120-662: Camden Sound is a relatively wide body of water in the Indian Ocean located in the Kimberley region of Western Australia . The Sound is bounded by the Bonaparte Archipelago to the north-east, the Buccaneer Archipelago to the south-west, and Montgomery Reef (the eastern extent of Collier Bay ) to the south. The Sound is an important area for a number of marine animals, in particular as
240-603: A monophyletic group. The earliest scleractinians were not reef builders, but were small, phaceloid or solitary individuals. Scleractinian corals were probably at their greatest diversity in the Jurassic and all but disappeared in the mass extinction event at the end of the Cretaceous, about 18 out of 67 genera surviving. Recently discovered Paleozoic corals with aragonitic skeletons and cyclic septal insertion – two features that characterize Scleractinia – have strengthened
360-462: A pearling industry zone, and general use zones. Another 48% of the park was closed to trawling and 23% of the park closed to commercial fishing . The 2013–2023 management plan maintained the zones specified by the Conservation and Land Management Act 1984 (the "CALM Act"): sanctuary, recreation, special purpose or general use zones. The marine park recognises two broad themes: Access to
480-588: A breeding ground for various species of whales , and is home to the world's largest population of humpback whales . The Lalang-garram / Camden Sound Marine Park is jointly managed by the Government of Western Australia 's Department of Biodiversity, Conservation and Attractions . The marine park lies about 300 km (190 mi) north-east of Broome , and is the second largest marine park in Western Australia after Shark Bay . As of 2020, there
600-403: A cup surrounding this part of the polyp. The interior of the cup contains radially aligned plates, or septa , projecting upwards from the base. Each of these plates is flanked by a pair of mesenteries. The septa are secreted by the mesenteries, and are therefore added in the same order as the mesenteries are. As a result, septa of different ages are adjacent to one another, and the symmetry of
720-468: A global rise in sea level. Sea level also increases in the Indian Ocean, except in the south tropical Indian Ocean where it decreases, a pattern most likely caused by rising levels of greenhouse gases . Among the tropical oceans, the western Indian Ocean hosts one of the largest concentrations of phytoplankton blooms in summer, due to the strong monsoon winds. The monsoonal wind forcing leads to
840-747: A maximum depth of 7,290 m (23,920 ft). All of the Indian Ocean is in the Eastern Hemisphere and the centre of the Eastern Hemisphere, the 90th meridian east , passes through the Ninety East Ridge . Within these waters are a number of islands. These include those controlled by surrounding countries, and independent island states and territories. Of the non-coastal islands, there are two broad clusters: one around Madagascar, and one south of India. A few other oceanic islands are scattered elsewhere. In contrast to
960-470: A period of six years, except for debris that gets indefinitely stuck in the centre of the gyre. The garbage patch in the Indian Ocean will, according to a 2012 study, decrease in size after several decades to vanish completely over centuries. Over several millennia, however, the global system of garbage patches will accumulate in the North Pacific. There are two amphidromes of opposite rotation in
1080-790: A process of aridification began in the southwest Indian Ocean began around 4,000 years ago. Mammalian megafauna once widespread in the MPA was driven to near extinction in the early 20th century. Some species have been successfully recovered since then — the population of white rhinoceros ( Ceratotherium simum simum ) increased from less than 20 individuals in 1895 to more than 17,000 as of 2013. Other species still depend on fenced areas and management programs, including black rhinoceros ( Diceros bicornis minor ), African wild dog ( Lycaon pictus ), cheetah ( Acynonix jubatus ), elephant ( Loxodonta africana ), and lion ( Panthera leo ). This biodiversity hotspot (and namesake ecoregion and "Endemic Bird Area")
1200-640: A rate up to three times faster than similar species without symbionts. These corals typically grow in shallow, well-lit, warm water with moderate to brisk turbulence and abundant oxygen, and prefer firm, non-muddy surfaces on which to settle. Most stony corals extend their tentacles to feed on zooplankton , but those with larger polyps take correspondingly larger prey, including various invertebrates and even small fish. In addition to capturing prey in this way, many stony corals also produce mucus films they can move over their bodies using cilia ; these trap small organic particles which are then pulled towards and into
1320-689: A result of teaming up with symbiotic algae . Nine of the sub-orders were in existence by the end of the Triassic and three more had appeared by the Jurassic (200 million years ago), with a further suborder appearing in the Middle Cretaceous (100 million years ago). Some may have developed from a common ancestor, either an anemone-like coral without a skeleton, or a rugose coral . A rugose coral seems an unlikely common ancestor because these corals had calcite rather than aragonite skeletons, and
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#17327986275831440-408: A ring of tentacles . The base of the polyp secretes the stony material from which the coral skeleton is formed. The body wall of the polyp consists of mesoglea sandwiched between two layers of epidermis. The mouth is at the centre of the oral disc and leads into a tubular pharynx which descends for some distance into the body before opening into the gastrovascular cavity that fills the interior of
1560-504: A significant portion of the world's tuna catch and is home to endangered marine species. It faces challenges like overfishing and pollution , including a significant garbage patch . Historically, the Indian Ocean has been a hub of cultural and commercial exchange since ancient times. It played a key role in early human migrations and the spread of civilizations. In modern times, it remains crucial for global trade, especially in oil and hydrocarbons. Environmental and geopolitical concerns in
1680-423: A spiritual place as well as a place of natural abundance”, relating to the ocean in a general sense. The conservation objectives of the government and the traditional owners are aligned, with the latter wanting to ensure that their saltwater country stays in good health, and that no plants or animals become extinct in the area. Many species and ecosystems have cultural significance to the local peoples, including
