Misplaced Pages

#489510

51-611: Horns Rev is a shallow sandy reef of glacial deposits in the eastern North Sea , about 15 km (9.3 mi) off the westernmost point of Denmark , Blåvands Huk . The reef contains the Horns Rev Offshore Wind Farm . At Horns Rev the Danish Energy company Elsam (now Ørsted ) built the first offshore wind farm in the North Sea. When the first phase was inaugurated in 2002, Horns Rev wind farm

102-445: A barrier reef forms a calcareous barrier around an island, resulting in a lagoon between the shore and the reef. Conversely, an atoll is a ring reef with no land present. The reef front, facing the ocean, is a high energy locale. Whereas, the internal lagoon will be at a lower energy with fine grained sediments. Both mounds and reefs are considered to be varieties of organosedimentary buildups, which are sedimentary features, built by

153-596: A crustose stage; some later become frondose . As sessile encrusting organisms, the corallines are prone to overgrowth by other "fouling" algae. The group have many defences to such immuration, most of which depend on waves disturbing their thalli. However, the most relied-upon method involves waiting for herbivores to devour the potential encrusters. This places them in the unusual position of requiring herbivory, rather than benefiting from its avoidance. Many species periodically slough their surface epithallus – and anything attached to it. Some corallines slough off

204-532: A day, and the farm has an availability of 96-97%. Two turbines are burnt out, and are uneconomic to replace with less than 10 years left. In April 2012, most of the Danish Folketing (parliament) agreed to send out tenders in 2013 for a 400 MW wind farm at Horns Rev called Horns Rev 3, and a 600 MW at Kriegers Flak in the Baltic Sea , both likely receiving 90 øre/kWh for the first 50,000 hours. This

255-429: A fairly massive hard stony calcium carbonate structure on which other reef organisms like sponges and seaweeds can grow, and provide a habitat for mobile benthic organisms. These biotic reef types take on additional names depending upon how the reef lies in relation to the land, if any. Reef types include fringing reefs , barrier reefs , and atolls . A fringing reef is a reef that is attached to an island. Whereas,

306-413: A guaranteed price of 0.453 DKK/kWh for the first 42,000 hours, paid by electricity consumers. Since 2005, the wind farm has been owned and operated by Vattenfall . It cost DKK2bn. A radar has shown details of the wind patterns, improving local short-term forecasting. Turbines are laid out as an oblique rectangle of 5 km x 3.8 km (8 horizontal and 10 vertical rows). The distance between turbines

357-451: A living organism was probably Corallina in the 1st century AD. In 1837, Rodolfo Amando Philippi recognized coralline algae were not animals, and he proposed the two generic names Lithophyllum and Lithothamnion as Lithothamnium . For many years, they were included in the order Cryptonemiales as the family Corallinaceae until, in 1986, they were raised to the order Corallinales. Many corallines produce chemicals which promote

408-649: A macroscopic skeletal framework. Instead, they are built by microorganisms or by organisms that also lack a skeletal framework. A microbial mound might be built exclusively or primarily by cyanobacteria . Examples of biostromes formed by cyanobacteria occur in the Great Salt Lake in Utah , United States, and in Shark Bay on the coast of Western Australia . Cyanobacteria do not have skeletons, and individual organisms are microscopic. However, they can encourage

459-544: A millimetre to several centimetres high. Some are free-living as rhodoliths (rounded, free-living specimens). The morphological complexity of rhodoliths enhances species diversity, and can be used as a non-taxonomic descriptor for monitoring. Thalli can be divided into three layers: the hypothallus , perithallus and epithallus . The epithallus is periodically shed, either in sheets or piecemeal. Corallines live in varying depths of water, ranging from periodically exposed intertidal settings to 270 m water depth (around

510-625: A smaller "green subsidy" (PSO) over the next years. A total of 49 Vestas V164-8.3 MW units, capable of producing 406.7 MW, will be installed. Three transformers were installed in July 2016. Findings released from an eight-year study about offshore wind farms in Denmark show that the projects "operate in harmony with the surrounding environment". The 2006 report confirms that both the Horns Rev and Nysted offshore wind farms will double in size in

