Coral Reef Bleaching : A Serious Problem That Should Be Addressed Immediately

Corals dislike warm water about as much as acidity. When oceans get typically warm, corals can eject the algae that symbiotically live in their skeletons, providing food in exchange for shelter. The ejection process is called bleaching, named by the white skeleton left behind when the coral gets sick and, in some cases, dies.

Elevated sea temperatures caused by climate change and extra-bright sunlight can result in coral bleaching. As the water gets warmer, corals will expel the algae known as zooxanthellae that lives in their tissues causing the coral to turn completely white. When temperatures drop, the corals can recover, but they might be vulnerable to disease and when

Coral reefs are found in shallow tropical waters along the shores of islands and continents. Coral bleaching is a topic that gets left in the dust. Not many people really pay attention or show much interest in it. Widespread bleaching, involving major coral reef regions and resulting in mass coral mortality has raised concerns about linkage of the events to global phenomenons including global warming or climate change and increased UV radiation from ozone depletion. Corals provide a lot not just for us humans but for marine life as well. Marine Biology provides information about how bleaching happens and how it affects the coral. Buchheims’ article is full of logos and a few pathos while the other source is full of ethos. In The Nature Conservancy’s director Stephanie Wear provides us with lots of professional opinions

Coral bleaching is normally characterized by the expulsion of the zooxanthellae algae, loss of algal pigmentation, or both. Coral bleaching events have had serious effects on corals and reefs worldwide. What is crucial to the understanding of zooxanthellae expulsion and bleaching is how the density of zooxanthellae within the coral is changing, if at all, under the prevailing range of environmental conditions (Gates and Edmunds, 1999). Over the last twenty years, there has been a dramatic increase in both the frequency and intensity of coral bleaching events. Sixty major bleaching events have been reported between 1960 and 1979, whereas only nine were reported prior to 1979 (Huppert and Stone, 1998). Given the dependence of the coral on this symbiotic algae, it is important to determine the cause of these bleaching events. According to Helvarg (2000, p.12):

Consisting of less than 1% of the world oceans, the coral reefs are ancient animals comprising of thin calcium carbonate deposits within the photic layer. Aside from its biologically diverse ecosystems, coral reefs are major source of food for millions and provides habitats and nursery areas for many marine organisms. Coral reefs also act as a physical buffer to protect the coastlines from tropical storms and erosion. In addition, many local communities rely on coral reefs to generate an income through activities such as fishing and diving. However, 75% of the coral reefs are under threat from induced impacts of humans and climate change (Burke, et al., 2011). This essay looks at the human impacts constantly being inflicted on coral reefs.

Bleached corals have reduced growth rates and have an elevated mortality rate. Coral bleaching also affects species such as fish and invertebrates that depend on living coral for food and shelter. Changes in the population and composition of reef fish occur when the corals they utilized are killed as a result of coral bleaching. Reefs affected by coral bleaching lose the aesthetic appeal that is fundamental to reef tourism. This aspect is highly relevant to the Great Barrier Reef because it is a popular tourist destination. It is estimated that the current bleached state of the Great Barrier Reef will cause Australia a loss of $1 billion in tourist income. Finally, coral reefs can be farmed for pharmaceutical compounds used to treat heart disease and cancer among other diseases. Bleached and dead corals are far less likely to provide these

living in their bodies. These plants help feed the corals, soak up their wastes and

Change in ocean Temperature: increased ocean temperature drastically caused by climate change is the leading cause of coral bleaching.

The Great Barrier Reef in Australia is experiencing bleaching. According to France-Presse, bleaching of a reef is “coral...that has been stressed by the heat” (France-Presse). When a coral has been “stressed by heat,” (France-Presse) the coral discards the algae that lives within itself which causes the coral to be more susceptible to disease. It can take up to several decades for a coral to recover from bleaching. Because of that fact that most coral does not have enough time to recover, it dies.

According to the latest research of scientist team led by the University of New South Wales (UNSW), tropical corals cannot survive without the Symbiodinium algae that live inside them. These photosynthetic organisms supply the corals with all their food, more than 90 percent. UNSW specialists say that increased water temperatures stress the algae, provoking them to produce an excess of toxic substances, which called reactive oxygen species. As a result of intoxication, damage both the algae and the corals.

Coral reefs are threatened by global warming. They can only live in waters between 18 C and 30 C. Therefore, with the increase in temperature of the surrounding water, there has been an unprecedented increase in the number of coral bleaching events during the past 2 decades (which have had some of the warmest years in history). When ocean temperatures get too high, coral polyps lose the symbiotic algae inside them, causing them to turn white, or "bleach," and eventually die.

Coral bleaching is the process of ejecting most or all of endosymbiotic zooxanthellae in a stress response to fluctuations in corals external environment (4 360 link). In extreme case which are happening at a more regular occurrence, the bleaching response is disastrous for the coral host as well as the entire reefscapes for the Great Barrier Reef (4 360 link).

Known for its color of various aquatic species, its diversity and liveliness of its residents, coral reefs are well known and popular among many around the world. But the increase in these admirers has come with a price. The colorful reefs have turned white as the chemical composition of the ocean and the ocean’s temperature changes as a result of climate change (Anthony 2009). Although many claim that climate change is naturally occurring, the extent and rapidity in which it is occurring is posing a great threat to many factors in earth, including the coral reefs. Formally known as coral bleaching, this phenomenon “is a process whereby the coral colonies lose their color, either due to the loss of pigments by microscopic algae living in symbiosis with their host organisms, or because these zooxanthellae have been expelled.” (Coral Bleaching 2008)

Coral bleaching is one of the visual effect of climate change. Caused by the stress put on the coral because of the temperature of the water becoming warmer. This major effect of climate change could lead to the death of the Coral. This has been especially noticed on the Great Barrier Reef. Only recently the earth has witnessed severe coral bleaching episodes all around the world.

Coral reefs contain symbiotic algae called zooxanthellae which gives the coral its healthy brownish color. The algae "utilizes sunlight and the coral animal's respired CO2 to produce energy rich compounds that feed the coral host" (AIMS, 2003). When stress factors such as "heat, solar radiation, pollution, reduced salinity and changes in oxygenation" occur around the coral, bleaching can begin (Dennis). When bleaching occurs, the algae, which create nutrients for the coral to feed from, is released due to stresses to the reef. Thus the coral starves and its white calcium carbonate skeleton of the coral becomes visible (AIMS, 2003). But one of the main stresses that contributes to the lifeless white appearance of the coral is the warmer temperatures of the sea surface water.