Coral reef
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2008-07-15T23:37:34Z
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Reverted edits by [[Special:Contributions/65.96.82.199|65.96.82.199]] to last version by JAnDbot (using [[WP:HG|Huggle]])
[[Image:Blue Linckia Starfish.JPG|thumb|right|250px|Some of the [[biodiversity]] of a coral reef, in this case the [[Great Barrier Reef]], Australia.]]
'''Coral reefs''' are [[aragonite]] structures produced by living organisms, found in shallow, tropical marine waters with little to no nutrients in the water. High nutrient levels such as those found in runoff from agricultural areas can harm the reef by encouraging the growth of [[algae]].<ref>{{cite web| url=http://www.coralcoe.org.au/news_stories/landimpacts.html | title= Corals reveal impact of land use | accessdate = 2007-07-12 | publisher=ARC Centre of Excellence for Coral Reef Studies}}</ref> In most reefs, the predominant organisms are stony [[corals]], colonial cnidarians that secrete an exoskeleton of [[calcium carbonate]]. The accumulation of skeletal material, broken and piled up by wave action and [[Bioerosion|bioeroders]], produces a massive calcareous formation that supports the living corals and a great variety of other animal and plant life. Although corals are found both in temperate and tropical waters, reefs are formed only in a zone extending at most from 30°N to 30°S of the equator. Reef-forming corals do not grow at depths of over 30 m (100 ft), and temperature has less of an effect on distribution but it is generally accepted that no corals exist in waters below 18 [[celsius|°C]].<ref>Achituv, Y. and Dubinsky, Z. 1990. Evolution and Zoogeography of Coral Reefs. Ecosystems of the World. Vol. 25:1-8.</ref>
[[Image:Coral reefs in papua new guinea.JPG|thumb|right|300px|[[Coral]]s reefs in [[Papua New Guinea]].]]
[[Image:Coral reefs 1.JPG|thumb|right|300px|[[Coral]]s reefs with [[Crinoid|feather star fish]] in [[Papua New Guinea]].]]
==Biology==
[[Image:Coral polyp.jpg|right|thumb|250px|Anatomy of a coral polyp.]]
{{see also|Coral}}
The building blocks of coral reefs are the generation of reef-building , and other organisms that are composed of [[calcium carbonate]]. For example, as a coral head grows, it lays down a skeletal structure encasing each new [[polyp]]. Waves, grazing fish (such as [[parrotfish]]), [[sea urchin]]s, [[sea sponge|sponges]], and other forces and organisms break down the coral skeletons into fragments that settle into spaces in the reef structure. Many other organisms living in the reef community contribute their skeletal [[calcium carbonate]] in the same manner. [[Coralline algae]] are important contributors to the structure of the reef in those parts of the reef subjected to the greatest forces by waves (such as the reef front facing the open ocean). These algae contribute to reef-building by depositing limestone in sheets over the surface of the reef and thereby contributing also to the structural integrity of the reef.
Reef-building or hermatypic corals are only found in the [[photic zone]] (above 50 m depth), the depth to which sufficient sunlight penetrates the water for [[photosynthesis]] to occur. The coral polyps do not photosynthesize, but have a [[symbiotic]] relationship with single-celled algae called [[zooxanthellae]]; these algal cells within the tissues of the coral polyps carry out photosynthesis and produce excess organic nutrients that are then used by the coral polyps. Because of this relationship, coral reefs grow much faster in clear water, which admits more sunlight. Indeed, the relationship is responsible for coral reefs in the sense that without their symbionts, coral growth would be too slow for the corals to form impressive reef structures. Corals can get up to 90% of their nutrients from their zooxanthellae symbionts.<ref name="Manager's Guide to Coral Bleaching">{{cite book
| coauthors =Marshall, Paul; Schuttenberg, Heidi.
| title =A Reef Manager’s Guide to Coral Bleaching
| publisher = [[Great Barrier Reef Marine Park Authority]],
| date = 2006
| location =Townsville, Australia
| pages =
| url =http://www.gbrmpa.gov.au/corp_site/info_services/publications/misc_pub/a_reef_managers_guide_to_coral_bleaching
| doi =
| id = 1 876945 40 0 }}</ref>
Corals can reproduce both sexually and asexually. An individual polyp may use both reproductive modes within its lifetime. Corals reproduce sexually by either internal or external fertilization. The reproductive cells are found on the mesentery membranes that radiate inward from the layer of tissue that lines the stomach cavity. Some mature adult corals are hermaphroditic; others are exclusively male or female. A few even change sex as they grow.
Internally fertilized eggs are brooded in the polyp for a period ranging from days to weeks. Subsequent development produces a tiny larva, known as a planula. Externally fertilized eggs develop during a synchronized spawning. Polyps release eggs and sperm into the water simultaneously. This spawning method disperses eggs over a larger area. Synchronous spawning depends on four factors: time of year, water temperature, and tidal and lunar cycles. Spawning is most successful when there is little variation between high and low tides. The less water movement there is over the reef, the better the chance that an egg will be fertilized. Ideal timing occurs in the spring, release of eggs or planula larvae usually occurs at night and is sometimes in phase with the lunar cycle (3-6 days after a full moon). The period from release to settlement lasts only a few days, but some planulae can survive afloat for several weeks (7, 14). They are vulnerable at this time to heavy predation and adverse environmental conditions. For the lucky few which survive to attach to substrate, the challenge comes from competition for food and space.
