factors responsible for coral bleaching upsc

Our editors will review what you’ve submitted and determine whether to revise the article. While the…. In addition, studies have found that the chemicals in sunscreens and other personal care products can accumulate in areas with significant marine tourism and recreational use by humans and can promote viral infections in hard corals that lead to bleaching. In many areas coral is…, A phenomenon known as bleaching caused extensive devastation among coral reefs in the east Pacific since the early 1980s and in the Caribbean since the mid- to late 1980s. Bleaching is associated with the devastation of coral reefs, which are home to approximately 25 percent of all marine species. Bleached coral and a starfish on a coral reef near the coast of Costa Rica. Coral bleaching at Apo Reef near the west coast of the island of Mindoro in the Philippines. Warmer water temperatures can result in coral bleaching. A warming planet means a warming ocean, and a change in water temperature—as little as 2 degrees Fahrenheit—can cause coral to drive out algae. While more coral bleaching may still occur in 2017, the absence of widespread coral bleaching in the Indian Ocean appears to signal that the three-year-long global event has ended. Coral bleaching on the Great Barrief Reef. Indian reefs suffered strong to moderate bleaching in the 2016 event depending on where they were. Coral reef communities are in a state of change throughout their geographical range. Given that both ocean acidification and increasing ocean temperatures are associated with global warming, anthropogenic climate change is a major existential threat to coral reefs worldwide. With the strongest bleaching being observed in east Africa, reefs there were found to be more stressed than reefs in Indonesia and Fiji. Normally, coral polyps live in an endosymbiotic relationship with these algae, which are crucial for the health of the coral and the reef. It is therefore difficult to unequivocally identify the causes for bleaching events. The researchers also found that the geographical location of the coral reef between east Africa and Fiji played a major role in determining whether they would be bleached or not. However, as this symbiosis is vital for reef building, the absence of it significantly reduces coral growth and reproductive ability, eventually leading to reef mortality. Bleaching refers to the loss of colour in symbioses between dinoflagellate algae of the genus Symbiodinium and marine benthic animals, e.g. Not only do they provide essential structure for habitats, but corals themselves are a unique and beautiful type of animal. John P. Rafferty writes about Earth processes and the environment. We believe information is a powerful driver for the new tomorrow. Marine Pollution: rising marine pollution and oil spills. Coral bleaching occurs when coral polyps expel algae that live inside their tissues. This is often due to temperatures higher than the coral colony's tolerance level (Glynn, 1993). Does a new era of bleaching beckon for Indian Ocean coral reefs. Cellular mechanisms of bleaching involve a variety of processes that include the degeneration of zooxanthellae in situ, release of zooxanthellae from mesenterial filaments and release of algae within host cells which become detached from the endoderm. These animals are very sensitive to changes in their environment and are under threat by a preventable problem: marine debris. We believe strongly that we can and must do things differently. To identify the organic UV filters or preservatives possibly responsible for coral bleaching, ... viruses and indicate that induction of the lytic cycle in zooxanthellae with latent infection represents an important factor contributing to coral bleaching. …temperatures increase the tendency for coral bleaching (a condition where zooxanthellae, or yellow-green algae, living in symbiosis with coral either lose their pigments or abandon the coral polyps altogether), and they also raise the likelihood of greater physical damage by progressively more destructive tropical cyclones. Degraded coral ecosystems are also vulnerable to invasive species, such as seaweed and other types of algae, which have the potential to bring about significant and long-lasting structural changes to affected reefs. Selected comments may also be used in the ‘Letters’ section of the Down To Earth print edition. Map of areas where 60% or more of the model ensemble members were predicting heat stress at each of NOAA Coral Reef Watch's bleaching heat stress alert levels through December 2017 (as of September … In such cases, the affected coral ecosystems may not be able to recover fully from the disturbance, because critical parts of the ecosystem would no longer be present. Their past histories influenced how they responded to bleaching events. Warm ocean temperatures are one condition that could lead to coral bleaching. Even a rise of just one degree celsius for only four weeks can trigger bleaching in a coral. Figure 3. By signing up for this email, you are agreeing to news, offers, and information from Encyclopaedia Britannica. Comments are moderated and will be published only after the site moderator’s approval. Coral bleaching, whitening of coral that results from the loss of a coral’s symbiotic algae (zooxanthellae) or the degradation of the algae’s photosynthetic pigment. Coral bleaching has a variety of causes. Our aim is to bring you news, perspectives and knowledge to