1800-562: A spring tide. The area has received worldwide recognition as a crucial breeding and calving area for the Breeding Group D population of humpback whales ( Megaptera novaeangliae ) – at approximately 22,000 individuals, the world's largest humpback whale population. The calves are suckled in the warm, tropical waters for several months until they gain the strength for the journey back to the Antarctic for summer feeding. Camden Sound
1920-464: A strong coastal and open ocean upwelling , which introduces nutrients into the upper zones where sufficient light is available for photosynthesis and phytoplankton production. These phytoplankton blooms support the marine ecosystem, as the base of the marine food web, and eventually the larger fish species. The Indian Ocean accounts for the second-largest share of the most economically valuable tuna catch. Its fish are of great and growing importance to
2040-473: Is a patchwork of small forested areas, often with a unique assemblage of species within each, located within 200 km (120 mi) from the coast and covering a total area of c. 6,200 km (2,400 sq mi). It also encompasses coastal islands, including Zanzibar and Pemba, and Mafia. This area, one of the only two hotspots that are entirely arid, includes the Ethiopian Highlands ,
2160-550: Is a plan to include this and three other nearby marine parks into one large marine park called Lalang-gaddam Marine Park (formerly named Great Kimberley Marine Park ). Aboriginal peoples lived and fished in the area for a long time before the colonisation of Western Australia . Camden Sound was "discovered" by Captain Phillip Parker King on HMS Bathurst on 15 August 1821. He named the sound Camden Bay after John Pratt, 1st Marquess Camden . Camden Harbour
2280-643: Is approximately 30° north in the Persian Gulf . The Indian Ocean covers 70,560,000 km (27,240,000 sq mi), including the Red Sea and the Persian Gulf but excluding the Southern Ocean, or 19.5% of the world's oceans; its volume is 264,000,000 km (63,000,000 cu mi) or 19.8% of the world's oceans' volume; it has an average depth of 3,741 m (12,274 ft) and
2400-825: Is artificially connected to the Mediterranean Sea without ship lock through the Suez Canal , which is accessible via the Red Sea. The Arabian Sea is connected to the Persian Gulf by the Gulf of Oman and the Strait of Hormuz . In the Persian Gulf, the Gulf of Bahrain separates Qatar from the Arabic Peninsula. Along the west coast of India, the Gulf of Kutch and Gulf of Khambat are located in Gujarat in
2520-449: Is particularly challenging. Many species were described before the advent of scuba diving , with little realisation by the authors that coral species could have varying morphologies in different habitats. Collectors were mostly limited to observing corals on reef flats, and were unable to observe the changes in morphology that occurred in more turbid, deeper-water conditions. More than 2,000 nominal species were described in this era, and by
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#17327986275832640-469: Is projected to push the tropical Indian Ocean into a basin-wide near-permanent heatwave state by the end of the 21st century, where marine heatwaves are projected to increase from 20 days per year (during 1970–2000) to 220–250 days per year. South of the Equator (20–5°S), the Indian Ocean is gaining heat from June to October, during the austral winter, while it is losing heat from November to March, during
2760-493: Is rich in other cetaceans including the Australian snubfin dolphin , blue whales , pygmy killer whales , pilot whales and bottlenose dolphins . In addition, the area is surrounded by fringing reefs with hard and soft corals , turtles , molluscs , fish and marine invertebrates . The Kimberley Marine Park is a Commonwealth government area covered by the national EPBC Act , covering an expanse of ocean outside
2880-497: Is the third-largest of the world's five oceanic divisions, covering 70,560,000 km (27,240,000 sq mi) or approximately 20% of the water area of Earth's surface . It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by the Southern Ocean , or Antarctica , depending on the definition in use. The Indian Ocean has large marginal, or regional seas, such as
3000-748: The Andaman Sea , the Arabian Sea , the Bay of Bengal , and the Laccadive Sea . Once called the Eastern Ocean, it is now named after India , which protrudes into it, and has been known by its current name since at least 1515. It is the only ocean named after a country. It has an average depth of 3,741 m. All of the Indian Ocean is in the Eastern Hemisphere . Unlike the Atlantic and Pacific,
3120-748: The Arabian Peninsula in the Northern Hemisphere and north of the trade winds in the Southern Hemisphere. The Indonesian Throughflow is a unique Equatorial connection to the Pacific. The climate north of the equator is affected by a monsoon climate. Strong north-east winds blow from October until April; from May until October south and west winds prevail. In the Arabian Sea, the violent Monsoon brings rain to
3240-593: The Bonaparte Archipelago to the north-east ( Augustus Island being the largest in this group), the Buccaneer Archipelago to the south-west (stretching to Sunday Island ), and Montgomery Reef (the eastern extent of Collier Bay ) to the south. Camden Sound includes Champagny , Byam Martin and the Heywood Islands to the west (all part of the Bonaparte Archipelago), and Bumpus Island, Rice Rocks, Sampson Inlet, Deception Bay and Prior Point to
3360-802: The CALM Act as a Class A reserve. Under the new arrangements, the zoning of the Camden Sound park would not change, but the plan is now to amalgamate the four marine parks ( Lalang-garram / Horizontal Falls Marine Park , North Lalang-garram Marine Park and the new Maiyalam Marine Park) to form the Lalang-gaddam Marine Park, all in the sea country of the Dambeemangarddee people. This plan will be amended by another 10-year final joint management plan. The new Maiyalam Marine Park will create add 47,000 ha (120,000 acres) to
3480-629: The Department of Parks and Wildlife (DPaW)) via its agency, the Parks and Wildlife Service and the traditional owners , the Dambimangari group. It is the first jointly managed marine park in Australia, and has benefited from the involvement of the traditional owners of the land and waters. The Dambimangari people chose the name "Lalang-garram", being a Worrorra word meaning “the saltwater as
3600-577: The East African Rift valley , the Socotra islands, as well as some small islands in the Red Sea and areas on the southern Arabic Peninsula. Endemic and threatened mammals include the dibatag ( Ammodorcas clarkei ) and Speke's gazelle ( Gazella spekei ); the Somali wild ass ( Equus africanus somaliensis ) and hamadryas baboon ( Papio hamadryas ). It also contains many reptiles. In Somalia,