==Formations==
Coral reefs can take a variety of forms, defined in following:
* '''[[Fringing reef]]''' – a reef that is directly attached to a shore or borders it with an intervening shallow channel or lagoon.
* '''Barrier reef''' – a reef separated from a mainland or island shore by a deep [[lagoon]] (''see [[Great Barrier Reef]]'').
* '''Patch reef''' – an isolated, often circular reef, usually within a [[lagoon]] or [[embayment]].
* '''Apron reef''' – a short reef resembling a fringing reef, but more sloped; extending out and downward from a point or peninsular shore.
* '''Bank reef''' – a linear or semi-circular in outline, larger than a patch reef.
* '''Ribbon reef''' – a long, narrow, somewhat winding reef, usually associated with an atoll lagoon.
* '''Atoll reef''' – a more or less circular or continuous barrier reef extending all the way around a lagoon without a central island; see [[atoll]].
* '''Table reef''' – an isolated reef, approaching an atoll type, but without a lagoon.
==Distribution==
[[Image:Coral reef locations.jpg|thumb|380px|Locations of coral reefs.]]
Coral reefs are estimated to cover 284,300 square kilometres, with the [[Indo-Pacific]] region (including the [[Red Sea]], [[Indian Ocean]], [[Southeast Asia]] and the [[Pacific]]) accounting for 91.9% of the total.{{Fact|date=December 2007}} Southeast Asia accounts for 32.3% of that figure, while the Pacific including [[Australia]] accounts for 40.8%. [[Atlantic]] and [[Caribbean]] coral reefs only account for 7.6% of the world total.<ref name="Spalding">Spalding, Mark, Corinna Ravilious, and Edmund Green. 2001. ''World Atlas of Coral Reefs''. Berkeley, CA: University of California Press and UNEP/WCMC.</ref>
Coral reefs are either restricted or absent from the west coast of the [[Americas]], as well as the west coast of [[Africa]]. This is due primarily to [[upwelling]] and strong cold coastal currents that reduce water temperatures in these areas.<ref name="Nybakken">Nybakken, James. 1997. ''Marine Biology: An Ecological Approach.'' 4th ed. Menlo Park, CA: Addison Wesley.</ref> Corals are also restricted from off the coastline of [[South Asia]] from [[Pakistan]] to [[Bangladesh]].<ref name="Spalding" /> They are also restricted along the coast around north-eastern [[South America]] and [[Bangladesh]] due to the release of vast quantities of freshwater from the [[Amazon River|Amazon]] and [[Ganges]] Rivers respectively.{{Fact|date=December 2007}}
'''Famous coral reefs and reef areas of the world include:'''
* The [[Great Barrier Reef]] - largest coral reef system in the world, [[Queensland|Queensland, Australia]];
* The [[Belize Barrier Reef]] - second largest in the world, stretching from southern Quintana Roo, Mexico and all along the coast of Belize down to the Bay Islands of Honduras.
* The [[New Caledonia Barrier Reef]] - second longest double barrier reef in the world, with a length of about 1500km.
* The [[Andros, Bahamas]] Barrier Reef - third largest in the world, following along the east coast of Andros Island, Bahamas between Andros and Nassau.
* The [[Red Sea]] Coral Reef - located off the coast of Egypt and Saudi Arabia.
* [[Pulley Ridge]] - deepest photosynthetic coral reef, [[Florida]]
* Many of the numerous reefs found scattered over the [[Maldives]]
==Ecology and biodiversity==
[[Image:Nwhi - French Frigate Shoals reef - many fish.jpg|right|thumb|250px|A school of [[Pennant coralfish]], [[Pyramid butterflyfish|Pyramid]] and [[Millet butterflyfish]]es, and others at the Rapture Reef, [[French Frigate Shoals]]]]
Coral reefs support an extraordinary [[biodiversity]]; although they are located in nutrient-poor tropical waters. The process of [[Biogeochemical cycle|nutrient cycling]] between corals, zooxanthellae, and other reef organisms provides an explanation for why coral reefs flourish in these waters: recycling ensures that fewer nutrients are needed overall to support the community.
