Nereocystis Postels & Ruprecht, 1840

Holotype species: Nereocystis luetkeana (K.Mertens) Postels & Ruprecht

Original publication and holotype designation: Postels, A. & Ruprecht, F. (1840). Illustrationes algarum in itinere circum orbem jussu imperatoris Nicolai I. Atque auspiciis navarchi Friderici L├╝tke annis 1826, 1827, 1828 et 1829 celoce Seniavin exsecuto in Oceano pacifico, inprimis septemtrionale ad littora rossica asiatico-americana collectarum. pp. [i-vi ], [i]- iv, 1-28 [1-2, index], [Latin:] [-iv], [1]-22, [1-2, index], 40 pls. Petropoli [St. Petersburg]: Typis Eduardi Pratz.

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Description: Thallus to 40 m long, annual, sometimes persisting to 18 months. Holdfast hemispherical, formed of mass of branched haptera produced in whorls. Single stipe from holdfast, up to 35 m long, solid and cylindrical through most of length, with the upper portion gradually enlarged into an elongate hollow apophysis, which is constricted at upper end and termimated by an ovoid or spherical pneumatocyst, to about 15 cm in diameter. Blades to 4 m long and 15 cm wide, borne in 2-4 clusters at top of pneumatocyst, arising from short dichotomous branches. Blades flat with straight margins. Growth of blades by longitudinal splitting, entirely above the pneumatocyst, starting with a single blade dividing dichotomously into 50 or more blades. Spores produced in summer and fall in unilocular sporangia with paraphyses in rectangular sori which are produced in a linear series on the blades. Sori progressively drop from the blade, starting with the distal sori, and sink, with spore release occurring before and after sorus abscission. Most sorus abscission occurs at dawn. Gametophytes dimorphic, dioecious, oogamous, branched uniseriate filaments.

Information contributed by: R.J. Lewis. The most recent alteration to this page was made on 2014-06-21 by M.D. Guiry.

Taxonomic status: This name is of an entity that is currently accepted taxonomically.

Most recent taxonomic treatment adopted: Silberfeld, T., Rousseau, F. & Reviers, B. de (2014). An updated classification of brown algae (Ochrophyta, Phaeophyceae). Cryptogamie Algologie 35(2): 117-156.

Comments: Nereocystis forms extensive forests with a floating canopy on rocks at 10-17 m depth along the Pacific coast of North America, ranging from central California to the Aleutian Islands. Nereocystis forests are harvested in some parts of British Columbia, Canada. The height of the plant matches the depth at which it grows, so that the pneumatocyst comes to the surface. This appears to be regulated by a phytochrome-mediated response, resulting in inhibition of stipe elongation by red light, which is greatly attenuated below the surface of the water column. Photosynthate is translocated from the blades to the stipe and holdfast, with radiolabelled photosynthate detected in the sieve filaments in the medulla during radiotracer experiments. The pneumatocyst contains carbon monoxide in concentrations to 12%. Maximum photosynthetic rate (Pmax) values are highest in summer and early fall, and are noticeably higher than for Macrocystis integrifolia. Even though it is an annual, many species of algae grow epiphytically on the stipe of Nereocystis, the most common of which are Hollenbergia subulata, Antithamnionella pacifica, Ulva (Enteromorpha) linza and Ectocarpus spp. Porphyra nereocystis mainly occurs on Nereocystis stipes. Nereocystis has a haploid number of 29-31 chromosomes. It has been hybridized in the laboratory with Macrocystis, producing hybrids that grew to 1 m in length.

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Some of the descriptions included in AlgaeBase were originally from the unpublished Encyclopedia of Algal Genera, organised in the 1990s by Dr Bruce Parker on behalf of the Phycological Society of America (PSA) and intended to be published in CD format. These AlgaeBase descriptions are now being continually updated, and each current contributor is identified above. The PSA and AlgaeBase warmly acknowledge the generosity of all past and present contributors and particularly the work of Dr Parker.

Descriptions of chrysophyte genera were subsequently published in J. Kristiansen & H.R. Preisig (eds.). 2001. Encyclopedia of Chrysophyte Genera. Bibliotheca Phycologica 110: 1-260.

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M.D. Guiry in Guiry, M.D. & Guiry, G.M. 21 June 2014. AlgaeBase. World-wide electronic publication, National University of Ireland, Galway.; searched on 28 September 2022

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