Download Division: Ochrophyta

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Order Laminariales:
Division: Ochrophyta- 16,999 species
Class: Phaeophyceae – 2,060 species
Order: 6. Laminariales- 148 species
- Saxicolous
- Sporangia always unilocular
- Most have sieve cells/elements
- Pheromone released
by female gametes lamoxirene
Genus: Macrocystis
Nereocystis
Pterogophora
Egregia
Postelsia
Alaria
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Life History and Reproduction
2.
Macrothallus Construction:
3.
Growth
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Microscopic gametophytes
Life History of Laminariales
Diplohaplontic Alternation of Generations: organism having a separate
multicellular diploid sporophyte and haploid gametophyte stage
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General Morphology:
All baby kelps look alike
Intercalary growth
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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
• Growth in both directions away from meristem
• Usually between stipe and blade (or blade and pneumatocyst)
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•Anticlinal = cell division
perpendicular to the plane of the
meristoderm  height
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Anticlinal Pattern of cell division perpendicular to surface of algae.
Phaeophyceae Morphology of intercellular connections
 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
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Transport:
Transport in Plants vs. Algae
completely independent evolutionary origins
sieve elements, sieve cells, trumpet hyphae
• Transport photosynthetic products
• Outgrowths of cortex cells that grow into the medulla
• Don’t divide again after formation, so they get drawn out into
long thin “trumpets” = trumpet hyphae
• Sieve plates are specialized plasmodesmata between the sieve
elements that allow transport of sugars between cells
•Important because kelps are so large: light levels don’t reach
lower portions
Plants
• Have water and sugar
conducting cells
Algae
• Only conduct sugars and some
nutrients
• Xylem  non-living
•All cells living
• Sieve elements  alive
• Sieve elements  alive
• Sieve elements lack
organelles
• Sieve elements lack organelles
except mitochondria
• Have companion cells
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• No companion cells
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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
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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
of a community by creating locally stable conditions for other species,
and by modulating and stabilizing fundamental ecosystem processes
Paul Dayton 1972
Macrocystis pyrifera = foundation species
• 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
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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 reefs)
f )
• Apical scimitar blade at growing tip
• Intercalary meristem between
blade and pneumatocyst
•Sporophylls- above holdfast,
no pneumatocysts,chemically defended
•Hapterous holdfast
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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
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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??
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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
and no shading)
• Woody stipe, terminal
vegetative blade and lateral
sporophylls
• Perennial – up to 25 years old!
• Growth rings in stipe, just like
trees
blade
sporophylls
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Egregia menziesii = feather boa kelp
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Egregia menziesii = feather boa kelp
Perennial
Mid-low intertidal
Max frond # per plant = 50
Max # fronds per m2= 150
• Midrib = rachis
• Sporophylls – deeper brown
color;
l ; shorter
sh t and
d more
m
narrow
than vegetative blades and
dispersed among them
• Intercalary meristem in
upper portion of rachis
•Northern morph and southern
morph
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Postelsia palmaeformis = the sea palm
Postelsia palmaeformis = the sea palm
• Grows in high wave exposed
habitats
• Grows in high wave exposed
habitats
• Sensitive to desiccation in high
zone
• Blade surface with deep
longitudinal grooves
•Does
Does not get enough light if too
submerged in low zone
• Sporangia in linear sori lining
grooves
• Zoospores released and drip
down grooves (1-5m away) land on:
• Mussels
• Bare rock
• Below mussels
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• Winter storms rip out mussels
which opens up space for light
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Kelp Harvest History
sporophylls
Alaria
-intertidal to 10 meters
-edible
-affected by climate change
disappeared from the English Channel
-17th century – kelp ash – French peasants
used for glazing pottery and making low
quaility glass
-1811 – discovery of iodine in kelps – used
to treat goiters – enlargements of the
thyroid gland
blade
g
- 2004-industrial use is for alginates-San
Diego based firm, ISP alginates (AKA
Kelco) largest in the world
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Kelp Harvest- 89 state-defined kelp beds
- 38 available for lease but only 9 are leased
-Harvest regulated by CA DFG: can cut only upper 1.2 m
-Abalone growers lease 7 beds
- The Nature Conservancy leased 2 kelp beds-2,710 acres
$5 800 for 3 years
$5,800
-Collaborative research by Kendra Karr UCSC and The Nature Consevancy
found that for juvenile rock fish better to half-harvest two kelp
forest patches than to whole- harvest one patch
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Laminariales
Family:
Laminariaceae
Macrocystis, Nereocystis, Pelagophycus, Postelsia, Laminaria
Alariaceae
Stipe derived sporophylls
Alaria, Pterogophora, Undaria, Lessoniopsis, Pleurophycus (but not this one)
Lessoniaceae
Eckolonia, Egregia, Eisenia, Lessonia
Costariacea
Flattened stipe with a perforated or reticulate blade
Costaria, Agarum, Dictyoneurum,
Lane et al. 2006
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