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Algae ii

  1. 1. ALGAE Multicellular Protist or Primitive Aquatic Plant? Cyanobacteria Plant-like Protists
  2. 2. Algae
  3. 3. Algal Characteristics • Vary in size from nanoplankton (< 2 µm cyanobacteria ) to Giant kelps (> 70 m long). Possess a cell wall. • Contain pigments • chlorophylls a, and many often have another chlorophyll, like b, c, or d and accessory red, blue and brown photosynthetic pigments
  4. 4. Algae - What are they? • Primitive plants • No true roots, only attachment structures (Holdfasts) • Produce spores (not seeds)– motile or non-motile • Most have sexual and asexual reproduction • Non-vascular, do not possess an internal transport system.
  5. 5. Algae vs. ‘REAL’ plants Similarities and differences: • Both are photoautotrophic • Similar metabolic functions to higher plants eg. photosynthesis • different anatomical structures, reproductive structures. • different reproduction. • No true roots, stems leaves. • Non-vascular, therefore nutrient uptake over surface. And wastes washed away from surface by aquatic environment
  6. 6. Classification - a few Algal Phyla • Cyanophyta: Blue-green or Cyanobacteria. Prokaryotic. Marine, FW and terrestrial. • Pyrrophyta, Chrysophyta, Euglenophyta: Marine and FW phytoplankton – Photosynthetic Protists. KINGDOM PLANTAE: • Rhodophyta: Red algae. Mostly marine. • Phaeophyta: Brown algae. Mostly marine. • Chlorophyta: Green algae. Marine, FW and terrestrial.
  7. 7. The role of these pigments is to absorb light - In water the problem is that red and violet wavelengths do not penetrate the vertical column very well. So Chlorophylls do not work well at greater depths. Algae that inhabit greater depths do so with the help of accessory pigments, these algae take on a variety of colours.
  8. 8. -Chlorophyta – Contain Chlorophyll a + b. So green wavelengths reflect. They store their products of photosynthesis as starch. - Phaeophyta – Contain Chlorophylls a + c as well as an accessory pigment Fucoxanthin. So yellow and brown wavelengths reflect. Store food as starch and as oil. Rhodophyta - Contain Chlorophyll a + (d) as well as accessory pigment Phycobillins. These phycobillins are specialized for absorbing blue light, which allows them to inhabit the deepest depths.
  9. 9. Where do Algae live? Marine habitats: • seaweeds, phytoplankton Freshwater habitats: • streams, rivers, lakes and ponds Terrestrial habitats: • stone walls, tree bark, leaves, in lichens, on snow
  10. 10. Marine Biomes
  11. 11. Freshwater habitats
  12. 12. Terrestrial habitats
  13. 13. How do algae function? Photoautotrophs: 6C02 + 6H20  C6H1206 + O2 • use carbon, light, and water • produce chemical energy (carbohydrates) and produce O2 as a by-product. • Basic storage products: carbohydrates as starch or converted to fats as oil • Require nutrients: N, P and minerals.
  14. 14. Why are ALGAE important? Ecological importance of algae a) Production of Oxygen as ‘by- product’ of photosynthesis: • All aerobic heterotrophic organisms require O2, • e.g. fungi and animals need O2, to run cellular respiration to stay alive b) Production of biomass: • autotrophic organisms - represent the base of the food chain/web, particularly in aquatic environments.
  15. 15. Algal diversity • Algae ARE NOT a single phylogenetic grouping, but give rise to several independent evolutionary lines. Our focus is on “CHLOROPHYTA” as it is believed to give rise to the terrestrial plants. • Very diverse, very well adapted to certain environments, • Range from unicellular,  colonial  multicellular • e.g. marine, freshwater, terrestrial; • often extreme habitats • CHLOROPHYTES share Similarities to true plants – Same two chlorophylls a and b, Store products of photosynthesis as starch, cell wall primarily made of cellulose.
  16. 16. Algal construction types : Morphology 1. Unicellular algae 2. Colonies 3. Filaments 4. Multicellular
  17. 17. Unicellular algae • ‘Microalgae’ - some may form colonies
  18. 18. Algal colonies e.g. Chlorophyta: Volvox (Order Volvocales) - 500-5000 cells per colony. - Colonies spherical up to 1.5 mm diameter. - Individual cells surrounded by a mucilaginous sphere - marine and freshwater http://www.youtube.com/watch?v=w8O4OolGcPg
  19. 19. Volvox colony – with Daughter colonies
  20. 20. Filamentous algae • Unbranched filaments • Branched filaments • Different branches can have different morphologies:
  21. 21. MULTICELLULAR - Macroscopic
  22. 22. Why are algae important? • Primary producers, basis of food webs, “FORESTS/GRASSES OF THE SEA” • Pioneer Species: on rocky shores, mudflats, hot springs, lichen communities, 'snow algae' • O2 production and carbon fixation in aquatic habitats. • Rare autotrophic organisms in extreme habitats.
  23. 23. Examples of ecological importance • Red tides, other algal blooms • Hot springs • Kelp forests • Rocky shore ecology • Aquaculture
  24. 24. Cyanobacterial bloom
  25. 25. Extreme halophytes
  26. 26. Uses of Seaweeds • Present • Food • Hydrocolloids and some chemical substances • Fertilizers • Potential • Source of energy/compost by digestion • Waste-water treatment
  27. 27. Algae as human food • Annual value is about US$6 billion • Main market and production area is Asia • “Mariculture” has become very important • Main high-value species are ‘Nori’, ‘Kombu’ and ‘Wakame’ (Porphyra, Laminaria and Undaria) • Mainly used as a subsidiary food: adding relish, taste and 'feel' to food • European and North American market presently very small but has potential
  29. 29. Phylum Chlorophyta • Green algae • 7000 diverse species • Biologist reason that green algae give rise to land plants. • Both green algae and land plants have chlorophyll a and B as well as carotenoids and store food as starch • Both have walls made of cellulose
  30. 30. Phylum Phaeophyta • 1500 species of Brown algae • Mostly marine and include seaweed and kelp • All are multicellular and large (often reaching lengths of 147 feet) • Individual alga may grow to a length of 100m with a holdfast, stipe and blade • Used in cosmetics and most ice creams
  31. 31. Phylum Rhodophyta • 4000 species of RED Algae • Most are marine • Smaller than brown algae and are often found at a depth of 200 meters. • Contain chlorophyll a and C as well as phycobilins which are important in absorbing light that can penetrate deep into the water • Have cells coated in carageenan which is used in cosmetics, gelatin capsules and some cheeses
  32. 32. Phylum Euglenophyta • 1000 species of Euglenoids • Have both plantlike and animal-like characteristics • Fresh water
  33. 33. Other Phylum Representatives Diatoms – used in detergents, paint removers, toothpaste Dinoflagellates – red tides Important in the formation of petroleum products Golden algae