3720-629: The Malacca , Sunda and Torres Straits . The Gulf of Carpentaria is located on the Australian north coast while the Great Australian Bight constitutes a large part of its southern coast. Several features make the Indian Ocean unique. It constitutes the core of the large-scale Tropical Warm Pool which, when interacting with the atmosphere, affects the climate both regionally and globally. Asia blocks heat export and prevents
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3840-818: The Mascarene Basin the CDW becomes a deep western boundary current before it is met by a re-circulated branch of itself, the North Indian Deep Water. This mixed water partly flows north into the Somali Basin whilst most of it flows clockwise in the Mascarene Basin where an oscillating flow is produced by Rossby waves . Water circulation in the Indian Ocean is dominated by the Subtropical Anticyclonic Gyre,
3960-546: The Northern Territory border. In 2020, a new management plan was released, titled Lalang-gaddam Marine Park: Amended joint management plan for the Lalang-garram / Camden Sound, Lalang-garram / Horizontal Falls and North Lalang-garram marine parks and indicative joint management plan for the proposed Maiyalam Marine Park . It was published ahead of the gazettal of the proposed Maiyalam Marine Park under
4080-695: The Sea of Zanj is located north of Madagascar. On the northern coast of the Arabian Sea , Gulf of Aden is connected to the Red Sea by the strait of Bab-el-Mandeb . In the Gulf of Aden, the Gulf of Tadjoura is located in Djibouti and the Guardafui Channel separates Socotra island from the Horn of Africa. The northern end of the Red Sea terminates in the Gulf of Aqaba and Gulf of Suez . The Indian Ocean
4200-451: The effects of global warming and ocean acidification . Scleractinian corals may be solitary or colonial . Colonies can reach considerable size, consisting of a large number of individual polyps. Stony corals are members of the class Anthozoa and like other members of the group, do not have a medusa stage in their life cycle. The individual animals are known as polyps and have a cylindrical body crowned by an oral disc surrounded by
4320-461: The endodermal cells are usually replete with symbiotic unicellular dinoflagellates known as zooxanthellae . There are sometimes as many as five million cells of these per 1 square centimetre (0.16 sq in) of coral tissue. Up to 50% of organic compounds produced by symbionts are used as food by polyps. The oxygen byproduct of photosynthesis and the additional energy derived from sugars produced by zooxanthellae enable these corals to grow at
4440-488: The pyrgomatids , but a recent study recorded evidence of living pyrgomatids in stylasterids , casting doubt on this idea. Stony corals have a great range of reproductive strategies and can reproduce both sexually and asexually. Many species have separate sexes, the whole colony being either male or female, but others are hermaphroditic , with individual polyps having both male and female gonads. Some species brood their eggs but in most species, sexual reproduction results in
4560-582: The runoff water to the Indian Ocean. Mainly in summer, this runoff flows into the Arabian Sea but also south across the Equator where it mixes with fresher seawater from the Indonesian Throughflow . This mixed freshwater joins the South Equatorial Current in the southern tropical Indian Ocean. Sea surface salinity is highest (more than 36 PSU ) in the Arabian Sea because evaporation exceeds precipitation there. In
4680-423: The "Hinge zone may represent the relict of continental and proto-oceanic crustal boundary formed during the rifting of India from Antarctica ." Australia, Indonesia, and India are the three countries with the longest shorelines and exclusive economic zones . The continental shelf makes up 15% of the Indian Ocean. More than two billion people live in countries bordering the Indian Ocean, compared to 1.7 billion for
4800-768: The 15th century called it the Western Oceans. In Ancient Greek geography , the Indian Ocean region known to the Greeks was called the Erythraean Sea . The borders of the Indian Ocean , as delineated by the International Hydrographic Organization in 1953 included the Southern Ocean but not the marginal seas along the northern rim but in 2002 the IHO delimited the Southern Ocean separately, which removed waters south of 60°s from
4920-478: The 19th and early 20th centuries. The two most advanced 19th century classifications both used complex skeletal characters; The 1857 classification of the French zoologists Henri Milne-Edwards and Jules Haime 's was based on macroscopic skeletal characters, while Francis Grant Ogilvie 's 1897 scheme was developed using observations of skeletal microstructures, with particular attention to the structure and pattern of
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5040-727: The Arabian Peninsula) and Limpopo rivers. After the breakup of East Gondwana and the formation of the Himalayas, the Ganges-Brahmaputra rivers flow into the world's largest delta known as the Bengal delta or Sunderbans . Marginal seas , gulfs, bays and straits of the Indian Ocean include: Along the east coast of Africa, the Mozambique Channel separates Madagascar from mainland Africa, while
5160-541: The Atlantic and 2.7 billion for the Pacific (some countries border more than one ocean). The Indian Ocean drainage basin covers 21,100,000 km (8,100,000 sq mi), virtually identical to that of the Pacific Ocean and half that of the Atlantic basin, or 30% of its ocean surface (compared to 15% for the Pacific). The Indian Ocean drainage basin is divided into roughly 800 individual basins, half that of
5280-549: The Atlantic and Pacific, the Indian Ocean is enclosed by major landmasses and an archipelago on three sides and does not stretch from pole to pole, and can be likened to an embayed ocean. It is centered on the Indian Peninsula. Although this subcontinent has played a significant role in its history, the Indian Ocean has foremostly been a cosmopolitan stage, interlinking diverse regions by innovations, trade, and religion since early in human history. The active margins of
5400-581: The Comoros. Although both species represent an order of lobe-finned fishes known from the Early Devonian (410 mya ) and though extinct 66 mya, they are morphologically distinct from their Devonian ancestors. Over millions of years, coelacanths evolved to inhabit different environments — lungs adapted for shallow, brackish waters evolved into gills adapted for deep marine waters. Of Earth's 36 biodiversity hotspots nine (or 25%) are located on
