Fucus

Taxobox
name = "Fucus"

---

image_width = 250px
image_caption = "Fucus serratus"
domain = Eukaryota
regnum = Chromalveolata
phylum = Heterokontophyta
classis = Phaeophyceae
ordo = Fucales
familia = Fucaceae
genus = "Fucus"
genus_authority = L.
subdivision_ranks = Species
subdivision = "See text"

"Fucus" is a genus of brown alga (seaweed) in the Class Phaeophyceae to be found in the intertidal zones of rocky shores. It is a common genus found on the Atlantic coasts of Europe and North America.

Description and life cycle

The thallus is perennial with an irregular or disc-shaped holdfast or with haptera cite book |author=H. Stegenga, J. J. Bolton & R. J. Anderson |year=1997 |title=Seaweeds of the South African West Coast. Contributions from the Bolus Herbarium Volume 18 |id=ISBN 0-7992-1793-X] . The erect portion of the thallus is dichotomous or subpinnately branched, flattened and with a distinct midrib. Gas-filled pneumatocysts (air-vesicles) are present in pairs in some species, one on either side of the midrib. The erect portion of the thallus bears cryptostomata and caecostomata (sterile surface cavities). The base of the thallus is stipe-like due to abrasion of the tissue lateral to the midrib and it is attached to the rock by a holdfast. The gametangia develop in conceptacles embedded in receptacles in the apices of the final branches. They may be monoecious or dioecious. [cite web |url=http://www.seaweed.ie/algae/fucus.lasso |title="Fucus" |author=Michael Guiry |accessdate=2007-04-28 |publisher=National University of Ireland, Galway]

These algae have a relatively simple life cycle and produce only one type of thallus which grows to a maximum size of 2 m. Fertile cavities, the conceptacles, containing the reproductive cells are immersed in the receptacles near the ends of the branches. After meiosis oogonia and antheridia are produced and released, fertilization follows and the zygote develops directly into the diploid plant. It may be considered to be analogous to the life cycle of the flowering plant. cite book |author=C. van den Hoek, D. G. Mann & H. M. Jahns |year=1995 |title=Algae: An Introduction to Phycology |publisher=Cambridge University Press, Cambridge |id=ISBN 0-521-39419-9] but in algae the oogonia are released and fertilised in the sea while in flowering plants the ovules are fertilised while attached to the parent plant and then released as a seed.

Distribution and ecology

Species of "Fucus" are recorded almost world-wide. They are dominant on the shores of the British Isles Cite book |author=F. G. Hardy & M. D. Guiry |year=2006 |title=A Checklist and Atlas of the Seaweeds of Britain and Ireland |publisher=British Phycological Society, London |id=ISBN 3-906166-35-X] , the northeastern coast of North America cite book |author=W. R. Taylor |year=1972 |title=Marine Algae of the Northeastern Coast of North America |publisher=Ann Arbor, University of Michigan Press |id=ISBN 0-472-04904-6] and California cite book |author=I. A. Abbott & G. J. Hollenberg |year=1976 |title=Marine Algae of California |publisher=Stanford University Press |id=ISBN 0-8047-0867-3] .

In the British Isles these larger brown algae occur on sheltered shores in fairly well defined zones along the shore from high water mark to below low water mark. On the more exposed shores not all of these species can be found and on very exposed shores few, if any, occur. "Pelvetia canaliculata" forms a zone at the top of the shore. Just below this "Fucus spiralis", "Fucus vesiculosus" and "Fucus serratus" and "Laminaria" form clear zones, one below the other, along the shore down to low water mark. On sheltered shores "Ascophyllum nodosum" usually forms a broad and dominating zone along the shore at the mid-littoral. On very exposed shores few if, any plants, of these species can be found. Other brown algae can be found at the low-littoral such as "Himanthalia", "Laminaria saxatilis" and "Alaria esculenta". Small green and red algae and animals occur protceted under these large brown algae cite book |author=J. R. Lewis |year=1964 |title=The Ecology of Rocky Shores |publisher=The English Universities Press Ltd, London] .

Uses

In Scotland and Norway, up until the mid 19th century, several seaweed species from "Fucus" and other genera were harvested, dried, burned to ash, and further processed to become "kelp", which was a type of soda ash that was less costly in Britain than the barilla imported from Spain. It has an alkali content of about 2.5–5% that was mainly sodium carbonate (Na₂CO₃); alkali is essential to soapmaking, glassmaking, and other industries. The seaweed was also used as fertiliser for crop land in the same areas in which it was harvested cite book |author=A. Clow & N. L. Clow |year=1952 |title=Chemical Revolution |piblisher=Ayer Co Pub |pages=65–90 |id=ISBN 0-836-91909-2
Clow and Clow indicate four species of seaweed as sources for kelp: "Fucus vesiculosus", "Ascophyllum nodosum" (formerly "Fucus nodosus" L.), "Fucus serratus", and"Laminaria digitata" (Hudson) J.V. Lamouroux (formerly "Fucus digitatus" L.). The "Fucus" species names noted in this book as sources of kelp do not reflect modern taxonomy for these species, which has been updated using Algaebase] . The purest barilla had a sodium carbonate concentration of about 30%.

