| Fucus distichus | |
|---|---|
 | |
Scientific classification  | |
| Domain: | Eukaryota |
| Clade: | Diaphoretickes |
| Clade: | SAR |
| Clade: | Stramenopiles |
| Phylum: | Gyrista |
| Subphylum: | Ochrophytina |
| Class: | Phaeophyceae |
| Order: | Fucales |
| Family: | Fucaceae |
| Genus: | Fucus |
| Species: | F. distichus |
| Binomial name | |
| Fucus distichus | |
| Synonyms [1] | |
| |
Fucus distichus or rockweed is a species of brown alga in the family Fucaceae to be found in the intertidal zones of rocky seashores in the Northern Hemisphere, mostly in rock pools.
This is a small tufted brown alga. The fronds are rarely more than 4 mm wide [2] narrow and grow up to thirty centimetres long. They do not include airbladders as in some other species of Fucus . [3] The fronds are fairly rigid and cartilaginous, partially flattened, and olive green to yellowish green in colour. The plant is branched and has a basal discoid holdfast. The midrib is conspicuous and near the holdfast the stalk is narrowed because of the thickening of the midrib and the erosion of the margins. The apices of the frond are rounded and the swollen receptacles at the tips are yellowish and up to six centimetres long. [4]
Two sub-species have been recorded from Great Britain and Ireland: F. distichus ssp. anceps and F. distichus ssp. edentates, each with a distinctive form. [2]
The brown colour is due to the xanthophyll, fucoxanthin which masks the colour of the other pigments, beta-carotene, chlorophyll a and c and other xanthophylls. [1] Fucus distichus has a high content of phlorotannins which may protect larger plants from grazing by periwinkles though young plants are susceptible. [3]
In Great Britain, rockweed is found on northern coasts of Scotland and the north and west coasts of Ireland where it is found on rock faces and in rock pools in the upper littoral zone. It also occurs on the eastern coast of North America [3] and on the west coast from Alaska to California. [4]
Like other brown algae, there is an alternation of haploid and diploid generations. The haploid thalli form isogamous, anisogamous or oogamous gametes and the diploid thalli form zoospores by meiosis. [1] Reproduction is seasonal, and receptacles start being formed in late autumn in response to short days. [5] The gametes are of both sexes and when released, ova can survive and disperse for several days. It is thought that self-fertilisation often occurs in this species and once a zygote is formed it can only be dispersed over a limited distance. [6] The plant dies back after reproducing and gets washed from its rock substrate by waves during the following winter. [4]
A study was undertaken to see what factors influenced natural gamete release and the rate of fertilisation success in Fucus distichus. The study sites were rock pools on the coast of Maine. [7] It was found that the release and settlement of eggs and zygotes occurred during daytime low tide periods, particularly when these fell between 10am and 2pm. Few gametes were released during the night time low tide period nor during the daytime period around noon when there was not a low tide. There was no correlation between the temperature or salinity of the water and gamete release and only a weak association with the lunar phase, few gametes being released around the times of full and new moons. The study showed that fertilisation was successful and in the range 80% to 100% in F. distichus due to the avoidance of gamete release when the water velocity is high under the turbulent conditions of high tide. [7]
It has been found that this species grows more abundantly on sloped than on vertical rock faces. Its presence increases species richness as it forms canopies in the mid to high intertidal zone that provide protection, shelter and food for a variety of small invertebrates including many gastropods and crustaceans. [8] [9]
Fucus vesiculosus, known by the common names bladder wrack, black tang, rockweed, sea grapes, bladder fucus, sea oak, cut weed, dyers fucus, red fucus and rock wrack, is a seaweed found on the coasts of the North Sea, the western Baltic Sea and the Atlantic and Pacific Oceans. It was the original source of iodine, discovered in 1811, and was used extensively to treat goitre, a swelling of the thyroid gland related to iodine deficiency.
Brown algae, comprising the class Phaeophyceae, are a large group of multicellular algae, including many seaweeds located in colder waters within the Northern Hemisphere. Brown algae are the major seaweeds of the temperate and polar regions. They are dominant on rocky shores throughout cooler areas of the world. Most brown algae live in marine environments, where they play an important role both as food and as a potential habitat. For instance, Macrocystis, a kelp of the order Laminariales, may reach 60 m (200 ft) in length and forms prominent underwater kelp forests. Kelp forests like these contain a high level of biodiversity. Another example is Sargassum, which creates unique floating mats of seaweed in the tropical waters of the Sargasso Sea that serve as the habitats for many species. Many brown algae, such as members of the order Fucales, commonly grow along rocky seashores. Some members of the class, such as kelps, are used by humans as food.
