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
(unranked):
Superphylum:
Class:
Order:
Family:
Genus:
Pelvetia

Species:
P. canaliculata
Binomial name
Pelvetia canaliculata
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[4] with terminal receptacles,[5] 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 no cryptostomata. It forms the uppermost zone of algae on the shore growing at or above high-water mark.[6] The reproductive organs form swollen, irregularly shaped receptacles at the end of the branches. The conceptacles are hermaphrodite and borne within the receptacles. at the apices.

Reproduction[edit]

Both sexes occur in the same plant, the reproductive structures develop at the apices.[7] The receptacles are swollen during the summer and are yellowish-green at maturity.[8]

Ecology[edit]

Pelvetia 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.[9] 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.[10]

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.[11] In Ireland, collection of Pelvetia canaliculata (Irish: dúlamán) has been recorded as a source of sustenance during times of famine.[12] 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. ^ Ester A. Serrão, Lawrence A. Alice & Susan H. Brawley (1999). "Evolution of the Fucaceae (Phaeophyceae) inferred from nrDNA-ITS" (PDF). Journal of Phycology. 35 (2): 382–394. doi:10.1046/j.1529-8817.1999.3520382.x. hdl:10400.1/4045.
  4. ^ W. E. Jones (1962). "A key to the genera of British seaweeds". Field Studies. 1 (4): 1–32.
  5. ^ L. Newton (1931). A Handbook of the British Seaweeds. British Museum, London.
  6. ^ C. I. Dickinson (1963). British Seaweeds. The Kew Series.
  7. ^ Bunker, F.StP. D., Brodie, J.A., Maggs, C.A. and Bunker, A.R. 2017 Seaweeds of Britain and Ireland. Second Edition. Wild Nature Press, Plymouth, UK. ISBN 978-0-9955673-3-7
  8. ^ Dickinson, C.I. 1963. British Seaweeds. The Kew Series
  9. ^ J. R. Lewis (1964). The Ecology of the Rocky Shores. The English Universities Press Ltd. London.
  10. ^ D. Thomas (2002). Seaweeds. Life Series. London: Natural History Museum. ISBN 978-0-565-09175-0.
  11. ^ M. D. Guiry & Wendy Guiry (October 25, 2006). "Pelvetia canaliculata (Linnaeus) Decaisne & Thuret". AlgaeBase.
  12. ^ Doreen McBride (1994). "When Hunger Stalked the North".

External links[edit]