Table of contentsEffect of coral bleaching on the entire marine ecosystemHow climate affects coral reefsHuman contributions and impact on bleachingHow the world's major reefs have been affectedCoral reefs are an essential cornerstone of the marine ecosystem. These reefs are home to thousands of aquatic species and protect the 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 corals to bleach and put them at high risk of catching diseases and possibly dying. Fish that use coral reefs as habitat also become more susceptible to predators when the reefs bleach. Mass bleaching events between 2014 and 2017 led to significant coral loss in the Great Barrier Reef and Japanese reefs. The major impacts of this massive bleaching have already been observed with a loss of 75% of fish biodiversity. Although many different factors come into play in bleaching, it is primarily caused by climate change and anthropogenic causes. If remaining healthy reefs continue to experience thermal stress, a domino effect could ensue, potentially catastrophic for the marine ecosystem. Say no to plagiarism. Get a tailor-made essay on “Why Violent Video Games Should Not Be Banned”? Get an Original Essay The ocean includes different ecosystems, including coral reefs. Coral reefs are a diverse aquatic ecosystem composed 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 habitat for aquatic species, but they protect coastlines and also provide aesthetic value to tourism. Coral reefs are generally found in shallow waters in tropical areas. Coral bleaching is a phenomenon that occurs when there is a breakdown in the relationship between scleractinian corals and their algal symbionts (Guest & Baird 2012). Coral bleaching is caused by several different factors. Pollution, rising ocean temperatures and storm runoff are some of the main causes of coral reef degradation. It is a common misconception that reefs die when they bleach. This is not the case, reefs only become more susceptible to disease when they bleach. Diseases such as red band and black band kill corals and render them unsalvageable. Mass bleaching events have occurred at an alarming rate over the past decade. Reefs in Australia, Japan and the Caribbean have all experienced mass bleaching events negatively affecting their coral reefs. There is no single concrete reason for coral bleaching, but there is a set 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 found to produce a catastrophic domino effect that can cause suffering to aquatic organisms and entire marine ecosystems. This article will provide more in-depth analysis on the causes of coral bleaching as well as how the phenomenon can impactnegative on the entire marine ecosystem. Studies conducted on major reefs will be used to support the idea that these reefs have been damaged by anthropogenic as well as natural causes. Effect of coral bleaching on the entire marine ecosystem The 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 their survival (Jones & McCormick 2009). While it is easy to say that fish depend on reefs for survival, it is important to examine the relationship between fish and coral reefs. 75% of reef fish species have declined in abundance and 50% have dropped to less than half their original numbers (Jones & McCormick 2009. In a study by Jones and McCormick, they investigated feeding patterns and habitat use by species in 20 reef fish families The results also showed that approximately 11% of the 538 species had an obligate association with living corals. adapt to exist without the reefs or they would inevitably die Another effect of coral bleaching on the marine ecosystem is the impact it can have on the coasts The structure of coral reefs helps provide a buffer. Coasts from waves and flooding Australia has seen its reefs suffer massive bleaching and coastline damage as a result of a damaged coastline will increase the risk of flooding or serious damage from such natural hazards. than a coastal storm (Hooidoink 2013). How climate affects coral reefs Climate change has emerged as the main factor contributing to coral reef bleaching. . Climate change has contributed to warming waters, causing corals to expel algae and turn white. Bleaching has been consistent among coral taxa and there has been a mass bleaching event in Southeast Asia. This may be indicative of how areas more sensitive to warmer temperatures can negatively impact coral reef health (Guest & Baird 2012). Thermal stress is considered any created change in temperature that can lead to the degradation of a material. In the case of coral reefs, this is one of the main factors contributing to bleaching. Studies have also been carried out to examine how coral reefs adapt to thermal variance. Understanding climate adaptation will provide more information about how coral reefs cope with different temperatures. In 2010, a study was conducted by researchers to see if coral reefs located 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 reefs located in thermally variable environments would be less likely to increase sea temperatures if they had already experienced mass bleaching. Corals appear to have low evolutionary potential and scleractinians are proof of this since they have exhausted their capacity to adapt to rising sea temperatures. Another climatic factor that contributes to thermal stress on coral reefs is the ocean acidification. Ocean acidification occurs when carbon dioxide dissolves in the ocean and decreases the pH of the ocean. It creates a negative impact by destroying reefs, as well as the calcium carbonate shells of several marine species. Ocean acidification damagescoral reefs by reducing coral diversity (Hoegh & Bruno 2010). Increasing CO2 emissions into the atmosphere are causing global temperatures to rise, leading to more frequent coral bleaching. Recent data suggest that thresholds will soon be exceeded for acidities correlated with atmospheric CO2. If atmospheric CO2 exceeds 450 ppm, this could push coral reefs towards a negative carbon balance (Hoegh-Guldberg & Bruno 2011). A negative carbon footprint would be bad for the oceans because it would mean an increase in global temperatures. 