Division: Heterokontophyta- 13,151 species Heterokontophyta II Class: Phaeophyceae – 1,836 species Order: 19 orders but we will focus on 6 4. Dictyotales- 242 species - Saxicolous - Common in tropical waters; also found locally subtidal - Pheromone= dictyotene Genus Dictyota Padina 1 14 Life history of Dictyota Order: Dictyotales • Reproductive structures in “sori” = cluster of gametangia or 1. Life History and Reproduction: sporangia • Tetraspores (non-flagellated) released by 2N sporophyte 2. Macrothallus Construction: • Gametophyte dioecious • Large egg one per “oogonium” = female reproductive structure 3. Growth: containing one or more eggs • Sperm single hairy flagella but has second basal body 20 21 1 Life History of Dictyota: A Dictyota Story: (Stachowicz and Hay 2000) Isomorphic Alternation of Generations Cape Hatteras Local adaptation Associational defences Southern Sites Northern Sites + Libinia dubia, the decorator crab + Libinia dubia, the decorator crab + Dictyota menstrualis, + No chemically noxious the chemically algae defended brown alga (diterpenes) + Carnivorous fishes + Omnivorous fishes + Crabs are specialists + Crabs are generalists in decoration in decoration 17 preference preference 21 The only calcified Phaeophycean: Padina Division: Heterokontophyta- 13,151 species Class: Phaeophyceae – 1,836 species Order: 19 orders but we will focus on 6 5. Ralfsiales- 54 species - Saxicolous or epiphytic - Common intertidally, tropics to poles - crustose in atleast one life history stage Increased Grazing Genus: Ralfsia Analipus 22 14 2 Analipus japonicus Order: Ralfsiales -perennial crustose base up to 5cm with erect axes that die back in the fall 1. Life History and Reproduction: 2. Macrothallus Construction: Ralfsia 3. Growth: 10 27 Division: Heterokontophyta- 13,151 species General Morphology: Class: Phaeophyceae – 1,836 species sorus (pl: sori) Order: 6. Laminariales- 129 species - Saxicolous - Sporangia always unilocular - Most have sieve cells/elements blade - Pheromone released by female gametes lamoxirene sporophylls Genus: Egregia stipe Postelsia haptera Pterogophora holdfast Macrocystis Nereocystis 12 14 3 Order Laminariales: Microscopic gametophytes 1. Life History and Reproduction 2. Macrothallus Construction: 3. Growth 13 14 Life History of Laminariales Diplohaplontic Alternation of Generations: organism having a separate General Morphology: multicellular diploid sporophyte and haploid gametophyte stage 15 All the baby kelps look the same 16 4 Intercalary growth Meristodermal growth Meristoderm/outer cortex – outermost cells Inner cortex – unpigmented cells Medulla – contains specialized cells (sieve elements) Meristodermal growth gives thallus girth (mostly), mostly periclinal cell division “transition zone” Periclinal vs. Anticlinal cell division: • Periclinal = cell division parallel to the plane of the meristoderm girth • Growth in both directions away from meristem •Anticlinal = cell division • Usually between stipe and blade (or blade and pneumatocyst) perpendicular to the plane of the meristoderm height 17 18 Phaeophyceae Morphology of intercellular connections Transport: Only alga to transport sugar/photosynthate in sieve elements sieve elements, sieve cells, or trumpet hyphae • Transport photosynthetic products Plasmodesmata = connections between adjacent cells, formed during cell division • Outgrowths of cortex cells that grow into the medulla - Used for cell-to-cell transport of photosynthetic products • Don’t divide again after formation, so they get drawn out and cell communication into long thin “trumpets”= trumpet hyphae • Sieve plates are specialized plasmodesmata between the sieve elements that allow transport of sugars between cells 20 9 5 Transport in Plants vs. Algae completely independent evolutionary origins Egregia menziesii = feather boa kelp Plants Algae • Have water and sugar • Only conduct sugars and conducting cells some nutrients • Midrib = rachis • Xylem non-living •All cells living • Sporophylls – deeper brown color; shorter and more narrow • Sieve elements alive than vegetative blades and • Sieve elements alive dispersed among them • Sieve elements lack • Sieve elements lack • Intercalary meristem in organelles organelles except upper portion of rachis mitochondria • Have companion cells • No companion cells 21 22 5 Postelsia palmaeformis = the sea palm Pteryogophora californica = the walking kelp • Grows in high wave exposed habitats • Understory kelp • Blade surface with deep • Woody stipe, terminal longitudinal grooves vegetative blade and lateral sporophylls • Sporangia in linear sori lining grooves • Perennial – up to 25 years old! • Zoospores released drip down • Growth rings in stipe, just like grooves to land on: trees • Mussels • Bare rock • “Walking” • Below mussels • Winter storms rip out mussels 23 which open up space for light 24 6 Macrocystis pyrifera = the giant kelp Nereocystis luetkeana = the bull kelp • Major canopy kelp, up to 60 m in length • Major canopy species locally • Hapterous holdfast • Hapterous holdfast • Capable of high growth rates: 1-2 ft/day! • Stipe to 35 m long • Perennial, but individual blades only last ~ 2 - 6 Months • Single big pneumatocyst filled with carbon dioxide and monoxide • Apical scimitar blade at growing tip • Annual!!! Most growth March-Sept • Intercalary meristem between (~200 days to get that big… ave. of blade and pneumatocyst 7”/day!) •Sporophylls- above holdfast, no pneumatocysts, •Sori on main blade, pop out and are chemically defended negatively buoyant 25 26 History of Kelp Harvest Laminariales -17th century – kelp ash – French peasants Family: used for glazing pottery and making low Laminariaceae quaility glass Macrocystis, Nereocystis, Pelagophycus, Postelsia, Laminaria -1811 – discovery of iodine in kelps – used Alariaceae to treat goiter – enlargement of the Stipe derived sporophylls thyroid gland Alaria, Pterogophora,Undaria, Lessoniopsis, Pleurophycus (but not this one) - Current industrial use is for alginates Lessoniaceae -West coast of U.S. = Macrocystis, Eckolonia, Egregia, Eisenia, Lessonia Nereocystis - Harvest regulated by CA DFG: can cut Costariacea only upper 1.2 m Flattened stipe with a perforated or reticulate blade - Kelp beds designated by number, some Costaria, Agarum, Dictyoneurum, are leased by harvesting companies -San Diego based firm, ISP alginates (AKA Kelco) largest in world 27 28 7 .