Coral reefs are one of the most diverse marine habitats in the world. The coral reef ecosystem is sometimes dubbed as the marine rain forest for its wide variety of marine life. It has been estimated that the coral reef ecosystem is the habitat of thousands of fish species and approximately 100,000 invertebrate species. The biodiversity of the coral reef ecosystem turns them into very productive ocean waters, which yield between four and eight million tons of fish every year. Coral reefs display a high level of marine biodiversity; however, they are also some of the most threatened.
Coral reefs develop well in the tropical waters of the world at 30 degrees north or south of the equator. It is in these regions where clear, warm and shallow waters make it possible for corals to host the growth of zooxanthellae, microalgae that the corals need to survive. In a mutualistic relationship, the algae provides the coral with the energy it needs and the algae benefits from consuming the corals nitrogenous wastes; however, environmental stresses can cause the coral to expel the algae in a process known as coral bleaching. Disturbances in the coral reef ecosystem can lead to massive coral bleaching. In recent years, massive coral bleaching cases have been reported in many marine regions around the world.
The changing of water levels, higher water temperatures, water turbidity, and sedimentation from mining, among other anthropogenic causes can adversely affect the coral reef ecosystem. Zooxanthellae need the sunlight for the process of photosynthesis. Turbid waters can block the light from the sun, leading to the death of zooxanthellae, thus, causing bleaching. Large ships passing by a coral reef can damage coral reefs seriously.
Some coastal communities rely on the coral reef ecosystem for limestone, which is used as concrete in construction. To extract limestone from coral reefs, they use dynamite, causing the death of marine biodiversity and damaging the coral reef structure. Coastal housing developments produce sewer wastes and pollution. These wastes are emptied on the coral reef ecosystem, damaging the coral reef biological structure. Channels for the passing of ships into the bays are other local threats to the coral reef ecosystem.
Global warming has altered climatic conditions which have threatened the survivability of coral reefs. Elevated temperatures due to global warming are the main caused of coral bleaching. Increases in atmospheric CO2, are causing the acidification of the ocean. In the last three decades about one third of the CO2 in the atmosphere has been absorbed by the ocean. This has caused changes in the chemistry of the ocean, leading to a decrease in the pH of ocean water. It has been estimated that approximately 60% of the world’s coral reefs are at risk due to anthropogenic activities and it has been predicted that if the trend continues, more than 50% of the world’s coral reefs may be significantly damaged in the next decades.
Coral reefs are vital in the marine ecosystem. They provide habitat for many kinds of species of fish and invertebrates. Coral reefs provide from 4 to 8 million tons of fish to fisheries every year. Coral reefs serve as natural barriers against strong ocean water currents , protecting coastal communities. Local measures and coral reef habitat restoration can reduce coral reef damage; however, long-term threats, such as ocean acidification and global warming are threats that need more radical measures. According to oceanworld.tamu, a coral reef is a marine structure that functions as a place in which animals and plants can thrive. In the present, artificial reefs are being created by humans to replace those that have been destroyed.