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38-798: Its average depth is 445 metres (1,460 ft) and maximum depth is 1,500 metres (4,900 ft). The International Hydrographic Organization defines the limits of the Alboran Sea as follows: On the West. The Eastern limit of the Strait of Gibraltar: A line joining from tip ( Europa Point ) of Cap Gibraltar in Europe to the tip of the Península de Almina of Ceuta in Africa ( 35°54′N 5°18′W  /  35.900°N 5.300°W  / 35.900; -5.300 ). On

76-612: A permanent organization was formed and statutes for its operations were prepared. The IHB, now the IHO, began its activities in 1921 with 18 nations as members. The Principality of Monaco was selected as the seat of the Organization as a result of the offer of Albert I of Monaco to provide suitable accommodation for the Bureau in the Principality. The International Hydrographic Organization (IHO)

114-521: A type of mountain cloud forest with relict plant species of a vegetation type that originally covered much of the Mediterranean Basin , when the climate of that region was more humid. These plant species, many of which are endemic , have evolved to adapt to the islands' variable climatic conditions. The Macaronesian islands have a biogeography that is unique in the world. They are home to several distinct plant and animal communities. Notably,

152-505: Is made up of a number of Atlantic oceanic islands , which are formed by seamounts on the ocean floor whose peaks have risen above the ocean's surface. Each of the archipelagos is a distinct political entity: the Azores and Madeira are autonomous regions of Portugal , the Canary Islands is an autonomous community of Spain , while Cape Verde is a sovereign state and member of

190-513: Is occasionally misspelled "Macronesia" in false analogy with Micronesia , an unrelated group of archipelagos in the Pacific Ocean whose English name is also derived from Greek. Macaronesia consists of four main archipelagos . In alphabetical order, these are: The islands of Macaronesia are volcanic in origin, and are thought to be the product of several geologic hotspots . Due to the geographic location, varied relief and altitudinal ranges,

228-560: Is ongoing and that complex interactions between the lithosphere and mantle are forming the region. The internal zones are made of Late Paleozoic to Triassic rocks that were piled up during the Tertiary and has been extended since the Early Miocene . The seafloor is morphologically complex with several sub-basins, including three main sub-basins named West, East, and South Alboran Basins, ridges, and seamounts. The most prominent structure in

266-445: Is the IHO standards and specifications that are normally used. During the 19th century, many maritime nations established hydrographic offices to provide means for improving the navigation of naval and merchant vessels by providing nautical publications, nautical charts, and other navigational services. There were substantial differences in hydrographic procedures charts, and publications. In 1889, an International Maritime Conference

304-587: Is the most important feeding grounds for loggerhead sea turtles in Europe. The Alboran sea also hosts important commercial fisheries , including sardines and swordfish . In 2003, the World Wildlife Fund raised concerns about the widespread drift net fishing endangering populations of dolphins, turtles, as well as other marine animals. In 2023, the European Union, Morocco, and Algeria agreed to ban bottom fishing practices around Cabliers Bank, protecting

342-403: Is typically a vertical rotary circulation, also known as a gyre , in the Alboran Sea as a result of this exchange of water. The Alboran Sea is a transition zone between ocean and sea, containing a mix of Mediterranean and Atlantic species. The Alboran Sea is habitat for the largest population of bottlenose dolphins and the last population of harbour porpoises in the western Mediterranean, and

380-719: The Hydrographic Dictionary and the Year Book are available to the general public free of charge from the IHO website. The IHO publishes the international standards related to charting and hydrography, including S-57, IHO Transfer Standard for Digital Hydrographic Data , the encoding standard that is used primarily for electronic navigational charts . In 2010, the IHO introduced a new, contemporary hydrographic geospatial standard for modelling marine data and information, known as S-100. S-100 and any dependent product specifications are underpinned by an on-line registry accessible via

418-676: The United Nations . Politically, the islands belonging to Portugal and Spain are parts of the European Union . Geologically, most of Macaronesia is part of the African tectonic plate . The Azores are located in the triple junction between the African , Eurasian , and North American plates. In one biogeographical system, the Cape Verde archipelago is in the Afrotropical realm while

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456-572: The jumping spider genus Macaroeris is named after Macaronesia. Because none of the Macaronesian islands were ever part of any continent, all of the native plants and animals reached the islands via long-distance dispersal. Laurel-leaved forests , called laurisilva , once covered most of the Azores, Madeira, and parts of the Canaries at an altitude of between 400 and 1,200 metres (1,300 and 3,900 ft),

