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Coral Reef Health and the Changing World
Coral reefs are defined by Fagerstrom as Òcarbonate structures produced and maintained by an assemblage of calcifying organisms.Ó (Barber, 1255-1271) Corals are characterized by a symbiotic relationship with surrounding photogenic algae, which along with plankton, is the basis of the oceanÕs food web. (Crib, 18-21) Inside individual coral Òpolyps,Ó algae called zooxanthellae, or ÒzooxÓ reside. Corals only eat about two percent of their food, plankton; the other ninety-eight percent of their diet comes from the zoox photosynthethesizing organic compounds from sunlight. In return, coral give zoox their nutrition, which is an ammonia mixture of carbon dioxide and nitrogen. (Davidson, 15-16) To allow corals to calcify and algae to go through their photogenic stage, high levels of light are needed with minimal amounts of ultraviolet radiation; the coral assemblages need numerous criteria met to thrive, including the following: a temperature range of 20-30¡C, while 25-29¡C is preferable; moderate wave motion; unbroken currents; and water high in salinity. (Barber, 1255-1271)
The coral system is a organization in constant flux; growth has been extreme, and growth has been minimal at different periods in the EarthÕs life. Former Chief Scientist of the Australian Institute of Marine Science, Charlie Veron, has stated that there have been five mass which either partly eliminated or completely wiped out coral from the fossil record. In each instance, it took the oceans at least ten million years for corals to reappear and the ocean to gain equilibrium once again. This appearance and disappearance routine is spurred by the cycle of carbon dioxide being released and absorbed by natural sources like volcanoes, dead organisms, and bacterial activity in the oceans. (Crib, 18-21)
So, why are corals so necessary in the world today, and why do we need to cease their rapid decline? Numerous reasons. Firstly, while reefs only cover about one percent of the ocean floor, they provide a home to more than twenty-five percent of the oceanÕs creatures. Secondly, reefs provide enormous protection, for humans and animals, against tsunamis and storm surges. And thirdly, in a global sense, coral contributes over thirty billion dollars annually in net benefit to the economy. (Dupree, 22-30) By saving these natural wonders and protecting our oceans, and atmosphere, human beingsÕ effort will result in victory.
Before the Industrial Revolution, coral reefs were in good health and growing at a healthy rate. However, the Revolution, along with all of the progress it gave the world, brought an extremely negative consequence with it as well- increased carbon dioxide emissions globally. Today, the increased CO2 levels of the atmosphere are causing an amplified absorption of CO2 into the oceans, and in result, causing lowered pH levels in the water. (Rahmstorf, 12-13) Annually, normal human activity results in the release of about twenty-seven billion tons of carbon dioxide into the atmosphere; in the last two centuries, the ocean has captivated approximately half of the CO2 produced by manufacturing cement and burning fossils fuels. Because of this, the pH of surface seawater has already declined by 0.1 units, which results in a thirty percent boost of hydrogen ions. If this pattern of carbon dioxide increase stays true, then in the next century the oceanic pH could ultimately decrease by 0.5 units. (Crib, 18-21) These lowered pH levels directly affect the calcification process of the worldÕs corals.
Plankton and corals form their skeletons when ocean water is saturated with carbonates and bicarbonates. As pH levels decrease and acidity intensifies, the carbonate saturation of the sea begins to dwindle, it become more difficult of all shellfish, and of course, corals to calcify. Currently, the CO2 levels in the atmosphere are about 385 ppm (parts per million), constantly rising since the 1960s. Even though the peoples of the world are gaining awareness to this problem and attempting to cut greenhouse emissions, atmospheric CO2 levels are expected to hit 500 ppm within the next fifty years. When carbon dioxide levels reach this level of 500 ppm, calcification in the seas is impossible. (Crib, 18-21) Scientists have recently discovered that even a 0.2 to 0.3 unit reduction in oceanic pH can impair aquatic calcification. (Zeebe, 51-57) Now remember, the decline of marine pH is expected to be 0.5 units by the year 2100. This research is staggering, and the results are quite obvious; however, the increase in global fossil fuel usage and severe expansion and industrialization of developing nations has caused this situation to present itself. More carbon dioxide coupled with higher global, and seawater, temperatures has made this situation quite imminent and menacing.
