Growth
The growth rate during maximal growth is reported.
Adults grow rapidly until about 5 years old. Peak growth occurs during winter (November to June) and stops in summer initiated by a photoperiodic response to day length. The total carbon content of canopy lamina is reported to vary with season reflecting a change in carbohydrate storage (Sjøtun, 1996). Carbon content is high in the summer and autumn and starts to decrease in winter with the onset of growth. The old blade is replaced by a new blade formed between the meristem (top of stripe) and the old blade. Nutrients from the old blade contribute to growth. The old blade is shed in spring to early summer.
In Laminaria hyperborea, the proportion of growth allocated to various regions of the plant is reported to vary with both the age of the plant and its habitat (Sjøtun & Fredriksen, 1995). The proportion of growth allocated to the stipe and hapteron, for instance, increases with exposure, the latter probably helping the plant to remain attached and help it to survive in exposed localities (Sjøtun & Fredriksen, 1995). In one year old plants however, growth mainly occurred in the lamina in order to maximize the area for photosynthesis in the light limited understory.