561-421: A spike in coralline diversity, and the extinction of many delicately branched (and thus predation-prone) forms. The group's internal taxonomy is in a state of flux; molecular studies are proving more reliable than morphological methods in approximating relationships within the group. Recent advances in morphological classification based on skeletal ultrastructure, however, are promising. Crystal morphology within

SECTION 10

#1732771929490

612-520: A surface layer of epithallial cells, which in a few cases may be an antifouling mechanism which serves the same function as enhancing herbivore recruitment. This also affects the community, as many algae recruit on the surface of a sloughing coralline, and are then lost with the surface layer of cells. This can also generate patchiness within the community. The common Indo-Pacific corallines, Neogoniolithon fosliei and Sporolithon ptychoides , slough epithallial cells in continuous sheets which often lie on

663-681: A taxonomic grouping: Geniculate corallines are branching, tree-like organisms which are attached to the substratum by crustose or calcified, root-like holdfasts. The organisms are made flexible by having noncalcified sections (genicula) separating longer calcified sections (intergenicula). Nongeniculate corallines range from a few micrometres to several centimetres thick crusts. They are often very slow growing, and may occur on rock, coral skeletons, shells, other algae or seagrasses. Crusts may be thin and leafy to thick and strongly adherent. Some are parasitic or partly endophytic on other corallines. Many coralline crusts produce knobby protuberances ranging from

714-615: A tropical coral fringing reef, or a temperate rocky intertidal reef. A variety of biotic reef types exists, including oyster reefs and sponge reefs , but the most massive and widely distributed are tropical coral reefs . Although corals are major contributors to the framework and bulk material comprising a coral reef, the organisms most responsible for reef growth against the constant assault from ocean waves are calcareous algae, especially, although not entirely, coralline algae . Oyster larvae prefer to settle on adult oysters and thereby develop layers building upwards. These eventually form

765-403: Is 560 m in both directions. The main method of transport to the first wind park is an adapted Eurocopter EC-135 helicopter when winds are less than 19 m/s. Hoisting the workers to and from a small platform on each turbine allows access to the park regardless of sea conditions which would otherwise prevent sailing in the area for a large part of the year. Vattenfall can change a gearbox in

816-455: Is energetically costly, does not affect seaweed recruitment when herbivores are removed. The surface of these plants is usually kept clean by herbivores, particularly the pear limpet, Patella cochlear . Sloughing in this case is probably a means of eliminating old reproductive structures and grazer-damaged surface cells, and reducing the likelihood of surface penetration by burrowing organisms. The corallines have an excellent fossil record from

867-443: Is probably an important factor affecting the distribution and grazing effects of herbivores within marine communities. Nothing is known about the microhabitat role of Indo-Pacific corallines. However, the most common species in the region, Hydrolithon onkodes , often forms an intimate relationship with the chiton Cryptoplax larvaeformis . The chiton lives in burrows it makes in H. onkodes plants, and comes out at night to graze on

918-546: The Mississippian period , produce a different kind of mound. Although bryozoans are small and crinoid skeletons disintegrate, bryozoan and crinoid meadows can persist over time and produce compositionally distinct bodies of sediment with depositional relief. The Proterozoic Belt Supergroup contains evidence of possible microbial mat and dome structures similar to stromatolite and chicken reef complexes. Rocky reefs are underwater outcrops of rock projecting above

969-476: The Rigs-to-Reefs program), scuttling ships , or by deploying rubble or construction debris . Other artificial reefs are purpose built (e.g. the reef balls ) from PVC or concrete. Shipwrecks become artificial reefs on the seafloor. Regardless of construction method, artificial reefs generally provide stable hard surfaces where algae and invertebrates such as barnacles , corals, and oysters attach;

1020-590: The Solenoporaceae , a view that has been disputed. Their fossil record matches their molecular history, and is complete and continuous. The Sporolithaceae tend to be more diverse in periods of high ocean temperatures; the opposite is true for the Corallinaceae . The group's diversity has closely tracked the efficiency of grazing herbivores; for instance, the Eocene appearance of parrotfish marked

