Pelvetia

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Pelvetia canaliculata
Pelvetia canaliculata.jpg
Close-up
Pelvetia canaliculata on slipway.jpg
Growing on the side of a slipway
Scientific classification
Kingdom: Chromalveolata
Division: Heterokontophyta
Class: Phaeophyta
Order: Fucales
Family: Fucaceae
Genus: Pelvetia
Decne. & Thur.
Species: P. canaliculata
Binomial name
Pelvetia canaliculata
(L.) Decne. & Thur.
Synonyms [1]
  • Fucus canaliculatus L.
  • Halidrys canaliculata (L.) Stackhouse
  • Fucodium canaliculatum (L.) J.Agardh
  • Ascophyllum canaliculatum L.) Kuntze
  • Ascophylla canaliculata (L.) Kuntze
  • Fucus excisus L.

Pelvetia canaliculata, channelled wrack, is a very common brown alga (Phaeophyceae) found on the rocks of the upper shores of Europe. It is the only species remaining in the monotypic genus Pelvetia.[1][2] In 1999, the other members of this genus were reclassified as Silvetia due to differences of oogonium structure and of nucleic acid sequences of the rDNA.[3]

Description[edit]

Pelvetia grows to a maximum length of 15 centimetres (6 in) in dense tufts, the fronds being deeply channelled on one side: the channels and a mucus layer help prevent the seaweed drying (desiccation) when the tide is out. It is irregularly dichotomously branched with terminal receptacles,[4] and is dark brown in colour. Each branch is of uniform width and without a midrib. The receptacles are forked at the tips.

It is distinguished from other large brown algae by the channels along the frond. It has no mid-rib, no air-vesicules and forms the uppermost zone of algae on the shore growing at or above high-water mark.[5] The reproductive organs form swollen, irregularly shaped receptacles at the end of the branches. The conceptacles are hermaphrodite and borne within the receptacles.

Ecology and distribution[edit]

P. canaliculata is the only large algae growing on rocks forming a zone along the upper shore at the upper littoral zone, on the shores of the British Isles. It tolerates a wide range of exposure conditions.[6] It needs periods of exposure to the air, and sometimes grows so high up a beach that coarse grass and other longshore angiosperms grow among it. If it is submerged for more than six hours out of 12 it begins to decay.[7]

Distribution[edit]

Pelvetia canaliculata is common on the Atlantic shores of Europe from Iceland to Spain, including Norway, Ireland, Great Britain, the Netherlands, France and Portugal.[8] In Ireland, collection of Pelvetia canaliculata (Irish: dúlamán) has been recorded as a source of sustenance during times of famine.[9] A popular Irish folk song, Dúlamán, describes events transpiring between two people who collected the seaweed as a profession.

References[edit]

  1. ^ a b M. D. Guiry & G. M. Guiry. "Genus: Pelvetia". AlgaeBase. National University of Ireland, Galway. Retrieved April 24, 2012. 
  2. ^ Fernando G. Cánovas, Catarina F. Mota, Ester A. Serrão & Gareth A. Pearson (2011). "Driving south: a multi-gene phylogeny of the brown algal family Fucaceae reveals relationships and recent drivers of a marine radiation". BMC Evolutionary Biology 11: 371. doi:10.1186/1471-2148-11-371. PMC 3292578. PMID 22188734. 
  3. ^ Serrão, Ester A.; Lawrence A. Alice and Susan H. Brawley (1999). "Evolution of the Fucaceae (Phaeophyceae) Inferred from nrDNA-ITS". Journal of Phycology 35: 382–394. doi:10.1046/j.1529-8817.1999.3520382.x. Retrieved 6-10-2013. 
  4. ^ L. Newton (1931). A Handbook of the British Seaweeds. British Museum, London. 
  5. ^ C. I. Dickinson (1963). British Seaweeds. The Kew Series. 
  6. ^ J. R. Lewis (1964). The Ecology of the Rocky Shores. The English Universities Press Ltd. London. 
  7. ^ D. Thomas (2002). Seaweeds. Life Series. Natural History Museum, London. ISBN 0-565-09175-1. 
  8. ^ M. D. Guiry & Wendy Guiry (October 25, 2006). "Pelvetia canaliculata (Linnaeus) Decaisne & Thuret". AlgaeBase. 
  9. ^ Doreen McBride, When Hunger Stalked the North (1994).

External links[edit]