Chlorophyta (green algae) Lecture 8. OVERVIEW Eubacteria & Protists Cyanophyta “Phytoplankton”...
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Transcript of Chlorophyta (green algae) Lecture 8. OVERVIEW Eubacteria & Protists Cyanophyta “Phytoplankton”...
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
Epiphytes
Cladophora
Enteromorpha
Chaetomorpha
Ulva Enteromorpha
Halimeda Caulerpa
THALLUS
SHEET
COARSLEY - BRANCHED
JOINTED -CALCAREOUS
THICK -LEATHERY
FILAMENT
ENCRUSTING
Form - Function
Incr productivity
Ulva Enteromorpha
Halimeda 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 life-strategies
• 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
Chlamydomonas
VOLVOX
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. UlvalesEnteromorpha
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) forsushi. Green algae a by-product. Ocean circulationmoved bloom of green algae north and east, so accumulatesonshore far from source population.
Chlorophyta in the “news”• Caulerpa taxifolia – Killer Algae escapes
Monaco aquarium. Covers 10’000acres in Med within <10years.
http://aquat1.ifas.ufl.edu/seagrant/cautax2.html
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 Porites – finger coral
Acropora - Elkhorn Montastrea – boulder coral
Global Distn
Reef Zonation
LagoonBack-reefReef flatRimSpur-and-
grooveSlope
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 ysmore than 50% of reefs have declined globally!!!!!
Importance of herbivores: fish, urchins, snails
Lytechinus die-off Caribbean-wide 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