[[Cyanobacteria]] also provide soluble [[nitrate]]s for the coral reef through the process of [[nitrogen fixation]]. Corals absorb nutrients, including inorganic nitrogen and [[phosphorus]], directly from the water, and they feed upon [[zooplankton]] that are carried past the polyps by water motion.<ref name="Castro">Castro, Peter and Michael Huber. 2000. ''Marine Biology.'' 3rd ed. Boston: McGraw-Hill.</ref> Thus, [[primary productivity]] on a coral reef is very high, which results in the highest values per square meter, at 5-10g C m<sup>-2</sup> day<sup>-1</sup>.<ref>Sorokin, Y. I. Coral Reef Ecology. Germany. Sringer-Herlag, Berlin Heidelberg. 1993.</ref> Producers in coral reef communities include the symbiotic zooxanthellae, coralline algae, and various [[seaweed]]s, especially small types called turf algae, although scientists disagree about the importance of these particular organisms.<ref name="Castro" />
Coral reefs are home to a variety of tropical or reef [[fish]], such as the colorful [[parrotfish]], [[Marine angelfish group|angelfish]], [[damselfish]] and [[butterflyfish]]. Other fish groups found on coral reefs include [[grouper]]s, [[snapper]]s, [[grunt (fish)|grunts]] and [[wrasse]]s. Over 4,000 species of fish inhabit coral reefs.<ref name="Spalding" /> It has been suggested that the high number of fish species that inhabit coral reefs are able to coexist in such high numbers because any free living space is rapidly inhabited by the first planktonic fish larvae that occupy it. These fish then inhabit the space for the rest of their life. The species that inhabit the free space is random and has therefore been termed 'a lottery for living space'.<ref>Coexistence of coral reef fishes—a lottery for living space
PF Sale 1978 - Environmental Biology of Fishes, 1978 </ref>
Reefs are also home to a large variety of other organisms, including [[sea sponge|sponges]], [[Cnidaria]]ns (which includes some types of corals and [[jellyfish]]), [[worm]]s, [[crustacean]]s (including [[shrimp]], [[spiny lobster]]s and [[crab]]s), [[mollusc]]s (including [[cephalopod]]s), [[echinoderm]]s (including [[starfish]], sea urchins and [[sea cucumber]]s), [[sea squirt]]s, [[sea turtle]]s and [[sea snake]]s. Aside from humans, [[mammal]]s are rare on coral reefs, with visiting [[cetacean]]s such as [[dolphin]]s being the main group. A few of these varied species feed directly on corals, while others graze on algae on the reef and participate in complex [[food web]]s.<ref name="Castro" /><ref name="Spalding" />
A number of invertebrates, collectively called '''cryptofauna''', inhabit the coral skeletal substrate itself, either boring into the skeletons (through the process of [[bioerosion]]) or living in pre-existing voids and crevices. Those animals boring into the rock include sponges, bivalve molluscs, and [[sipuncula]]ns. Those settling on the reef include many other species, particularly crustaceans and [[polychaete]] worms.<ref name="Nybakken" />
Due to their vast biodiversity, many governments world-wide take measures to protect their coral reefs. In Australia, the Great Barrier Reef is protected by the [[Great Barrier Reef Marine Park Authority]], and is the subject of much legislation, including a [[Biodiversity Action Plan]].
===Algae and coral reef===
Researchers found evidence of algae dominance in locations of healthy coral reefs. In surveys done around largely uninhabited US Pacific islands, algae consists of a large percentage of the surveyed coral locations. <ref>{{Citation | title=Algae-Dominated Reefs | first1=Peter S. | last1=Vroom | first2=Kimberly N. | last2=Page | first3=Jean C. | last3=Kenyon | first4=Russell E. | last4=Brainard | journal=American Scientist | year=2006 | volume=94 | issue=5 | pages=pp.430-437}}</ref> [[The]] algae population consists of turf algae, [[coralline algae]], and [[macroalgae]].
==Threats==
[[Image:Coral-reef-bioerosion.jpg|thumbnail|250px|left|''Bioerosion'' (coral damage) such as this may be caused by [[coral bleaching]].<ref>{{cite web| url=http://www.biology.iastate.edu/intop/1Australia/Australia%20papers/Bioerosion.htm|title=Bioerosion: an essential, and often overlooked, aspect of reef ecology | date = [[17 April]] [[2003]] | accessdate = 2006-11-02 | author = Ryan Holl| publisher = [[Iowa State University]]}}</ref>]]
Human activity may represent the greatest threat to coral reefs living in Earth's [[oceans]]. In particular, [[pollution]] and over-fishing are the most serious threats to these ecosystems. Physical destruction of reefs due to boat and shipping traffic is also a problem. The [[live food fish trade]] has been implicated as a driver of decline due to the use of [[cyanide]] and
disaster for peoples living in the tropics. Hughes, et al, (2003), writes that "with increased [[World population|human population]] and improved storage and transport systems, the scale of human impacts on reefs has grown exponentially. For example, markets for fishes and other [[natural resource]]s have become global, supplying demand for reef resources far removed from their tropical sources."<ref>{{cite web|author=Hughes etal.|year=2003|title=Climate Change, Human Impacts, and the Resilience of Coral Reefs. ''[[Science]]''. Vol 301 [[15 August]] [[2003]]| url= http://www.sciencemag.org/cgi/content/abstract/301/5635/929|accessdate=2008-06-03 }}</ref>
Currently researchers are working to determine the degree various factors impact the reef systems. The list of factors is long but includes the oceans acting as a [[carbon dioxide sink]], changes in [[Earth's atmosphere]], [[ultraviolet light]], [[ocean acidification]], biological [[virus]], impacts of [[dust storms]] carrying agents to far flung reef systems, various pollutants, impacts of [[algal bloom]]s and others. Reefs are threatened well beyond coastal areas and so the problem is broader than factors from land development and pollution though those are too causing considerable damage.
