Bleaching Away the Beauty of Coral Reefs Pretend you are about to go scuba diving in the ocean. You jump in the water and begin to sink down. As you start surveying the coral reefs around you, something catches your eye. The coral has turned white, and no longer moves with life. This whiteness seems to have spread over a large area of the reef. You no longer see the colorful branches swaying in the current, or the schools of tropical fish swimming through the leaves.
This death-ridden reef will never have the same life it once had. This phenomenon is known as coral reef bleaching. This makes corals unattractive and lifeless. The biodiversity of a reef is important to the ecosystem. There are different organizations that have joined together to stop this from happening, but it will take a long time to repair most of the damage that has already been done. The futures of the reefs are in danger right now.
There are many causes of coral reef bleaching. The biggest concern of oceanographers is the effect global warming is having on the reefs. It is a stress condition that involves a breakdown of the symbiotic relationship between corals and unicellular algae called. These microscopic plants live within the coral tissue, giving it color and food.
One of the first symptoms of bleaching is the loss of color (? Coral Bleaching? ). Though a coral does not have color does not necessarily mean it is dead. If there is still tissue on the coral, it still has a chance to live and regain its original appearance (? Global Coral Reef Alliance? ). It does not take much to kill coral. Some corals existed in past geological periods when temperatures were higher that they are today. However, those species disappeared during mass extinctions at the start of the ice ages about 2 million years ago.
The ones that survived had the greatest tolerance for cold weather conditions. They have little or no ability to adapt to warmer waters (? Global Coral Reef Alliance? ). Coral lives in a very narrow temperature range. A mere 1-2 degree increase for a period of a few weeks can cause bleaching. In 1978, two men, Coles and Jokier, ran a laboratory test to see how coral survives in different temperatures. They tested it at 28 o, 26 o, 24 o, and 20 o Celsius.
Then they exposed the coral to high temperatures to see what the survival rate was. Between the 28 o and 26 oC groups there was only a 13% of survival (Rosenberg 411). This means the slightest change in average seawater temperature can alter the entire ecosystem of the coral reefs. Every mass bleaching event was followed by periods when sea surface temperatures were 1 oC or more above the average values in the warmest month (? GCR A? ). Temperature variations from an extremely cold winter or blistering hot summer are not the only causes of bleaching. Prolonged exposure to air, especially during a very low tide, freshwater dilution due to heavy rainfall, intense sunlight causing increased ultraviolet radiation, and pollution are all causes of coral bleaching (Wells et al.
54). All of these causes alter the homeostasis that the reef environment needs to live. Various anthropogenic and natural variations in the reef environment can cause the symbiosis to deteriorate. Solar irradiance affects shallow water coral during the summer. Both UV radiation and photosynthetically active radiation penetrate the coral, causing it to lose its color. Sub aerial exposure occurs during a low tide.
El Ni~no Southern Oscillation (ENSO) caused the sea levels to drop some. Also, tectonic uplifts can induce bleaching. Sedimentation, though uncommon, can cause loading of sediments, which choke off the corals. Freshwater dilution is also rare, but deadly. A storm that generates large amounts of precipitation and runoff can lower the salinity of the reef water, thus killing the corals.
Increased inorganic nutrient concentrations such as ammonia and nitrate increase? s densities 2 to 3 times more. Eutrophication is an indirect cause of bleaching. Xeno biotics cause a more localized bleaching as opposed to an entire reef being bleached. It is a result of elevated concentrations of chemical contaminants such as Cu, herbicides, and oil. It reduced the number of. Epizootic's are pathogen bleachers.
It is a coral disease that causes patching or whole colony death through the sloughing of tissues. It results in a white skeleton, but should not be confused with the bleached coral (? Odyssey Expeditions? ). With all of these factors, it would seem like it is impossible to stop bleaching from happening. Global warming seems to be the main problem though. The effects of this problem are very important, especially when dealing with biodiversity. Bleaching is detrimental for the ecosystem and the organisms living within it.
The organisms face lower protein, lipid, and carbohydrate levels. They encounter problems with skeletal grown and reproductive output. Tissue necrosis in the coral host is also a problem. An effect on the ecosystem is the invasion of the dead coral framework by benthic algae. It also serves as a grazing surface for sponges, in faunal mollusks, and grazing sea urchins and fishes (Birkeland 136). There are three main effects of global warming on fish and fisheries.
First of all, the loss of coral cover increases space for fast-growing turf algae. Organic production will increase, and as a result an elevated abundance of herbivores and other trophic groups will be influenced. Secondly, a loss of coral will lead to a loss of reef diversity. The fish that live there will lose their homes, which will lead to a decrease in fish production. Lastly, the loss of coral will affect the successional stages of algae, which is important to the ecology of reef fishes. The loss will open up space, reduce the intensity of herb ivory and, therefore, lead to colonization of the reef benthos by late-successional algae.
A dominance of algae lowers benthic production and increases covers of the less palatable algae. The result is the reduced abundance of fish diversity (Rosenberg 165). These three effects all impact the biodiversity that thrives among reefs. It is very important to protect the reefs from dangers. In 1998, there were some experiments conducted to test these three ideas to see which one is the biggest factor is the problems with fish and fisheries. An increase in surgeonfish which supports the increased organic production idea.
There was also a loss of damselfish, butterfly fish, and wrasse which supports the loss of fish hypothesis. The decrease in damselfish numbers in fished reefs exhibited both positively and negatively to increased algae. The bleaching phenomena can be used as a sentinel for the environment. It serves as an indicator of environmental stress. There still is no single cause for bleaching. Damage is already come and gone before bleaching is noticed.
