GS 450 Global Studies Seminar & Portfolio
Professor Thorburn
November 21, 2007

Coral Reefs


Figure 1: (http://www.montereybayaquarium.org/efc/efc_se/content/images/coral_photo.jpg)

Increasing Sea Temperatures & Ocean Acidification Destroying Coral Reefs

Coral reefs are an essential part of the world's ecosystem. They provide habitat for wide varieties of ocean flora and fauna. In many cases the habitat they provide is essential to keeping the ocean alive and productive. In other cases, larger reefs, like the Great Barrier Reef around much of Australia, provide physical protection of the land against erosive forces of wind and water:

Reefs form near the shores of low lying coastal lands. They are a natural barrier of protection against currents, strong waves, and storms. Without the reefs to slow the water before it reaches the shore, these areas are very vulnerable. In one area where a reef was destroyed, it cost about $10 million per kilometer to build a protective wall along the coastline. (Oceanworld)

Most people do not understand how vital coral reefs are to life on our planet. Humanity itself is proving to be the number one threat to the health existence of these reefs. Through pollution and global warming, reefs throughout the world's oceans are coming under constant threat. Of particular concern is how increasing ocean temperatures and acidity are destroying coral reefs worldwide.

Coral reefs are often called the rich "rainforests of the sea." They are so fundamental to ocean life. They harbor everything from seaweed, grasses, anemones, worms, and shrimp to fish, seahorses, turtles, octopus, eels and sharks (Brooks). In Indonesia alone, "a single reef contains as many fish as exist in the entire Caribbean" (Discovery). This gives us an idea of how their delicate nature effects millions of species everywhere. Although coral reefs cover less than 1 percent of the ocean's floor, they support approximately 25 percent of all marine creatures (Appenzeller). Nearly 1 million species globally are supported by coral reefs. Reefs are, by far, the most biodiverse marine ecosystems on the planet (Knudby).

Many coral reefs are estimated to be approximately 5,000 to 10,000 years old (Brooks). There are approximately 400 species of coral (Forsman). Three main types of reef include the atoll, the barrier, and the fringe (Brooks). Fringe and barrier reefs both run along islands or continental coastlines, but barrier reefs are farther away from shore than fringes. With barrier reefs, there is a lagoon of calm water between the reef and the shore, such as the Great Barrier Reef in Australia (Brooks). Atolls are found mostly in the Pacific and Indian oceans and are ring shaped (circular) coral islands surrounding a lagoon. They start out as fringing reefs around islands, such as the low-lying Maldives in the Indian Ocean (Brooks).
Figure 2: (http://www.iyor.org/reefs/default.asp)

Not only are reefs such as the Great Barrier Reef the largest structures of living organisms on Earth, they are so large that along with the Great Wall of China, they can be seen from the moon (Discovery). According to Brooks, they are often mistaken as plants:

To the untutored eye, a coral reef looks like a piece of rock. But at night the truth is revealed. Hard or reef-building coral such as brain or lettuce coral is made up of millions of tiny but multitalented carnivores called coral polyps. Mostly mouth and tentacles, they belong to the cnidaria family, also occupied by jellyfish and anemones. When the sun sets they come out of hiding to feed, using their stinging tentacles to paralyze passing zooplankton (microscopic animals) The reef structure is strengthened by cementing algae, microscopic invertebrates called bryozoans and the shells of mollusks. (Brooks)

In addition to their importance in terms of marine biodiversity, coral reefs have a direct impact on the economy. First, they are a divers' and tourists' paradise. "Around the world, reefs generate an estimated $300 billion each year in products and services. In the United States alone, tourism to reef areas generates more than $17 billion annually" (Forsman). Secondly, according to some estimates, 10 percent of reef inhabitants feed the human world. "It is estimated that reef fish and mollusks feed between thirty and forty million people each year" (Oceanworld). And finally, reefs offer the possibility of medicinal cures:

Coral reefs are probable sources of medicines to cure the diseases that currently plague the earth. Chemicals found in the reefs have been used to treat ulcers, heart disease, leukemia, and more. In one of the most famous instances, AZT, which is based on chemicals extracted from a Caribbean reef sponge, has been used to treat HIV infections. Currently, more than half of all cancer research is focused on finding cures from marine sources. Every time a reef is destroyed, the chance of relieving the pain and suffering of people all over the world is reduced. (Ocean World)

Increasing Ocean Temperatures

Recently, from Japan to India to Australia, there have been significant threats to coral reefs everywhere. The most common stressors are rising sea level, pollution, and over-fishing, but increasing sea temperature is revealing how delicate coral reefs really are. Algae, which normally helps keep coral alive -- supplying their food while living inside them -- is being driven away by higher temperatures (See figure 3 for abnormal sea temperatures).

