Chlorophyta (green algae)
Lecture 8
OVERVIEW
Eubacteria & Protists
• Cyanophyta
• “Phytoplankton”
• Chlorophyta, Phaeophyta, Rhodophyta
Vascular Plants (Gymnosperms & Angiosperms)
• Seagrasses – Hydrocharitaceae & Potamogetonaceae
• Saltmarshes – Poaceae, Juncaceae, etc
• Mangroves – Rhizophoraceae, Avicenniaceae
• Beach & Dune plants
Fan-Shaped Phylogenetic Tree
“MACRO-ALGAE” = seaweeds
• Divisions:
– Chlorophyta (green)
– Phaeophyta (brown)
– Rhodophyta (red)
• Separated on basis of pigments (color)
• Evolved 900-600 Mio (Cambrian)
• Continental Margins – Rocky shores or
lagoons predominantly.
Div Chlorophyta
– Chlorophyta (green) – 900 spp (about 10% of
known spp, rest are freshwater).
– Ancestor of terrestrial plants (Kingdom
Plantae)
– Chl a + b, (B-carotene, xanthophylls –
photoprotective role)
– Uni-nucleate, also Multi-nucleate (siphonous)
– 6 Orders: e.g. Ulvales, Cladophorales,
Caulerpales
– Cosmopolitan and tropicals
Algal pigments
Pigment Molecules
CHLOROPHYLL
CAROTENES
Enteromorpha
Epiphytes
Chaetomorpha
Cladophora
Ulva
Halimeda
Enteromorpha
Caulerpa
THALLUS
COARSLEY - BRANCHED
SHEET
ENCRUSTING
FILAMENT
JOINTED CALCAREOUS
THICK LEATHERY
Form - Function
Incr productivity
Ulva
Halimeda
Enteromorpha
Caulerpa
Why simple = more productive?
• Nutrient uptake, waste removal in single
cell relies on diffusion, some active
uptake.
• No translocation within plant necessary
• Reduce boundary layer effects – promotes
diffusion into cell.
• No metabolic losses to structural tissues
• Faster life-cycle (hrs – days)
Boundary Layers
• Zone of little-no flow
around an
object/surface.
• Inhibits diffusion
• Movement promotes
flow past object,
breaking down
boundary layer
• Important for algal
nutrient and CO2
uptake
Boundary Layers
• Zone of little-no flow
around an
object/surface.
• Inhibits diffusion
• Movement promotes
flow past object,
breaking down
boundary layer
• Important for algal
nutrient and CO2
uptake
Diffusion across cells/membranes
Simple Structure and Succession
• r vs K selected lifestrategies
• r = Ulva, Enteromorpha
• K = Halimeda, Penicillus
• Taxonomy generally
from simple to complex:
single cells, filaments,
multi-filament, corticated,
specialized structures
Chlorophyte taxonomy
• Number of classes has increased from 1 in
1903, to 3 in 1990, to 10 in 1995.
• Based on EM (2 types of cell division, flagellum
ultrastructure) and RNA sequence in chloroplast
and mitrochondria, DNA in nuclei.
• Ancestors of terrestrial vascular plants
• Class Prasinophyceae – single cell (plankton).
• Class Chlorophyceae – 6 of 15 orders have
seaweeds.
Thallus organization
•
•
•
•
•
•
Unicell flagellate – Chlamydomonas
Colonial flag – Volvox
Tetrasporal, Coccoid, Sarcinoid groups
Filamentous – Ulothrix
Thallose – Ulva
Siphonous - Caulerpa
Evolution
VOLVOX
Chlamydomonas
Spyrogyra
Chara - muskgrass
Chlorophyceae taxonomy (recent)
• Or. Ulvales (Ulotrichales) – Fam. Ulvaceae + 5
others
• Cladophorales – Cladophoraceae +
Anadyomenaceae
• Acrosiphoniales – 1 order
• Siphonocladales – Siphonocladaceae,
Boodleaceae, Valoniaceae
• Caulerpales – Bryopsidaceae, Caulerpaceae,
Codiaceae, Udoteaceae, + 2 others (FW)
• Dasycladales – Dasycladaceae +
Acetabulariaceae
Cl. Chlorophyceae taxonomy
Dawes, pg 122
Or. Ulvales
Ulva
Or. Ulvales
Enteromorpha
Or. Cladophorales
Cladophora
Or. Cladophorales
Anadyomene
Or. Siphonocladales
Boodlea
Siphonocladus
Or. Siphonocladales
Holdfast
Valonia
Or. Caulerpales
Or. Caulerpales
Or. Caulerpales
Caulerpa mexicana
Or. Caulerpales
Or. Caulerpales
Codium
Or. Caulerpales - rhizophytic
“root-ball”
Or. Caulerpales
Or. Caulerpales
Halimeda
Or. Dasycladales
Dasycladus
Batophora
Or. Dasycladales
Acetabularia
MS Chlorophyta (1957)
• Ulvales – Enteromorpha flexuosa, E.
lingulata, E. plumosa, Ulva lactuca
– Ulotrichaceae – Stichooccus marinus
– Chaetophoraceae – Entocladia viridis,
Phaeophila floridaerum, Ulvella lens
• Cladophorales – Cladophora fascicularis,
C gracilis, Rhizoclonium riparium.
