Floating island

Afloating islandis a mass of floating aquatic plants, mud, and peat ranging in thickness from several centimeters to a few meters. Sometimes referred to astussocks,floatons, orsuds, floating islands are found in many parts of the world. They exist less commonly as anartificial island. Floatingislandsare generally found onmarshlands,lakes, and similarwetlandlocations, and can be manyhectaresin size.
Natural floating islands are composed of vegetation growing on a buoyant mat of plant roots or other organic detritus.
In aquatic regions of Northwestern Europe, several hundred hectares or a couple thousand acres of floating meadows (GermanSchwingrasen, Dutchtrilveen) have been preserved, which are partly used as agricultural land, partly as nature reserves.
They typically occur when growths ofcattails,bulrush,sedge, andreedsextend outward from the shoreline of a wetland area. As the water gets deeper the roots no longer reach the bottom, so they use the oxygen in their root mass forbuoyancy, and the surrounding vegetation for support to retain their top-side-up orientation. The area beneath these floating mats is exceptionally rich in aquatic lifeforms. Eventually, storm events tear whole sections free from the shore, and the islands thus formed migrate around a lake with changing winds, eventually either reattaching to a new area of the shore or breaking up in heavy weather.
Somecenotesin northern Mexico have natural floating islands.
In the Brazilian Amazon, floating islands form in lakes on the floodplains of white-water rivers and are known as Matupá and range in size from a few square meters to a few hectares.
InCrow Wing County, Minnesotaa floating bog over four acres (1.6 ha) in size moved about the area resulting in docks and boat lifts being destroyed. As decaying mass decomposes it releases gases which keep the bog floating.
Another type of natural floating island is thepumice raft, which is created by an explosivevolcanic eruption, and can float on the ocean for months or even years before becoming fully saturated and sinking.They may assist in the migration of plants and animals.
Floatingartificial islandsare generally made of bundled reeds, and the best known examples are those of theUrospeople ofLake Titicaca,Peru, who build their villages upon what are in effect huge rafts of bundledtotorareeds. The Uros originally created their islands to prevent attacks by their more aggressive neighbours, theIncasandCollas.
TheAzteccapital,Tenochtitlan, was surrounded withchinampas, small artificial islands used for agriculture known as "floating gardens" (though not really floating). Floating gardens on a large scale have been demonstrated withaquaponicssystems in China growing rice, wheat and canna lily on islands.
Spiral Islandwas a more modern one-person effort to build an artificial floating island, on the Caribbean coast ofMexico. Modern artificial islands mimicking the floating reedbeds of the Uros are increasingly used bylocal governmentsandcatchmentmanagers to improvewater qualityat source, reducingpollutantsin surface water bodies and providingbiodiversityhabitat. Examples includeGold Coast City Councilin Australia. Artificial floating reedbeds are commonly anchored to the shoreline or bottom of water body, to ensure the system does not float away in a storm event or create a hazard.
DuringWorld War II, the BritishProject Habakkukproposed the construction ofaircraft carriersmade of ice-likePykrete. Its size and speed made it more of an artificialicebergor island than a ship.
Commercial development of floating islands has begun taking place. Floating habitat islands were installed withsalicorniasalt marsh plants atSydney Olympic Park Authorityin 2011providing nesting sites for local and migratory birds includingblack swans,black-winged stilts,red-necked avocets,Pacific black ducksandchestnut teals, using the Aqua Biofilter product.The world's largest vegetated floating islands 1.6 hectares (4 acres) in size were installed in 2004 using Aqua Biofilter product withcannaatLake Tai, China using materials including a combination of polyurethane open cell filter foam, closed cell polyethylene flotation foam, bamboo and coconut fibre filter foam mix with wicking ability to supply water to plant roots.
A commercially produced floating island was installed in theriver otterenclosure atZoo Montanain 2007.In 2009 and the beginning of 2010, a few larger islands were launched to provide nesting habitat forCaspian terncolonies. The largest of the islands, at a record-setting 44,000 sq ft (4,100 m), was launched into the water atSheepy Lake. These islands are a collaboration between theUnited States Army Corps of Engineers,Oregon State University, and Floating Islands West, a Floating Island International license holder.
A US Army Corps of Engineers project was built in 2012 inThe Hideout, Pennsylvania, as part of awatershed managementproject. The floating island was created to mimic nature; help improve water quality, including reducingphosphoruslevels; and buffer habitats against surges in nutrients and pollution.
Buoyancy in artificial floating reedbeds is commonly provided by polyethylene or polyurethane foam, or polyethylene plastic containing air voids. Growth media include coconut fibre; mats made of polyester or recycled PET bottles; synthetic geotechnical mat; jute; soil; and sand.
Artificial floating islands are sometimes made by planting cattails and other plants on floating plastic rafts in order to reduce phosphorus levels in the water.InCleveland'sCuyahoga Riverfloating rafts were made to restore fish populations.
Artificial floating islands have been sought out as structures for different habitational and industrial purposes,e.g. floatingoil rigs.
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