Coral expels this essential algae when the waters warm. The warmer water also encourages the growth of harmful algae on top of the coral, which kills it because it blocks out the sun. Without the sun, the zooxanthellae cannot photosynthesize and so they die. "Zooxanthellae are microscopic algae found within the tissue of all reef-building corals" (Nystrom).
Figure 3: 		The number of weeks that ocean temperature exceeded its long-term weekly average by more than one degree Celsius between 1999 and 2004. Anomalously warm conditions like these can cause outbreaks of the coral disease white syndrome, contributing to reef decline. Credit: Elizabeth Selig (http://news.mongabay.com/2007/0808-coral.html)


Figure 4: Zooxanthellae (http://plaza.ufl.edu/bettie/coralreef.html)

"Without Zooxanthellae, coral have clear bodies and white skeletons" (Ocean World). Due to rising sea temperatures and acidity, some coral are never able to form at all (ARC Centre of Excellence for Coral Reef Studies).

Coral Bleaching


Figure 5: Bleached Coral (http://www.scidev.net/scidev_images/coral-bleached1-browse.jpg)

Coral bleaching is the phrase used when "coral expels its symbiotic zooxanthellae. As a result, the coral loses it coloration. Without zooxanthellae, the coral polyps have little energy available for growth or reproduction" (SeaWorld). A temperature increase of even as little as 1 degree affects the coral. Global climatic change must be reversed to preserve the coral reefs and their inhabitants, because increasing sea temperatures are killing or hindering the growth of coral reefs worldwide.

It is evident the bleaching is occurring everywhere due to global climate change. For example, in the Maldives alone, in addition to local stressors, "global sources of stress include climate change, El Nino conditions, ozone depletion, and sea-level rise. Stress to the reefs threatens fresh water and other natural resources, making island communities more vulnerable to natural disasters, as evidenced in the 2004 Asian tsunami" (Ebi). Ebi suggests the coral reefs can recover from brief periods of increasing sea temperature, yet prolonged periods greater than 6 months result in irreversible bleaching. It is also worth noting how widespread bleaching has become:

The yellow areas below are places where bleaching has occurred.


Figure 6: (http://www.marinebiology.org/coralbleaching.htm)

Mass Bleaching Events

As noted above, sea surface temperatures directly affect mass bleaching.

According to the Global Coral Reef Alliance,

Coral bleaching has been observed for nearly a century, but before the 1980s all known cases were very limited in extent and duration. Known bleaching mostly took place in small tide pools or shallow enclosed lagoons cut off from the sea by extreme low tides during mid day. In the 1980s bleaching spread dramatically from a few small areas clearly affected by extreme local stress to huge areas of the ocean covering up to thousands of kilometers. Of all stresses which could potentially cause widespread mass bleaching, only excessively high temperature was present in all cases. (Global Coral Reef Alliance)

And according to the Global Coral Reef Alliance, mass bleaching events occurred following periods "when sea surface temperatures were 1 degree C or more above average values in the warmest month. This implies that coral reefs are the most temperature-sensitive of all ecosystems, and cannot take a further warming of 1 degree" (Global Coral Reef Alliance).

"Canaries in a coal mine" is another common metaphor for coral reefs. Canaries were kept below ground as an early warning system to let miners know the presence of poisonous gases in the air. Coral reefs serve a similar function in letting us know when there are problems coming in the oceans. With recent climate changes, the warming of the oceans are threatening coral reefs everywhere due to human activity. According to Earth Justice, "the earth's climate system has demonstrably changed in both global and regional scales since the pre-industrial era. The atmospheric concentrations of key greenhouse gases (GHG)4 reached their highest recorded levels in the 1990s, primarily due to the combustion of fossil fuels, agricultures, and land-use changes." Reefs are being destroyed, and "marine species are being pushed toward the poles", leaving others to simply die off (The Associated Press).