5520-483: The East India Coastal Current to the Arabian Sea from January to April. An Indian Ocean garbage patch was discovered in 2010 covering at least 5 million square kilometres (1.9 million square miles). Riding the southern Indian Ocean Gyre , this vortex of plastic garbage constantly circulates the ocean from Australia to Africa, down the Mozambique Channel , and back to Australia in
5640-475: The Indian Ocean but included the northern marginal seas. Meridionally , the Indian Ocean is delimited from the Atlantic Ocean by the 20° east meridian , running south from Cape Agulhas , South Africa, and from the Pacific Ocean by the meridian of 146°49'E, running south from South East Cape on the island of Tasmania in Australia. The northernmost extent of the Indian Ocean (including marginal seas)
5760-405: The Indian Ocean have an average width (horizontal distance from land to shelf break ) of 19 ± 0.61 km (11.81 ± 0.38 mi) with a maximum width of 175 km (109 mi). The passive margins have an average width of 47.6 ± 0.8 km (29.58 ± 0.50 mi). The average width of the slopes (horizontal distance from shelf break to foot of slope) of
5880-509: The Indian Ocean includes beaches and intertidal zones covering 3,000 km (1,200 sq mi) and 246 larger estuaries . Upwelling areas are small but important. The hypersaline salterns in India covers between 5,000–10,000 km (1,900–3,900 sq mi) and species adapted for this environment, such as Artemia salina and Dunaliella salina , are important to bird life. Coral reefs, sea grass beds, and mangrove forests are
6000-445: The Indian Ocean is bordered by landmasses and an archipelago on three sides, making it more like an embayed ocean centered on the Indian Peninsula. Its coasts and shelves differ from other oceans, with distinct features, such as a narrower continental shelf . In terms of geology, the Indian Ocean is the youngest of the major oceans, with active spreading ridges and features like seamounts and ridges formed by hotspots . The climate of
6120-503: The Indian Ocean is characterized by monsoons . It is the warmest ocean, with a significant impact on global climate due to its interaction with the atmosphere. Its waters are affected by the Indian Ocean Walker circulation , resulting in unique oceanic currents and upwelling patterns. The Indian Ocean is ecologically diverse, with important marine life and ecosystems like coral reefs, mangroves, and sea grass beds. It hosts
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#17327986275836240-481: The Indian Ocean region, or almost half of the world's mangrove habitat, of which 42,500 km (16,400 sq mi) is located in Indonesia, or 50% of mangroves in the Indian Ocean. Mangroves originated in the Indian Ocean region and have adapted to a wide range of its habitats but it is also where it suffers its biggest loss of habitat. In 2016, six new animal species were identified at hydrothermal vents in
6360-730: The Indian Ocean, during the past six decades. The tuna catch rates have also declined 50–90% during the past half-century, mostly due to increased industrial fisheries, with the ocean warming adding further stress to the fish species. Endangered and vulnerable marine mammals and turtles: 80% of the Indian Ocean is open ocean and includes nine large marine ecosystems : the Agulhas Current , Somali Coastal Current , Red Sea , Arabian Sea , Bay of Bengal , Gulf of Thailand , West Central Australian Shelf , Northwest Australian Shelf and Southwest Australian Shelf . Coral reefs cover c. 200,000 km (77,000 sq mi). The coasts of
6480-432: The Indian Ocean, probably caused by Rossby wave propagation. Icebergs drift as far north as 55° south latitude , similar to the Pacific but less than in the Atlantic where icebergs reach up to 45°S. The volume of iceberg loss in the Indian Ocean between 2004 and 2012 was 24 Gt . Since the 1960s, anthropogenic warming of the global ocean combined with contributions of freshwater from retreating land ice causes
6600-411: The Indian Ocean. While the Indian Ocean warmed at a rate of 1.2°C per century during 1950–2020, climate models predict accelerated warming, at a rate of 1.7 °C–3.8 °C per century during 2020–2100. Though the warming is basin-wide, maximum warming is in the northwestern Indian Ocean including the Arabian Sea, and reduced warming off the Sumatra and Java coasts in the southeast Indian Ocean. Global warming
6720-401: The Indian subcontinent. In the southern hemisphere, the winds are generally milder, but summer storms near Mauritius can be severe. When the monsoon winds change, cyclones sometimes strike the shores of the Arabian Sea and the Bay of Bengal . Some 80% of the total annual rainfall in India occurs during summer and the region is so dependent on this rainfall that many civilisations perished when
6840-469: The Kimberley marine reserves. The larger plan is to create a total of 5,000,000 ha (12,000,000 acres) of new national and marine reserves in Western Australia. The new spelling, "Lalang-gaddam", reflects the correct pronunciation of the word, and "Maiyalam" means "between islands", or "a gap through". The new Maiyalam Marine Park covers an area off the north-western coast of King Sound and around Macleay Island . The new Lalang-gaddam Marine Park borders
6960-408: The Monsoon failed in the past. The huge variability in the Indian Summer Monsoon has also occurred pre-historically, with a strong, wet phase 33,500–32,500 BP; a weak, dry phase 26,000–23,500 BC; and a very weak phase 17,000–15,000 BP, corresponding to a series of dramatic global events: Bølling–Allerød warming , Heinrich , and Younger Dryas . The Indian Ocean is the warmest ocean in
7080-399: The Pacific, of which 50% are located in Asia, 30% in Africa, and 20% in Australasia. The rivers of the Indian Ocean are shorter on average (740 km (460 mi)) than those of the other major oceans. The largest rivers are ( order 5 ) the Zambezi , Ganges - Brahmaputra , Indus , Jubba , and Murray rivers and (order 4) the Shatt al-Arab , Wadi Ad Dawasir (a dried-out river system on
7200-441: The Southeast Arabian Sea salinity drops to less than 34 PSU. It is the lowest (c. 33 PSU) in the Bay of Bengal because of river runoff and precipitation. The Indonesian Throughflow and precipitation results in lower salinity (34 PSU) along the Sumatran west coast. Monsoonal variation results in eastward transportation of saltier water from the Arabian Sea to the Bay of Bengal from June to September and in westerly transport by
7320-411: The Southwest Indian Ridge, from where it continues into the Mozambique Channel and Prince Edward Fracture Zone . North of 20° south latitude the minimum surface temperature is 22 °C (72 °F), exceeding 28 °C (82 °F) to the east. Southward of 40° south latitude , temperatures drop quickly. The Bay of Bengal contributes more than half (2,950 km or 710 cu mi) of