===Land development and pollution===
Extensive and poorly managed land development can threaten the survival of coral reefs. Within the last 20 years, once prolific [[mangrove forest]]s, which absorb massive amounts of nutrients and [[sediment]] from runoff caused by farming and construction of roads, buildings, ports, channels, and harbors, are being destroyed. Nutrient-rich water causes fleshy algae and phytoplankton to thrive in coastal areas in suffocating amounts known as [[algal blooms]]. Coral reefs are biological assemblages adapted to waters with low nutrient content, and the addition of nutrients favors species that disrupt the balance of the reef communities. Both the loss of wetlands and mangrove habitats are considered to be significant factors affecting [[water quality]] on inshore reefs.<ref>{{cite web|author=Australian Government Productivity Commission|year=2003|title=Industries, Land Use and Water Quality in the Great Barrier Reef Catchment - Key Points| url= http://www.pc.gov.au/study/gbr/finalreport/keypoints.html|accessdate=2006-05-29 }}</ref>
Poor water quality has also been shown to encourage the spread of [[infectious disease]]s among corals.<ref>{{cite web|author=Rachel Nowak|publisher=New Scientist|date=[[2004-01-11]]|title=Sewage nutrients fuel coral disease|url=http://www.newscientist.com/article.ns?id=dn4539|accessdate=2006-08-10}}</ref>
[[Copper]], a common industrial pollutant, has been shown to interfere with the [[life history]] and development of coral polyps.<ref> {{cite web|author=Emma Young|year=2003|title=Copper decimates coral reef spawning|url= http://www.newscientist.com/article.ns?id=dn4391|accessdate=2006-08-26}}</ref>
Fish Trade
The hobby of keeping saltwater aquaria has experienced an increase in world popularity since the 1990s. Beyond sales of aquaria, air pumps, food, medications and other supplies, the primary product of the aquarium industry is fish. However, the world market is limited in the diversity of collected species. For example, among 4000 coral reef fish species, only 200–300 are exploited. Selection of species results from a demand for fish being highly colorful and being able to be maintained and fed in aquaria. The last point is very important in the choice of imported species.
Although a few fish species (e.g. Pomacentridae) can be reproduced in aquaria, 95% of exploited fish are directly collected in the coral environment. Intense sampling of coral reef fish, especially in South-East Asia (including Indonesia and the Philippines), has caused great damage to the environment. A major catalyst of [[cyanide fishing]] is poverty within fishing communities. In areas like the Philippines where cyanide is regularly used to catch live aquarium fish, the percentage of the population below the poverty line is 40%.<ref>{{cite web| url=https://www.cia.gov/library/publications/the-world-factbook/geos/rp.html | title= CIA - The World Factbook -- Philippines | accessdate = 2006-11-02 | publisher=[[CIA]]}}</ref> In such [[Developing country|developing countries]], a fisherman might resort to such unethical practices in order to prevent his or her family from starving.
Most, 80–90%, of aquarium fish exported from the Philippines are captured with [[sodium cyanide]]. This toxic chemical is dissolved in sea water and released into fish shelters. It has a rapid narcotic effect on fish, which are then easily captured. However, most fish collected with cyanide die a few months after capture from extensive liver damage. Moreover, other fish species that are not interesting for the aquarium market also die in the field.<ref>{{cite web| url=http://www.blackwell-synergy.com/doi/full/10.1111/j.1444-2906.2006.01114.x | title= David LECCHINI, Sandrine POLTI, Yohei NAKAMURA, Pascal MOSCONI, Makoto TSUCHIYA, Georges REMOISSENET, Serge PLANES (2006) "New perspectives on aquarium fish trade" Fisheries Science 72 (1), 40–47 | accessdate = 2007-01-16 | publisher=Blackwell Synergy}}</ref>
===Dynamite fishing===
[[Blast fishing|Dynamite fishing]] is another extremely destructive method that fishermen use to harvest small fish. Sticks of dynamite, grenades, or home-made explosives are lit or activated and thrown in the water. Once the dynamite goes off the explosion brings about an underwater shockwave, causing the internal organs of fish to liquefy, killing them almost instantly. A second blast is often set off after the first to kill any larger predators that are attracted to the initial kill of the smaller fish. This method of fishing not only kills the fish within the main blast area, but also takes the lives of many reef animals that are not edible or wanted. Also, many of the fish do not float to the surface to be collected, but sink to the bottom. The blast also kills the corals in the area, eliminating the very structure of the reef, destroying the habitat for fish and other animals important for the maintenance of a healthy reef. Areas that used to be full of coral become deserts, full of coral rubble, dead fish and little else after dynamite fishing. With dynamite fishing especially around the Maldives in the Indian Ocean, have caused a vast majority of problems. With the rising sea level already the coral reefs act as a natural defence against flooding. With the dynamite fishing, the coral reefs are destroyed making the islands more vulnerable to flooding.
