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Post- fertilization Events Distinguishing
between Orders of Florideophyceae
Triphasic Life Histories :Terminology
Connecting filament or Ooblast filament = tube that carries the zygote nucleus
from fertilized egg to internal auxiliary cell where it is cloned and
differentiates into carpospores (in some Orders!)
Auxiliary cell = vegetative cell (N) that receives the 2N zygote nucleus after
fertilization (in some Orders!)
cp
Gonimoblast = 2N filaments bearing carposporangia in the carposporophyte (ALL
Florideophyceans have this)
Auxiliary cell present
oo
Auxiliary branch & carpogonial
branch arise from same
supporting cell
Auxiliary cell absent
Gominoblast initiated
from carpogonium
Auxiliary cell present
Ooblast filament transfers
zygote nucleus to auxiliary cell
Gonimoblast initiated
from a fused carpogonium
& auxiliary cell
Gonimoblast initiated
from auxiliary cell
Division: Rhodophyta- 7117 species
3.Class: Florideophyceae-6767 species
3.Class: Florideophyceae Auxiliary cell absent
1.Order Nemaliales Gominoblasts initiated from carpogonium
Pit plugs characterized by 2 cap layers
Order: 29 orders but we will focus on 5
1. Nemaliales -273 species
2. Rhodomeniales-382 species
3. Ceramiales- 2662 species
4. Gigartinales- 880 species
p
5. Corallinales- 725 species
Spermatium
2N carpospores
on gonimoblast
filaments
Tricogyne
Carpogonium
Carpogonial
branch
14
1N female gametophyte
2N carposporophyte on
1N female gametophyte
1
3.Class: Florideophyceae
2. Order Rhodomeniales
3.Class: Florideophyceae
1.Order Nemaliales
Genus: Cumagloia
- cylindrical
with branchlets
- multiaxial
- saxicolous
- intertidal
Auxiliary cell formed before fertilization
Auxiliary branch & carpogonial branch arise
from same supporting cell
Gominoblast initiated from a fused
carpogonium & auxiliary cell
Spermatium
2N carpospores
on gonimoblast
i bl
filaments
Carpogonium
Carpogonial
branch
S
A
S
Auxiliary Cell
Supporting Cell
1N female gametophyte
3.Class: Florideophyceae
2. OrderRhodomeniales
Genus: Rhodomenia
2N carposporophyte on
1N female gametophyte
3.Class: Florideophyceae
2. Order Rhodomeniales
Genus: Botryocladia
-Subtidal, saxicolous
- Mucus-filled sacs
- Multiaxial
- “sea grapes”
-Subtidal, saxicolous
- Associated with juvenile fish
- Dichotomous branching
- Multiaxial
2
3. Class: Florideophyceae
3. Order: Ceramiales Auxiliary cell develops from supporting cell of
carpogonial branch after fertilization
Genus: Ceramium
Ooblast filament forms between carpogonium &
auxiliary cell
Gominoblast initiated from axiliary cell
Spermatium
Tricogyne
3.Class: Florideophyceae
3. Order Ceramiales
Genus Polysiphonia
After
fertilization
Carpogonium
Carpogonial
Branch
S
Supporting cell
1N female gametophyte
- Prominent trichoblasts
which leave scars after
they fall off.
- Number of pericentral
cells helps to identify to
species
- Polysiphonous
S A
S A
Ooblast filament
trasfers
zygote nucleus
2N carpospores
on gonimoblast
filaments
2N carposporophyte on
1N female gametophyte
3. Class: Florideophyceae
3. Order: Ceramiales
Genus: Ceramium
3.Class: florideophyceae
3. Order Ceramiales
Genus Microcladia
- saxicolous or epiphytic
- fully corticated
- distichous
- uniaxial
- saxicolous or ephiphytic
- fully or partially corticated
- uniaxial
alternate
pectinate
3
3.Class: Florideophyceae
4. Order Gigartinales
Auxiliary cell present BEFORE fertilization but on a distant branch
Ooblast filament transfers zygote nucleus to auxiliary cell
Gominoblast initiated from auxiliary cell
Spermatium
Ooblast filament
trasfers
zygote nucleus
Supporting
Cell
A
A
Auxiliary
Cell
2N carpospores
on
gonimoblast
filaments
3.Class: Florideophyceae
4. Order Gigartinales
Genus Mazzaella
Common local species:
•M. flaccida – yellow/green; mid to upper intertidal
•M. splendens – red/purple; low intertidal
Iridescence
• Proteinaceous cuticle
• Multiple layers
• Alternating opaque and translucent layers
• Layering produces light interference
patterns that give iridescent appearance
when submerged
• Adaptive advantage unknown
2N carposporophyte on
1N female gametophyte
1N female gametophyte
3.Class: Florideophyceae
4. Order Gigartinales
Genus Mazzaella
3.Class: Florideophyceae
4. Order Gigartinales
Genus Mastocarpus species complex
2N carposporophytes
on female gametophyte
1N gametophytes
- multiaxial
- filamentous
medulla
Gametophyte
Carposporophyte
Tetrasporophyte
2N tetrasporophyte
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3. Class: Florideophyceae
4. Order: Gigartinales
Genus: Constantinea
3.Class: Florideophyceae
4. Order Gigartinales
Genus Endocladia
- uniaxial
- thallus covered with
bumps (antiherbivory)
- very high intertidal
- saxicolous
- can facilitate recruitment
of other algae (Fucoids)
- cup and
saucer algae
- intertidal to
subtidal
Other spp in Gigartinales are important for carageenan production
3. Class: Florideophyceae
5. Order: Corallinales
• Isomorphic alternation of
generations
• Reproductive structures in
conceptacles
• Cell walls impregnated with CaCO3
(
(anti-herbivory)
i h bi
)
• More calcified red algae than any
other algae
• Ecological importance: stabilize
reefs, induce invert settlement
• Especially sensitive to desiccation
– occur IN tidepools (not nearby
surfaces)
3. Class: Florideophyceae
5. Order: Corallinales
• Fossils from 500 million years ago
• A crustose coralline alga
g in AK is
~700 years old – oldest alga known
on earth?!!