Increasing Ocean Acidity

We have seen how increasing sea temperatures has led to coral and mass coral bleaching, but rising acidity levels also threaten the survival of our world's coral reefs. Until recently, the waters were able to absorb CO2:

When mixed with seawater, CO2 forms carbonic acid, which effectively lowers prevailing pH levels. To date, the ocean has absorbed so much CO2 that the pH of the surface water around Antarctica is 1/10th lower than it was before the industrial era. In fact, at the current rate of acidification, the Southern ocean's surface pH will reach 3/10th lower by 2100, the lowest it's been in 300 million years. (Jennings)

This combination of rising sea temperatures and acidity are contributing to the destruction of what's left of the world's coral reefs and their inhabitants.

According to a recent article in National Geographic, the ocean is absorbing almost half of the Earth's missing carbon - 2 billion tons (Appenzeller). Greenhouse gases in the atmosphere absorb heat from the sun and radiate it back to Earth. The leading greenhouse gas, CO2, is absorbed by the sea, creating an acidity increase. This acidity kills the algae necessary to keep coral alive.

We often overlook the power of the oceans as a balancing force in controlling global climate changes. Jennings states that "about half of the carbon dioxide produced by burning fossil fuels is absorbed by the oceans, equivalent to a 30% increase in the concentration of hydrogen ions, with most of it remaining near the surface. Once in seawater it undergoes a chemical transformation and in high enough concentrations, can behave like an oceanic cancer."

Ocean acidification is the name given to the ongoing decrease in the pH of the oceans, caused by their uptake of anthropogenic carbon dioxide from the atmosphere. Between 1751 and 2004 surface ocean pH is estimated to have dropped from approximately 8.25 to 8.14. This changing ocean chemistry may lead to sharp decline in marine biodiversity. Many species of marine organisms that form calcite shells may become extinct as a direct result of ocean acidification. (Tare)

Furthermore, in a study conducted by Peter Brewer at Stanford University, "The effects of ocean CO2 are likely to be mainly on pH," he says, "which alters things like calcification in corals and other organisms with carbonate skeletons." Brewer sees the pH changes as "an additional insult" on top of other effects of CO2, in particular, warmer sea temperatures, which are hardest on coral reefs" (Appenzeller).

Increasing ocean temperatures and acidity correlate with the destruction of coral reefs worldwide, which, in turn, correlates with human tragedy in addition to marine life tragedy.

This combination of increasing sea temperature and ocean acidity has global implications.

It will bring devastating consequences to coastal communities and islands worldwide. Economies and livelihoods will be destroyed, and the chance of coastal destruction itself will increase due to absent storm wave protection reefs provide. This destruction and loss of life cannot just be accepted as inevitable. Something must be done internationally to protect coral reefs. (Coral Reefs & Ocean Warming)

This graph shows a simulation of the effect of increased atmospheric CO2 on percent change in coral reef calcification. Rising atmospheric CO2 harms coral directly by making surface waters less alkaline, reducing corals' calcification and making their skeletons smaller and weaker. Warmer ocean temperatures will be another significant added stress, causing corals to expel the algae that live inside them and are crucial to their survival. Because these algae also give coral its color, this process is called "coral bleaching." Coral can recover after a short episode of warmer water, but if the warming persists the coral die. Under these combined stresses in addition to the existing stresses posed by human activities, corals may not survive in many areas.
Figure 7: (The Potential Consequences of Climate Variability & Change)


Figure 8: Healthy Coral (http://plaza.ufl.edu/bettie/coralreef.html)

What is most devastating is that areas hardest hit harbor the people least responsible for the greenhouse gas emissions that contribute to global climate change:

Ironically, the people who are most dependent on coral reef ecosystems are responsible for only a small fraction of the world's greenhouse gas emissions. The per capita greenhouse gas emission rate of the 424 million people living within 100 km of reefs in developing countries is 1.78 metric tons per person of carbon dioxide - equivalent. By comparison, greenhouse gas emissions average 20.1 metric tons per person - 11 times higher - in the United States and 11.4 metric tons per person in Europe, Japan, Russia, and the other nations party to the Kyoto Protocol. (Donner)

As a result, many are calling on the industrial world to take responsibility for the causes of global warming (Normile).