1071-722: The ecology of coral reefs . Sea urchins , parrot fish , and limpets and chitons (both mollusks) feed on coralline algae. In the temperate Mediterranean Sea , coralline algae are the main builders of a typical algal reef, the Coralligène ("coralligenous"). Many are typically encrusting and rock-like, found in marine waters all over the world. Only one species lives in freshwater. Unattached specimens ( maerl , rhodoliths ) may form relatively smooth compact balls to warty or fruticose thalli. A close look at almost any intertidal rocky shore or coral reef will reveal an abundance of pink to pinkish-grey patches, distributed throughout

SECTION 20

#1732771929490

1122-477: The 18th century. This is particularly significant in Britain and France , where more than 300,000 tonnes of Phymatolithon calcareum ( Pallas , Adey & McKinnin) and Lithothamnion corallioides are dredged annually. The earliest use of corallines in medicine involved the preparation of a vermifuge from ground geniculate corallines of the genera Corallina and Jania . This use stopped towards

1173-546: The Early Cretaceous onwards, consistent with molecular clocks that show the divergence of the modern taxa beginning in this period. The fossil record of nonarticulated forms is better: the unmineralized genuiculae of articulated forms break down quickly, scattering the mineralized portions, which then decay more quickly. This said, non-mineralizing coralline algae are known from the Silurian of Gotland showing that

1224-513: The Mediterranean. Their ability to calcify in low light conditions makes them the some of deepest photosynthetic multicellular organisms in the ocean, having been found as deep as 268 metres (879 ft), and as such a critical base of mesophotic ecological systems. Since coralline algae contain calcium carbonate, they fossilize fairly well. They are particularly significant as stratigraphic markers in petroleum geology. Coralline rock

1275-514: The accumulation of attached marine life in turn provides intricate structure and food for assemblages of fish. Coralline algae Coralline algae are red algae in the order Corallinales . They are characterized by a thallus that is hard because of calcareous deposits contained within the cell walls. The colors of these algae are most typically pink, or some other shade of red, but some species can be purple, yellow, blue, white, or gray-green. Coralline algae play an important role in

1326-481: The adjacent unconsolidated surface with varying relief. They can be found in depth ranges from intertidal to deep water and provide a substrate for a large range of sessile benthic organisms, and shelter for a large range of mobile organisms. They are often located in sub-tropical, temperate, and sub-polar latitudes. Ancient reefs buried within stratigraphic sections are of considerable interest to geologists because they provide paleo-environmental information about

1377-512: The calcified cell wall of coralline algae was found to have a high correspondence with molecular studies. These skeletal structures thus provide morphologic evidence for molecular relationships within the group. According to AlgaeBase : According to the World Register of Marine Species : According to ITIS : Fresh surfaces are generally colonized by thin crusts, which are replaced by thicker or branched forms during succession over

1428-684: The coming years. Reef Earth's largest coral reef system is the Great Barrier Reef in Australia, at a length of over 2,300 kilometres (1,400 miles). The word "reef" traces its origins back to the Old Norse word rif, meaning "rib" or "reef". Rif comes from the Proto-Germanic term ribją meaning "rib". Reefs may be classified in terms of their origin, geographical location, depth, and topography . For example

1479-752: The community level; the presence of herbivores associated with corallines can generate patchiness in the survival of young stages of dominant seaweeds. This has been seen this in eastern Canada , and it is suspected the same phenomenon occurs on Indo-Pacific coral reefs , yet nothing is known about the herbivore enhancement role of Indo-Pacific corallines, or whether this phenomenon is important in coral reef communities. Some coralline algae develop into thick crusts which provide microhabitat for many invertebrates. For example, off eastern Canada , Morton found juvenile sea urchins , chitons , and limpets suffer nearly 100% mortality due to fish predation unless they are protected by knobby and undercut coralline algae. This

1530-503: The course of one (in the tropics) to ten (in the Arctic) years. However, the transition from crusts to branched form depends on environmental conditions. Crusts may also become detached and form calcareous nodules known as Rhodoliths . Their growth may be also disrupted by local environmental factors. While coralline algae are present in most hard substrate marine communities in photic depths, they are more common in higher latitudes and in