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#17327986275837440-399: The Southwest Indian Ridge: a "Hoff" crab, a "giant peltospirid" snail, a whelk-like snail, a limpet, a scaleworm and a polychaete worm. The West Indian Ocean coelacanth was discovered in the Indian Ocean off South Africa in the 1930s and in the late 1990s another species, the Indonesian coelacanth , was discovered off Sulawesi Island , Indonesia. Most extant coelacanths have been found in
7560-421: The adjacent colonies of the same species form a single colony by fusing. Most colonial species have very small polyps, ranging from 1 to 3 mm (0.04 to 0.12 in) in diameter, although some solitary species may be as large as 25 cm (10 in). The skeleton of an individual scleractinian polyp is known as a corallite. It is secreted by the epidermis of the lower part of the body, and initially forms
7680-525: The age of the coral. Solitary corals do not bud. They gradually increase in size as they deposit more calcium carbonate and produce new whorls of septa. A large Ctenactis echinata for example normally has a single mouth, may be about 25 cm (10 in) long and have more than a thousand septa. Stony corals occur in all the world's oceans. There are two main ecological groups. Hermatypic corals are mostly colonial corals which tend to live in clear, oligotrophic, shallow tropical waters; they are
7800-477: The amount of water movement and other factors. Many shallow-water corals contain symbiont unicellular organisms known as zooxanthellae within their tissues. These give their colour to the coral which thus may vary in hue depending on what species of symbiont it contains. Stony corals are closely related to sea anemones , and like them are armed with stinging cells known as cnidocytes . Corals reproduce both sexually and asexually. Most species release gametes into
7920-503: The assembling of species into the existing families , but not into the traditional suborders. For example, some genera affiliated with different suborders were now located on the same branch of a phylogenetic tree . In addition, there is no distinguishing morphological character that separates clades , only molecular differences. The Australian zoologist John Veron and his co-workers analyzed ribosomal RNA in 1996 to obtain similar results to Romano and Palumbi, again concluding that
8040-442: The austral summer. In 1999, the Indian Ocean Experiment showed that fossil fuel and biomass burning in South and Southeast Asia caused air pollution (also known as the Asian brown cloud ) that reach as far as the Intertropical Convergence Zone . This pollution has implications on both a local and global scale. Forty percent of the sediment of the Indian Ocean is found in the Indus and Ganges fans. The oceanic basins adjacent to
8160-452: The body and tentacles. Unlike other cnidarians however, the cavity is subdivided by a number of radiating partitions, thin sheets of living tissue, known as mesenteries . The gonads are also located within the cavity walls. The polyp is retractable into the corallite , the stony cup in which it sits, being pulled back by sheet-like retractor muscles. The polyps are connected by horizontal sheets of tissue known as coenosarc extending over
8280-400: The bordering countries for domestic consumption and export. Fishing fleets from Russia, Japan, South Korea , and Taiwan also exploit the Indian Ocean, mainly for shrimp and tuna. Research indicates that increasing ocean temperatures are taking a toll on the marine ecosystem. A study on the phytoplankton changes in the Indian Ocean indicates a decline of up to 20% in the marine plankton in
8400-404: The budding of new polyps. There are two types of budding, intratentacular and extratentacular. In intratentacular budding, a new polyp develops on the oral disc, inside the ring of tentacles. This can form individual, separate polyps or a row of partially separated polyps sharing an elongate oral disc with a series of mouths. Tentacles grow around the margin of this elongated oral disc and not around
8520-414: The capture of plankton and suspended organic particles. The growth rates of most species of non-zooxanthellate corals are significantly slower than those of their counterparts, and the typical structure for these corals is less calcified and more susceptible to mechanical damage than that of zooxanthellate corals. Scleratinians were previously believed to be obligatory hosts of another group of barnacles,
8640-701: The centre of the 1,500,000 km (580,000 sq mi) hotspot, the landscape is dominated by Acacia - Commiphora deciduous bushland, but also includes the Yeheb nut ( Cordeauxia edulus ) and species discovered more recently such as the Somali cyclamen ( Cyclamen somalense ), the only cyclamen outside the Mediterranean. Warsangli linnet ( Carduelis johannis ) is an endemic bird found only in northern Somalia. An unstable political situation and mismanagement has resulted in overgrazing which has produced one of
8760-505: The continental shelves are 50.4–52.4 km (31.3–32.6 mi) for active and passive margins respectively, with a maximum width of 205.3–255.2 km (127.6–158.6 mi). In correspondence of the Shelf break , also known as Hinge zone, the Bouguer gravity ranges from 0 to 30 mGals that is unusual for a continental region of around 16 km thick sediments. It has been hypothesized that
8880-551: The continental slopes mostly contain terrigenous sediments. The ocean south of the polar front (roughly 50° south latitude ) is high in biologic productivity and dominated by non-stratified sediment composed mostly of siliceous oozes . Near the three major mid-ocean ridges the ocean floor is relatively young and therefore bare of sediment, except for the Southwest Indian Ridge due to its ultra-slow spreading rate. The ocean's currents are mainly controlled by
9000-687: The eastern extension of which is blocked by the Southeast Indian Ridge and the 90°E Ridge. Madagascar and the Southwest Indian Ridge separate three cells south of Madagascar and off South Africa. North Atlantic Deep Water reaches into the Indian Ocean south of Africa at a depth of 2,000–3,000 m (6,600–9,800 ft) and flows north along the eastern continental slope of Africa. Deeper than NADW, Antarctic Bottom Water flows from Enderby Basin to Agulhas Basin across deep channels (<4,000 m (13,000 ft)) in
9120-589: The end of the 20th century prompted new evolutionary hypotheses that were different from ones founded on skeletal data. Results of molecular studies explained a variety of aspects of the evolutionary biology of the Scleractinia, including connections between and within extant taxa, and supplied support for hypotheses about extant corals that are founded on the fossil record. The 1996 analysis of mitochondrial RNA undertaken by American zoologists Sandra Romano and Stephen Palumbi found that molecular data supported