In the past one hundred years, the average temperature of the oceans have risen 1¡F; accompanying this, there have been higher prolonged temperature jumps in many tropical areas. These warmer temperatures have prompted incidents of coral Òbleaching.Ó In the Natural Wildlife article Coral Crisis, Joe Dupree defined bleaching as when corals Òrid themselves of the microscopic algae (the zoox) that live inside them and give coral polyps their distinctive colors.Ó This condition is associated with stress of the surrounding environment. To prosper, reefs require very specific conditions including, but not limited to, the following: tropical waters that are warm, but not too warm; shallow water; and, low amounts of sediment and nutrients. If these conditions are not maintained, and if high temperatures persevere, the corals will die. Dupree went on to explain how the 1998 El Ni–o weather pattern was a wakeup call for the world. These extremely high temperatures allowed a mass bleaching to commence in the ocean that affected almost every reef. In one year, over fifteen percent of the worldÕs corals died with numerous more Òinjuries.Ó In the Indian Ocean reefs alone seventy-five percent of reefs were lost, and in the Seychelles Islands, over ninety percent were lost. (Dupree, 22-30) This extreme example is demonstrative of the affects of aquatic temperature increase; by studying these cases, the world can imagine what will happen if global warming and human destruction rules the planet.
Along with producing more CO2 emissions than any other time in global history, humans detriment coral reefsÕ lives in other ways: pollution, overfishing, and general human activity in the waters. Things as simple as oil spill clean-up are vast problems. The common thought process would be that oil spills are extremely detrimental to coral reefs and marine life in general. While this is true, a new study actually proves that the chemicals used to remove oil from water are more harmful to the environment than the oil itself. (Branan, 8-9) Before automatically throwing these chemicals into the water, scientists, and the population at large, need to reevaluate their practices. How can we safely clean the oceans after a terrible spill? Simple accidents like these need to demand more attention to improve the coral situation. More research needs to be done to help preserve all life in the oceans.
Also, destructive fishing patterns have become commonplace in the world. Overfishing is harmful to the ecological equilibrium found in the oceans, the equilibrium that allows coral reefs and other organisms to thrive in symbiosis, and the boats used for this market can efficiently harm reefs as well; commercial fishing boats can even destroy reefs by simply sailing over them. Hunting fish for hobby is also harming this environment. Many of the tropical fish found in reefs can be caught and sold globally for large sums of money. (Walsh, 42-43)
A main source of pollution in the ocean system stems from fertilizer run-off into areas like the Gulf of Mexico. A steady stream of phosphates and nitrates is running into the water and can create Òvast algae blooms.Ó These ÒbloomsÓ can remove all of the oxygen from the water surrounding them. While some fish can simply out-swim this run-off, it will effectively ÒchokeÓ coral, which is essentially immobile. This run-off isnÕt simply harming the waters at the Gulf, either. One study has found that pollutants can be moved almost eighty miles from the shore by natural occurrences such as heavy rainfall. (Walsh, 42-43) This is another problem that the global community must address and curb if it wants to save the coral reefs of the world and support aquatic life in the process.
