Coral island

A coral island is a type of island formed from coral detritus and associated organic material.[1] They occur in tropical and sub-tropical areas, typically as part of coral reefs which have grown to cover a far larger area under the sea.


Coral reef at palmyra
Healthy reef system

Coral reefs are some of the oldest ecosystems on the planet. Over geological time forming massive reefs made of limestone. The reef environment supports more plant and animal species than any other habitat. Coral reefs are vital for life for multiple aspects some of which include structure, ecology, and nutrient cycles which all support biodiversity in the reefs.

The reefs build massive calcareous skeletons that serve as homes for animals from fish hiding inside the crooks and crannies of the reef and barnacles attaching themselves directly to the coral’s structure. The reef’s structure also helps with plants that need the sun to photosynthesize; by lifting the plants to the ocean’s surface where the sunlight can penetrate the water. The structure of the reef also creates a calm zone in the ocean providing a great place for fish and plant species to thrive.

Over geological time the reefs reach the surface and can become a coral island, where it begins a whole new ecosystem for land based creatures.[2]


Coral atoll formation animation
Volcano with fringing reef, to barrier reef, and finally formation into a coral atoll

Coral islands begin as a volcanic island over a hot spot. As the volcano emerges from the sea a fringing reef grows on the outskirt of the volcano. The volcano eventually moves off of the hot spot through a process known as plate tectonics. Once this occurs the volcano can no longer keep up with the erosion that is taking place due to the ocean and undergoes subsidence.

Once the island is submerged the coral must keep growing to stay in the epipelagic zone (sunlit). This causes the coral to grow into an atoll with a shallow lagoon in the middle. The lagoon can then undergo accretion and create an island completely made of carbonate materials.The process is later enhanced with the remains of plant life which grows on the island.[3]

Human impacts on coral islands

Bleached coral, Acoropora sp
Bleached coral due to rising sea temperature, increased acidity, or pollution.

Coral is important for biodiversity and the growth of fish populations, so maintaining coral reefs is important. Coral reefs are threatened by numerous anthropogenic impacts, some of which have already had major effects worldwide.[4] Reefs grow in shallow, warm, nutrient poor waters where they are not out competed by phytoplanktons. By adding fertilizers into the water runoff phytoplankton populations can explode and choke out coral reef systems. Adding too many sediments can cause a similar problem by blocking out the sun starving the zooxanthellae that live on coral causing it to undergo a process known as coral bleaching. The oceans acidity is also a factor. Coral is made of calcium carbonate and is dissolved by carbonic acid. With the increase in carbon dioxide from combustion reactions in the atmosphere through precipitation carbon dioxide mixes with water and forms carbonic acid raising the oceans acidity which slows coral growth. Through chemical and physical changes humans can cause significant harm to reef systems and slow the creation of coral island chains.[2]


Most of the world's coral islands are in the Pacific Ocean. The American territories of Jarvis, Baker and Howland Islands are clear examples of coral islands.The Lakshadweep Islands union territory of India is a group of 39 coral Islands, and some minor islets and banks. Also, some of the islands belonging to Kiribati are considered coral islands. The Maldives also consist of coral islands. St. Martin's Island is an 8 km2 coral island located in Bangladesh. Coral islands are also located near Pattaya and Ko Samui, Thailand.[5]

Many coral islands are small with low elevation above sea level. Thus they are at threat from storms and rising sea levels.

See also


  1. ^ "coral island". Encyclopædia Britannica. Retrieved 2012-12-26.
  2. ^ a b Heatwole, Harold (1981). A Coral IslandL The story of One Tree Island. Australia: William Collins. p. 130. ISBN 978-0002164429.
  3. ^ Erickson, Jon (2003). Marine Geology: Exploring New Frontiers of the Ocean. United States: Facts on File, Inc. p. 126. ISBN 978-0816048748.
  4. ^ SEBENS, KENNETH P. (February 1994). "Biodiversity of Coral Reefs: What are We Losing and Why?". American Zoologist. 34 (1): 115–133. doi:10.1093/icb/34.1.115. ISSN 0003-1569.
  5. ^ Andréfouët, Serge; Guzman, Hector M. (2005-03-01). "Coral reef distribution, status and geomorphology–biodiversity relationship in Kuna Yala (San Blas) archipelago, Caribbean Panama". Coral Reefs. 24 (1): 31–42. doi:10.1007/s00338-004-0444-4. ISSN 0722-4028.
Aniwa Island

Aniwa is a small island in the southernmost province of Tafea, Vanuatu.As a coral island (a raised coral atoll), it rises a mere 42 m above sea level. In the northwest is Itcharo (Tiaro) lagoon, which is open to the sea. The nearest large island is Tanna, about 24 km to the southwest.