===Bleaching===
{{main|Coral bleaching}}
During the 1998 and 2004 [[El Niño]] weather phenomena, in which [[sea surface temperature]]s rose well above normal, many tropical coral reefs were [[coral bleaching|bleached]] or killed. Some recovery has been noted in more remote locations, but [[global warming]] could negate some of this recovery in the future. High seas surface temperature (SSTs) coupled with high irradiance (light intensity), triggers the loss of zooxanthellae, a symbiotic algae, and its dinoflagellate pigmentation in corals causing coral bleaching. Zooxanthellae provide 95% of the energy to the coral host. Refer to Hoegh-Guldberg 1999 for more information.
===Ocean acidification===
{{main|Ocean acidification}}
The decreasing ocean surface pH is of increasing long-term concern for coral reefs.<ref>Kleypas, J.A., R.A. Feely, V.J. Fabry, C. Langdon, C.L. Sabine, and L.L. Robbins, 2006, Impacts of Ocean Acidification on Coral Reefs and Other Marine Calcifiers: A guide for Future Research, NSF, NOAA, & USGS, 88 pp.</ref>
Increased atmospheric CO<sub>2</sub> increases the amount of CO<sub>2</sub> dissolved in the oceans.<ref>{{cite web |url=http://science.hq.nasa.gov/oceans/system/carbon.html |title=The Ocean and the Carbon Cycle |accessdate=2007-03-04 |date=2005-06-21 |work=[[NASA]] Oceanography ([http://science.hq.nasa.gov/index.html science@nasa])}}</ref> Carbon dioxide gas dissolved in the ocean reacts with water to form [[carbonic acid]], resulting in [[ocean acidification]]. Ocean surface pH is estimated to have decreased from approximately 8.25 to 8.14 since the beginning of the industrial era,<ref name=jacob05>Jacobson, M. Z. (2005). Studying ocean acidification with conservative, stable numerical schemes for nonequilibrium air-ocean exchange and ocean equilibrium chemistry. ''J. Geophys. Res. Atm.'' '''110''', D07302.</ref> and it is estimated that it will drop by a further 0.3 - 0.4 units by 2100 as the ocean absorbs more anthropogenic CO<sub>2</sub>.<ref name=orr05>Orr, J. C. ''et al.'' (2005). [http://www.ipsl.jussieu.fr/~jomce/acidification/paper/Orr_OnlineNature04095.pdf Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms.] ''Nature'' '''437''', 681-686.</ref> Under normal conditions, the conditions for calcium carbonate production are stable in surface waters since the carbonate ion is at [[supersaturation|supersaturating]] concentrations. However, as ocean pH falls, so does the concentration of this ion, and when carbonate becomes under-saturated, structures made of calcium carbonate are vulnerable to dissolution. Research has already found that corals experience reduced calcification or enhanced dissolution when exposed to elevated CO<sub>2</sub>.<ref name=gatt98>Gattuso, J.-P., Frankignoulle, M., Bourge, I., Romaine, S. and Buddemeier, R. W. (1998). [http://www.obs-vlfr.fr/~gattuso/jpg_papers_list.php Effect of calcium carbonate saturation of seawater on coral calcification.] ''Glob. Planet. Change'' '''18''', 37-46.</ref>
===African and Asian dust outbreaks===
[[Image:Barbadosdustgraph.gif|thumb|right|150px]]
Dust from the [[Sahara]] moving around the southern periphery of the [[subtropical ridge]] moves into the [[Caribbean]] and [[Florida]] during the warm season as the ridge builds and moves northward through the subtropical Atlantic. Dust can also be attributed to a global transport from the [[Gobi]] and [[Taklamakan]] deserts across [[Korea]], [[Japan]], and the Northern [[Pacific]] to the [[Hawaiian Islands]].<ref>Duce, R.A., Unni, C.K., Ray, B.J., Prospero, J.M., Merrill, J.T. 1980. Long-range atmospheric transport of soil dust from Asia to the tropical North Pacific:Temporal variability. Science 209:1522–1524.</ref> Since 1970, dust outbreaks have worsened due to periods of drought in Africa. There is a large variability in the dust transport to the Caribbean and Florida from year to year;<ref>Usinfo.state.gov. [http://www.gcrio.org/OnLnDoc/pdf/african_dust.pdf Study Says African Dust Affects Climate in U.S., Caribbean.] Retrieved on [[2007-06-10]].</ref> however, the flux of dust is greater during positive phases of the [[North Atlantic Oscillation]].<ref>Prospero, J.M., Nees, R.T. 1986. Impact of the North African drought and El Niño on mineral dust in the Barbados trade winds. Nature 320:735–738.</ref> Dust events have been linked to a decline in the health of coral reefs across the Caribbean and Florida, primarily since the 1970s.<ref>[[U. S. Geological Survey]]. [http://coastal.er.usgs.gov/african_dust/ Coral Mortality and African Dust.] Retrieved on [[2007-06-10]].