Chapter 6 - Seaweed

Marine Biology - Chapter 6 Seaweeds and Marine Plants

1. CHAPTER 6 SEAWEED AND PLANTS

2. Seaweed and Plants Most seaweeds are considered “plants” or plant-like

3. Seaweed and Plants Primary Producers : Organisms that produce organic matter from CO2 usually by photosynthesis

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. Multicellular Algae The Seaweeds

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. 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. Multicellular Algae   Thallus : the complete body of a seaweed Lack true roots, stems, and leaves

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. 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. Multicellular Algae Stipe : stem-like support structure of seaweeds from which the blade originates long and tough in large kelps

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. Multicellular Algae the stipe and holdfast usually lack tissues specialized for water and nutrient transport

14. Types of Seaweed

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. Green Algae Chlorophyta most live in freshwater and terrestrial environments the group from which embryophytes (higher plants) emerged only 10% are marine

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. Green Algae Examples Enteromorpha Sea Lettuce

19. Green Algae Examples Ulva Valonia

20. Green Algae Examples Caulerpa Halimeda

21. Brown Algae Phaeophyta color varies from olive green to dark brown due to yellow-brown pigments over chlorophyll particularly fucoxanthin

22. Brown Algae almost all 1,500 species are marine almost always the dominant primary producers on temperate and polar rocky coasts

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. 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. 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. 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. 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. Kelp Forests

29. Other Brown Algae Fucus Sargassum

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. 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. 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. 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. Other Red Algae Palmaria Chondrus

35. Nori

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. 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. Seaweed Reproduction

39. Seaweed Reproduction usually asexual fragments of the thallus can usually grow into new individuals ex. sargassum

40. Seaweed Reproduction some produce spores typically one-celled, reproductive unit capable of giving rise to a new individual without sexual fusion

41. Sexual Reproduction 4 basic types of life histories: diploid sporophyte alternation of generation of three generations animal-like reproduction haploid thallus

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. Economic Importance

44. Economic Importance mariculture : the farming of seaweed

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. Algin stabilizer and emulsifier keeps smooth used in: ice cream, shampoos, dairy topping, cosmetics major source is giant kelp harvested in California

47. Carageenan obtained from red algae like Irish moss valued as an emulsifier used in: dairy products, puddings,

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. Angiosperms Flowering Plants

50. Angiosperms have true roots, stems and leaves specialized tissues only seagrasses are truly marine

51. Angiosperms - Seagrasses adapted to marine life horizontal stems called rhizomes pollen carried by currents Eelgrass is the most commonly distributed

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. 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