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 on ocean ecosystems. If atmospheric CO2 exceeds the threshold, it can trigger a large number of irreversible changes in the system that could cause permanent damage to coral reefs (Hoegh-Guldberg & Bruno 2011). Although ocean acidification is a major problem for coral reefs, considered a long-term problem for reef health. Studies have shown that by doubling atmospheric CO2 to 560 ppm, coral calcification decreases by almost 40% due to the restriction of aragonite formation (Hoegh-Guldberg & Bruno 2011). It was predicted that ocean acidity would decrease to 0.4 pH by the end of the century, which would be detrimental to the accretion of coral reefs, as pH levels would fall below levels required for maintain the reefs. Acidity can be different from region to region. For example, the Great Barrier Reef in Australia can reach high levels of aragonite faster than any region in the United States. The reason aragonite and pH are a problem for coral reefs is because reefs are made of a calcite skeleton with a high magnesium content. This means they are very sensitive, leading to skeletal loss. It can also weaken coral growth, which can harm their settlement (Hoegh-Guldberg 2007). Bleaching locations can be accurately predicted using the weekly heating degree index. It can show the extent of accumulated heat stress in an area and whether or not it is important to coral health. To date, the ECS index has been a near-perfect, but conservative, indicator of global money laundering. For 23 of the 24 virtual stations monitored, bleaching was reported in all cases where NOAA issued a coral bleaching alert (Eakin, Lough & Heron 2009). In 1998, a reef in the western Indian Ocean was negatively associated with the ECS index. These areas have been observed to have a massive loss of coral cover (Mccalanahan & Weil 2009). The DHW Index will continue to help researchers predict events that may cause coral loss and identify trends in different regions to understand why other areas are more stressed than others. Human Contributions and Impact on Bleaching Although there are few natural factors that play a role in coral bleaching, many anthropogenic factors contribute to coral reef bleaching. One of human contributions to the degradation of coral reefs is the discharge of plastic waste into the ocean. There was plastic debris on 17 genera belonging to eight families of reef-forming corals. When corals come into contact with plastic debris, the risk of contracting disease increases by4% in the eight regions (Lamb et al. 2018). This is worrying when you consider how much the increase in plastic contributes to ocean pollution. It is predicted that by 2025, the cumulative amount of plastic waste entering the marine ecosystem will increase by an order of magnitude (Lamb et al. 2018). Reefs appear to be more susceptible to various diseases when interacting with plastics. This mechanism is still being studied, but the influence of plastic debris on development has been observed in all regions with significant plastic spills. The size of the human population around coastal regions and waste management systems also play a role in plastic contamination. It is estimated that 80% of plastic debris entering the ocean is discharged via land (Lamb et al. 2018). Four countries (Australia, Myanmar, Thailand and Indonesia) were studied based on the levels of plastic waste they released into the ocean. This study was conducted from 2011 to 2014 and the model showed that 88% of mismanaged plastic waste entered the ocean from these Asia-Pacific countries. These levels total 804,214 tonnes of plastic over the years. Nine of these Asia-Pacific countries rank among the top ten global plastic polluters (Lamb et al. 2018). If this trend continues, 11.1 billion pieces of plastic debris will be deposited on coral reefs along the Asia-Pacific coasts. This is also considered a more generous estimate since it does not include China and Singapore as they fall 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. Although this does not appear to have a direct impact on coral reefs, some fish play a major role in maintaining coral reef ecosystem processes (Burke & Reytar 2011). This becomes a serious problem from an economic point of view, because most of the underdeveloped riparian countries need to fish for their local businesses and their country's economy. Overfishing can lead to a chain reaction that would be catastrophic for these economies due to coral decline, and would in turn lead to loss of habitat for other species. Benthic communities along the North American coast suffered the most from these events. Besides plastics, there are other forms of pollution that can play a significant role in the degradation of coral reefs. Certain events such as runoff of fertilizers and nutrients into the oceans can damage reefs. Runoff from agricultural resources can lead to microalgae blooms, leading to reduced abundance and impaired growth of coral reefs. This also reduces the competitive behavior of reefs and ultimately pushes reefs into ecological collapse (Burke & Reytar 2011). Agriculture is a key part of society along coastlines, so fertilizer runoff is to be expected, but it continues to harm reef communities. Hypoxia is one of the main problems faced by reef communities due to added fertilizer. Coral tissues are deprived of oxygen, which ultimately damages the coral. Finding a solution is tricky because many communities rely on agriculture to sustain their economies. How the world's major reefs were affected To understand the severity of coral bleaching, the world's major reefs can be used as examples to show how reefs were affected by bleaching events that occurred in..