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 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

UlvaEnteromorpha HalimedaCaulerpa

THALLUS SHEET COARSLEY - BRANCHED JOINTED - CALCAREOUS THICK - LEATHERY FILAMENT ENCRUSTING

Form - Function Incr productivity

UlvaEnteromorpha HalimedaCaulerpa

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 CO 2 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 CO 2 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 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. Ulvales Enteromorpha

Or. Cladophorales Cladophora

Or. Cladophorales Anadyomene

Or. Siphonocladales Boodlea Siphonocladus

Or. Siphonocladales Holdfast Valonia

Or. Caulerpales

Caulerpa mexicana

Or. Caulerpales

Codium

Or. Caulerpales - rhizophytic “root-ball”

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)

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.

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 - staghornPorites – finger coral Acropora - ElkhornMontastrea – boulder coral

Global Distn

Reef Zonation Lagoon Back-reef Reef flat Rim Spur-and- groove 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.

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 Caribbean- wide in 1983 results in macroalgal blooms on reefs

Alternate Stable States Coral dominated Nutrient poor, lots grazers Coral dominated Nutrient elevated, lots grazers Algal dominated Nutrient poor, few grazers Algae dominated Nutrient rich, few grazers

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