1581-520: The end of the 18th century. Medical science now uses corallines in the preparation of dental bone implants. The cell fusions provide the matrix for the regeneration of bone tissue. Maërl is also used as a food additive for cattle and pigs , as well as in the filtration of acidic drinking water. As a colorful component of live rock sold in the marine aquarium trade, and an important part of reef health, coralline algae are desired in home aquariums for their aesthetic qualities, and ostensible benefit to

Horns Rev - Misplaced Pages Continue

1632-608: The framework builders. The corals which build reefs today, the Scleractinia , arose after the Permian–Triassic extinction event that wiped out the earlier rugose corals (as well as many other groups). They became increasingly important reef builders throughout the Mesozoic Era. They may have arisen from a rugose coral ancestor. Rugose corals built their skeletons of calcite and have a different symmetry from that of

1683-486: The interaction of organisms and their environment. These interactions have a synoptic relief and whose biotic composition differs from that found on and beneath the surrounding sea floor . However, reefs are held up by a macroscopic skeletal framework, as what is seen on coral reefs. Corals and calcareous algae grow on top of one another, forming a three-dimensional framework that is modified in various ways by other organisms and inorganic processes. Conversely, mounds lack

1734-697: The lineage has a much longer history than molecular clocks would indicate. The earliest known coralline deposits date from the Ordovician , although modern forms radiated in the Cretaceous . True corallines are found in rocks of Jurassic age onwards. Stem group corallines are reported from the Ediacaran Doushantuo formation ; later stem-group forms include Arenigiphyllum , Petrophyton , Graticula , and Archaeolithophyllum . The corallines were thought to have evolved from within

1785-674: The location in Earth's history . In addition, reef structures within a sequence of sedimentary rocks provide a discontinuity which may serve as a trap or conduit for fossil fuels or mineralizing fluids to form petroleum or ore deposits . Corals, including some major extinct groups Rugosa and Tabulata , have been important reef builders through much of the Phanerozoic since the Ordovician Period. However, other organism groups, such as calcifying algae, especially members of

1836-519: The main reef structures that prevent oceanic waves from striking adjacent coastlines , helping to prevent coastal erosion . Because of their calcified structure, coralline algae have a number of economic uses. Some harvesting of maërl beds that span several thousand kilometres off the coast of Brazil takes place. These beds contain as-yet undetermined species belonging to the genera Lithothamnion and Lithophyllum . The collection of unattached corallines (maërl) for use as soil conditioners dates to

1887-479: The maximum penetration of light). Some species can tolerate brackish or hypersaline waters, and only one strictly freshwater coralline species exists. (Some species of the morphologically similar, but non-calcifying, Hildenbrandia , however, can survive in freshwater.) A wide range of turbidities and nutrient concentrations can be tolerated. Corallines, especially encrusting forms, are slow growers, and expand by 0.1–80 mm annually. All corallines begin with

1938-436: The precipitation or accumulation of calcium carbonate to produce distinct sediment bodies in composition that have relief on the seafloor. Cyanobacterial mounds were most abundant before the evolution of shelly macroscopic organisms, but they still exist today. Stromatolites , for instance, are microbial mounds with a laminated internal structure. Whereas, bryozoans and crinoids , common contributors to marine sediments during

1989-598: The red algae ( Rhodophyta ), and molluscs (especially the rudist bivalves during the Cretaceous Period) have created massive structures at various times. During the Cambrian Period, the conical or tubular skeletons of Archaeocyatha , an extinct group of uncertain affinities (possibly sponges), built reefs. Other groups, such as the Bryozoa, have been important interstitial organisms, living between

2040-535: The reef materials into a sturdy structure. Corallines are particularly important in constructing the algal ridge's reef framework for surf-pounded reefs in both the Atlantic and Indo-Pacific regions. Algal ridges are carbonate frameworks constructed mainly by nongeniculate coralline algae (after Adey, 1978). They require high and persistent wave action to form, so develop best on windward reefs with little or no seasonal change in wind direction. Algal ridges are one of

