By Dr. John Turner
A coral reef is a team effort, but the players don’t know that. Each does their own thing, but together they form a silent web. The web has to be intact for the reef to flourish. So, as with any team, injury or loss of even one player-group (e.g. one fish species) can lead to a loss for the whole team. While sports teams play out their game on a minutes-to-hours scale, coral reefs do so on a scale of years, and final score can take decades. Because the time is so spread out, the team work is not obvious, but it is there.
Let’s look at the basic parts of a coral reef system. It starts with tiny young corals that attach to the sea bed, often in rocky areas. The corals grow and spread to cover the area. There are all kinds and shapes of coral, so they make lots of nooks and crannies for other creatures to live in. The coral that most people are familiar with is called stony coral, but there are also soft-coral species that look like plants . Examples of common stony coral shapes that make up the hard reef include boulder coral (brain, star), branch coral (staghorn, elkhorn, cauliflower), disk coral (plate, mushroom) and pillarcoral. The living part of the coral is almost microscopic, and what you see are the calcified secretions of these tiny organisms. Because they use sunlight for their energy, most corals need to live in water less than 60 feet deep. The Great Barrier Reef off the coast of Australia is 134,000 square miles in area and is by far the largest structure on the planet made up of living organisms.
While corals are the reef builders, many other species live there. Coral reefs occupy less than 0.1% of the world’s ocean surface, but 25% of all marine species call reefs home. All phyla are present in the coral reef ecosystems, from microscopic plankton to fish that can weigh hundreds of pounds. There are numerous invertebrate species (sponges, cnidarians, worms, mollusks, crustaceans, echinoderms, fishes and reptiles). Some reefs have more than 500 species of fish.
There is a complex interrelationship among the various reef inhabitants, and part of this is known as the Food Web. This web consists of hierarchies of predators and prey, including species that do particular jobs like reef cleaning, scavenging, photosynthesis and water filtration. Each species contributes to the functioning of the reef system. Loss or long-term compromise of a given species can result in dysfunction in the system and eventual reef decline. While the reef system does have duplication in many cases (more than one species performing a given role), chronic disruption of reef function and the food web will lead to decreased diversity in reef species and less resilience in the system.
This website and blog is about the celebration of one of nature’s grandest, most beautiful and most complex creations. Many human activities are directly and indirectly compromising reef inhabitants and reef ecosystem health. Recognition of the unique and precious character of coral reefs provides motivation for protecting them, while education and knowledge about coral reefs and the forces impacting them provide power for positive change to help them.