</ref> Studies have shown that corals can incorporate dust into their skeletons as identified from dust from the 1883 eruption of [[Krakatoa]] in [[Indonesia]] in the annular bands of the reef-building coral ''[[Montastraea annularis]]'' from the [[Florida]] reef tract.<ref>Merman, E.A. 2001. Atmospheric inputs to the tropical ocean—unlocking the record in annually banded corals. Master’s thesis. University of South Florida, St. Petersburg.</ref> The relative abundance of chemical elements, particularly metals, has been used to distinguish soil derived from volcanic dust from [[mineral dust]].<ref>Muhs, D.R., Bush, C.A., Stewart, K.C., Rowland, T.R., Crittenden, R.C. 1990. Geochemical evidence of Saharan dust parent material for soils developed on Quaternary limestones of Caribbean and Western Atlantic islands. Quaternary Research 33:157–177.</ref>
===Destruction worldwide===
[[Image:Coral reefs with fishes.JPG|Coral reefs and fishes in [[Papua New Guinea]]|thumb|250px]]
[[Southeast Asia coral reefs|Southeast Asian coral reefs]] are at risk from damaging [[fishing]] practices (such as [[Cyanide fishing|cyanide]] and [[blast fishing]]), [[overfishing]], sedimentation, pollution and bleaching. A variety of activities, including education, regulation, and the establishment of marine protected areas are under way to protect these reefs. [[Indonesia]], for example has nearly {{convert|33000|sqmi|km2}} of coral reefs. Its waters are home to a third of the world’s total corals and a quarter of its fish species. Indonesia's coral reefs are located in the heart of the Coral Triangle and have been victim to destructive fishing, unregulated tourism, and bleaching due to climatic changes. Data from 414 reef monitoring stations throughout Indonesia in 2000 found that only 6% of Indonesia’s coral reefs are in excellent condition, while 24% are in good condition, and approximately 70% are in poor to fair condition (2003 [[Johns Hopkins University|The Johns Hopkins University]]).
On [[September 24]], [[2007]], [[Reef Check]] (the world’s largest reef [[Habitat conservation|conservation]] [[organization]]) stated that only 5% of [[Philippines]] 27,000 square-[[kilometers]] of coral reef are in “''excellent condition''” : [[Tubbataha Reef]], [[Marine Park]] in [[Palawan]], [[Apo Island]] in [[Negros Oriental]], Apo Reef in [[Puerto Galera]], [[Mindoro]], and [[Verde Island]] Passage off [[Batangas]]. [[Philippine]] [[coral reefs]] is 2nd largest in [[Asia]].<ref>[http://www.abs-cbnnews.com/storypage.aspx?StoryID=93671 Abs-Cbn Interactive, ‘RP coral reefs, second largest in Asia, in bad shape’]</ref>
General estimates show approximately 10% of the coral reefs around the world are already dead.<ref>Save Our Seas, 1997 Summer Newsletter, Dr. Cindy Hunter and Dr. Alan Friedlander</ref><ref>Tun, K., L.M. Chou, A. Cabanban, V.S. Tuan, Philreefs, T. Yeemin, Suharsono, K.Sour, and D. Lane, 2004, p:235-276 in C. Wilkinson (ed.), Status of Coral Reefs of the world: 2004.</ref>Problems range from [[environmental effects of fishing]] techniques, described above, to [[ocean acidification]].<ref>Kleypas, J.A., R.A. Feely, V.J. Fabry, C. Langdon, C.L. Sabine, and L.L. Robbins, 2006, Impacts of Ocean Acidification on Coral Reefs and Other Marine Calcifiers: A guide for Future Research, NSF, NOAA, & USGS, 88 pp.</ref> [[Coral bleaching]] is another manifestation of the problem and is showing up in reefs across the planet.
==Protection and restoration==
[[Image:ManusReefs L7 2000Feb20.jpg|thumb|250px|Aerial photo of Ahus Island, [[Papua New Guinea]]]]Inhabitants of Ahus Island, [[Manus Province]], [[Papua New Guinea]], have followed a generations-old practice of restricting fishing in six areas of their reef lagoon. While line fishing is permitted, net and spear fishing are restricted based on cultural traditions. The result is that both the [[biomass]] and individual fish sizes are significantly larger in these areas than in places where fishing is completely unrestricted.<ref>Cinner, J. et al. (2005). Conservation and community benefits from traditional coral reef management at Ahus Island, Papua New Guinea. Conservation Biology 19 (6), 1714-1723</ref><ref>{{cite web| url=http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=17182 |title=Coral Reef Management, Papua New Guinea |publisher = [[Nasa]]'s [[Earth Observatory]]|accessdate=2006-11-02}}</ref>
It is estimated that about 60% of the world’s reefs are at risk due to destructive, human-related activities. The threat to the health of reefs is particularly strong in [[Southeast Asia]], where an enormous 80% of reefs are considered [[endangered species|endangered]].