Bipi Island

Bipi Island is a flat coral island located off the west coast of the main island of Manus in the Admiralty Group, Papua New Guinea. Adjacent and to the North West of Bipi Island is Sisi Island. Bipi Island consists of three villages, namely Masoh, Matahai, and Kum (the latter is also known as "Salapai") with approximately one thousand inhabitants.Bipi men were known as master woodcarvers in the 1970s and 1980s and sold carvings to supplement their meagre incomes made from copra production. Today, the main economic activity is fishing and the sale of bêche-de-mer to licensed buyers supplying the Asian markets. This activity is conducted on the surrounding coral islands and reefs which are owned by traditional islands, reefs and sea-owning groups of Bipi Island.

Bipi Island has one primary school that also caters to the students of nearby islands.

Coëtivy Island

Coëtivy Island is a small coral island in the Seychelles 290 km (180 mi) south of Mahé, at 07°08′S 56°16′E.

Along with Île Platte, the nearest neighbor 171 km (106 mi) northwest, it comprises the Southern Coral Group and therefore belongs to the Outer Islands.

Flint Island

Flint Island is an uninhabited coral island in the central Pacific Ocean, part of the Southern Line Islands under the jurisdiction of Kiribati. In 2014 the Kiribati government established a twelve-nautical-mile (22-kilometre; 14-mile) exclusion zone around each of the southern Line Islands (Caroline (commonly called Millennium), Flint, Vostok, Malden, and Starbuck).

Geography of Anguilla

Anguilla is an island in the Leeward Islands, which lies between the Caribbean Sea in the west and the open Atlantic Ocean in the east. It is a long, flat, dry/wet, scrub-covered coral island, south and east of Puerto Rico and north of the Windward chain. It is separated from the British Virgin Islands by the Anegada Passage. The island has no significant elevations with its terrain consisting entirely of beaches, dunes, and low limestone bluffs.

Jarvis Island

Jarvis Island (; formerly known as Bunker Island or Bunker's Shoal) is an uninhabited 1 3⁄4-square-mile (4.5 km2) coral island located in the South Pacific Ocean, about halfway between Hawaii and the Cook Islands. It is an unincorporated, unorganized territory of the United States, administered by the United States Fish and Wildlife Service of the United States Department of the Interior as part of the National Wildlife Refuge system. Unlike most coral atolls, the lagoon on Jarvis is wholly dry.

Jarvis is one of the Line Islands and for statistical purposes is also grouped as one of the United States Minor Outlying Islands.

Jemo Island

Jemo Island Atoll (Marshallese: Jemo̧ or Jāmo̧, [tʲææ̯mʲæ͡ɒɒ̯]) is an uninhabited coral island in the Pacific Ocean, in the Ratak Chain of the Marshall Islands north-east of Likiep Atoll. The island is oval-shaped and occupies the southwestern end of a narrow submarine ridge that extends to the northeast for several kilometers. Its total land area is only 0.16 square kilometres (0.062 sq mi). The island is traditionally held as a food reserve for the family of Joachim and Lijon deBrum, passed down to Lijon debrum from Iroijlaplap Lobareo and is owned by the current Likiep land-owning families of Joachim and Lijon debrum, grandkids of Iroijlaplap Jortõka of Ratak Eañ. There is also a shipwreck on the west side of the island.

First recorded sighting of Jemo Island by Europeans was by the Spanish expedition of Miguel López de Legazpi on 10 January 1565. It was charted as Los Pajaros (The Birds in Spanish).

Lisianski Island

Lisianski Island (Hawaiian: Papa‘āpoho) is one of the Northwestern Hawaiian Islands, with a land area of 384.425 acres (155.571 ha) and a maximum elevation of 40 feet (12 m) above sea level. It is a low, flat sand and coral island about 905 nautical miles (1,676 km) northwest of Honolulu. The island is surrounded by reefs and shoals, including the extensive Neva Shoals. Access to the island is limited by helicopter or by boat to a narrow sandy inlet on the southeastern side of the island.

Lord of the Flies

Lord of the Flies is a 1954 novel by Nobel Prize–winning British author William Golding. The book focuses on a group of British boys stranded on an uninhabited island and their disastrous attempt to govern themselves.

The novel has been generally well received. It was named in the Modern Library 100 Best Novels, reaching number 41 on the editor's list, and 25 on the reader's list. In 2003 it was listed at number 70 on the BBC's The Big Read poll, and in 2005 Time magazine named it as one of the 100 best English-language novels from 1923 to 2005.

Postage stamps and postal history of Kiribati

This is a survey of the postage stamps and postal history of Kiribati.

The Republic of Kiribati, is an island nation located in the central tropical Pacific Ocean. It is composed of 32 atolls and one raised coral island, dispersed over 3.5 million square kilometres, and straddling the equator.

Kiribati was formerly the Gilbert Islands, part of the Gilbert and Ellice Islands which split into Kiribati and Tuvalu upon gaining independence from the United Kingdom in 1978 and 1979.

Pulau Sudong

Pulau Sudong is a 209-hectare coral island off the southern coast of Singapore. It was enlarged through a land reclamation process during the late 1970s.

