Division: Ochrophyta- 16,999 Species Order Laminariales: Class: Phaeophyceae – 2,060 Species 1
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4/28/2015 Division: Ochrophyta- 16,999 species Order Laminariales: Class: Phaeophyceae – 2,060 species 1. Life History and Reproduction Order: 6. Laminariales- 148 species - Saxicolous - Sporangia always unilocular 2. Macrothallus Construction: - Most have sieve cells/elements - Pheromone released by female gametes lamoxirene Genus: Macrocystis 3. Growth Nereocystis Pterogophora Egregia Postelsia Alaria 2 14 Microscopic gametophytes Life History of Laminariales Diplohaplontic Alternation of Generations: organism having a separate multicellular diploid sporophyte and haploid gametophyte stage 3 4 1 4/28/2015 General Morphology: All baby kelps look alike 6 Intercalary growth Meristodermal growth Meristoderm/outer cortex – outermost cells (similar to cambia in land plants) Inner cortex – unpigmented cells Medulla – contains specialized cells (sieve elements/hyphae) Meristodermal growth gives thallus girth (mostly) “transition zone” Periclinal vs. Anticlinal cell division: • Periclinal = cell division parallel to the plane of the meristoderm girth •Anticlinal = cell division • Growth in both directions away from meristem • Usually between stipe and blade (or blade and pneumatocyst) perpendicular to the plane of the 7 meristoderm height 8 2 4/28/2015 Phaeophyceae Morphology of intercellular connections Anticlinal Pattern of cell division perpendicular to surface of algae. Only alga to transport sugar/photosynthate in sieve elements Periclinal Cell division parallel to surface of plant. Plasmodesmata = connections between adjacent cells, formed during cell division - Used for cell-to-cell transport of photosynthetic products and cell communication 9 Transport: Transport in Plants vs. Algae completely independent evolutionary origins sieve elements, sieve cells, trumpet hyphae • Transport photosynthetic products Plants Algae • Have water and sugar • Outgrowths of cortex cells that grow into the medulla • Only conduct sugars and some conducting cells nutrients • Don’t divide again after formation, so they get drawn out into •Xylem non-living long thin “trumpets” = trumpet hyphae •All cells living • Sieve plates are specialized plasmodesmata between the sieve • Sieve elements alive • Sieve elements alive elements that allow transport of sugars between cells • Sieve elements lack • Sieve elements lack organelles •Important because kelps are so large: light levels don’t reach organelles except mitochondria lower portions • No companion cells • Have companion cells 11 12 3 4/28/2015 Kelp Evolution : Evidence on NE Pacific Origin Kelp Distribution 1. Kelp forests are found in shallow rocky habitats along temperate coasts throughout the world 2. Area world ocean covered by kelp forest is comparable to that covered by coral reefs 3. Kelps thrive in cool nutrient rich water-> explains why the most extensive kelp forests are found on western continental margins, where extensive upwelling occurs 4. Not found at low latitudes because intolerant of H2O temps above 20 deg C (metabolic effect or because of grazers/pathogens…) M.H. Graham Kelp Evolution : Evidence on NE Pacific Origin How did kelp get to the Southern Hemishere? Theory 1: It floated Earliest kelps: •Simple morphology •Dichotomous branching •Pneumatocysts present •Hybrid of Macrocystis and Pelagophychus •Found in So Cal Fossils •Dated back to 20 mya Obligate species evolved at the same time: •Sea Otters •Steller’s Sea Cow •Abalone •Sea Urchins 4 4/28/2015 How did kelp get to the Southern Hemishere? Theory 2: It traveled far enough to reach cold water refugia Eisenia galapagensis Foundation Species- a single species that defines much of the structure Macrocystis pyrifera = foundation species of a community by creating locally stable conditions for other species, and by modulating and stabilizing fundamental ecosystem processes Paul Dayton 1972 • Influence water motion • Dispersal