9240-676: The form of "polyp bail-out", which may allow polyps to survive even though the parent colony dies. It involves the growth of the coenosarc to seal off the polyps, detachment of the polyps and their settlement on the seabed to initiate new colonies. In other species, small balls of tissue detach themselves from the coenosarc, differentiate into polyps and start secreting calcium carbonate to form new colonies, and in Pocillopora damicornis , unfertilised eggs can develop into viable larvae. The overwhelming majority of scleractinian taxa are hermaphroditic in their adult colonies. In temperate regions,
9360-444: The form of crystals of aragonite , however, a prehistoric scleractinian ( Coelosimilia ) had a non-aragonite skeletal structure which was composed of calcite . The structure of both simple and compound scleractinians is light and porous, rather than solid as is the case in the prehistoric order Rugosa . Scleractinians are also distinguished from rugosans by their pattern of septal insertion. In colonial corals, growth results from
9480-405: The humpback whale. The park is divided into different zones, with differing levels of protection, which are subject to change as management plans evolve. The initial plan included several different zones, including a whale sanctuary zone of approximately 1,067 km (412 sq mi), two sanctuary zones comprising about 20% of the marine park area around Champagny Islands and Montgomery Reef,
9600-521: The hypothesis for an independent origin of the Scleractinia. Whether the early scleractinian corals were zooxanthellate is an open question. The phenomenon seems to have evolved independently on numerous occasions during the Tertiary, and the genera Astrangia , Madracis , Cladocora and Oculina , all in different families, each have both zooxanthellate and non-zooxanthellate members. The fact that zooxanthellate coral make up only about half of
9720-430: The individual mouths. This is surrounded by a single corallite wall, as is the case in the meandroid corallites of brain corals. Extratentacular budding always results in separate polyps, each with its own corallite wall. In the case of bushy corals such as Acropora , lateral budding from axial polyps form the basis of the trunk and branches. The rate at which a stony coral colony lays down calcium carbonate depends on
9840-593: The islands of the Indian Ocean are textbook cases of evolutionary processes; the dung beetles , day geckos , and lemurs are all examples of adaptive radiation . Many bones (250 bones per square metre) of recently extinct vertebrates have been found in the Mare aux Songes swamp in Mauritius, including bones of the Dodo bird ( Raphus cucullatus ) and Cylindraspis giant tortoise. An analysis of these remains suggests
9960-486: The limits of the Camden Sound and other state parks, stretching from south of King Sound to nearly the top of the North Kimberley Marine Park . This area consists mostly of Multiple Use Zone ( IUCN VI), but also includes sections of national park (IUCN II) and Habitat Protection (IUCN IV) zones, the latter two mostly just outside the Camden Sound and King Sound areas. The Camden Sound Marine Park
10080-481: The margins of the Indian Ocean. The origin of this diversity is debated; the break-up of Gondwana can explain vicariance older than 100 mya, but the diversity on the younger, smaller islands must have required a Cenozoic dispersal from the rims of the Indian Ocean to the islands. A "reverse colonisation", from islands to continents, apparently occurred more recently; the chameleons , for example, first diversified on Madagascar and then colonised Africa. Several species on
10200-634: The mid-18th century, as opposed to the Western Ocean ( Atlantic ) before the Pacific was surmised. In modern times, the name Afro-Asian Ocean has occasionally been used. The Hindi name for the Ocean is हिंद महासागर ( Hind Mahāsāgar ; lit. transl. Ocean of India ). Conversely, Chinese explorers (e.g., Zheng He during the Ming dynasty ) who traveled to the Indian Ocean during
10320-400: The monsoon. Two large gyres , one in the northern hemisphere flowing clockwise and one south of the equator moving anticlockwise (including the Agulhas Current and Agulhas Return Current ), constitute the dominant flow pattern. During the winter monsoon (November–February), however, circulation is reversed north of 30°S and winds are weakened during winter and the transitional periods between
10440-622: The monsoons. The Indian Ocean contains the largest submarine fans of the world, the Bengal Fan and Indus Fan , and the largest areas of slope terraces and rift valleys . The inflow of deep water into the Indian Ocean is 11 Sv , most of which comes from the Circumpolar Deep Water (CDW). The CDW enters the Indian Ocean through the Crozet and Madagascar basins and crosses the Southwest Indian Ridge at 30°S. In
10560-659: The most degraded hotspots where only c. 5 % of the original habitat remains. Hard coral About 35, see text . Scleractinia , also called stony corals or hard corals , are marine animals in the phylum Cnidaria that build themselves a hard skeleton . The individual animals are known as polyps and have a cylindrical body crowned by an oral disc in which a mouth is fringed with tentacles. Although some species are solitary, most are colonial . The founding polyp settles and starts to secrete calcium carbonate to protect its soft body. Solitary corals can be as much as 25 cm (10 in) across but in colonial species
10680-543: The most productive ecosystems of the Indian Ocean ;— coastal areas produce 20 tones of fish per square kilometre. These areas, however, are also being urbanised with populations often exceeding several thousand people per square kilometre and fishing techniques become more effective and often destructive beyond sustainable levels while the increase in sea surface temperature spreads coral bleaching. Mangroves covers 80,984 km (31,268 sq mi) in
10800-705: The mouth. In a few stony corals, this is the primary method of feeding, and the tentacles are reduced or absent, an example being Acropora acuminata . Caribbean stony corals are generally nocturnal, with the polyps retracting into their skeletons during the day, thus maximising the exposure of the zooxanthellae to the light, but in the Indo-Pacific region, many species feed by day and night. Non-zooxanthellate corals are usually not reef-formers; they can be found most abundantly beneath about 500 m (1,600 ft) of water. They thrive at much colder temperatures and can live in total darkness, deriving their energy from
10920-638: The northern end while the Laccadive Sea separates the Maldives from the southern tip of India. The Bay of Bengal is off the east coast of India. The Gulf of Mannar and the Palk Strait separate Sri Lanka from India, while Adam's Bridge separates the two. The Andaman Sea is located between the Bay of Bengal and the Andaman Islands. In Indonesia, the so-called Indonesian Seaway is composed of
