Alginate content and composition ofMacrocystis pyrifera from New Zealand

Tissue samples ofMacrocystis pyrifera from 2 sites in southern New Zealand and harvested over a period of 12 months were analysed for alginate content and composition (M:G ratio). Plants were divided into three frond classes of different length and each frond was further separated into age categories of blades and stipes (viz young, mature and old blades; mature and old stipes). Within each size class, younger blades had higher alginate content than older blades. Stipes did not show such variation with age. Alginate from younger blades and stipes had higher proportions of mannuronic acid residues than those from old blades and stipes. The range of M:G ratios for age categories of either blades or stipes from longer fronds was greater than those for smaller fronds. Alginate content and M:G ratios of stipes were always higher than for blades. The difference between M:G ratios of blades and stipes was greater for smaller fronds than for longer ones. Differences between collection sites and seasonal trends are also discussed.author for correspondence