of plankton •Sea otters wrap themselves with this kelp to keep from floating away while sleeping •Dissolved matter from these kelps = important food source 20 5 4/28/2015 Macrocystis pyrifera = the giant kelp • Major canopy kelp, up to 60 m in length • Capable of high growth rates: 1-2 ft/day! • Perennial, but individual blades only last ~ 2 - 6 Months •High turnover rates ( compared with trees and coral reeff)s) • Apical scimitar blade at growing tip • Intercalary meristem between blade and pneumatocyst •Sporophylls- above holdfast, no pneumatocysts,chemically defended •Hapterous holdfast 21 Macrocystis pyrifera = the giant kelp Macrocystis pyrifera = the giant kelp vs. M. integrifolia Northern limit- set by hydrodynamic forces Demes et al. 2009 Southern limit – set by lack of substrate and temperature and nutrient conditions 23 6 4/28/2015 Kelp forests vulnerable to disturbance and local extinction How far do spores travel? Removal by storm waves Poor environmental conditions Grazer outbreaks Imbreeding Nereocystis luetkeana = the bull kelp •Major canopy species •Hapterous holdfast • Stipe up to 50 m long!! • Single big pneumatocyst filled with carbon dioxide and monoxide • Annual!!! Most growth March-Sept (~200 days to get that big…can grow >1 ft/day!) •Sori on main blade, pop out and are negatively buoyant WHY?? 28 7 4/28/2015 Nereocystis luetkeana = the bull kelp Pteryogophora californica = the walking kelp Morphological plasticity: • Low flow environments– ruffled blades (increases motion and therefore nutrient uptake, broad blades for light interception) •Understory kelp • High flow environments- flat and narrow (less drag so not ripped out • Woody stipe, terminal and no shading) vegetative blade and lateral sporophylls • Perennial – up to 25 years old! • Growth rings in stipe, just like blade trees sporophylls 29 30 Egregia menziesii = feather boa kelp Egregia menziesii = feather boa kelp Perennial Mid-low intertidal Max frond # per plant = 50 Max # fronds per m2= 150 • Midrib = rachis • Sporophylls – deeper brown col;lor; shshtorter and more narrow than vegetative blades and dispersed among them • Intercalary meristem in upper portion of rachis •Northern morph and southern morph 32 5 8 4/28/2015 Postelsia palmaeformis = the sea palm Postelsia palmaeformis = the sea palm • Grows in high wave exposed • Grows in high wave exposed habitats habitats • Sensitive to desiccation in high • Blade surface with deep zone longitudinal grooves •Does not get enough light if too • Sporangia in linear sori lining submerged in low zone grooves • Zoospores released and drip down grooves (1-5m away) land on: • Mussels •Bare rock • Below mussels • Winter storms rip out mussels 35 which opens up space for light 36 9 4/28/2015 Kelp Harvest History Alaria sporophylls -intertidal to 10 meters -edible -17th century – kelp ash – French peasants -affected by climate change used for glazing pottery and making low disappeared from the English Channel quaility glass -1811 – discovery of iodine in kelps – used to treat goiters – enlargements of the thyroid gland blade - 2004-industrial use is for alginates-San Diego based firm, ISP alginates (AKA Kelco) largest in the world 37 38 Kelp Harvest- Laminariales - 89 state-defined kelp beds Family: - 38 available for lease but only 9 are leased Laminariaceae -Harvest regulated by CA DFG: can cut only upper 1.2 m Macrocystis, Nereocystis, Pelagophycus, Postelsia, Laminaria -Abalone growers lease 7 beds Alariaceae Stipe derived sporophylls - The Nature Conservancy leased 2 kelp beds-2,710 acres Alaria, Pterogophora, Undaria, Lessoniopsis, Pleurophycus (but not this one) $5, 800 for 3 years Lessoniaceae -Collaborative research by Kendra Karr UCSC and The Nature Consevancy Eckolonia, Egregia, Eisenia, Lessonia found that for juvenile rock fish better to half-harvest two kelp forest patches than to whole- harvest one patch Costariacea Flattened stipe with a perforated or reticulate blade Costaria, Agarum, Dictyoneurum, Lane et al. 2006 40 10.