Raised coral atoll

A raised coral atoll or uplifted coral atoll is an atoll that has been lifted high enough above sea level by tectonic forces to protect it from scouring by storms and enable soils and diverse – often endemic – species of flora and fauna to develop. With the exception of Aldabra Island in the Indian Ocean and Henderson Island in the Pacific, most tropical raised atolls have been dramatically altered by human activities such as species introduction, phosphate mining and even bomb testing.

Rawa Island

Rawa Island (Malay: Pulau Rawa) is a coral island in Mersing District, Johor, Malaysia. Nearby islands include Harimau and Mensirip.

"Rawa" is the local term for white doves, which are abundant in the island.

Rawa is a relatively small island. There are no proper roads, only a few walkways. One side of the island is a beach covered with white sand, while the other side has a rocky vertical cliff. The water is clear. There are many sea and land creatures such as fishes, squids, jellyfish, octopuses, Malayan sea eagles, and reptiles. Also sharks Blacktip reef sharks can be found feeding in the sea off rawa. Rawa's waters are home to an abundance of corals. There are two resorts on the island: Rawa Island Resort and Alang's Rawa.

Starbuck Island

Starbuck Island (or Volunteer Island) is an uninhabited coral island in the central Pacific, and is part of the Central Line Islands of Kiribati. Former names include "Barren Island", "Coral Queen Island", "Hero Island", "Low Island", and "Starve Island".

Tepoto (North)

Tepoto, also known as Te Poto, Toho, or Pukapoto, is a coral island. It is the northwesternmost of the Disappointment Islands, in the Tuamotu Archipelago. Despite being often referred to as "atoll", Tepoto is not a typical Tuamotu atoll, but a single separate island without lagoon. It is located at the limit of the Tuamotu archipelago; the closest land is Napuka, which lies 16 kilometres (10 miles) to the southeast.

Tepoto is 2.6 kilometres (1.6 miles) long and 800 metres (2,625 feet) wide; it has an area of 4 square kilometres (2 square miles). This island is sometimes called Tepoto Nord in French, to avoid confusion with Tepoto Atoll (Tepoto Sud) 400 km (249 mi) to the southwest, in the Raeffsky Islands of central Tuamotu. An obsolete name is Otuho.

According to the 2012 census, its population was 61 inhabitants. The primary village is Tehekega. There is a 5m wide road running around the whole island.

In 2018 there were about 40 residents, 13 of which were children under the age of 12.

The Coral Island

The Coral Island: A Tale of the Pacific Ocean (1858) is a novel written by Scottish author R. M. Ballantyne. One of the first works of juvenile fiction to feature exclusively juvenile heroes, the story relates the adventures of three boys marooned on a South Pacific island, the only survivors of a shipwreck.

A typical Robinsonade – a genre of fiction inspired by Daniel Defoe's Robinson Crusoe – and one of the most popular of its type, the book first went on sale in late 1857 and has never been out of print. Among the novel's major themes are the civilising effect of Christianity, 19th-century British imperialism in the South Pacific, and the importance of hierarchy and leadership. It was the inspiration for William Golding's dystopian novel Lord of the Flies (1954), which inverted the morality of The Coral Island; in Ballantyne's story the children encounter evil, but in Lord of the Flies evil is within them.

In the early 20th century, the novel was considered a classic for primary school children in the UK, and in the United States it was a staple of high-school suggested reading lists. Modern critics consider the book's worldview to be dated and imperialist, but although less popular today, The Coral Island was adapted into a four-part children's television drama broadcast by ITV in 2000.

The Coral Island (TV series)

The Coral Island is a children's television series, adapted from the 19th-century novel The Coral Island by Scottish author R. M. Ballantyne. The series of 9 episodes was a joint production of the Australian Broadcasting Corporation and Thames Television. It was filmed on location in the western Samoan village of Salamumu and then on the Whitsunday Islands off the Queensland coast in 1981.The series was first broadcast in Australia on ABC-TV on 6 January 1983.

Vilo Acuña Airport

Vilo Acuña Airport (Spanish: Aeropuerto Internacional Vilo Acuña) (IATA: CYO, ICAO: MUCL) is an international airport serving Cayo Largo del Sur, a small coral island in Cuba. It is located within the special municipality (municipio especial) of Isla de la Juventud.

Zanzibar Archipelago

The Zanzibar Archipelago (Arabic: أرخبيل زنجبار‎, Swahili: Funguvisiwa la Zanzibar) consists of several islands lying off the coast of East Africa south of the Somali sea. The archipelago is also known as the Spice Islands. There are four main islands, three primary islands with human populations, a fourth coral island that serves as an essential breeding ground for seabirds, plus a number of smaller islets that surround them and an isolated tiny islet.Most of the archipelago belongs to the Zanzibar semi-autonomous region of Tanzania, while Mafia Island and its associated islets are part of the Pwani Region on the mainland.


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