11040-645: The order is unusual, as symbiosis is almost always an all-or-nothing phenomenon. This symbiotic equilibrium suggests that there must be evolutionary processes simultaneously maintaining and limiting symbiotic relationships. This is likely because despite the energetic benefits it provides, photosymbiosis appears to be an evolutionary disadvantage during mass extinctions. Traits that generally enable corals to survive mass extinction include deep-water or large habitat range, non-symbiotic, solitary or small colonies, and bleaching resistance, all of which tend to characterize azooxanthellate (non-symbiotic) corals. Endosymbionts, on
11160-523: The other hand, which rely on specialized conditions and access to light to survive, are especially vulnerable to prolonged darkness, temperature change, and eutrophication, all of which have been hallmarks of past mass extinctions. This makes zooxanthellate coral especially vulnerable to unstable conditions. Therefore, it is possible that coral and zooxanthellate coevolved loosely, with the relationship dissolving when advantages decreased, then reforming when conditions stabilized. The taxonomy of Scleractinia
11280-428: The outer surface of the skeleton and completely covering it. These sheets are continuous with the body wall of the polyps, and include extensions of the gastrovascular cavity, so that food and water can circulate between all the different members of the colony. In colonial species, the repeated asexual division of the polyps causes the corallites to be interconnected, thus forming the colonies. Also, cases exist in which
11400-581: The park is usually via one of the many cruise vessels that operate between Broome, Wyndham , Darwin and Cairns . A 2016 management plan saw this park, along with the Lalang-garram / Horizontal Falls Marine Park and the North Kimberley Marine Park make up part of what was to be named the Great Kimberley Marine Park, covering about 30,000 km (12,000 sq mi) of coastal waters from west of Ganbadba (Talbot Bay) to
11520-815: The plan. An Indigenous land use agreement (ILUA) already covers the Lalang-garram/ Camden Sound, Lalang-garram/ Horizontal Falls and North Lalang-garram marine parks, but an additional ILUA will be needed to allow the creation of the proposed Maiyalam Marine Park in accordance with the Native Title Act 1993 . Much of Collier Bay will remain a general use zone, but the Walcott Inlet will be zoned as sanctuary. 15°26′47″S 124°25′5″E / 15.44639°S 124.41806°E / -15.44639; 124.41806 ( Camden Sound ) Indian Ocean The Indian Ocean
11640-399: The polyps are usually only a few millimetres in diameter. These polyps reproduce asexually by budding , but remain attached to each other, forming a multi-polyp colony of clones with a common skeleton, which may be up to several metres in diameter or height according to species. The shape and appearance of each coral colony depends not only on the species, but also on its location, depth,
11760-463: The production of a free-swimming planula larva that eventually settles on the seabed to undergo metamorphosis into a polyp. In colonial species, this initial polyp then repeatedly divides asexually, to give rise to the entire colony. The most common means of asexual reproduction in colonial stony corals is by fragmentation. Pieces of branching corals may get detached during storms, by strong water movement or by mechanical means, and fragments fall to
11880-422: The proposed Mayala Marine Park to the south-west (covering the Buccaneer Archipelago ), and the North Kimberley Marine Park ( Uunguu waters) to the north-east. The land and sea border to the south abut Bardi Jawi land and a proposed Bardi Jawi Marine Park . Maps show the extent of the various marine parks, native title determinations , zones within the areas, etc. Details such as port areas are outlined in
12000-530: The region include the effects of climate change , piracy, and strategic disputes over island territories. The Indian Ocean has been known by its present name since at least 1515, when the Latin form Oceanus Orientalis Indicus ( lit. ' Indian Eastern Ocean ' ) is attested, named after India, which projects into it. It was earlier known as the Eastern Ocean , a term that was still in use during
12120-410: The risk of self-fertilization. Immediately after spawning, the eggs are delayed in their capability for fertilization until after the release of polar bodies. This delay, and possibly some degree of self-incompatibility, likely increases the chance of cross-fertilization. A study of four species of Scleractinia found that cross-fertilization was actually the dominant mating pattern, although three of
12240-642: The rules of nomenclature, the name given to the first described species has precedence over the rest, even when that description is poor, and the environment and even sometimes the country of the type specimen is unknown. Even the concept of "the species" is suspect, with regard to corals which have large geographical ranges with a number of sub-populations; their geographic boundaries merge with those of other species; their morphological boundaries merge with those of other species; and there are no definite distinctions between species and subspecies. The evolutionary relationships among stony corals were first examined in
12360-470: The scleractinian skeleton is radial or biradial . This pattern of septal insertion is termed "cyclic" by paleontologists. By contrast, in some fossil corals, adjacent septa lie in order of increasing age, a pattern termed serial and produces a bilateral symmetry . Scleractinians secrete a stony exoskeleton in which the septa are inserted between the mesenteries in multiples of six. All modern scleractinian skeletons are composed of calcium carbonate in
12480-469: The sea bed. In suitable conditions, these are capable of adhering to the substrate and starting new colonies. Even such massive corals as Montastraea annularis have been shown to be capable of forming new colonies after fragmentation. This process is used in the reef aquarium hobby to increase stock without the necessity to harvest corals from the wild. Under adverse conditions, certain species of coral resort to another type of asexual reproduction in
12600-481: The sea where fertilisation takes place, and the planula larvae drift as part of the plankton , but a few species brood their eggs. Asexual reproduction is mostly by fragmentation , when part of a colony becomes detached and reattaches elsewhere. Stony corals occur in all the world's oceans. Much of the framework of modern coral reefs is formed by scleractinians. Reef-building or hermatypic corals are mostly colonial; most of these are zooxanthellate and are found in
