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Carbon and nitrogen contents of two intertidal fucoid species, Fucus serratus and Himanthalia elongata, were investigated with respect to variations in seasonal resource availability, growth and reproductive requirements. The linear growth rate of F. serratus peaked in spring at 2.3 cm 28 d−1, compared with

Partial nucleotide sequences from the 5′ terminus of the nuclear large-subunit (LSU) ribosomal DNA gene (domains C1, C2, D1, and D2) have been determined for ten fucalean species representing eight genera to assess their interfamilial and intergeneric relationships: Ascophyllum nodosum (Linnaeus) Le Jolis, Fucus vesiculosus Linnaeus, Pelvetia canaliculata (Linnaeus) Decaisne et Thuret, Himanthalia elongata (Linnaeus) S.F. Gray, Bifurcaria bifitrcata Ross, Cystoseira humilis Kutzing, C. nodicaulis (Withering) M. Roberts, C. tamariscifolia (Hudson) Papenfuss, Halidrys siliquosa (Linnaeus) Lyngbye, and Sargassum muticum (Yendo) Fensholt. Sequences of five other species were used as an outgroup: three from Laminariales [Chorda filum (Linnaeus) Stackhouse, Macrocystis pyrifera (Linnaeus) C. Agardh, and Saccorhiza polyschides (Lightfoot) Batters], one from Sphacelariales [Cladostephus spongiosus (Hudson) C. Agardh,] and one from Cutleriales [Cutleria multifida (Smith) Greville as both its gametophytic ...

13C nuclear magnetic resonance spectroscopy (NMR) has been used to study the metabolic flux of carbon through the intracellular pools of the isomeric hexitols d-altritol and d-mannitol in Himanthalia elongata. Natural abundance 13C NMR spectra of freshly collected plant material showed altritol as the dominant intracellular low-molecular-weight organic solute, with mannitol present at less than 20% of the altritol concentration. Plant material incubated in seawater medium with added 13C-enriched bicarbonate showed a rapid increase in the 13C signal due to mannitol, with an increase of more than 12-fold in under 48 h, in contrast to the altritol signal, which increased by approximately 2-fold over the same period. The intracellular mannitol signal decreased rapidly when 13C-enriched plant material was transferred to a non-enriched medium, while altritol showed a slower decline. These results are consistent with previous observations on the effects of salinity on the intracellular hexitol pools of H. elonga...

Summary The brown alga Himanthalia elongata (L.) Gray, commonly known as the sea bean, is beginning to be used as human food in Europe. Large quantities are also exported from Europe to Japan where this Pheophyceae is particularly appreciated. The purpose of this work was to determine the food value of this species by studying the variations in its main chemical constituents during the harvesting period (March or June) with respect to different parts of the thallus. We considered variations in nitrogen and protein content, the presence of the main amino acids, the percentage of alginic acid and lipids and the concentrations of mineral salts, soluble and insoluble fibers and fat- and water—soluble vitamins. Except for alginic acid and fibers, the fertile parts of the plant were richer than the sterile parts. This alga has greater food value at the beginning than at the end of spring, and lipid concentrations are higher than those of other food algae.

Biomass measurements of vegetative thalli of Himanthalia elongata have been made on a single population on the Isle of Man for the period 1987 to 1989. Annual differences were observed in the size (biomass) structure of the population and in the numbers of plants sampled. The data did not produce unequivocal evidence on plant longevity and it is concluded that deductions of population age composition from biomass data alone may be unwarranted, even when the sample size is large.

The distribution of altritol (talitol), an isomer of the hexitol, mannitol, was studied in species thought to be closely related to Himanthalia elongata, in which it is already known to occur. Natural abundance 13C nuclear magnetic resonance (NMR) spectroscopy has shown its existence in a further four species endemic to the southern hemisphere: Notheia anomala, Hormosira banksis and Xiphophora chondrophylla, from Australia, and Bijurcariopsis capensis from South Africa. H. banksis, X. chondrophylla and B. capensis all exhibit ‘primitive’ fucalean characters. N. anomala has also been shown to have characteristics common to some members of the Fucales. Therefore the distribution of altritol supports recent views on the relationships between these species and the origin of the Fucales.