Coral Bleaching: Potential Mechanisms and Observed Adaptations

2776 Words6 Pages
bulb-icon

Recommended: Essay on ocean life

Coral Bleaching: Potential Mechanisms and Observed Adaptations

Coral reefs are the most biologically diverse marine ecosystems. Driving this diversity are cnidarian corals which are obligate mutualistic symbioses between coral animals and dinoflagellate algae of the genus symbiodinium. These algae are commonly called zooxanthellae. This symbiosis between heterotrophic hosts and photosynthetic symbionts allows coral to thrive in nutrient poor seas and deposit calcium carbonate to build reefs (Toller et al. 2001, 348).

Coral bleaching occurs when there is a loss of zooxanthellae from their coral host. This is accompanied by loss of a coral's normal color that may or may not be detectable to the human eye. Bleaching can lead to coral death when prolonged, although links between bleaching and subsequent coral recovery or death are not well known. Causes of bleaching have been observed to include salinity, exposure to air, and sedimentation. The primary reasons cited to cause most instances of coral bleaching are increased sea temperatures and solar radiation. These two factors have been observed to cause the most damage in combination (Fitt et al. 2001, 51).

The two types of bleaching that result from organism damage or disturbance are algal-stress bleaching and animal-stress bleaching. Algal-stress bleaching is characterized by expulsion of individual zooxanthellae from a host cell. Animal-stress bleaching is characterized by host cell detachment, which is expulsion of zooxanthellae from the coral animal along with the host cell they occupy. Radiation and temperature induced animal-stress bleaching and host cell detachment have not been observed in the field at current sea temperatures. This type of bleaching has only been observed under laboratory conditions (Fitt et al. 2001, 55). A third type of bleaching, physiological bleaching, occurs in an unstressed coral-zooxanthellae holobiont as a method of shedding excess zooxanthellae from host cells. Zooxanthellae density within host cells varies seasonally in this manner. Maximum zooxanthellae density is observed to occur during the coolest season with the lowest solar radiation. The minimum density is observed to occur at the end of the warmest season with the highest solar radiation (Fitt et al. 2001, 54).

The temperature at which coral bleaching occurs has been observed to be from 30 to 34 degrees Celsius (Ralph et al. 2001, 163). Solar radiation exacerbates bleaching in this temperature range and can also cause bleaching at ‘normal’ temperatures when at sufficient intensity.

Show More
Related

  • Depresion in Adolescents is Becoming and Epidemic

    1027 Words  | 3 Pages

    The concept of a happy childhood being a carefree, never-ending recess before the responsibilities of adulthood set in is just as realistic as the cartoons children watch on television. To the contrary, adolescents today feel less safe, less inspired and less hopeful than ever before. It is not surprising then that depression is a common concomitant to adolescent development (Tharper, Collishaw, & Pine, 2012). According to the National Institute of Mental Health, approximately one in five adolescents between the ages of nine and twenty four is clinically depressed and more than twenty percent of adolescents will have experienced a major depressive episode before reaching adulthood (“Suicide in the U.S.: Statistics and Prevention”, n.d.). Such episodes can affect developmental growth, interfere with educational achievement, and increase the risk of attempted and completed suicide as well as major depressive disorder prior to adulthood. Depression in adolescents has become an increasingly important mental epidemic and is thus a major risk factor for suicide, the third leading cause of death among this age group (Tharper et al., 2012). One hundred percent of those teens who suffer from depression can get help but less than thirty three percent of teens with depression are properly diagnosed and actually seek treatment (“Suicide in the U.S.: Statistics and Prevention”, n.d.). Therefore, the early recognition of and the development of effective treatments for adolescent depression clearly should be a high public health priority.

    Read More

  • Early Theories on Communism, Capitalism, and the Economy

    669 Words  | 2 Pages

    Though there are little signs of change for the better and not just change towards greed, people will always find a way to survive and better themselves. With the current state of the economy there is bound to be change coming. Towards communism? Maybe, but America seems to be stuck in their ways, but something is coming.