Although a full investigation of the causes of global warming is beyond the scope of this paper, there are several steps we can take to preserve coral reef ecosystems. A close examination of higher sea temperatures and ocean acidity reveals a consistent relation to the destruction of coral reefs worldwide. According to a recent study in Science Daily, "Reducing CO2 emissions is the only way to prevent further damage to coral reefs" (ARC Centre of Excellence). In the meantime, The National Oceanic and Atmospheric Administration recommends steps we, as individuals, can take to help save coral reefs:

  1. Support reef-friendly businesses
  2. Don't use chemically enhanced pesticides and fertilizers
  3. Volunteer for a reef cleanup
  4. Learn more about coral reefs
  5. Become a member of your local aquarium or zoo
  6. When you visit a coral reef, help keep it healthy by respecting all local guidelines, recommendations, regulations, and customs
  7. Support conservation organizations
  8. Spread the word
  9. Be an informed consumer
  10. Don't pollute
  11. Recycle
  12. Conserve Water
  13. Report dumping or other illegal activities
  14. Keep it clean
  15. Only buy marine aquarium fish if you know they have been collected in an ecologically sound manner
  16. Surf the net!
  17. Don't start a live rock aquarium
  18. Hire local guides when visiting coral reef ecosystems
  19. Don't anchor on the reef
  20. If you dive, don't touch!
  21. Participate in the Great American Fish Count
  22. Volunteer
  23. Support the creation and maintenance of marine parks and reserves
  24. Be a wastewater crusader!
  25. Inform yourself

To recap, coral reefs are so important, yet so fragile, because they harbor entire ecosystems. They are aesthetically beautiful and have many uses for humanity. Coral reefs serve as a natural barrier against vulnerable coasts and wetlands and prevent coastal erosion. They have medicinal cures. According to some estimates, 10 percent of reef populations feed the human world. And, lastly, they are a divers' and tourists' paradise.

Increasing sea temperatures pose a serious threat to the existence of coral reefs because "the rate of coral bleaching is not natural" (Tare). Warmer water encourages the growth of harmful algae above the coral, blocking important sunlight for their survival. The essential algae which feeds the coral is expelled, causing the coral to become "bleached", a process by which the coral loses its color and eventually dies. Global climate change has contributed to a rise in oceanic temperatures, which is, in turn, affecting the entire ecology of Earth's waters.

In addition to increasing sea temperatures, current CO2 levels pose a serious threat as to whether or not the acidity is becoming too much for coral reefs and calcite forming reef inhabitants to handle, as pH levels are dropping. Increasing sea temperatures and ocean acidification combined cause coral and mass coral bleaching, even preventing specific marine organisms from forming calcite shells.

Coral and mass coral bleaching will only become more frequent occurrences unless we put our minds together and work toward a common solution. It is important we learn how to protect this valuable ecosystem before it vanishes forever by reversing our current trend. Awareness, education, and action are necessary steps we must take in order to accomplish this goal.


Figure 9: (http://www.projectaware.org/americas/english/cra.asp)



References

Appenzeller, Tim. "The Case of the Missing Carbon". National Geographic. Retrieved 6 November, 2007 at http://magma.nationalgeographic.com/ngm/0402/feature5/index.html

ARC Centre of Excellence. "Acid Oceans Threaten Coral". ARC Centre of Excellence for Coral Reef Studies. ScienceAlert. Australia & New Zealand. Retrieved 6 November, 2007 at http://www.sciencealert.com.au/news/20071710-16463.html

ARC Centre of Excellence. "Coral Reefs on Brink of Disaster. Scientists Urge Action Now". ScienceDaily. Retrieved 7 November, 2007 at http://www.sciencedaily.com/releases/2007/10/071021225256.htm

Brooks, Yolanda. "Tropical Treasure". The Inside Story; Coral Reefs; No. 4674; pg. 8. Retrieved 4 November, 2007 at http://www.lexisnexis.com.ezproxy.nu.edu/us/Inacademic/frame.do?tokenKey-rsh-20.290

Bruckner, Andrew W. "New threat to coral reefs: Trade in coral organisms. Issues in Science and Technology. Washington: Fall 2000. Vol. 17, Iss. 1; pg. 63, 6 pgs. Retrieved 16 November 2007 at http://proquest.umi.com.ezproxy.nu.edu

Butler, James N, Burnett-Herkes, James, Barnes, John A. Ward, Jack. Environment. Washington: Jan 1993. Vol. 35, Iss. 1; pg. 6, 18pgs. Retrieved 16 November, 2007 at http://proquest.umi.com/ezproxy.nu.edu

