Corals under stress due to changes in PH levels or temperature of the water will expel the algae (zooxanthellae) living within their tissues causing the coral to turn completely white. This is called coral bleaching. Another cause of coral bleaching is produced formation water, an effluent of offshore oil and gas industries that cause significant bleaching ( White et al .2012) .When a coral bleaches, it is not dead. Corals can survive a bleaching event, but they are under more stress and are subject to mortality. Mortality amongst corals has appeared to be the breakdown of the symbiotic association between the zooxanthellae and the coral host.
They break down dead biological matter and waste products and convert them into useable energy; returning important materials to the environment. Decomposers are a particular important feature in the Great Barrier Reef considering the heavy bio-load. Main decomposers inside the reef include bacteria, sea cucumbers, some species of snails, crabs and bristle worms. Bacteria sis not only vital for the Great Barrier Reef’s food web, but is also said by scientists that it could be the key to keeping the coral healthy and able to withstand the impacts of global warming. Dr Tracy Ainsworth stated “it is very likely that these microorganisms play a vital role in the capacity of coral to recovering from bouts of bleaching caused by rising temperatures.” Corals rely on these good bacteria’s crucially although we don’t yet understand these microbe’s ell enough to know how they influence coral survival, which is vital in maintaining the food web of the Great Barrier Reef.
With only about one-sixth of the original coral cover left, most Caribbean coral reefs may disappear in the next 20 years. This statistics according to the latest report by the Global Coral Reef Monitoring Network (GCRMN), the International Union for Conservation of Nature (IUCN) and the United Nations Environment Program (UNEP). First of all, as we know nearly two-thirds of coral reefs in the Caribbean are threatened by human activities. For example of human activities that effect the coral reefs are coastal development, watershed-based sediment and pollution, marine based threats and also overfishing. Within the years, the Reefs at Risk Threat Index identified that about one-tenth of Caribbean coral reefs are at very high levels of threat,
Although we have explored less than five percent of our vast oceans, humans have set them on a path to devastation long before we could discover the rest. Mark Prigg for dailymail.com warns by the end of the century, the oceans will have been damaged to an irreversible point. Without the oceans, the global climate cannot be regulated, where the world’s environmental state would then be far worse than what we have seen to be possible by, for example, global warming. It begins with our oceans becoming filled with various forms of waste by humans, atmospheric changes causing acidity in water increase, and imbalances of organism life leading to lower levels of oxygen. How the oceans may die is crucial to understand in order for them to be preserved for the survival of the planet.
This issue is not a new problem; coral bleaching has had a substantial effect on coral for many years. “In 2005, the U.S lost half of its coral reefs in the Caribbean in one year due to a massive bleaching event”(National Ocean Service). Another article states that in January 2010, cold-water temperatures in the Florida Keys caused a coral bleaching event that resulted in some coral death. Researchers have evaluated the cold-stress of the water will make coral more susceptible to disease, in the same way warmer water impact coral. Luckily there are things that we can do to help stop this
Coral reef destruction Last year, scientists remarked the "unprecedented" collapse of Florida's reef, that expands along the south-eastern part of the state of Florida. This ecosysten, that was the only barrier reef in the continental US, was attacked by bleaching in 2014 and 2015 and is now is "beginning to dissolve away", according to Chris Langdon, a coral expert at the University of Miami. More than 80% of shallow water reefs of Christmas Island have died and it has been shown by pictures released to the public not too long ago, that 90% of the reefs in Okinawa, Japan were bleached as well. This is an alarming news, not only because it will affect marine life's ecosystems, but us as well. The most common phenomenon we've seen thus far has been the bleaching event.
“Coral reefs are biological assemblages adapted to waters with low nutrient content, and the addition of nutrients favours species that disrupt the balance of the reef communities” ( The International Coral Reef Initiative). With all of the pollution there is not any clean water for the reefs to thrive; the
However, when the population of this specific kind of starfish increases at the Great Barrier Reef the reef “might be completely destroyed in two to three years”1. An invasion by these starfish causes devastation to the reef, as happened in 1970. Many parts of the Great Barrier Reef have been destroyed, and although the population of crown-of-thorns starfish near the reef is now negligible the reef still needs a long time to recover from this plague.2
The zooxanthellae, an algae that live in the tissues of corals and their source of food, leave their tissue if higher temperatures carry on for weeks. This causes the corals to turn white since it is the zooxanthellae that produces their color. ‘Bleached corals’ are the ones that are white and unhealthy which means they are weak and less able to fight disease. As climate change (higher or warmer water temperature) continues, bleaching will become more common and overall health of coral reefs will deteriorate. Across the Pacific Ocean, coral reefs are declining at a rate of about two percent a year, and it may be only 40 to 50 years before they’re completely gone.