Algae seaweeds
- 2. Why is algae so important?
- 3. Carbon sink Indicator Fertilser species Weather Food telling production device Why? Nursery Coastal habitat defence Food for Symbiotic marine relationships species
- 4. Kingdom • Protoctista Characteristics • Single celled to mutlicelled • Autotrophic • Form reproductive structures • Aquatic • Have flagellum at some point in their life • Many contain organelles which store and synthesise starch (pyrenoids) Types • Unicellular • Colonial • Filamentous • multicellular
- 5. •7 Phylum •Based on •Colour •Type of Chlorophyll •Food Storage substance •Cell wall composition •Focus on Multicelled or Macroalgae •3 Phylum •Chlorophyta •Phaeophyta •Rhodophyta
- 8. Green Algae (Chlorophyta) • Land based plants have arisen from evolution of green seaweeds. • Mostly freshwater species (~700 marine species) • Some species common in nearshore environments • Structurally simple • Many unicellular or filamentous • Photosynthetic pigments and energy storage products similar to higher plants • May have shared a common ancestor with plants • No pigments to mask green color Habitat • Many live as epiphytes • Some species bore into calcium carbonate shells
- 9. Examples of Green Algae Enteromorpha • Often found in polluted areas; Used as bioassay tool Ulva (Sea Lettuce) • Found in areas with high nutrient levels Valonia (Bubble Algae) • Tropical and subtropical Caulerpa • Invasive species (C. taxifolia) Codium (Dead Man’s Fingers) • Multinucleated Halimeda • Calcareous alga
- 10. • Brown Algae (Phaeophyta) • Mostly marine (~1500 species) • Includes largest and most complex algae - kelps • Especially abundant on rocky coasts in temperate and polar regions • Dominant accessory pigment is fucoxanthin • Imparts yellow-brown to brown color • Structurally simple to complex • Some with simple flat thalli (Padina) • Others with complex structures • Holdfast, stipe, blade, pneumatocysts • Includes fast growing species • Some kelps can grow up to 50 cm per day! • Most anchored to substrate • Some float (Sargassum – Sargasso Sea) • Common in intertidal zone • Good at withstanding mechanical stress • Tolerant of exposure and desiccation
- 11. Examples of Brown Algae (Phaeophyta) • Examples • Fucus (Rockweeds) • Intertidal and subtidal species; Ecologically important • Laminaria (Kelp) • Some species consist of a single blade • Commonly used for food • Postelsia (Sea Palm) • Usually on exposed rocky shorelines • Egregia (Feather Boa) • Common on rocky Pacific coast • Pelagophycus (Elk Kelp) • Large float • Macrocystis (Giant Kelp) • May reach 100 m and grow up to 50 cm day-1 • Most common in cold water
- 12. D. Red Algae (Rhodophyta) Mostly marine (~4000 species) Common in shallow water but also found in depths up to 200 metres. Contain accessory pigments called phycobilins (phycoerythrin, phycocyanin) Structurally less complex than brown algae • Most are filamentous • Much smaller than large brown algae May be heterotrophic or parasitic May incorporate calcium carbonate into tissues (Why?) • Coralline red algae • May be important in formation and cementing of coral reefs • May contribute to formation of carbonate sand • Some encrusting, others arborescent Many are commercially important
- 13. Next session: •Bring life cycle of Red, Green and Brown seaweed. •Box Justification
- 14. Angiosperms
- 15. Key Features •Marine flowering plants •NOT seaweeds •Salt tolerant or able to withstand constant emersion •Oxygen absorbed from water •Produce rhizome roots •Only able to photosynthesise on leaves
- 17. Habitats
- 18. Eelgrass beds