It has been reported that to loosen dried earth a machine which sticks probes a meter into the ground and loosens the earth by blasting air in under pressure. Dried seaweed (bladderwrack) can then be injected into the fissures to hold the drainage cracks open Verify source|date=July 2007.

In 2005, it was announced that bacteria grown on "Fucus" have the ability to attack and kill the MRSA superbug [cite news|url=http://news.bbc.co.uk/1/hi/scotland/4561062.stm|title=Sponge puzzles superbug experts|publisher=BBC News|date=2005-12-26] .

Taxonomy

This list of species of "Fucus" excludes names of uncertain status [cite web |work=AlgaeBase |title="Fucus" Linnaeus 1753: 1158 |url=http://www.algaebase.org/generadetail.lasso?genus_id=71 |accessdate=2006-08-21 |author=M. D. Guiry |year=2006] :
* "Fucus ceranoides" L.*
* "Fucus chalonii" Feldmann
* "Fucus cottonii" M.J. Wynne & Magne *(="Fucus cottonii" M.J.Wynne & Magne "nom. illeg.")
* "Fucus distichus" L. *
* "Fucus evanescens" C.Agardh *
* "Fucus gardneri" P.C. Silva
* "Fucus nereideus" Lightfoot
* "Fucus serratus" L. — toothed wrack *
* "Fucus spermophorus" L.
* "Fucus spiralis" L. *
* "Fucus tendo" L.
* "Fucus vesiculosus" L.— bladder wrack *
* "Fucus virsoides" J. Agardh

* = Species recorded around the coast of Britain.

"Fucus distichus"

"F. distichus" is up to 10 cm long with a short stout cylindrical stipe, branching dichotomous, flat and with a mid-rib cite book |author=G. Russell |year=1978 |editor=D. E. G. Irvine & J. H. Price |title=Modern Approaches to the Taxonomy of Red and Brown Algae |pages=339–369 |publisher=Systematics Association] . "F. distichus" subsp. "edentatus" was first described from Shetland Islands by Börgesen in 1903. Powell found "F. distichus" subsp. "anceps" on the north coast of Caithness. It had also been recorded from: Orkney Islands, Fair Isle, St Kilda and the Outer Hebrides in Scotland; in Ireland it had been recorded from Counties Clare, Donegal and Kerry Cite journal |quotes=no |author=H. T. Powell |year=1957 |title=Studies in the genus "Fucus" L. II. Distribution and ecology of forms of "Fucus distichus" L. emend. Powell in Britain and Ireland |journal=Journal of the Marine Biology Association of the United Kingdom |volume=36 |pages=663–693] Cite journal |quotes=no |author=H. T. Powell |year=1957 |title=Studies in the genus "Fucus" L. I. "Fucus distichus" L. emend. Powell |journal=Journal of the Marine Biology Association of the United Kingdom |volume=36 |pages=407–432] . Two subspecies of "F. distichus" (subsp. "anceps" and subsp. "edentatus") have been described from the British Isles .

"Fucus distichus" is the organism used as a model to study the development of cell polarity, since it forms an apolar zygote that can develop polarity given a varying number of gradients.

"Fucus serratus"

"F. serratus", toothed wrack, is the most distinctive of all the "Fucus" species. It clearly shows a distinctive serrated edge to the frond not shown by the other species of the genus Cite book |quotes=no |author=H. T. Powell |year=1963 |chapter=Speciation in the genus "Fucus" L., and related genera |publisher=Syst. Assoc. Publ.: 5 |pages=63–77 |editor=J. P. Harding & N. Tebble |title=Speciation in the Sea] .

"Fucus spiralis"

"F. spiralis" is one of the three most common algae on the shores of the British Isles. It grows to about 40 cm long and does not show air bladders or a toothed edge as is found on "F.vesiculosus" and "F. serratus". It forms a zone near the top of the shore above the zones of "F. vesiculosus" and "F. serratus".

"Fucus vesiculosus"

This is one of the most common species of "Fucus", common on most shores in the mid-littoral. Readily identified by a distinct mid-rib and air vesicles in pairs on either side of the mid-rib cite book |author=Lily Newton |year=1931 |title=A Handbook of the British Seaweeds |publisher=British Museum, London] .

References

ee also

http://www.pznow.co.uk/marine/wrack.html