    Read More

  • Essay On The Impact Of Climate Change On Coral Reef

    789 Words  | 2 Pages

    Climate change has been affecting coral reefs in a negative way. If the climate continues to get warmer more of our coral reef become bleached, the structure of the reefs will become weak, and algae that keeps coral healthy will die. In the essay, “A framework for understanding Climate change impacts on Coral Reefs” by Joshua Clinner (2016), he emphasizes our climate change has become one of the long-term threats to coral reef. The article “Climate change and human impacts are damaging the world’s coral reefs”, which didn’t include an author (2001), states that the sea temperatures throughout the tropics has increased dramatically leaving much of the coral unhealthy. Spencer Hall (2008), discussed in his article “Coral Reefs and Climate Change”, how the increase in climate change puts a lot of stress on coral reefs because they are very sensitive to the change of temperature. Rigel B (2003) states in his essay, “Climate Change and Coral Reefs”, that coral reef has already been negatively impacted by

    Read More

  • Climate Change In Great Barrier Reef

    990 Words  | 2 Pages

    Leading scientists advise climate change will cause increases to the frequency and intensity of extreme weather events. Rising sea levels pose a significant risk to coastal communities, while the world’s oceans could become too acidic to support coral reefs and other calcifying marine organisms. Coral reefs contain only six per cent of the area of the Great Barrier Reef, yet they provide critical habitat and food for numerous species in the ecosystem. However, climate change has already impacted coral reefs in the Great Barrier Reef as corals are very helpless against its potential impacts. Eight mass coral bleaching events has occurred since 1979, triggered by unusually high water temperatures. And because of this, zooxanthellae (photosynthetic algae) leave their tissues and corals will have no more colours hence ‘bleaching’. Without the zooxanthellae, the corals that remain gradually starve to death. Once the coral dies, fish and a multitude of other marine species are soon affected. Rising sea levels and more frequent and intense storm surges will see more erosion of Australia’s coastline, causing community and residential

    Read More

  • Acidification and the Ocean’s Changing Climate

    638 Words  | 2 Pages

    In absence of calcium carbonate, coral and shellfish can’t survive. The ecosystem of ocean depends on these organisms because they offer a large source of food at the bottom of the food chain. They need to be abundant in order t...

    Read More

  • coral reef

    2542 Words  | 6 Pages

    We need coral reefs, and not just to make the ocean look pretty and colourful, they are more than just that…

    Read More

  • Anthropogenic Effects on Coral Reefs

    2166 Words  | 5 Pages

    Coral Reefs are said to be the “tropical rainforest” of the sea. They are home to over 25% of all marine life (http://coralreefalliance.org.stories/storyReader$77). Over the past few decades they have been subjected to destructive anthropogenic practices. Some of the major threats to coral reefs include sedimentation, water pollution, harmful recreational activities, and global warming. All of these things cause stress on corals and can potentially cause mortality. Corals are made up of two parts, a polyp and zooxanthellae. A polyp is a calcerous body that grows from a hard part of the ocean floor. Zooxanthellae is a photosynthetic algae which lives in the polyp and provide energy for themselves and the coral. In many cases, corals undergo “bleaching,” which is a process where corals lose the zooxantheallae or chlorophyll pigment, and turn white (Wilkinson et all). After bleaching corals can survive for several months. It is possible for corals to recover by hosting more zooxantheallae, but it can take between 5 and 50 years for them to recover completely (Wilkinson et all, 1999).

    Read More

  • Teen Depression: The Negative Effects Of Teenage Depression

    1057 Words  | 3 Pages

    Being a teenager is not as easy as you think, as you grow older life becomes more complicated and frustrating. Sometimes, you get lost. You don’t know what do, you don’t know who to trust anymore and unsure of the path you wish to embark upon. You find it hard to enjoy the things you once found pleasure in. As time passes by the feeling doesn’t stop and then there will come a point that you’ll discover something terrifying. You’re depressed. The world doesn’t seem as beautiful anymore. You don’t want anybody else to help you. You have become an introvert now. You’ll feel as if you don’t have any worth in this world anymore for days or months at a time. Sometimes the pain feels lighter. It’s because time heals all wounds. I chose this topic because I know a few people with depression and honestly speaking, it’s not easy. I know that this research will be beneficial to many people.