"Coral Reef Bleaching and Sea Surface Temperature". Global Coral Reef Alliance. Retrieved 4 November, 2007 at http://www.globalcoral.org

"Coral Reefs & Ocean Warming". Retrieved 7 November, 2007 at http://www.biology.duke.edu/bio217/2001/sealevel/page3.html

Discovery. Retrieved 11 November 2007 at http://www.discovery.com

Donner, Simon B. "The Inequity of the Global Threat to Coral Reefs". Bioscience. Washington: Mar 2007. Vol. 57, Iss. 3; pg. 214, 2 pgs. Retrieved 2 November, 2007, from http://proquest.umi.com.ezproxy.nu.edu/pqdweb/index=9&did=1255154371&SrchMode

Earth Justice. Retrieved 11 November 2007 at http://www.earthjustice.org

Ebi, Kristie L., Lewis, Nancy D., Corvalan, Carlos. "Climate Variability & Change & Their Potential Health Effects in Small Island States: Info for Adaptation Planning in the Health Sector". Environmental Health Perspectives. Research Triangle Park; Dec. 2006. Vol. 114, Iss. 12; pg 1957, 7 pgs

Forsman, Rick B. "Life and death on the coral reef: an ecological perspective on scholarly publishing in the health sciences". Journal of the Medical Library Association. Chicago: Jan 2005, Vol. 93, Iss. 1; pg. 7, 9 pgs. Retrieved 16 November 2007 at http://proquest.umi.com.ezproxy.nu.edu

Goreau, Thomas J. "Elevated Sea Temperatures Correlate With Caribbean Coral Reef Bleaching". Global Coral Reef Alliance. Retrieved 7 November, 2007 at http://globalcoral.org/elevated_sea_surface_temperature.htm

Graphics copyright Yahoo Images, 2007, unless noted otherwise

International Year of the Reef 2008 (IYOR). Retrieved 7 November 2007 at http://www.iyor.org/reefs/default.asp

Jennings, Malin. "The Pathology of Acidification: An Ocean Cancer?" Conservation Science Institute. Retrieved 7 November, 2007 at http://www.conservationinstitute.org/ocean_change/ocean_pollution/ocean_acidification.htm

Knudby, Anders. "Progress in the use of remote sensing for coral reef biodiversity studies." Department of Geography. University of Waterloo, Canada. Retrieved 18 November 2007 at http://proquest.umi.com.ezproxy.nu.edu

National Oceanic & Atmospheric Administration (NOAA) Retrieved 4 November, 2007 at http://www.noaa.gov

Normile, Dennis. "Warming Waters More Deadly to Coral Reefs than Pollution". Science. Washington: Oct. 27, 2000

Nystrom, Magnus. "Redundancy and Response Diversity of Functional Groups: Implications for the Resilience of Coral Reefs." Ambio. Stockholm: Feb 2006, Vol. 35, Iss. 1; pg. 30, 6 pgs. Retrieved 17 November, 2007 at http://proquest .umi.com.ezproxy.nu.edu

Ocean World. Retrieved 11 November at http://www.oceanworld.tamu.edu

Odyssey Expeditions. "Coral Reef Bleaching". Retrieved 19 November 2007 at http://www.odysseyexpeditions.com/coralbleaching.htm

reefED. "Coral Bleaching on the Great Barrier Reef". Retrieved 19 November at http://www.reefed.edu.au/home/explorer/hot_topics/coral_bleaching/coral_bleaching_on_the_great_barrier_reef

Schwabach, Aaron. Texas International Law Journal. "Using International Law to prevent environmental harm from increased used of desalination". Austin: Spring 1999. Vol. 34

SeaWorld. Retrieved 11 November 2007 at http://www.seaworld.com

Tare. CSI's Global Climate Change Initiative. Conservation Science Institute. Retrieved 7 November 2007 at http://www.conservation institute.org/climate_change/globalclimatechange.htm

The Associated Press. Panel:Warming Will End Some Species. AP correspondents Charles J. Hanley, New York; Ben Fox, San Juan; Rohan Sullivan, Sydney; Karl Ritter, Stockholm; Beth Duff-Brown, Toronto; Courtney French, London; and Heidi Vogt, Dakar. Retrieved 31 March 2007 at http://home.peoplepc.com/psp/newsstory.asp?cat=TopStories&referrer=welcome&id=200



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