Fucus is a genus of brown algae found in the intertidal zones of rocky seashores almost throughout the world.
Ascophyllum nodosum is a large, common cold water seaweed or brown alga (Phaeophyceae) in the family Fucaceae, being the only species in the genus Ascophyllum. It is a seaweed that grows only in the northern Atlantic Ocean, also known in localities as feamainn bhuí, rockweed, Norwegian kelp, knotted kelp, knotted wrack or egg wrack. It is common on the north-western coast of Europe including east Greenland and the north-eastern coast of North America, its range further south of these latitudes being limited by warmer ocean waters.
Ulva lactuca, also known by the common name sea lettuce, is an edible green alga in the family Ulvaceae. It is the type species of the genus Ulva. A synonym is U. fenestrata, referring to its "windowed" or "holed" appearance.
Fucus serratus is a seaweed of the north Atlantic Ocean, known as toothed wrack, serrated wrack, or saw rack.
Fucus spiralis is a species of seaweed, a brown alga, living on the littoral shore of the Atlantic coasts of Europe and North America. It has the common names of spiral wrack and flat wrack.
Postelsia palmaeformis, also known as the sea palm or palm seaweed, is a species of kelp and classified within brown algae. It is the only known species in the genus Postelsia. The sea palm is found along the western coast of North America, on rocky shores with constant waves. It is one of the few algae that can survive and remain erect out of the water; in fact, it spends most of its life cycle exposed to the air. It is an annual, and edible, though harvesting of the alga is discouraged due to the species' sensitivity to overharvesting.
Padina pavonica, commonly known as the peacock's tail, is a small brown alga found in the Indian Ocean, the Pacific Ocean, the Atlantic Ocean and the Mediterranean Sea. It inhabits pools in the littoral zone typically with clayey, silty or sandy sediments. Other habitats include rocks and shell fragments in the shallow sublittoral, seagrass meadows, mangrove roots and coral reefs on tidal flats.
Polysiphonia is a genus of filamentous red algae with about 19 species on the coasts of the British Isles and about 200 species worldwide, including Crete in Greece, Antarctica and Greenland. Its members are known by a number of common names. It is in the order Ceramiales and family Rhodomelaceae.
Durvillaea antarctica, also known as cochayuyo and rimurapa, is a large, robust species of southern bull kelp found on the coasts of Chile, southern New Zealand, and Macquarie Island. D. antarctica, an alga, does not have air bladders, but floats due to a unique honeycomb structure within the alga's blades, which also helps the kelp avoid being damaged by the strong waves.
Osmundea pinnatifida is a species of red alga known by the common name pepper dulse.
Fucus gardneri is a species of seaweed, a brown alga living on the littoral shore of the Pacific coasts of North America. It has the common names of rockweed and bladderwrack.
Lobophora variegata is a species of small thalloid brown alga which grows intertidally or in shallow water in tropical and warm temperate seas. It has three basic forms, being sometimes ruffled, sometimes reclining and sometimes encrusting, and each form is typically found in a different habitat. This seaweed occurs worldwide. It is the type species of the genus Lobophora, the type locality being the Antilles in the West Indies.
Ralfsia verrucosa is a species of crustose brown seaweed in the family Ralfsiaceae. It grows intertidally in temperate waters around the world. In South Africa it is part of a mutualistic relationship with a limpet.
Fucus guiryi is a brown alga in the family Fucaceae. It is known from numerous locations along the east coast of the North Atlantic Ocean, from Ireland to the Canary Islands.
Ulva paschima is a green alga in the family Ulvaceae, a green seaweed endemic to the West Coast of India. The species was identified in 2014 based on molecular phylogenetics using ITS sequences as belonging to the “Paschima” clade.
Fucus ceranoides is a species of brown algae found in the littoral zone of the sea shore.
Acetabularia acetabulum is a species of green alga in the family Polyphysaceae. It is found in the Mediterranean Sea at a depth of one to two metres.