Observers must do retrospective analysis based on limited environmental data (Rosenberg 402). Other effects of coral reef bleaching are its effect on tourism (Ray 214). There are countries that rely on tourism as their main economic income (Wilkinson et al. 61).
Scuba diving and snorkeling are very popular in the tropics. Everybody wants to see the? tropical rainforest of the ocean? when they go some place exotic. It is important that this biodiversity is preserved, so that future generations can see how beautiful the reefs truly are. Bleaching was first noticed about 70 years ago on the Great Barrier Reef. However, it did not become in issue until the 1980 s when El ni~no struck in the Pacific Ocean. El ni~no is a set of disruptive weather patterns that occurs in 3 to 5 year intervals, usually at Christmas.
The winds that typically move East are redirected West, changing the current. This causes the normally cool water to be replaced with warm water (Wells et al 54). And as mentioned already, warmer water is fatal for most corals. Global warming is not the only cause of bleaching.
Disease also destroys corals. Disease is produced by a variety of adverse physical, chemical, and biological conditions. There are different degrees and patterns of color loss, as opposed to uniform loss of pigment. Two major diseases are the Black Band and White Band disease. Black Band disease is caused by a bacterium that produces a black mat of fine filaments where it attaches the coral. It is mainly found in massive brain corals and gorgonian's.
This disease kills the tissue with poison. Reefs under stress are more prone to get diseases (Wells et al. 65). White Band disease mainly occurs in branching coral. It kills and bleaches the tissue in certain parts of a colony. Left behind is a white skeleton.
This disease causes lumps and tumors to appear. Some corals are resistant to disease. But for those that are not, there is a solution. Scientists have designed a way to prevent diseases from killing coral. They use an aspirator to suck the diseased growth from the corals. They also use molding clay to cover the coral and keep it from spreading the disease.
Though effective, these two solutions are very costly and time-consuming, especially for a large area (Wells et al 65). It is hard to preserve every reef in the world with so many factors working against saving the reefs. There are some things that are impossible to beat. Global change is difficult to control. It is also one of the reasons the corals are bleached white.
Ozone depletion increases UVR reaching the surface of the planet. During periods of low wind velocity, calm seas, clear skies, and low turbidity this UVR is most effective at warming the surface of Earth. Less oxygen is held by water at higher temperatures (? Odyssey Expeditions? ). This in turn affects the number of organisms that can actually live in low oxygen waters.
That is why it is important that energy is conserved in order to prevent further depletion of the ozone layer. Conservation is a priority because of diversity, productivity, spectacular beauty, and importance to tourism. Reefs are the most species diverse out of all coastal marine environments (Ray 214). Approximately 298 species of hard coral are present in the ocean.
There are 1, 198 species of reef fish (? Coral Reef Alliance? ). Many different things threaten the reefs. Anchor and boat damage, dive site congestion, lack of awareness by marine recreation providers, lack of tourist education, diver and snorkeler damage, lack of community awareness, and trash and marine debris are all catalysts for the destruction of the reefs (? CRA? ). In the future, existing corals and might be replaced by strains adapted to higher temps. Seasonal temperatures changes may begin to alter breeding cycles. Increased cloud cover can slow coral growth, which in turn causes decreased sunlight for the.
Adaption has been considered as a possible means for survival of the corals. Different bleaching thresholds span from a range of 9 oC or more. Species show differences in thermal tolerance. Some colonies bleach, while adjacent ones of the same or similar species do not bleach (Rosenberg 411). This gives some people home that the beauty of the corals will still be preserved. There are lots of people who care about preserving the coral reefs.
Some major Non-Governmental Organizations (NGO) are Reef Relief that protects the living coral, National Parks Conservation Association (NPC A) where 13 national parks contain coral reefs, the International Union for the Conservation of Nature (IUCN) which named coral reefs as one of the life-support systems essential for survival, World Wildlife Federation fights against global warming, and Greenpeace which is an environmental advocacy group. There are also some international organizations that deal with the coral reef problem. The International Coral Reef Initiative (ICR) was established in 1994. It is a partnership seeking to stop and reverse global degradation of reefs. National Oceanic and Atmospheric Administration is a part of the government that deals with the oceans. They actually recorded ocean temperatures during the 1980 s and 1990 s that prove water temperatures were higher than average.
The Australian Institute of Marine Science is another organization dealing with coral reefs. The United Nations Environmental Program (UNEP) is developing the environment. Reef Check is trying to save reefs worldwide through research, education and conservation. They were founded in 1996 and use volunteers. The National Coral Reef Institute (NCR I) heads research projects dealing with the environment.
There is also an International Society for Reef Studies (IS RS) and an Intergovernmental Oceanographic Commission (IOC) that protects marine environments and use a global ocean observing system. It is very clear that if something is not done immediately, then that will be the end of coral reefs. They are too sensitive to last through an extremely hot summer or bitter cold winter. The weather patterns are going to mess up the homeostasis that the corals live at. Some view bleaching as healthy adaption to reduce coral mortality. They believe that only the strongest should survive.
It is also important to remember that increased bleaching is an early warning sign of deteriorating reef health. Bleached corals enter a starving stage where it cannot grow or reproduce. This should be reason enough to do something to fix the problem. As long as it still has tissue on it, it has a chance of surviving. In order to maintain biodiversity, the coral reefs must be preserved.
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