Coral bleaching has become an urgent topic among the experts who are involved in the analysis of various environmental issues. Many people do not understand the problem of coral bleaching. Corals are individual organisms that live according to their style. Some corals are colorful. Others are white. Why do people care about the color of corals? The answer is easy. When corals become pale, they are luckier to die. Consequently, we lose vast areas of coral reefs that make our planet beautiful. What is more, corals are the parts of large ecosystems. Millions of microorganisms, plants, and fish live among corals. These reefs are the home to such organisms. When corals die, millions of water bodies disappear too. Thus, the problem of coral bleaching is very considerable. Its effects are harmful to biological diversity and global economy. The best solution is to stop coral bleaching defeating the cause of this process.
Before we try to understand the cause of coral bleaching, let us get to know why they lose their color. You ought to know that corals live in the tight interconnection with the algae called zooxanthellae. This symbiotic relationship enables both organisms to survive. Zooxanthellae live in the tissues of corals and fulfill their specific functions there. Corals play the role of home to the algae. They protect these microorganisms from the harmful and dangerous environment. On their turn, the zooxanthellae provide corals with oxygen and clean them from wastes. Moreover, these algae are the primary source of food to corals. Therefore, this interconnection is useful to both sides. When the concentration of the algae declines, corals begin to starve. They suffer from the lack of food and oxygen. They are ‘stressed’ and close to dying. The color of corals depends on the type of the symbionts that live in their tissues. When symbionts disappear, corals become pale. This color is natural to them whereas their skeletons consist of calcium carbonate. Colorful symbionts cover these frames, protect them from the dangerous environment and feed corals at the same time. It is easy to notice that spectacular colorful coral reefs become pale and monotonous. They no longer serve as the home for algae, fish, and microorganisms. Coral reefs begin to look devastated. Scientists are concerned about the condition of the coral ecosystems. They try to understand the cause of the process of coral bleaching.
Enumerating many causes of coral bleaching is possible. However, I will focus on the several most notable ones. The most obvious reason is the water temperature. When the temperature is increased or decreased, algae feel uncomfortable and leave corals. They are very sensitive and require stable temperatures that maintain their functioning. Nowadays, the temperature has changed everywhere because of global warming. The streams of the incredibly warm (or cold) water appear in the areas where they noticed. This shift is harmful to microorganisms and they have to leave these inaccessible areas.
Secondly, there is a problem of pollution. When people pour wastes and litter into seas and oceans, the water becomes contaminated with the substances that can be harmful to microorganisms. As a result, they die disappearing from the coral reefs.
The third cause is oxygen starvation. This problem posed by the increase of zooplankton in the water. Overfishing determines the increased amount of zooplankton. When people fish too much, there is not enough fish to consume zooplankton. Thereof, its level is too high. It consumes oxygen depriving algae of it.
The next problem is solar irradiance. Bear in mind that corals located close to the sea surface and they are vulnerable to the impact of solar radiation.
The following problem is the change of salinity. This indicator is vital whereas many organisms live in the water with the definite saltiness. If its level moves forward or back, it is stressful for animals, fish, corals, and algae.
If you look at the factors that cause coral bleaching, you will understand that they are interconnected. It is impossible to save corals if we do not solve such problems as global warming, pollution or overfishing. Every problem causes a chain of other related problems. Therefore, bleaching will be defeated if we apply multiple methods aimed at the improvement of the ecological situation on Earth. Coral bleaching causes the extinction of biological species and causes harm to our economy since many countries make money on tourists who come to admire colorful coral reefs.