2091-443: The rock surfaces. These patches of pink "paint" are actually living crustose coralline red algae. The red algae belong to the division Rhodophyta , within which the coralline algae form the order Corallinales . There are over 1600 described species of nongeniculate coralline algae. The corallines are presently grouped into two families on the basis of their reproductive structures. Coralline algae are widespread in all of

Horns Rev - Misplaced Pages Continue

2142-421: The rugosan corals (which disappeared in the late Permian). An artificial reef is a human-created underwater structure, typically built to promote marine life in areas with a generally featureless bottom, to control erosion, block ship passage, block the use of trawling nets, or improve surfing . Many reefs are built using objects that were built for other purposes, for example by sinking oil rigs (through

2193-471: The scleractinian corals, whose skeletons are aragonite . However, there are some unusual examples of well-preserved aragonitic rugose corals in the Late Permian . In addition, calcite has been reported in the initial post-larval calcification in a few scleractinian corals. Nevertheless, scleractinian corals (which arose in the middle Triassic) may have arisen from a non-calcifying ancestor independent of

2244-458: The settlement of the larvae of certain herbivorous invertebrates , particularly abalone . Larval settlement is adaptive for the corallines because the herbivores remove epiphytes which might otherwise smother the crusts and preempt available light. Settlement is also important for abalone aquaculture ; corallines appear to enhance larval metamorphosis and the survival of larvae through the critical settlement period. It also has significance at

2295-402: The structure of the reef, help cement the reef together, and are important sources of primary production. Coralline algae are especially important in reef construction, as they lay down calcium carbonate as calcite. Although they contribute considerable bulk to the calcium carbonate structure of coral reefs, their more important role in most areas of the reef, is in acting as the cement which binds

2346-433: The surface of the coralline. This combination of grazing and burrowing results in a peculiar growth form (called "castles") in H. onkodes , in which the coralline produces nearly vertical, irregularly curved lamellae. Coralline algae are part of the diet of shingle urchins ( Colobocentrotus atratus ). Nongeniculate corallines are of particular significance in the ecology of coral reefs, where they add calcareous material to

2397-496: The surface of the plants. Not all sloughing serves an antifouling function. Epithallial shedding in most corallines is probably simply a means of getting rid of damaged cells whose metabolic function has become impaired. Morton and his students studied sloughing in the South African intertidal coralline alga, Spongites yendoi , a species which sloughs up to 50% of its thickness twice a year. This deep-layer sloughing, which

2448-522: The world's oceans, where they often cover close to 100% of rocky substrata . Only one species, Pneophyllum cetinaensis , is found in freshwater. Its ancestor lived in brackish water, and was already adapted to osmotic stress and rapid changes in water salinity and temperature. Many are epiphytic (grow on other algae or marine angiosperms), or epizoic (grow on animals), and some are even parasitic on other corallines. Corallines have been divided into two groups, although this division does not constitute

2499-560: Was expected to raise wind power in Denmark above the current 39% of annual electricity production, which includes the 400 MW Anholt Offshore Wind Farm . Some of the area is an old minefield from World War Two. Four bidders were qualified for the tender. Vattenfall won the tender in February 2015, at a price of 77 øre/kWh, well below the 105 øre at Anholt. Vattenfall states that they bid unaggressively against strong competition without sacrificing margins . The price reduction contributes to

2550-546: Was the first large scale offshore wind farm in the world at 160 MW, four times larger than the previous largest offshore wind farm in the world, the Middelgrunden at 40MW. A total of 80  Vestas V80-2.0 MW units, capable of producing 160 MW, were installed by the Danish offshore wind farms services provider A2SEA in 2002 with the last turbine coming into operation on 11 December 2002. It receives

2601-531: Was used as building stone since the ancient Greek culture. The calcite crystals composing the cell wall are elongated perpendicular to the cell wall. The calcite normally contains magnesium (Mg) , with the magnesium content varying as a function of species and water temperature. If the proportion of magnesium is high, the deposited mineral is more soluble in ocean water, particularly in colder waters, making some coralline algae deposits more vulnerable to ocean acidification . The first coralline alga recognized as

SECTION 50

#1732771929490
#489510