IndexEffects of coral bleaching on the entire marine ecosystemHow climate is affecting coral reefsHuman contributions and impacts on bleachingHow the world's major coral reefs have been affectedThe Coral reefs are an essential cornerstone of the marine ecosystem. These coral reefs are home to thousands of aquatic species and provide protection to coasts. Over the past two decades, a phenomenon known as coral bleaching has occurred. Coral bleaching occurs when the water becomes warm, causing algae to be released from their tissues. This causes the corals to turn white and puts them at high risk of contracting diseases and eventually dying. Fish that use coral reefs as habitat also become more susceptible to predators when coral reefs are bleached. Massive bleaching events that occurred between 2014 and 2017 caused severe coral loss in the Great Barrier Reef and Japanese coral reefs. The major impacts of this mass bleaching have already been observed, with the loss of 75% of fish biodiversity. Although there are many different factors that contribute to bleaching, these are mainly caused by climate change and anthropogenic causes. If the remaining healthy coral reefs continue to experience thermal stress, a potentially catastrophic domino effect for the marine ecosystem could result. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an Original Essay The ocean includes several ecosystems, one of which is coral reefs. Coral reefs are a diverse aquatic ecosystem made up of calcium carbonate. Although they cover only 0.1% of the oceans, coral reefs provide living space for 25% of all marine species (Jones & McCormick 2009). Not only do they provide a habitat for aquatic species, but they provide protection to coasts and also provide aesthetic value to tourism. Coral reefs are typically found in shallow water in tropical areas. Coral bleaching is a phenomenon that occurs when there is a breakdown in the relationship between scleractinian corals and their symbiotic algae (Guest & Baird 2012). Coral bleaching is caused by a few different factors. Pollution, rising ocean temperatures, and storm runoff are some of the major causes of coral reef degradation. It is a common misconception that coral reefs are dead when they bleach. This is not the case, coral reefs only become more susceptible to disease when they are bleached. Diseases like red band and black band are those that kill corals and make them unsalvageable. Over the past decade, massive bleaching events have occurred at an alarming rate. Coral reefs in Australia, Japan, and the Caribbean have all seen mass bleaching events that have negatively affected their reefs. There is no concrete reason for coral bleaching, but there are a number of factors believed to be generated by anthropogenic causes. Some of these anthropogenic factors are direct, such as overfishing and pollution, while others are indirect, such as climate change and heat stress. The consequences of coral bleaching have been observed to produce a catastrophic domino effect that can cause suffering to aquatic organisms and entire marine ecosystems. This document will provide further analysis on the causes of coral bleaching and how the phenomenon can cause a negative impact on the wholemarine ecosystem. Studies conducted on major coral reefs will be used to support the idea that these coral reefs have been damaged by anthropogenic and natural causes. Effects of coral bleaching on the entire marine ecosystemThe effect of coral bleaching on the entire marine ecosystem is almost impossible to quantify. Coral reefs are home to many different fish throughout the ocean that depend on the reef for survival (Jones & McCormick 2009). While it's easy to say that fish depend on coral reefs to survive, it's important to take a look at the relationship between fish and coral reefs. 75% of coral reef fish species have declined in abundance and 50% have declined to less than half their original numbers (Jones & McCormick 2009. In a study by Jones and McCormick, they examined feeding patterns and Habitat use by species in 20 coral reef fish families. Results also showed that approximately 11% of the 538 species had an obligate association with living corals coral reefs or that these species would inevitably die. Another effect that coral bleaching has on the marine ecosystem is. The structure of coral reefs helps provide a buffer that protects coasts from waves and from flooding. Australia has seen its coral reefs undergo a massive bleaching event and as a result the coastline has suffered some damage. A damaged coastline will increase the risk of flooding or severe damage from natural hazards such as a coastal storm (Hooidoink 2013). How climate is affecting coral reefs Climate change has emerged as the main factor contributing to coral reef bleaching. Climate change has contributed to warming waters, which causes corals to expel algae and result in the white color. Bleaching has been consistent across coral taxa, and a mass bleaching event has occurred in Southeast Asia. This may be indicative of how areas more susceptible to warmer climates may have a negative impact on the health of coral reefs (Guest & Baird 2012). Thermal stress is considered to be any created change in temperature that can lead to material degradation. In the case of coral reefs, it is one of the main factors contributing to bleaching. There have also been studies examining how coral reefs adapt to thermal variation. Understanding climate adaptation will provide further insight into how coral reefs manage different temperatures. In 2010, researchers conducted a study to test whether coral reefs in more thermally variable environments were less susceptible to severe bleaching during episodes of high sea temperatures (Guest and Baird 2012). Based on their study, they concluded that coral reefs in thermally variable environments would be less susceptible to rising sea temperatures if they had already undergone a massive bleaching event. Corals are believed to have low evolutionary potential and scleractinians are proof of this as they have exhausted their ability to adapt to rising sea temperatures. Another climate factor contributing to coral reef heat stress is ocean acidification. Ocean acidification occurs when carbon dioxide is dissolved in the ocean and decreases the ocean's pH. It creates a negative impact by destroying coral reefs and the calcium carbonate shells of several marine species. One of the ways in whichOcean acidification damages coral reefs and