494-557: The Alboran Sea (known as the internal zones) together with the surrounding mountains (known as the external zones; the Gibraltar Arc and Atlas Mountains ), is mostly made of continental crust and marks the westernmost terminus of the terranes that were subducted between the African and Eurasian Plates when the Tethys Ocean closed. Reoccurring earthquakes at a depth of about 600 km (370 mi) indicate that this subduction

532-566: The Alboran Sea is the 180 km long (110 mi) Alboran Ridge which stretches southwest from the volcanic Alborán Island. Surface currents in the Alboran Sea, influenced by the prevailing winds, flow eastward, bringing water from the Atlantic into the Mediterranean; deeper subsurface currents flow westward, carrying saltier Mediterranean water over the Gibraltar sill into the Atlantic. Thus there

570-533: The Alboran Sea, the Baetic-Rifan complex represents a transition between the Mediterranean and Atlantic ( Macaronesian ) ecological zones. The moderating influence of the Atlantic has allowed many relict species in the Baetic and Rif mountains to survive the climatic fluctuations of the last few million years that have caused them to become extinct elsewhere around the Mediterranean basin. There are some small islands in

608-706: The Canary Islands, 561,901 (17%) in Cape Verde, 250,769 (8%) in Madeira, and 236,440 (7%) in the Azores. The name Macaronesia was originally used by Ancient Greek geographers to refer to any islands west of the Strait of Gibraltar . It is derived from the Greek words meaning ' islands of the fortunate ' ( μακάρων νῆσοι , makárōn nēsoi ). The term fell out of use until it was revived in 1917 with its current meaning. The name

646-514: The Convention on the IHO, the secretariat is headed by a Secretary-General, supported by two Directors. As before, all three senior members of the secretariat continue to be elected to their positions by the Member States at the regular Assembly of the IHO (formerly, IHO Conferences). The secretariat staff comprise a number of technical specialists, administrators, and support personnel. The bulk of

684-553: The East. A line joining from Cabo de Gata in Andalusia in Europe to Cap Fegalo , near Oran, Algeria in Africa ( 35°36′N 1°12′W  /  35.600°N 1.200°W  / 35.600; -1.200 ). Several small islands dot the sea, including the eponymous Isla de Alborán . Most, even those close to the African shore, belong to Spain. The Alboran domain, the seafloor beneath

722-474: The IHO website. S-100 is aligned with the ISO 19100 series of geographic standards, thereby making it fully compatible with contemporary geospatial data standards. Because S-100 is based on ISO 19100, it can be used by other data providers for their maritime-related (non-hydrographic) data and information. Various data and information providers from both the government and private sector are now using S-100 as part of

760-470: The IHO's technical and specialist expertise comes from Member States' personnel, often assisted by invited industry experts, who all provide technical contributions through participation in various IHO committees and working groups. A Council, comprising a sub-set of all the IHO Member States, meets annually and oversees the work of the IHO. A full description, together with details of the workings of all

798-441: The Macaronesian mountains represent a wide range of climates. These climates include oceanic , Mediterranean , and humid subtropical climates in the Azores; the tropical savanna climates in Madeira; the desert and semi-desert climates in the Canary Islands; and a tropical climate in Cape Verde . In some locations, there are variations in climate due to the rain shadow effect. The laurisilva forests of Macaronesia are

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836-403: The Mediterranean before the ice ages. Much of the original native vegetation has been displaced because of human activity, including felling forests for timber and firewood, clearing vegetation for grazing and agriculture, and introducing foreign plants and animals into the islands. The laurisilva habitat has been reduced to small disconnected pockets. As a result, many of the endemic biota of

874-428: The eastern Canaries and Cape Verde being too dry. These forests resemble the ancient forests that covered the Mediterranean Basin and northwestern Africa before the cooling and drying of the ice ages . Trees of the genera Apollonias , Clethra , Dracaena , Ocotea , Persea , and Picconia , which are found in the Macaronesian laurel forests, are also known, from fossil evidence, to have flourished around

912-474: The field of standardization since the IHO was founded. The IHO has encouraged the formation of Regional Hydrographic Commissions (RHCs). Each RHC coordinates the national surveying and charting activities of countries within each region and acts as a forum to address other matters of common hydrographic interest. The 15 RHCs plus the IHO Hydrographic Commission on Antarctica effectively cover

950-563: The implementation of the e-Navigation concept that has been endorsed by the UN International Maritime Organization (IMO). Another in the series of publications of interest is S-23, Limits of Oceans and Seas . The 3rd edition dates back to 1953 while the potential 4th edition, started in 1986, has remained a draft since 2002. It was distributed to IHO members, but its official publication has been suspended pending agreement between South Korea and Japan regarding