Organisations as [http://www.coralcay.org/expeditions/marine/fj1/ Coral Cay], [http://www.counterpart.org/ Counterpart] <ref>[http://www.bbc.co.uk/programmes/b009jsjv 'The Coral Gardener'-documentary on coral gardening by Counterpart]</ref> and the [http://www.fspi.org.fj/programs.htm Foundation of the peoples of the South Pacific] are currently undertaking coral reef/atoll restoration projects. They are doing so using simple methods of [[plant propagation]]. Other organisations as [[Practical Action]] have released informational documents on how to set-up coral reef restoration to the public.<ref>[http://practicalaction.org/docs/technical_information_service/coral_reefs.pdf Practical Action coral reef restoration]</ref>
===Marine Protected Areas===
One method of coastal reef management that has become increasingly prominent is the implementation of [[Marine Protected Area|Marine Protected Areas (MPAs)]]. MPAs have been introduced in Southeast Asia and elsewhere around the world to attempt to promote responsible [[Fisheries management|fishery management]] and [[habitat (ecology)|habitat protection]]. Much like the designation of [[national park]]s and wild life refuges, potentially damaging extraction activities are prohibited. The objectives of MPAs are both social and biological, including restoration of coral reefs, aesthetic maintenance, increased and protected biodiversity, and economic benefits. Conflicts surrounding MPAs involve lack of participation, clashing views and perceptions of effectiveness, and funding.
===Reef Restoration Technology===
Low voltage electrical currents applied through seawater crystallizes dissolved minerals onto steel structures. The resultant white carbonate ([[aragonite]]) is the same mineral that makes up natural coral reefs. Corals rapidly colonize and grow at faster than normal rates onto these coated structures. The change in the environment produced by electrical currents also accelerates formation and growth of both chemical limestone rock and the skeletons of corals and other shell-bearing organisms. Within the vicinity of the anode and cathode is a high pH environment which inhibits the growth of filamentous and fleshy algae, which compete with coral for space. This, and the increased growth rates cease when the mineral accretion process stops.<ref>Sabater, Marlowe G.; Yap, Helen T. 2004. "Long-term effects of induced mineral accretion on growth, survival, and corallite properties of Porites cylindrica Dana." Journal of Experimental Marine Biology and Ecology. Vol. 311:355-374.</ref>
The effects of mineral accretion is, however, only temporary. During the process the settled corals have an increased growth rate, and size, and density, but after the process is complete the corallites are comparable to naturally growing corallites in growth rate and density, and are about the same size or slightly smaller.<ref>Sabater, Marlowe G.; Yap, Helen T. 2004. "Long-term effects of induced mineral accretion on growth, survival, and corallite properties of Porites cylindrica Dana." Journal of Experimental Marine Biology and Ecology. Vol. 311:355-374.</ref>
== Reefs in the past ==
Throughout the [[Earth]] history, from a few million years after hard skeletons were developed by marine organisms, there were almost always reefs formed by reef-building organisms in the ancient seas. The times of maximum development were in the [[Middle Cambrian]] (513-501 [[Annum|Ma]]), [[Devonian]] (416-359 My) and [[Carboniferous]] (359-299 Ma), due to Order [[Rugosa]] [[extinction|extinct]] corals, and [[Late Cretaceous]] (100-65 Ma) and all [[Neogene]] (23 Ma - present), due to Order [[Scleractinia]] corals.
Not all reefs in the past were formed by corals: in the [[Early Cambrian]] (542-513 Ma) resulted from calcareous [[algae]] and [[Archaeocyatha|archaeocyathids]] (small animals with conical shape, probably related to [[sponges]]) and in the [[Late Cretaceous]] (100 -65 Ma), when there also existed reefs formed by a group of [[Bivalvia|bivalves]] called [[rudists]]; one of the valves formed the main conical structure and the other, much smaller valve acted as a cap.
==See also==
*[[Algae]]
*[[Black band disease]]
*[[Bruno Van Peteghem]]
*[[Coral]]
*[[Coral bleaching]]
*[[Coral rag]]
*[[Coral Reef Alliance]]
*[[Ivory Bush Coral]]
*[[Marine conservation]]
*[[Project AWARE]]
*[[Reef shark]]
*[[White band disease]]
==References==
<!--See http://en.wikipedia.org/wiki/Wikipedia:Footnotes for an explanation of how to generate footnotes using the <ref(erences/)> tags-->
{{reflist|2}}
====General references====
<div class="references-small">
*Barber, Charles V. and Vaughan R. Pratt. 1998. Poison and Profit: Cyanide Fishing in the Indo-Pacific. ''Environment'', Heldref Publications.
*Butler, Steven. 1996. "Rod? Reel? Dynamite? A tough-love aid program takes aim at the devastation of the coral reefs". ''U.S. News and World Report'', 25 November 1996.
*Christie, P. 2005a. University of Washington, Lecture. 18 May 2005.
*Christie, P. 2005b. University of Washington, Lecture. 4 May 2005.
*[https://www.cia.gov/library/publications/the-world-factbook/geos/rp.html CIA - World Factbook -- Philippines]
*Clifton, Julian. 2003. Prospects for Co-Management in Indonesia's Marine Protected Areas. ''Marine Policy'', 27(5): 389-395.
