Allocation of blade surface area to meiospore production in annual and perennial representatives of the genus Laminaria

Allocation of blade surface area to meiospore production was quantified for semelparous and iteroparous representatives of the genus Laminaria (Phaeophyta: Laminariales) at each of two sites in Barkley Sound, Vancouver Island, B.C. The annual semelparous sporophyte Laminaria ephemera produced sori between April and July; a maximum mean percentage of 31.7% of total vegetative blade area was devoted to sorus production, and 100% of the individuals were reproductive within at least one sample. The perennial iteroparous sporophyte Laminaria setchellii produced sori throughout the year; a maximum mean percentage of 30.4% of total blade area was devoted to sorus production, and a maximum of 54% of the individuals were reproductive within any sample. These results are discussed in the context of life history evolution. Concentric rings are visible in cross-section of the stipes of Laminaria setchellii. These rings were demonstrated to form annually, and thereby permitted estimation of individual age and of age structure among populations of L. setchellii at two sites in Barkley Sound. Age structures were dissimilar between populations, and showed no evidence of stability. The twelve year age class was most abundant at one site (Wizard Rock), and the two and three year age classes were most abundant at a second site (Execution Bay).Science, Faculty ofBotany, Department ofGraduat