prepare you to change the world. Coral bleaching occurs when zooxanthellae — the symbiotic algae that provide coral polyps with nutrients and their color — are lost from coral tissues. Factors such as temperature changes, pollution and overfishing can destabilize the relationship and cause the coral to expel the algae. “Our results suggest that coral responses to global climate change may be changing as corals have different past experiences and tolerances to heat and stress,” said Tim McClanahan, lead author of the study. Coral response may differ because holobionts are biologically different (intrinsic factors), they were exposed to different environmental conditions (extrinsic factors), or inconsistencies in reporting (measurement uncertainty). If ocean temperatures stay high for eight weeks or longer, the coral cannot recover and begins to die. Bleaching is associated with the devastation of coral reefs, which are home to approximately 25 percent … Since bleaching can cause corals to die, this means that coral … (Knowlton, 2001) “For instance,” said Rohan Arthur of Nature Conservation Foundation (NCF), Bengaluru, who took part in the study, “although Lakshadweep reefs bleached as badly as they did, the amount of subsequent mortality was actually lower than in previous El Niño events.”, He added: “This was most likely because these reefs had been subject to multiple events in the past two decades. An additional factor for Caribbean reefs is the aftereffects of the epizootic that reduced the abundance of the herbivorous sea urchin, Diadema antillarum . Coral polyps, the animals primarily responsible for building reefs, can take many forms: large reef building colonies, graceful flowing fans, and even small, solitary organisms.Thousands of species of corals have been discovered; some live in warm, shallow, tropical seas and others in the cold, dark depths of the ocean. Express Explained is now on Telegram. Coral bleaching in a shallow coral reef off the coast of the Mariana Islands. Raised ocean temperatures result in severe damage to reefs in the Caribbean. Coral death was further accelerated by warmer waters, the team reports in Proceedings of the Royal Society of London B. All rights reserved. It can be induced by a variety of factors, alone or in combination. When water is too warm, corals will expel the algae (zooxanthellae) living in their tissues causing the coral to turn completely white. This will mean a lot for our ability to bring you news, perspectives and analysis from the ground so that we can make change together. Exposure to increased temperatures and solar irradiance also causes zooxanthellae to manufacture abnormally large quantities of reactive oxygen species (molecules that contain oxygen and at least one unpaired electron), which are toxic to both the algae and their coral symbionts. Coral reefs are diverse and important marine ecosystems, supporting a wide array of wildlife. ‘Bleaching’ is a process in which corals, on getting stressed due to higher sea temperatures, get stressed and expel the very algae that produce food for them and give them their vibrant colours. Bleached corals continue to live but begin to starve after bleaching. In the new study Temperature patterns and mechanisms influencing coral bleaching during the 2016 El Niño published in the journal Nature Climate Change, scientists studied how coral in the Indian and Pacific Oceans was affected by the El Niño of 2016, one of the warmest years on record. © Copyright Down To Earth 2020. Coral bleaching comes to the Great Barrier Reef as record-breaking global temperatures continue, After Great Barrier Reef, bleaching kills 70 per cent of Japan’s coral reef, Coral bleaching of 2016 caused severe mortality in Gulf of Mannar: study. Coral bleaching, whitening of coral that results from the loss of a coral’s symbiotic algae (zooxanthellae) or the degradation of the algae’s photosynthetic pigment. It may result from increases in seawater temperature, particularly when associated with elevated levels of solar irradiance (e.g., ultraviolet radiation), or it may be caused by changes in seawater chemistry (e.g., due to ocean acidification or pollution), increased levels of sediment in seawater, or a coral’s exposure to sodium cyanide (a chemical used in the capture of coral reef fish). Down To Earth is a product of our commitment to make changes in the way we manage our environment, protect health and secure livelihoods and economic security for all. Rather, many other factors could be responsible, including the location of the coral reef, according to a press statement. There is concern that widespread coral bleaching may cause some species to become extinct locally. The following stressors have been implicated in coral reef bleaching events. Omissions? Corals are bleaching more and more often around the world because of warming ocean waters, a new study shows. Factors responsible for Coral Bleaching. By the summer of 2016, a large portion of the northern sector of Australia's Great Barrier Reef had experienced severe bleaching. Factors contributing to this change include bleaching (the loss of algal symbionts), storm damage, disease, and increasing abundance of macroalgae. The corals that made it through these events are likely to be relatively well adapted to heat stress.”. Recent studies have reported that pesticides, hydrocarbons, and other contaminants can cause coral bleaching (Brown 2000; Douglas 2003). 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