*Courtney, Catherine and Alan White. 2000. ''Integrated Coastal Management in the Philippines''. Coastal Management; Taylor and Francis.
*Fox, Helen. 2005. ''Experimental Assessment of Coral Reef Rehabilitation Following Blast Fishing''. The Nature Conservancy Coastal and Marine Indonesia Program. Blackwell Publishers Ltd, Feb 2005.
*Gjertsen, Heidi. 2004. ''Can Habitat Protection Lead to Improvements in Human Well-Being? Evidence from Marine Protected Areas in the Philippines.''
*Martin, Glen. 2002. "The depths of destruction Dynamite fishing ravages Philippines' precious coral reefs". ''San Francisco Chronicle'', 30 May 2002
*Sadovy, Y.J. ''Ecological Issues and the Trades in Live Reef Fishes, Part 1''
*[http://www.epa.gov/awow/oceans/coral/about.html USEPA].
*[http://www.unepscs.org/SCS_Documents/Download/13_-_Habitat_Booklets/UNEP_or_GEF_Review_of_Coral_Reefs_in_the_South_China_Sea.html UNEP. 2004. Coral Reefs in the South China Sea. UNEP/GEF/SCS Technical Publication No. 2.]
*[http://www.unepscs.org/SCS_Documents/Download/19_-_Technical_Publications_and_Guidelines/Technical_Publication_05_-_Coral_Reef_Demonstration_Sites_in_the_South_China_Sea.html UNEP. 2007. Coral Reefs Demonstration Sites in the South China Sea. UNEP/GEF/SCS Technical Publication No. 5.]
*[http://www.unepscs.org/SCS_Documents/Download/19_-_Technical_Publications_and_Guidelines/Technical_Publication_11_-_National_Reports_on_Coral_Reefs_in_the_Coastal_Waters_of_the_South_China_Sea.html UNEP, 2007. National Reports on Coral Reefs in the Coastal Waters of the South China Sea. UNEP/GEF/SCS Technical Publication No. 11.]
</div>
==External links==
{{Commonscat|Coral reefs}}
*[http://animals.howstuffworks.com/marine-life/coral-reef.htm How Coral Reefs Work]
*[http://www.reeffest.org/ Reef Fest Concert Series] Non-profit organization to benefit coral reef conservation globally during the International Year of the Reef 2008
*[http://www.iyor.org International Year of the Reef in 2008]
*[http://mcr.lternet.edu Moorea Coral Reef Long Term Ecological Research Site (US NSF)]
*[http://www.coralcoe.org.au/index.html ARC Centre of Excellence for Coral Reef Studies]
*[http://coral.aoml.noaa.gov/mailman/listinfo/coral-list/ NOAA's Coral-List Listserver for Coral Reef Information and News]
*[http://www.coralreef.noaa.gov/ NOAA's Coral Reef Conservation Program]
*[http://www.coris.noaa.gov/ NOAA's Coral Reef Information System]
*[http://ccma.nos.noaa.gov/ecosystems/coralreef/coral_report_2005/ NOAA Report: The State of Coral Reef Ecosystems of the United States and Pacific Freely Associated States: 2005]
*[http://www.reefbase.org/ ReefBase: A Global Information System on Coral Reefs]
*[http://www.nova.edu/ncri/ National Coral Reef Institute] Nova Southeastern University
*[http://globalcoral.org/ Global Coral Reef Alliance]
*[http://www.gcrmn.org Global Coral Reef Monitoring Network] (GCRMN)
*[http://www.aquariumcouncil.org Marine Aquarium Council]
*[http://www.ncoremiami.org/ NCORE National Center for Coral Reef Research] University of Miami
*[http://www.coral.org/ The Coral Reef Alliance] (CORAL)
*[http://www.unepscs.org/index.php?option=com_content&task=view&id=51&Itemid=83 Science and Management of Coral Reefs in the South China Sea and Gulf of Thailand]
*[http://www.motherjones.com/news/special_reports/coral_reef/ A special report on the plight of the planet's coral reefs—and how you can help—from ''Mother Jones'' magazine]
*[http://albany.edu/~sd179845/pathfinder.html A guide to finding sources and literature about coral reefs]
*[http://coralreefs.nbii.gov/portal/server.pt NBII portal on coral reefs]
{{fisheries and fishing}}
[[Category:Animal products]]
[[Category:Coral reefs|*]]
[[Category:Fisheries]]
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[[bg:Коралов риф]]
[[cs:Korálový útes]]
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[[de:Korallenriff]]
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[[es:Arrecife de coral]]
[[eu:Koralezko uharri]]
[[fa:آبسنگ مرجانی]]
[[fr:Récif corallien]]
[[it:Barriera corallina]]
[[he:שונית אלמוגים]]
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[[ja:サンゴ礁]]
[[no:Korallrev]]
[[pl:Rafa]]
[[pt:Recife de coral]]
[[ru:Коралловые рифы]]
[[simple:Coral reef]]
[[sk:Koralový útes]]
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[[ta:பவளப் பாறைகள்]]
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[[uk:Коралові споруди]]
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