10 reasons for the disappearance of coral reefs
Earthquakes . The age of coral reefs in the lagoons of Belize is about 8−9 thousand years. The 7.3 magnitude Caribbean earthquake in May 2009 destroyed more than half of the reefs. At the time of the disaster, reefs recovered from natural diseases and discoloration. But worst of all, they were poorly attached to the walls of the lagoon, and an avalanche easily destroyed a significant part of the reef. According to scientists, a full recovery may take from 2 to 4 thousand years.
A sharp change in water temperature . Both warming and cooling of sea water lead to the eviction of the symbiotic algae that inhabit corals. Algae are important for reef life and give it the famous bright color. Therefore, the process of algae loss is called called bleaching.
Oil spill . The explosion at the BP oil rig in the Gulf of Mexico in April 2010 led to one of the largest oil spills in history. An oil slick is a mixture of the actual oil, natural gas and dispersant. Contrary to the usual notions, the oil slick does not float on the surface of the water, but settles at the bottom, preventing the penetration of oxygen into the coral reefs.
Killer algae . Many species of algae living in the Pacific Ocean can be harmful to corals. The chemicals they secrete discolor nearby coral reefs. There are several versions why algae have a similar function: it is possible that in this way they defend themselves from other algae, perhaps they protect themselves from microbial infections. In any case, corals are sensitive to these substances, and contact with these algae can be harmful.
Microplastic contamination . A small piece of plastic thrown overboard becomes a serious threat to all marine living organisms, including corals. The main problem is that they are not digested. Corals feed not only on algae, but also on zooplankton, which, in turn, can accidentally absorb microplastics. Particles of plastic falling into the digestive system of corals can cause irreparable harm to the entire ecosystem.
Starfish feeding on corals . The multi-beam starfish Acanthaster is perhaps the main predator threatening the corals of the Great Barrier Reef. Covered with poisonous spikes, they feed on corals, resulting in massive reef loss. On the one hand, this starfish helps to balance the population of fast-growing coral; on the other hand, a surge in the starfish population puts the coral reef at risk of total destruction. To prevent this from happening, the Australian government has taken a number of measures to control the population of predatory starfish.
Shipping . If a ship comes across a coral reef, this becomes a problem not only for the ship, but also for the reef. The vessel can carry cargo, the ingress of which into the water violates the ecosystem, in addition, it oxidizes the water and causes toxic algae to bloom food waste and sewage from cruise ships. But all the processes associated with towing a ship are especially traumatic for coral reefs. Unfortunately, towing damage is usually irreversible.
Excessive fishing is the main cause of the extinction of many species of marine life and the destruction of coral reefs. Firstly, it is about disturbing the balance of the ecosystem. Secondly, modern fishing methods cause irreparable harm to corals. This is trawl fishing, which literally crushes reefs, and the use of cyanide, with which corals are collected. Needless to say, dynamite, which is still used when fishing, does not make the life of coral reefs better.
Household waste . For 15 years, Elkhorn coral species that once flourished in the Caribbean have declined by 90%. You will be surprised, but the reef has ruined ... smallpox! Corals turned out to be defenseless against a disease from which a person is successfully vaccinated today. Pathogens were contained in household waste that entered sea water due to sewage leaks. Coral death within 24 hours of exposure to the virus is inevitable.
A sunscreen containing the toxic oxybenzone compound causes massive coral bleaching. Just one drop of lotion is enough to cause reef damage. First of all, danger is posed by vacationers who use sunscreen and then swim in the waters near the reefs. A cream applied to the skin leaves oil-like stains on the water that reach the seabed and damage corals. But even someone who does not go to the beach can also be involved in the destruction of reefs. So, washing away the sunscreen in his own bathroom, a person hardly thinks that the water from his shower will return to the sea at some point. As always, at the root of all the troubles of nature is an anthropogenic factor.