Although the taxonomy of the brown algal genus Alaria Greville of the order Laminariales has recently been elucidated, neither the morphological nor the cytological aspects of the life-cycles of the species occurring on the west coast of North America has been investigated. Therefore a major part of this present project has been to establish the morphological and cytological phases of several species of Alaria. Since the earliest investigations into the cytology of the Laminariales the concepts of the nuclear division processes have not changed as they have in higher organisms. A supplementary objective has therefore been the application of modern techniques and interpretations to nuclear divisions in the genus Alaria. During 1964-1967 samples of Alaria marginata Postels et Ruprecht, Alaria nana Schrader, Alaria tenuifolia Setchell, Alaria taeniata Kjellman, Alaria fistulosa Postels et Ruprecht and Alaria grandifolia J. Agardh were collected from the west coast of North America, from Cape St. Elias, Alaska to Pescadero Point, California. Cultures of these species were established from spore suspensions and maintained under controlled conditions until young sporophytes were produced. From these cultures it has been demonstrated that the life-cycles of all six species show an alternation of heteromorphic generations: macroscopic sporophytic and microscopic dioecious gametophytic generations. It has also been established that there is a corresponding chromosomal alternation of generations, the sporophyte being diploid and the gametophyte, haploid. The development of male and female gametophytes, the production of gametangia, fertilisation, and the early developmental stages of the young sporophytes have been examined. The similarities and differences between these phases in Alaria and other members of the Laminariales have been investigated and found to be similar except for the germination of zoospores of A. marginata, the formation of the egg cells in all the Alaria spp. and the occurrence of a possible "fertilisation pore" and "tube" in the eggs of A. taeniata. The occurrence of parthenogenesis and the production of malformed haploid "parthenosporophytes" are reported. Meiosis in the immature zoosporangia and mitosis in gametophytes and young sporophytes have been observed, compared with these processes in other members of the Laminariales, and found to be similar in a number of cases. However, the concepts of meiosis held by many earlier authors are not applicable to this process in Alaria. A haploid chromosome number of approximately 14 alternates with a diploid number of approximately 28 in A. marginata, A. nana, A. tenuifolia, A. fistulosa and A. taeniata. The haploid number of A. grandifolia is approximately 24. Consequently only A. grandifolia can possibly be distinguished on the basis of chromosome numbers. The methods used in laminarian cytology and the difficulties involved in counting the extremely small chromosomes of the members of this order have been critically discussed. / Science, Faculty of / Botany, Department of / Graduate

No description available.

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 of / Botany, Department of / Graduate

Zoospores of 17 species in 14 genera and sperm of 13 species in 11 genera of Laminariales were studied by electron microscopy. The zoospores are unique in the brown algae in lacking both an eyespot in the single chloroplast and an associated swelling at the base of the shorter, posterior flagellum. Spores of all species possess a distal whiplash on the longer, mastigoneme-bearing anterior flagellum; although it is only seldom preserved for electron microscopy, this appendage may sometimes be as long as the mastigoneme-bearing portion of the flagellum. A microtubular cytoskeleton with connections to the flagellar basal bodies is responsible for maintaining the shape of the zoospore. The sperm are also unique in the brown algae. They are elongate and possess two to three plastids and several mitochondria, but lack an eyespot. Their most distinctive feature is the long posterior flagellum which tapers distaliy as the doublet microtubules of the axoneme are transformed into singlets and then decrease in number. The sperm also bear a distal whiplash on the mastigoneme-bearing anterior flagellum. These laminarialean zoospores and sperm are ultrastructurally distinct from those known in other orders of brown algae, and from Chorda of the Laminariales, which confirms that Chorda is primitive. The longer posterior flageilum of the sperm recalls similar modifications in sperm of other oogamous brown algae, and suggests a common functional significance. / Science, Faculty of / Botany, Department of / Graduate

This study of the brown algal genus Laminaria Lamour consisted of (1) a critical review of the taxonomy and distribution of taxa of Laminaria occurring in the northeast Pacific, (2) a description of the life histories and growth patterns of long and short stipe forms of L. groenlandica and L. saccharina, (3) an evaluation of the roles of temperature, salinity, and water motion as possible determinants of local distributions of long and short stipe forms of L. groenlandica and L. saccharina, and (4) an evaluation of the roles of temperature, salinity, exposure, and submarine illumination in determining the vertical distribution of L. saccharina. These studies were made from 1961 to 1965. Ten species of Laminaria are recognized for the northeast Pacific: L. groenlandica Rosenv.; L. farlowii Setchell; L. saccharina (L.) Lamour.; L. setchellii Silva; L. dentigera Kjellman; L. longlpes Bory; L. sinclairii (Harvey ex Hooker f. et Harvey) Farlow, Anderson et_ Eaton; L. ephemera Setchell; L. yezoensis Miyabe; and L. complanata (Setchell et Gardner) Setchell. Laminaria cordata Dawson is considered conspecific with L. saccharina, L. personata Setchell and Gardner is regarded conspecific with L. yezoensis, and L. platymeris De la Pyl. (sensu Setchell and Gardner) is considered conspecific with L. groenlandica. Pour forms of L. groenlandica are recognized for the northeast Pacific. These forms are not considered as legitimate taxonomic entities but are distinguished merely to provide a means of facilitating discussion. The known habitat requirements for all ten species were broadened and the known distributions of all species, excepting L. groenlandica, were extended. Laminaria saccharina and L. groenlandica produced sori in the late spring and winter. New sporophytes of L. groenlandica appeared throughout the year, whereas those of L. saccharina appeared in late winter and early fall. Depending upon culture conditions, two morphologically distinct forms of gametophytes were produced by both species: large gametophytes were produced in conditions of high temperature and low salinity; and small gametophytes in conditions of low temperature and high salinity. Abnormal sporophytes were observed under conditions conducive to formation of large gametophytes. Patterns of growth for the blades of the two species were essentially the same.. The growth rate decreased with increase in distance from the blade base, and the position of greatest longitudinal growth coincided with the position of greatest lateral growth. The distributions of L. saccharina and the two forms of L. groenlandica about Vancouver Island were correlated with temperature, salinity, and water motion. The two forms of L. groenlandica were absent from areas of high temperature and low salinity; L. saccharina was absent from areas subjected to surf. These field conclusions were subjected to laboratory and field tests involving gametophytes and sporophytes of both species. The distributions of the two forms of L. groenlandica can be explained on the basis of temperature and salinity distributions. Both forms require low temperature and high salinity for survival. Laminaria saccharina has a wide range of tolerance to temperature and salinity. Surf appears to be the agent controlling the distribution of this species. The upper limits of L. saccharina, as observed in Burrard Inlet, are thought to-be directly related, to air temperature and insolation and indirectly related to tidal characteristics. The lower limits appear to reflect the compensation depth of this species. / Science, Faculty of / Botany, Department of / Graduate