Coral is one of the ocean's most important forms of life. Of course, all life is important, but coral reefs form a complete ecosystem, as they create a habitat for many other marine creatures. Coral reefs are feeding and breeding grounds for a wide range of marine life and this means that when they are destroyed many other marine animals are affected. There are many ways in which a coral reef can suffer damage or die. Bottom trawling, which is a method of fishing, can wipe out entire reef systems. Explosives and cyanide are also often used by divers to catch fish that live on coral reefs. However, probably the biggest threat to coral reefs is something known as coral bleaching.
The worst of the coral bleaching is a direct result of global warming. As the planet warms up, and it is doing so, the oceans also warm up. Now, we are not talking drastic temperature jumps of many degrees. We are talking about a degree or two rise in average annual temperature, but when it comes to coral reefs, this is enough to cause severe damage. When the water warms up, the coral gets sick. Coral is formed by tiny living creatures called polyps. These animals build a limestone shell around themselves so that they are protected. The reefs themselves are a product of generations upon generations of corals that have built upon the limestone remains of the ones that came before them.
Corals often display very bright colors, but these colors are not actually from the corals themselves, but are rather the brilliant colors of a type of algae known as zooxanthellae. These zooxanthellae live in a symbiotic relationship inside the coral. The coral offers the algae protection and in return the zooxanthellae give the coral oxygen as the byproduct of the photosynthesis process. When the corals get stressed out, as it does with an increase in water temperature, they will reject the algae and when this happens the corals turn plain white. There are other conditions in which coral bleaching can occur, such as storms and an influx of fresh water, but rising ocean temperatures remain the biggest cause.
In some cases, the coral dies when the zooxanthellae are gone but can recover, although it is a lengthy process. The other, once puzzling aspect of coral bleaching is that there would be a mix of bleached corals in the same area as corals that were still thriving. Scientists wondered how this was possible. However, it was discovered that the ones that were thriving were better sheltered from the sun, so they had shade and cooler water, and this made them more resilient than the coral that had higher exposure.
Since this discovery, the goal has been to create protection for these resilient coral reefs so that they can in turn repopulate the bleached coral reefs. This protection has come in the form of Marine Protected Areas that are placed strategically around the world. There is a challenge in locating resilient reefs, but when they are found they are included within the protected area so that they can support the bleached reefs. When there are weather events, such as an El Nino, and ocean temperatures rise, scientists and managers of these protected areas monitor the reefs to see how well they bounce back, how well the resilient reefs can support the sick ones. Then scientists can make adjustments to the level of protection the reefs are getting, if current protections are not adequate.
Of course, combating global warming is also crucial if we are to save our precious reef systems. Global warming is the heating of the atmosphere due to an accumulation of what are termed greenhouse gases. These gases are primarily produced from the burning of fossil fuels, on which the human race is entirely dependent. New and cleaner forms of energy must be found and used in order to halt global warming.
Coral reefs form a huge and vital part of the ocean ecosystem. They provide homes, food, shelter, and protection for a quarter of the ocean's marine life. They form a habitat for plants and animals of many different shapes and sizes and they have a significant value to humans for medicinal purposes. For these reasons it is crucial that we all do what we can to protect these vast and beautiful structures that reside beneath the sea.