So, what will happen if we continue to let the corals diminish at this high rate? NOAA marine biologist, Jenny Waddell, began describing these consequences: ÒCoral reefs are beautiful, but they are also tremendous economic resources.Ó (Vergano, 2008) Many animals and humans will begin to go hungry; because coral is the base of the oceanic food web, creatures like tuna, whales, and krill will begin to die off, and in return, our fishery market will suffer immensely. With the global economy the way it is presently, are we, the peoples of the world, prepared to wipe out a market and force coastal nations to become dependent on imports for their source of animal protein? The economic tourism industry will lose revenue if the reefs disappear. Another issue that will impact all nations alike deals with the CO2 increase the atmosphere will experience if coral reefs disappear; reefs play a crucial role in removing carbon dioxide from out atmosphere. If all the corals die, the oceans will lose ability to soak up the excess carbon dioxide, which many experts warn, may trigger a runaway greenhouse effect. Compounding this problem, are the marine plankton forced to live in more acidic waters; they are one of the main producers of breathable oxygen in the world, so if they disappear due to lowered pH levels in the water, and CO2 becomes more prevalent as described above, an un-ignorable issue will present itself. (Crib, 18-21)
Steps need to be taken to slow the horrific event of losing coral reefs from the planet. In the article Acid Oceans, Julian Crib stated, Òthe only known way to reverse this is the slow weathering and dissolution of limestone mountain ranges and carbonaceous rocks into the sea, a process that takes millions of years.Ó (Crib, 18-21) Simply put, the best hope to maintain our present world is Òcontainment.Ó Reversing this process will take longer than the world can afford, so the chief stride that needs to be taken is to cut carbon dioxide emissions and become aware and active in fighting the problem. The world needs to look at Òcoral winnersÓ of the oceans- the exceptions to the plague. Despite increased temperatures and coral bleaching in the Pacific Oceans, the uninhabited atolls of the Central Pacific are still flourishing and support huge numbers of prosperous coralline algae and coral, sustaining large colonies of fish and other organisms. Scientists do not yet know if the reefs have simply escaped mass bleaching episodes, or if, in a more promising light, these reefs actually recovered from bleaching. If they have indeed found a way to recover, there exists hope that science can discover their ÒsecretÓ and use it to help save other reefs across the world. (Knowlton, 54)
Packaging this optimism, there is hope for coral reefs and their inhabitants for the future. Hopefully, through more research and observation, science can help save our floundering oceanic and atmospheric systems to help sustain life. Half of the worldÕs coral reefs are already considered to be in Òfair or poor condition,Ó and over a third of all coral polyps are threatened with extinction, so time is precious. (Walsh, 42-43) The head of the Global Marine Species Assessment summed up the importance of coral reefs nicely: ÒThe corals will be the canary in the coal mine in terms of the effect climate change will have on our ocean.Ó (Walsh, 42-43) I believe that this statement could be further expanded to Òthe corals will be the canary in the coal mine in terms of the effect climate change will have on our world.Ó Hopefully, the people of the world are ready to respond to this crisis.
Works Cited
Barber, Richard T., and Anna K. Hilting. "THE CHANGING HEALTH OF CORAL REEFS." Human and Ecological Risk Assessment 7 (2001): 1255-271.
Branan, Nicole. "CHEMICALS WORSE FOR CORALS THAN OIL." Geotimes 52 (2007): 8-9.
Crib, Julian. "ACID OCEANS." Ecos Apr. 2008: 18-21.
Dupree, Joe. "CORAL CRISIS." National Wildlife 45 (2007): 22-30.
Davidson, Osha G. THE ENCHANTED BRAID. New York: John Wiley & Sons, Inc., 1998.
Knowlton, Nancy, and Jeremy B.C. Jackson. "SHIFTIN BASELINES, LOCAL IMAPCTS, AND GLOBAL CHANGE ON CORAL REEFS." PLoS Biology Feb. 2008: Pe54.
Rahmstorf, Stefan. "ACID LEVELS INCREASE IN OCEANS." Pollution Engineering 39 (2007): 12-13.
Vergano, Dan. "'INVASIVE HUMANS THREATEN U.S. CORAL REEFS." USA Today [McLean, Virginia] 7 July 2008.
Walsh, Bryan, and David Bjerklie. "CORAL UNDER SIEGE." TIME 4 Aug. 2008: 42-43.
Zeebe, Richard E., and James C. Zachos. "CARBON EMISSIONS AND ACIDIFICATION." Science 321 (2008): 51-57.
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