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 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 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.
|Spongites yendoi together with the gardening limpet Scutellastra cochlear|
Silva & Johansen, 1986
|Families and subfamilies|
Coralline algae are widespread in all of 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. Despite their ubiquity, the coralline algae are poorly known by ecologists, and even by specialist phycologists (people who study algae). For example, a recent book on the seaweeds of Hawaii does not include any crustose coralline algae, even though corallines are quite well studied there and dominate many marine areas.
Corallines have been divided into two groups, although this division does not constitute 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 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.
Corallines live in varying depths of water, ranging from periodically exposed intertidal settings to 270 m water depth (around 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.
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 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 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 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 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 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 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 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.
According to AlgaeBase:
According to the World Register of Marine Species:
According to ITIS:
Since coralline algae contain calcium carbonate, they fossilize fairly well. They are particularly significant as stratigraphic markers in petroleum geology. Coralline rock 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 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 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 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 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 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 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 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 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 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 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.
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 the tank ecosystem.
Apletodon incognitus is a species of clingfish of the family Gobiesocidae. The species is endemic to north-eastern Atlantic Ocean to north-western Mediterranean Sea. The juvenile fish which measure around 1–2 centimetres (0.39–0.79 in) standard length (SL) are frequently recorded as having an association with sea urchins and in beds of Posidonia oceanica. The adults hide under stones covered with red coralline algae and in the empty shells of mussels near beds of Posidonia and Cymodocea nodosa. Within the beds of Posidonia it is often found in sympatry with Opeatogenys gracilis.Austrolithoideae
The Austrolithoideae are a subfamily of Coralline algae.Bossiella
Bossiella is a genus of coralline algae with 5 recognised species. It reproduces via conceptacles; individual thalli only produce conceptacles of a single sex.Carraroe
Carraroe (Irish: An Cheathrú Rua Irish pronunciation: [ənˠ ˌça(h).ɾˠuː ˈɾˠuˑə] ("The Red Quarter"), its official name) is a village in County Galway, Ireland, in the Irish-speaking region (Gaeltacht) of Conamara, famous for its traditional fishing boats known as Galway Hookers. Its population is widely dispersed over An Cheathrú Rua peninsula between Cuan an Fhir Mhóir (Greatman's Bay) and Cuan Chasla (Casla Bay). An Cheathrú Rua has an unusual beach, Trá an Dóilín, a biogenic gravel beach made of coralline algae known as "maerl".Chathamiidae
Chathamiidae is a family of case making caddisflies more commonly known as the marine caddisflies. Chathamiids are unique among insects in their invasion of the tide pool environment. Larvae construct their cases of coralline algae. The four described species are distributed along the coasts of New Zealand, New South Wales, and the Chatham Islands.Choreonematoideae
The Choreonematoideae are a monogeneric nongeniculate subfamily of Coralline algae.Coralline rock
Coralline rock is a type of rock formed by the death of layers of coralline algae. It is visually quite bright like the algae, and is often desired as aquarium decoration. Since it is formed from the dead algae, it contains some nutrients and calcium carbonate, which has allowed it to be used in some building structures.Corallinoideae
The Corallinoideae are a subfamily of coralline algae. All its genera are geniculate.Jania
Jania may refer to:
Jania (given name), a female given name, also spelled Janiya
Jania (alga), J.V.Lamouroux, 1812, a coralline algae genus
Jania Schult. & Schult.f., 1830, a plant genus, now considered a synonym of Moraea
Jania, a 1996 album by Pakistani singer Ali Haider
Jania, Barpeta district, a Satra holding village of Barpeta District, Assam, India
Jania (Vidhan Sabha constituency), an assembly constituency of Assam Legislative Assembly in India
Al-Janiya, Palestinian village on the occupied West BankList of coralline algae species in the British Isles
This is a list of coralline algae species in the British Isles.
The Lithophylloideae are a monophyletic subfamily of Corallinaceaen Coralline algae with uniporate conceptacles.Live rock
Live rock is rock from the ocean that has been introduced into a saltwater aquarium. Along with live sand, it confers to the closed marine system multiple benefits desired by the saltwater aquarium hobbyist. The name sometimes leads to misunderstandings, as the "live rock" itself is not actually alive, but rather is simply made from the aragonite skeletons of long dead corals, or other calcareous organisms, which in the ocean form the majority of coral reefs. When taken from the ocean it is usually encrusted with coralline algae and inhabited by a multitude of marine organisms. The many forms of micro and macroscopic marine life that live on and inside of the rock, which acts as an ideal habitat, give it the name "live rock".Mastophoroideae
The Mastophoroideae are a subfamily of Corallinaceaen coralline algae with uniporate conceptacles.Melobesioideae
The Melobesioideae are a subfamily of Corallinacean Coralline algae with multiporate conceptacles.Metagoniolithoideae
The Metagoniolithoideae are a monogeneric subfamily of genucilate Corallinaceaen coralline algae.Reef
A reef is a bar of rock, sand, coral or similar material, lying beneath the surface of water.
Many reefs result from natural, abiotic processes—deposition of sand, wave erosion planing down rock outcrops, etc.—but the best known reefs are the coral reefs of tropical waters developed through biotic processes dominated by corals and coralline algae.
Artificial reefs (e.g. shipwrecks) sometimes have a role in enhancing the physical complexity of featureless sand bottoms, in order to attract a diverse assemblage of organisms, especially algae and fish.
Earth's largest reef system is the Great Barrier Reef in Australia, at a length of over 2,300 kilometres (1,400 miles).Sporolithaceae
The Sporolithaceae are one of the two extant families of coralline algae (algae in the order Corallinales). They are differentiated from the other family, the Corallinaceae, by their formation of conceptacles with one or many pores.The morphologically-indeterminable Graticulaceae date to the Wenlock (Silurian).Sporolithon
Sporolithon is a genus of red coralline algae in the family Sporolithaceae, in the order Corallinales.White-spotted puffer
The white-spotted puffer (Arothron hispidus) is a medium to large-sized puffer fish, it can reach 50 cm length. It is light grey in color, or greyish or yellowish, and clearly covered with more or less regular white points, that become concentric contrasting white and dark grey lines that radiate around the eyes and pectoral fins. The ventral part is white. The "shoulder" (around the pectoral fins) is dark. It also has concentric contrasting white and dark grey lines that radiate around the eyes and pectoral fins.
Its distribution extends through the Indo-Pacific area, Red Sea included, to the eastern Pacific Ocean. It can be found at depths of three to 35 metres. Its habitat types include reefs, lagoons, estuaries, and tidepools. Its diet includes calcareous or coralline algae, molluscs, tunicates, sponges, corals, zoanthids, crabs, polychaetes, starfish, urchins, krill, and silversides.
The adult is nocturnal and solitary. It is territorial, becoming somewhat aggressive.