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Chapter 6 - Seaweed

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Chapter 6 - Seaweed

  2. 2. Seaweed and Plants  Most seaweeds are considered “plants” or plant-like
  3. 3. Seaweed and Plants  Primary Producers: Organisms that produce organic matter from CO2 usually by photosynthesis
  4. 4. Seaweed and Plants  Most seaweeds, although some are parasitic to other seaweeds  Transform solar energy into chemical energy in the form of organic matter  Produce oxygen for organisms both on land and in the ocean
  5. 5. Multicellular Algae The Seaweeds
  6. 6. Multicellular Algae  Seaweed: large, multicellular algae  Most familiar type of marine algae  Some biologists prefer the name macrophytes or macroalgae  All multicellular and eukaryotic
  7. 7. Multicellular Algae  Takes structure, types of pigments and stored food products into consideration  Lack highly specialized structures and reproductive mechanisms like terrestrial plants  Vary in shapes and sizes
  8. 8. Multicellular Algae  Thallus: the complete body of a seaweed  Lack true roots, stems, and leaves
  9. 9. Multicellular Algae  Blades: The leaf-like, flattened portions of the thallus of seaweeds  have a large surface area  main photosynthetic region  not true leaves, no veins  the upper and lower surfaces of blades are identical to each other
  10. 10. Multicellular Algae  Pneumatocysts: Gas-filled bladders that sometimes keep the blades close to the sea surface  maximizing the exposure of blades to the sunlight  gases include carbon monoxide
  11. 11. Multicellular Algae  Stipe: stem-like support structure of seaweeds from which the blade originates  long and tough in large kelps
  12. 12. Multicellular Algae  Holdfast: root-like structure in seaweeds  attaches the thallus to the bottom  not involved in significant water or nutrient absorption  do not penetrate through sand or mud like roots do  water and nutrients are picked up directly across the surface
  13. 13. Multicellular Algae  the stipe and holdfast usually lack tissues specialized for water and nutrient transport
  14. 14. Types of Seaweed
  15. 15. Types of Seaweed  Three types: green, brown and red  not always easy to recognize visually because of pigment proportions  primarily limited to areas of shallow water and rocky shores
  16. 16. Green Algae  Chlorophyta  most live in freshwater and terrestrial environments  the group from which embryophytes (higher plants) emerged  only 10% are marine
  17. 17. Green Algae  most have a simple thallus  pigments and food reserves are the same as terrestrial plants  chlorophyll is not usually masked  thallus is usually a bright green color  may be branched or unbranched
  18. 18. Green Algae Examples  Enteromorpha  Sea Lettuce
  19. 19. Green Algae Examples  Ulva  Valonia
  20. 20. Green Algae Examples  Caulerpa  Halimeda
  21. 21. Brown Algae  Phaeophyta  color varies from olive green to dark brown  due to yellow-brown pigments over chlorophyll  particularly fucoxanthin
  22. 22. Brown Algae  almost all 1,500 species are marine  almost always the dominant primary producers on temperate and polar rocky coasts
  23. 23. Brown Algae  include largest and most complex seaweeds  belong to the group Heterokontophyta, a eukaryotic group distinguished by chloroplasts surrounded by four membranes  play an important role in food supplies and environment development
  24. 24. Kelps  most common and complex of all brown algae  about 30 different species  most found below the low tide level in temperate and sub-polar latitudes  provide food and shelter for many other organisms
  25. 25. Kelps  Some kelps  consist of a single large blade  ex laminaria  harvested for food in several parts of the world  several blades may grow from a single holdfast  in some species blade is split or branched  in some species the blade can be up to 25m long (82 ft)  some deep ocean species have a stipe up to 30m high (almost 100ft)
  26. 26. Kelps  macrocystis  largest kelp  enormous holdfast  several stipes  elongated blades  at base of each blade is a pneumatocyst  can grow up to 50cm per day under optimal conditions
  27. 27. Kelps Forests  Kelp bed/forest: many individual kelps with fast-growing and intertwining stipes  colder waters of the North and South Pacific  harvested by chopping off the tops for the extraction of several natural products  among the richest, most productive environments in the marine realm
  28. 28. Kelp Forests
  29. 29. Other Brown Algae  Fucus  Sargassum
  30. 30. Red Algae  Rhodophyta  more species of red than green and brown combined  have red pigments called phycobillins  mask chlorophyll  most species are actually red
  31. 31. Red Algae  very few of the 4,000 species live in freshwater or soil  inhabit most shallow- water marine environments  harvested for food and for the extraction of various products
  32. 32. Red Algae  most filamentous, many branches with intricate patterns  increases light- gathering surface for the seaweed  dense clumps are more common  some have lost almost all traces of chlorophyll  became parasitic
  33. 33. Coralline Red Algae  red algae that deposit calcium carbonate within their cell walls  important to several marine environments  creates smooth or rough encrusting growths on rocks  actively involved in the formation and development of coral reefs
  34. 34. Other Red Algae  Palmaria  Chondrus
  35. 35. Nori
  36. 36. Nori  Japanese name for various edible seaweed species of red algae  The term nori also commonly used to refer to food products created from these “sea vegetables”
  37. 37. Nori  finished products are made by a shredding and rack- drying process that resembles paper-making  Japan, Korea and China are the current major producers valued up to $2 billion per year
  38. 38. Seaweed Reproduction
  39. 39. Seaweed Reproduction  usually asexual  fragments of the thallus can usually grow into new individuals  ex. sargassum
  40. 40. Seaweed Reproduction  some produce spores  typically one-celled, reproductive unit capable of giving rise to a new individual without sexual fusion
  41. 41. Sexual Reproduction  4 basic types of life histories:  diploid sporophyte  alternation of generation of three generations  animal-like reproduction  haploid thallus
  42. 42. Sexual Reproduction  Factors affecting the number or quality of spores/gametes  amount of nutrients in the water  temperature of the surrounding environment  day length/amount of light received
  43. 43. Economic Importance
  44. 44. Economic Importance  mariculture: the farming of seaweed
  45. 45. Economic Importance  phycocolloids: gelatinous chemicals produced by seaweeds that are used in food production and product manufacturing  form viscous suspensions or gels (even at low concentrations)
  46. 46. Algin  stabilizer and emulsifier  keeps smooth  used in: ice cream, shampoos, dairy topping, cosmetics  major source is giant kelp  harvested in California
  47. 47. Carageenan  obtained from red algae like Irish moss  valued as an emulsifier  used in: dairy products, puddings,
  48. 48. Agar  jelly like substance  used to protect canned meats, in low calorie foods, laxatives, cosmetics  used as a medium in research  especially for DNA analysis  obtained from red algae
  49. 49. Angiosperms Flowering Plants
  50. 50. Angiosperms  have true roots, stems and leaves  specialized tissues  only seagrasses are truly marine
  51. 51. Angiosperms - Seagrasses  adapted to marine life  horizontal stems called rhizomes  pollen carried by currents  Eelgrass is the most commonly distributed
  52. 52. Angiosperms – Salt-Marsh Plants  Cordgrasses - true members of the grass family  not true marine plants, tolerant of salt  live in salt marshes and other soft-bottom environments  offer protection against erosion and provide natural water purification  Halophytes - salt tolerant plants  ex. pickle weed
  53. 53. Angiosperms - Mangroves  Trees and shrubs adapted to live along tropical and subtropical shores around the world  land plants that can tolerate salt  form lush forests in places like Florida  can survive in both fresh and salt water environments