988-502: The international standard name of the sea called " Japan Sea " in the 1953 edition. Macaronesia 24°15′24″N 22°28′16″W  /  24.25667°N 22.47111°W  / 24.25667; -22.47111 Macaronesia ( Portuguese : Macaronésia ; Spanish : Macaronesia ) is a collection of four volcanic archipelagos in the North Atlantic Ocean , off the coast of North Africa and Europe . Each archipelago

1026-405: The islands are now seriously endangered or extinct. Introduced predators – in particular domestic cats , many in feral populations  – currently pose one of the most serious threats to the endemic fauna. Even though cats prey mostly on other foreign-introduced mammals, such as rodents and rabbits, the abundance of such prey sustains such a large feline population that it has initiated

1064-404: The most convenient form to enable them to be readily used; of instituting a prompt system of mutual exchange of hydrographic information between all countries; and of providing an opportunity to consultations and discussions to be carried out on hydrographic subjects generally by the hydrographic experts of the world." This is still the major purpose of the IHO. As a result of the 1919 Conference,

1102-556: The only cold-water coral reef known to be growing in the Mediterranean. An arc of mountains, known as the Gibraltar Arc , wraps around the northern, western and southern sides of the Alboran Sea. The Gibraltar Arc is made up of the Baetic Cordillera of Southern Spain and the Rif Mountains of Morocco. These mountains, known to ecologists as the Baetic-Rifan complex, comprise one of the Mediterranean's biodiversity hotspots ; like

1140-519: The organs of the IHO is available on the IHO website: www.iho.int The IHO develops hydrographic and nautical charting standards. These standards are subsequently adopted and used by its member countries and others in their surveys, nautical charts, and publications. The almost universal use of the IHO standards means that the products and services provided by the world's national hydrographic and oceanographic offices are consistent and recognizable by all seafarers and for other users. Much has been done in

1178-673: The other three archipelagos are in the Palearctic realm . According to the European Environment Agency , the three archipelagos within the European Union constitute a unique bioregion , known as the Macaronesian Biogeographic Region . The World Geographical Scheme for Recording Plant Distributions places the whole of Macaronesia in its botanical continent of Africa. In 2022, Macaronesia had an estimated combined population of 3,222,054 people; 2,172,944 (67%) in

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1216-444: The sea: International Hydrographic Organization The International Hydrographic Organization ( IHO ) (French: Organisation Hydrographique Internationale ) is an intergovernmental organization representing hydrography . As of May 2024 , the IHO comprised 100 member states. A principal aim of the IHO is to ensure that the world's seas, oceans and navigable waters are properly surveyed and charted. It does this through

1254-513: The secretariat was renamed the "IHO Secretariat," which consists of an elected Secretary-General, two supporting Directors, and a small permanent staff (18 in 2020) at the Organization’s headquarters in Monaco. Until 2016 the IHO was administered by a secretariat headed by a Directing Committee comprising a President and two Directors. Since 8 November 2016, upon the entry in to force of revisions to

1292-444: The setting of international standards for hydrographic surveys, the co-ordination of the endeavors of the world's national hydrographic offices, and through its capacity building program. The IHO enjoys observer status at the United Nations , where it is the recognized competent authority on hydrographic surveying and nautical charting . When referring to hydrography and nautical charting in conventions and similar instruments, it

1330-754: The world. The IHO, in partnership with the Intergovernmental Oceanographic Commission, directs the General Bathymetric Chart of the Oceans program. Establishment of the Chart Specifications Committee and International Charts: Most IHO publications, including the standards, guidelines and associated documents such as the International Hydrographic Review , International Hydrographic Bulletin ,

1368-538: Was established in June 1921 as the International Hydrographic Bureau (IHB). In 1970, the organization adopted its current name as part of a new International Convention on the IHO, which was agreed upon by its member nations. The term "International Hydrographic Bureau" continued to describe the IHO's secretariat until 8 November 2016, when a major revision to the Convention took effect. Following this change,

1406-620: Was held at Washington, D.C. , and it was proposed to establish a "permanent international commission." Similar proposals were made at the sessions of the International Congress of Navigation held at Saint Petersburg in 1908 and the International Maritime Conference held at Saint Petersburg in 1912. In 1919, the national Hydrographers of Great Britain and France cooperated in taking the necessary steps to convene an international conference of Hydrographers. London

1444-534: Was selected as the most suitable place for this conference, and on 24 July 1919, the First International Conference opened, attended by the Hydrographers of 24 nations. The object of the conference was "To consider the advisability of all maritime nations adopting similar methods in preparation, construction, and production of their charts and all hydrographic publications; of rendering the results in

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