12720-507: The septa were arranged serially rather than cyclically. However, it may be that similarities of scleractinians to rugosans are due to a common non-skeletalized ancestor in the early Paleozoic. Alternatively, scleractinians may have developed from a Corallimorpharia -like ancestor. It seems that skeletogenesis may have been associated with the development of symbiosis and reef formation, and may have occurred on more than one occasion. DNA sequencing appears to indicate that scleractinian corals are
12840-486: The septal trabeculae . In 1943, the American zoologists Thomas Wayland Vaughan and John West Wells , and Wells again in 1956, used the patterns of the septal trabeculae to divide the group into five suborders . In addition, they considered polypoid features such as the growth of the tentacles. They also distinguished families by wall type and type of budding . The 1952 classification by French zoologist J. Alloiteau
12960-529: The shallow waters into which sunlight penetrates. Other corals that do not form reefs may be solitary or colonial; some of these occur at abyssal depths where no light reaches. Stony corals first appeared in the Middle Triassic , but their relationship to the tabulate and rugose corals of the Paleozoic is currently unresolved. In modern times stony corals numbers are expected to decline due to
13080-558: The south. There is no road access and the nearest town is Kalumburu , 268 km (167 mi) to the east. The area is a drowned valley in the western end of the MacDonald Range, the islands that are found within the sound are remnant emergent features formed by basalt and sandstone formations. As with the rest of the Kimberley coast, the area is marked by an extreme tidal variation of up to 11 m (36 ft) on
13200-511: The species were also capable of self-fertilization to varying extents. There is little evidence on which to base a hypothesis about the origin of the scleractinians; plenty is known about modern species but very little about fossil specimens, which first appeared in the record in the Middle Triassic ( 240 million years ago ). It was not until 25 million years later that they became important reef builders, their success likely
13320-498: The species, but some of the branching species can increase in height or length by around 10 cm (4 in) a year (about the same rate as human hair grows). Other corals, like the dome and plate species, are more bulky and may only grow 0.3 to 2 cm (0.1 to 0.8 in) per year. The rate of aragonite deposition varies diurnally and seasonally. Examination of cross sections of coral can show bands of deposition indicating annual growth. Like tree rings, these can be used to estimate
13440-449: The traditional families were plausible but that the suborders were incorrect. They also established that stony corals are monophyletic, including all the descendants of a common ancestor , but that they are divided into two groups, the robust and complex clades. Veron suggested that both morphological and molecular systems be used in future classification schemes. All Scleractinian corals (excluding fossils) are listed under Appendix II of
13560-441: The usual pattern is synchronized release of eggs and sperm into the water during brief spawning events, often related to the phases of the moon. In tropical regions, reproduction may occur throughout the year. In many cases, as in the genus Acropora , the eggs and sperm are released in buoyant bundles which rise to the surface. This increases the concentration of sperm and eggs and thus the likelihood of fertilization , and reduces
13680-528: The ventilation of the Indian Ocean thermocline . That continent also drives the Indian Ocean monsoon , the strongest on Earth, which causes large-scale seasonal variations in ocean currents, including the reversal of the Somali Current and Indian Monsoon Current . Because of the Indian Ocean Walker circulation there are no continuous equatorial easterlies. Upwelling occurs near the Horn of Africa and
13800-504: The world's largest population of humpback whales. The park is the second largest in Western Australia after Shark Bay , and links to the Prince Regent National Park . The area includes Montgomery Reef , Champagny Island and St George Basin. The Lalang-garram / Camden Sound Marine Park is jointly managed by the Government of Western Australia 's Department of Biodiversity, Conservation and Attractions (formerly
13920-408: The world's primary reef -builders. Ahermatypic corals are either colonial or solitary and are found in all regions of the ocean and do not build reefs. Some live in tropical waters but some inhabit temperate seas, polar waters, or live at great depths, from the photic zone down to about 6,000 m (20,000 ft). Scleractinians fall into one of two main categories: In reef-forming corals,
14040-487: The world. Long-term ocean temperature records show a rapid, continuous warming in the Indian Ocean, at about 1.2 °C (34.2 °F) (compared to 0.7 °C (33.3 °F) for the warm pool region) during 1901–2012. Research indicates that human induced greenhouse warming , and changes in the frequency and magnitude of El Niño (or the Indian Ocean Dipole ), events are a trigger to this strong warming in
14160-581: Was a short-lived settlement within the sound. Three native title claims have been registered in the area of the marine park by the Dambimangari , Uunguu and Mayala native title groups. The Dambimangari claim lies over the majority of the park, with the Uunguu claim overlying a small portion of the St George Basin, and Mayala at the southwestern end of the park. Camden Sound is bounded by
14280-697: Was built on these earlier systems but included more microstructural observations and did not involve the anatomical characters of the polyp. Alloiteau recognized eight suborders. In 1942, W.H. Bryan and D. Hill stressed the importance of microstructural observations by proposing that stony corals begin skeletal growth by configuring calcification centers, which are genetically derived. Therefore, diverse patterns of calcification centers are vital to classification. Alloiteau later showed that established morphological classifications were unbalanced and that there were many examples of convergent evolution between fossils and recent taxa . The rise of molecular techniques at
14400-467: Was the first of four new marine parks announced under the Kimberley Science and Conservation Strategy, and covers an area of 7,062 km (2,727 sq mi). In October 2009, Donna Faragher , Western Australia's Environment Minister, announced that Camden Sound would become the Kimberley 's first Marine Park , largely in recognition of the area's status as nursery and breeding area to
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