Coral reef is a shallow marine complex ecosystem built by coral animals, especially hermatipic corals as its main component. Initially, coral reefs were built by attachment of free swimming coral larvae on submerged hard substrate in the edge of islands or continents. Then many corals grow and die over a long period of time, making the reef as a stable platform for many biota to settle on and interact. In Indonesia, there are four main types of reefs, including atoll, barrier reefs, fringing reefs and patch reefs (the last two are the most common ones).
In coral reef ecosystem, there are various marine creatures which become potential sources of protein and sources of medicinal materials. Coral reefs are also known as natural fortresses that function to protect islands and beaches from erosion caused by the waves. In addition, breathtaking underwater landscape has attracted many people to dive and explore coral reefs. In short, coral reefs provide goods and services that are very important for coastal communities’ well-being.
Indonesia, located in tropics and almost two-thirds of its territory are sea, is an ideal place for coral reefs to grow and develop. Based on the one map policy mandated in Law No.4 of 2011, it is confirmed that the total area of coral reefs in Indonesia, based on analysis of satellite imagery, is around 2.5 million hectares. Considering the function and benefits of coral reefs which are very huge, therefore coral reefs should be managed properly. Unfortunately coral reefs are very prone to degradation. In this case, the degradation can be caused by anthropogenic factors,including land based pollution, sedimentation, destructive fishing, mining activities and coral exploitation. In addition, natural disturbances, such as elevated sea temperature, earthquakes and tsunamis, also have adverse effects on the reefs.
There are alot of marine creatures living in the coral reef ecosystem, such as fish, sponges, algae, mollusc and crustaceans. The interactions among them are not always benefitting each other, but can be a competition and even predation. Therefore, the absence or prensence of one component can affect the stability of the ecosystem.