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How do coralline algae become calcified?
Coralline Algae and Global Warming
Carbon reaction in seawater:
What is known:
• Sequestering of Calcium ions from the water column, synthesis
of calcium carbonate (CaC03) into cell wall
• Synthesis of calcium carbonate (precipitation) requires high
pH (basic/alkaline)
• High
g rates of
fp
photosynthesis
y
correlate with high
g rates of
f
calcification
CO2 + H20
H2C03
Carbonic acid
more acidic
• Highest in young tissue (growth at apices and intergenicula)
Bicarbonate
Increasing CO2
pushes
h RXN in
i this
hi
2
CO3 + H+
Carbonate
more basic
direction
• Photosynthesis may raise the pH immediately outside cells
• Calcification is 10x faster in the light than the dark
HCO3 + H+
• Global warming likely to lead to a lower in pH (raise in acidity
of the world’s oceans
• Acidic environment is bad for calcification process  big
(complicated) trouble for calcified critters and algae!!
• Lots of current research on this
3. Class: Florideophyceae
5. Order: Corallinales
Supporting cell acts as an auxiliary cell
Carpogonial branches located in conceptacles
Gominoblast initiated from a fusion of cells in carpogonial branch
Spermatium
Geniculate corallines
Intergeniculum
(hard part
between genicula)
2N carpospores
on gonimoblast
filaments
Non-geniculate corallines
Supporting
Cell
Crustose
Encrusting
Carpogonial
Branch
Geniculum
(flexible joint)
• upright
•articulated
or
Unattached
Branching
Tricogyne
Carpogonium
1N female gametophyte
2N carposporophyte on
1N female gametophyte
6
3. Class: Florideophyceae
5. Order: Corallinales
Genus Bossiella
3. Class: Florideophyceae
5. Order: Corallinales
Genera Corallina
- Common intertidaly
- Intergenicula
typically “heartshaped”
- Common intertidally
- Conceptacles
p
on tips
p
-Finely branched, more
so than Bossiella or
- Conceptacles in pairs
on the face of a
segment, not margins
Calliarthron
- Intergenicula are thin
and tubular and smaller
than those on Bossiella
or Calliarthron
3.Class: florideophyceae-6767 species
5. Order Corallinales- 725 species
Genus Caliarthron
-Common intertidally
-Intergenicula
n
g n u typically
yp
y
“wingnut-shaped”
- Intergenicula are
larger than Corallina
3. Class: Florideophyceae
5. Order: Corallinales
Genus Lithothamnion
• rhodolith
•unattached
• free-living
• non- geniculate form
g
habitat for lots of inverts!
• biogenic
- Conceptacles mainly on
margins of segments
- Calcareous sections are
larger than Corallina
7
Distributional Limits
World Rhodolith Distribution
•Depth -light limited in deep, dessicated in shallows
•Water motion-need intermediate amount of hydraulic energy
•Sedimentation -smothered by fine sediments
low
DISTURBANCE
high
Rhodolith Beds
New Report
Foster 2001
Biogenic Ecosystems – Foundation Species
Kelp Forests
Seagrass Meadows
buried by
siltation
‘intact’
rhodolith
bed
‘reduced’
size, cover
sand
Rhodolith beds, reefs that rock and roll
Coral Reefs
Rhodolith Beds
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What are other important features of rhodolith beds?
Form complex habitat for a
variety of orgamisms
Cover extensive ares of
the seafloor, globally
distributed
Rhodolith Bed Community
Cryptofauna/Infauna
Epifauna/Epiflora
• hard bottom species
• soft bottom species
Seasonal Macroalgal Species
Scinaia confusa
Halymenia hollenbergii
Sporochnus bolleanus
Kallymenia pertursa
9
Growth Rate
L. muellerii
0.6 mm/yr
L. margaritae 5.6 mm/yr
S. trichotomum 7-8 mm/yr
Catalina rhodoliths
1.6 mm/yr
Internal Banding
New
growth
Coralline algae as global palaeothermometers
Baja California
Banding
reflects
sea surface
temperature
signal using
SrCO3 and
M CO3
MgCO
They are found
in Pleistocene
and Pleiocene
fossil deposits
Lithothamnion glaciale
Kamenos et al. 2008
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Post-fertilization in a nutshell
auxiliary cell?
No
Yes
Before
After
Ceramiales –
Ooblast?
(has ooblast)
Yes. Gigartinales –
Auxiliary cell is anywhere
in thallus
No. Rhodymeniales –
Fusion with carpegonium
Nemaliales –
Gonimoblasts from
carpegonium
Corallinales –
Fusion of
carpegonium with
carpegonial
branch
* Supporting cell acts
as auxiliary cell
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