• Siphonales – Osterobium queketti
• about 12 species…
Chlorophyta in the “news”
• Ulva and Enteromorpha abundance increases in Baltic
Sea / Adriatic Sea due to eutrophication – smothering
seagrass and mudflats, smelly wrack driving tourists from
beaches.
• Enteromorpha bloom in China largest ever recorded –
thought to originate from aquaculture.
• Caulerpa taxifolia – Killer Algae escapes Monaco
aquarium. Covers 10’000acres in Med within <10years.
• Halimeda and Dictyota (brown) smother Fla Keys reef
tract – response to eutrophication from septic systems?
• Acetabularia used in studies of abiotic and genetic cues
for algal development.
Chlorophyta in the “news”
• Ulva and Enteromorpha abundance
increases in Baltic Sea / Adriatic Sea due to
eutrophication – smothering seagrass and
mudflats, smelly wrack driving tourists from
beaches.
Enteromorpha bloom seen from
space! (Liu et al. 2009)
Enteromorpha bloom seen from
space! (Liu et al. 2009)
Cause: more aquaculture of seaweed (Porphyra) for
sushi. Green algae a by-product. Ocean circulation
moved bloom of green algae north and east, so accumulates
onshore far from source population.
http://aquat1.ifas.ufl.edu/seagrant/cautax2.html
Chlorophyta in the “news”
• Caulerpa taxifolia – Killer Algae escapes
Monaco aquarium. Covers 10’000acres in
Med within <10years.
Chlorophyta in the “news”
• Halimeda and Dictyota (brown) smother Fla
Keys reef tract – response to eutrophication
from septic systems?
Orange Bay, Jamaica. Eutrophication from sugar cane fields
SAND KEY, FLA
Chlorophyta in the “news”
• Acetabularia used in studies of abiotic and
genetic cues for algal development.
Chlorophyta and Coral reefs
Coral Reefs
Acropora - staghorn
Acropora - Elkhorn
Porites – finger coral
Montastrea – boulder coral
Global Distn
Reef Zonation
Lagoon
Back-reef
Reef flat
Rim
Spur-andgroove
Slope
Deep plain
GBR – Heron Island
Reef Plant-Animal interactions
• "The Living Coral Reef is one of the most diverse and complex
communities in the world".
• The Florida Keys coral reef community presents approximately 107
species of corals (over 80% of all coral species of the tropical Atlantic)
and over 500 species of tropical fish.
• The interaction and interdependence among all these organisms is so
critical that many reef inhabitants cannot live outside the reef zone
(e.g. Grunts).
• Sunlight, water, fish, invertebrates and plants play major roles in the
sustaining and building of the reef:
–
–
–
–
Sunlight --> Photosynthesis.
Water --> Brings nutrients, O2, CO2.
Fish --> Excrements help build and cement reef.
Invertebrates and Plants --> Secrete calcium carbonate sediments that
cement reef; food source; also graze the reef algae, creating space for
corals to get established and grow.
http://www.reefrelief.org/ecosystem.html
Reef formation
• Fringing reefs – Fla
Keys
• Barrier Reefs – GBR,
Belize
• Atoll reefs – Pac
volcanic islands
Reefs in peril
1960’s
2000’s
In <40 ys
more than
50% of reefs
have
declined
globally!!!!!
Importance of herbivores:
fish, urchins, snails
Lytechinus die-off Caribbeanwide in 1983 results in
macroalgal blooms on reefs
Bottom-up Vs Top-down
• Coral dominance under low nutrient, high grazer
abundance.
• Algal dominance under high nutrient and/or low
grazing.
• Bottom-up = eutrophication. Algae out-grow
corals and smother recruits.
• Top-down = overfishing of large fish predators
AND herbivores. Trophic cascade, results in too
few micrograzers to check algal growth.
Seen this before in seagrasses – remember Heck and Valentine 2006paper?
Summary
•
•
•
•
Chlorophyta – ancestors of vascular plants
10% marine, high tropical diversity
Unicell -> Filamentous -> Siphonous
Ulva, Enteromorpha cosmopolitan
indicators of eutrophication
• Coral reef algae and “alternate stable
states”: eutrophication vs trophic cascade