Variations in the alginate content and composition of Durvillaea antarctica and D. willana from southern New Zealand

摘要

The brown seaweeds Durvillaea antarctica and D. willana are dominant components of the lower littoral and upper sublittoral of exposed rocky shores in southern New Zealand. Tissue samples of both species, harvested from a site on the south-east coast of South Island over a period of 2 years, were analysed for alginate content and composition. Individuals of both species were further separated into different blade (lamina and palm) and stipe (cortex and medulla) fractions to assess variation within the thallus. On average the alginate content and frequency of mannuronic acid (F_m) was higher in D. antarctica than in D. willana. Blades contained more alginate than stipes, laminae and stipes were rich in mannuronic acid whereas holdfasts were rich in guluronic acid. Variations in composition are considered to reflect the functional differences of the tissue, giving flexibility to blade and stipe and rigidity to the holdfast. Despite fluctuations in content and composition between collection times no seasonal trends in either component were apparent.