    Read More

  • Depression in America's Teens

    2855 Words  | 6 Pages

    Teenage Depression. Everywhere you look these two words appear together as one, in newspapers and magazines, as well as in scholarly reports. Teenage depression is one of today's "hot topics" this among other teenage mental health problems, has been brought to the forefront of public consciousness in recent years after several incidents involving school shootings (CQ 595). The environment that teens grow up in today is less supportive and more demanding than it was twenty years ago. Not only are the numbers of depressed teens rising, but children are also being diagnosed at younger and younger ages. Studies have found that, "There is an estimated 1.5-3 million American children and adolescents who suffer from depression, a condition unrecognized in children until about 20 years ago" (CQR 595). This increase in depression is due to social factors that teenagers have to deal with everyday. A recent study found that, "About five percent of teenagers have major depression at any one time. Depression can be very impairing, not only for the affected teen, but also for his or her family-and too often, if not addressed, depression can lead to substance abuse or more tragic events" (NAMI.org). Gender roles and other societal factors including the pressures on girls to look and act a certain way, the pressures on boys to suppress their emotions and put on a tough front and the pressures on both sexes to do well in school and succeed, all contribute to depression in teens today. Depression is a growing problem which crosses gender lines and one that needs to be dealt with with more than just medication.

    Read More

  • Persuasive Essay On Coral Bleaching

    1638 Words  | 4 Pages

    Imagine a lush underwater place. Beautiful structures colorful animals and places that would never have been thought of before. In reality that's not what it really looks like, really the ocean is a desolate place that is barren like a desert. Many marine species have been lost by as much as 49%.(seeker) A big part of that reason is because of coral bleaching which causes as stated above a decline in species that depend on the coral as there home. Coral bleaching is a serious problem that could cause problems for everyone if we don’t fix it.

    Read More

  • Asexual and Sexual Reproduction in Soft Corals

    3155 Words  | 7 Pages

    Soft corals are grouped in the phylum Cnidaria, class Anthozoa, and order Alcyonacea. Their distinguishing characteristic is that their polyps always bear eight tentacles which are on both edges fringed by rows of pinnules (Fabricius and De’ath, 2002). The common name “soft coral” comes from the fact that they have no massive external skeleton as compared to the more commonly studied hard corals.

    Read More

  • Essay On Effects Of Climate Change On Coral Reefs

    964 Words  | 2 Pages

    Rates of coral calcification on the Great Barrier Reef and many other reef systems around the world have declined by 15-20% since 1990 due to increasing thermal stress (De’ath 2012). It has already been mentioned that the oceans absorb almost all of the excess heat from climate change. This affects coral reef systems in what is known as coral bleaching. The term bleaching refers to the loss of corals’ colors. A coral’s color is the result of the zooxanthellae present.

    Read More

  • Coral Reef Destruction

    1564 Words  | 4 Pages

    The Great Barrier Reef is an exemplary model of the famous exotic coral reef seen in a copy of the National Geographic or the popular animated film Finding Nemo. Located on the coast of Australia, it is known as the “largest biological organism in the world” (“Human Impact on the Great Barrier Reef” par. 1). The idea bears that coral reefs are again not an assortment of organisms functioning separately but rather working together to thrive. The groups of coral that are seen in t...

    Read More

  • The Conservation of Coral Reefs

    440 Words  | 1 Pages

    Coral Reefs need to be preserved for many reasons. In this paper I will discuss a

    Read More

  • Causes of Teenage Depression

    1549 Words  | 4 Pages

    A famous author John Green said, “Whenever you read a cancer booklet or website or whatever they list depression among the side effects of cancer. But, in fact, depression is not a side effect of cancer. Depression is a side effect of death (“The Only Thing Worse”).” Occasional bad moods or acting out is to be expected, but depression is something different. Depression can destroy the very essence of a teenager’s personality, causing an overwhelming sense of sadness, despair, or anger (“A Guide for Parents”). The depression rate in the teen’s generation is rising every day. Teenage depression is not just bad moods and occasional melancholy; it’s a serious problem that impacts every aspect of a teen’s life (“A Guide for Parents”). To better understand why teens are depressed, it would help to know the causes of depression, such as, trauma, life experiences, and social anxiety or peer pressure.

    Read More

More about Coral Bleaching: Potential Mechanisms and Observed Adaptations

Open Document