Corals are found in all seas, temperate or tropical, but only in the tropical waters do they produce the classic reefs that we have come to love. These huge calcareous structures have taken many millennia to grow and provide rich habitats for all manner of marine life.
Coral is actually a colony of tiny polyps not too dissimilar to jellyfish or sea-anemones. They feed on tiny microscopic protozoa and secrete the calcareous deposits that form the hard corals we are familiar with. The living part of the coral are the soft polyps that coat the coral skeleton. Inside these polyps live coloured algae which live symbiotically with the coral. They provide the colour, oxygen and sugars. In return they get shelter and a variety of nutrients.
Corals are very delicate and sensitive to changes in sea level, temperature and acidity. If the water warms, becomes more acidic due to carbon dioxide, or increases in depth, the coral becomes stressed and then dies.
The first symptoms of stress is when the coral ejects its symbiotic algae. This is called bleaching as the normal coloured corals become white. The coral then dies.
Bleaching is occurring in many areas of the Great Barrier Reef as well as many other reefs around the world. The death of the reefs would not just be a tragedy for the coral but also the huge number of fish and other creatures associated with the reef. What a great loss this would be for all of us.
The reefs are in danger from rising CO2 levels, rising sea levels and rising temperature due to man’s burning of fossil fuels. Reefs have died in the past due to natural warming processes. It was a disaster back then and it would be a disaster now – doubly so because we are directly causing it.
I believe that we desperately need to limit our CO2 output, turn to alternative renewable energies and make the world a cleaner place.