coral will also die if the water temperature changes by more than a degree or two beyond its normal range or if the salinity of the water drops. If any of the two of these conditions occur, the zooxanthellae contained inside the coral will be expelled or digested by the coral leaving