Comparing The Bleaching Of Coral And Zooxanthellae

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

Global temperatures are steadily rising due to anthropogenic causes; this increase in temperature is causing changes to ocean properties that can impact the organisms that call this medium their home. One of the most evident impacts of climate change on the world’s oceans is the resulting raise in ocean surface temperatures. Rising ocean temperatures can directly affect biogenic reef building organisms like corals which produce some of the most diverse and productive ecosystems in the world. Previous studies within this field have determined that climate change is a notable stressor for these corals causing large scale bleaching events; where they release their photosynthetic symbionts. Once the symbionts of these organisms are released corals begin to starve and ultimately die resulting in

Coral reefs exist all over the world and are generally known as being one of the most diverse, intricate and beautiful of all existing marine habitats. They have many varying structures which are developed by algae and are symbiotic with various reef building corals which are referred to as, zooxanthellae (algae). There are many other factors such as, coralline algae, sponges and other various organisms that are combined with a number of cementation processes which also contribute to reef growth, (CORAL REEFS, 2015).

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):

Since early 1998, climate change has been demonstrating its effects in increasing the ocean 's temperature (West & Salm, 2003). Warm water stress corals causing the phenomenon known as coral bleaching, by which expulsion of colourful symbiotic algae the zooxanthellae, vital for

Coral bleaching usually occurs when the surface of a sea with coral in it becomes too warm for the coral. When the water heats to as little as one degree higher than normal, coral expels the algae living in its tissue, which causes it to turn completely white. The rise in temperature of the sea surface has been linked mainly to global warming. Other causes of coral bleaching include oxygen starvation caused by an increase in zooplankton, increased solar irradiance, increased sedimentation, bacterial infections, changes in salinity, herbicides, low tide and exposure, cyanide fishing and elevated sea levels. Bleaching events in 2016 were unprecedented, nearly 90% of the coral in the Great

In 1980, NOAA’s marine biologist started noticing the coral bleaching. There has been three important coral reef bleaching events in the history. The first global bleaching event “El Niño” was in 1998, it was a “huge underwater heatwave killed 16% of the corals on reefs around the world” . The second bleaching event was in 2010 and was called La Niña. This event affected especially areas near Palau and Micronesia in the Pacific. In October of 2015, NOAA announced the third global bleaching event in which has already become the longest event recorded, affecting coral reefs for consecutive years.

The bleaching of coral reefs is when warm water forces algae to leave the reef. Once the algae disappear, the coral goes from a vibrant color to a pale white. As one marine biologist said, “You go from a vibrant, three-dimensional structure teeming with life, teeming with color, to a flat pavement...” This bleaching makes the coral more vulnerable to diseases and a greater risk of death. The biggest bleaching events to have occurred in

The Great Barrier Reef is on the brink of dying, and humans are to blame. Corals are the center of marine ecosystems as they provide food and shelter for animals as well as a source of income for Australia, in terms of tourism and fishing. However, as said by NASA research scientist Liane Guild, “Coral reefs are considered ‘canaries of the oceans,’ acting as an early warning system for marine ecosystems” . If the corals die off then everything in the ocean will follow. Of course weather is unpredictable and is a big part of why coral bleaching has occurred, but humans have also had a negative impact on them. There are currently Catholic movements aimed at saving the reef, and Pope Francis mentions the gravity of this situation in his recent encyclical. That being said, if we as a human race were told about coral bleaching by governments and were educated about it in school then global warming and weather wouldn’t have affected it as much as it has.

Coral bleaching may seem new and a strange topic, but it has been around and wreaking havoc for many of years. Bleaching starts to happen when the water temperatures rise slightly above average temps for more than several days, which then kills the vibrant coral (“Global Warming”). The coral reefs get their vivid color from algae and other small organisms. They are found in the coral’s tissue. Algae helps supply food for the reef through carbohydrates. The algae creates the carbohydrates through photosynthesis (“Coral Reefs”). Coral bleaching

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).

Even a one degree Celsius can cause the zooxanthellae to leave the corals causing bleaching (Hoegh-Gulderg). Mass amounts of bleaching can result in death of the coral due to lack of food. Over the past 20 years the increase in sea surface temperature has caused chronic bleaching in coral reefs around the world (Brown). The zooxanthellae within the coral polyps go through photosynthesis and produce sugars, lipids, and oxygen (NOAA). The coral can use these products for food and respiration.

Microalgae plants called zooxanthellae coexist in symbiosis with corals. The algae provide for the corals beautiful colours and other important factors (Nace, 2016). When the algae plant dies, the colours on the corals disappear and when the corals turn white - they are basically considered as dead (Cotes, 1998, p. 26). This is why it’s called coral bleaching! The relationship between corals and zooxanthellae are so critical that if the symbiosis between them gets disturbed - the corals cannot survive without. Further zooxanthellae plants can not survive when the water temperature becomes abnormally warm or contaminated (Nace, 2016). This explains how mass coral bleaching appears. Mass coral bleaching won’t only cause the destruction of corals, but also the habitat for the fish would be long gone. And without the coral reefs incredible colours or the fishes, it’s arguably that GBR won’t appeal to visitors in the same way, and that the reef may end up with an ecosystem that will not longer attract visitors (Newsome et al, 2002, p. 60). This might further lead Queensland to lose a billion dollar tourism industry and in addition a workplace for thousands of people (Armbruster,

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.