Studies on British Laminariaceae. I. Growth in Laminaria Saccharina (L.) Lamour

The production, longevity, growth, regeneration and reproduction of Laminaria saccharina (L.) Lamour. on the Devon and Argyll coasts are described. Bathymetric zone and habitat control the fertility and longevity of the gametophyte and consequently the production of the sporophyte. Sporophytes develop at the higher levels during the winter, early spring, late summer and autumn, and at the lower levels during spring, summer and autumn. Longevity of the sporophyte depends on season of germination, bathymetric zone and habitat. Winter sporophytes rarely persist to maturity. Spring sporophytes form the bulk of all L. saccharina populations except on very sheltered coasts in the sublittoral zone where summer sporophytes may be equally numerous. On the British coast the life-span of a L. saccharina sporophyte does not exceed 3 years.