reduces coral diversity (Hoegh & Bruno 2010). The increase in CO2 emissions into the atmosphere causes an increase in global temperature which translates into more frequent coral bleaching. Recent data suggests that acidity thresholds related to atmospheric CO2 will soon be exceeded. If atmospheric CO2 exceeds 450 ppm, it could push coral reefs into a negative carbon balance (Hoegh-Guldberg & Bruno 2011). A negative carbon balance would be harmful to the oceans because it would mean global temperatures would rise. The 400-450 ppm range has been identified in other key ocean components such as the loss of polar sea ice, the melting of Greenland, and the melting of the West Antarctic ice sheets. These thresholds can be used to predict large-scale consequences for ocean ecosystems. If atmospheric CO2 exceeds the threshold, it can trigger a wide range of irreversible changes in the system that could leave permanent damage to coral reefs (Hoegh-Guldberg & Bruno 2011). While ocean acidification is a serious problem for coral reefs, it is seen more as a long-term problem for coral reef health. Studies have shown that by doubling atmospheric CO2 to 560 ppm, coral calcification decreases by nearly 40% through limiting aragonite formation (Hoegh-Guldberg & Bruno 2011). It has been predicted that ocean acidity will decrease to 0.4 pH by the end of the century, this will be detrimental to coral reef growth because pH levels will drop below the levels required to support coral reefs . Acidity may differ from region to region. For example, the Great Barrier Reef in Australia can reach high levels of aragonite more quickly than any region of the United States. The reason aragonite and pH cause a problem for coral reefs is that coral reefs are made up of a calcite skeleton that is high in magnesium. This means that they are very sensitive, which causes the loss of the skeleton. It can also weaken coral growth which can damage coral settlement (Hoegh-Guldberg 2007). Bleaching locations can be accurately predicted using the grade heating week index. It can show how much thermal stress is building up in an area and whether or not it is significant to the health of the coral. To date, the ACS index has been a near-perfect, but conservative, predictor of whitening worldwide. For 23 of 24 virtual stations monitored, bleaching was reported in all cases where NOAA issued a coral bleaching advisory (Eakin, Lough & Heron 2009). In 1998, a coral reef in the western Indian Ocean was negatively associated with the ACS index. The areas have been observed to have massive loss of coral cover (Mccalanahan & Weil 2009). The DHW Index will continue to help researchers predict events where coral loss may occur and find patterns in different regions to understand why other areas are under more stress than others. Human Contributions and Impact on Bleaching While there are few natural factors that play a role in coral bleaching, there are many anthropogenic factors that contribute to coral reef bleaching. One of the contributions that humans can make to the degradation of coral reefs is to introduce plastic waste into the ocean. Plastic debris was present on 17 genera of eight reef-building coral families. When corals come into contact with debrisplastic, the chance of contracting a disease increases by 4% in all eight regions (Lamb et al. 2018). This is concerning considering how the increase in plastic is contributing to ocean pollution. The cumulative amount of plastic waste entering the marine ecosystem is expected to increase by an order of magnitude by 2025 (Lamb et al. 2018). Coral reefs are believed to be more susceptible to various diseases when they interact with plastic. This mechanism is still being studied, but the influence that plastic debris has on development has been observed in all regions where plastic dumping is high. The size of the human population around coastal regions and waste management systems also play a role in plastic contamination. It has been estimated that 80% of plastic debris entering the ocean is dumped over land (Lamb et al. 2018). Four countries (Australia, Myanmar, Thailand and Indonesia) were studied based on the levels of plastic waste entering the ocean. This study was conducted from 2011 to 2014 and the model showed that 88% of mismanaged plastic waste ended up in the ocean from these Asia-Pacific countries. At these levels over the years there have been 804,214 tonnes of plastic. Nine of these Asia-Pacific countries ranked among the top ten plastic polluters globally (Lamb et al. 2018). If this trend continues, 11.1 billion pieces of plastic waste will end up on coral reefs along Asia-Pacific coasts. This is also considered a more generous estimate as it does not include China and Singapore as they are outside the model's range. Another anthropogenic factor contributing to coral bleaching is overfishing. Overfishing occurs when more fish are caught than the system can support. While this may not appear to have a direct impact on coral reefs, some fish play an important role in maintaining ecosystem processes on coral reefs (Burke & Reytar 2011). This becomes a serious problem when viewed from an economic point of view because most of the underdeveloped countries around the coasts need to catch fish for their local businesses and the country's economy. Overfishing can cause a chain reaction that would be catastrophic for these economies due to coral decline and, in turn, cause habitat loss for other species. Benthic communities along the coast of North America have suffered the most from these events. In addition to plastic, there are other forms of pollution that can play an important role in the degradation of coral reefs. Some events, such as fertilizer and nutrient spills into the oceans, can damage coral reefs. Runoff from agricultural supplies can cause microalgae blooms, resulting in reduced abundance and impaired growth of coral reefs. This also reduces the competitive behavior of coral reefs and ultimately pushes coral reefs into ecological collapse (Burke & Reytar 2011). Agriculture is a key part of society along coasts, so fertilizer runoff is to be expected, but it continues to harm coral reef communities. One of the major problems coral reef communities face due to fertilizer addition is hypoxia. The coral's tissues are deprived of oxygen, which ultimately damages the coral. Finding a solution is complicated as many communities rely on agriculture to maintain their economy. How the main barriers have been affected.