1. Multicellular Primary Producers: Seaweeds and Plants
Chapter 6
Multicellular Primary Producers:
Seaweeds and Plants

2. BBC films

3. Seaweeds NOT PLANTS! (or weeds) More accurately, Eukaryotic
Multicellular algae
Primary producers
No roots, stems, leaves
Difference reproductive mechanisms than plants
More accurately,
MACROPHYTES or
MACROALGAE

4. Seaweed Structure Thallus – the entire body
Blades – flattened, leaf-like portion; large area for photosynthesis (NOT leaves)
Pneumatocysts (floats) – gas- filled bladders (usually carbon monoxide) that keep blades close to surface
Stipe – stem-like structure used for support; not used for transport of water or nutrients
Holdfast – attaches the thallus to the bottom (not used in transport)
Thallus – entire body

5. Types of Seaweeds

6. Types of Seaweeds Classified based upon their pigments
Revealed upon chemical analysis
Green (phylum Chlorophyta)
Brown (phylum Heterokontophyta; Class Phaeophyta)
Red (phylum Rhodophyta)

7. Green Algae - Chlorophyta
Only 10% of species (around 700) are marine
Most marine species are unicelluar
More dominant in estuarine and tide pool areas
Tolerate salinity variation
Land plants believed to have evolved from them
Examples:
Enteromorpha
Ulva
Caulerpa
Codium
Halimeda

8. Enteromorpha Filamentous Thallus is tube shaped.
Common in bays, estuaries, exposed coastlines.
Re-colonizers that can tolerate polluted areas
Photo: Enteromorpha prolifera – Elkhorm Slough, CA by Judith Connor
Photo: Enteromorpha intertinalis -- Stillwater Cove, Pebble Beach CA

9. Ulva Sea lettuce Not a distinct genera from Enteromorpha
Forms sheets but only in the presence of bacteria or other algal species
Widespread, first-colonizers on new substrate
© 2006 Jan Holmes

10. Caulerpa Composed of multiple think tubes (siphons) Multinucleated
Proliferative, especially in marine aquariums
Tropical/subtropical
Caulerpa sp.
Caulerpa racemosa

11. Codium
“Multinucleated filaments woven into a spongy, branching thallus”
Eaten by sea slugs
Chloroplasts of the algae can remain alive inside these animals

12. Halimeda Calcareous green alga
Play an important role in the build up of tropical reefs.

13. Brown Algae - Phaeophyta
Almost all 1,500 species are marine
Can dominate temperate and polar rocky coasts
Vary in complexity (few celled to kelps)
Color varies: olive green to dark brown
Due to presence of yellow-brown pigment, fucoxanthin
Examples:
Ectocarpus
Dictyota
Fucus
Sargassum
Laminaria
Nereocystis
Macrocystis

14. Ectocarpus branching, filamentous
May exist attached to substrate or free-floating
widespread

15. Dictyota Fan-shaped Lightly calcified
Now widespread, but originally from Northeast North America and Mediterranean.

16. Fucus Known as a ‘rockweed’ or ‘wracks’ along coastlines
Have gas-filled floats (pneumatocysts)
Leathery thalli often covered with mucus to withstand prolonged air exposure
Strong disk-shaped holdfasts to endure intertidal zone

17. Sargassum Have many gas-filled bladders
Can grow on rocks or in huge floating masses
Common in the Gulf of Mexico & Sargasso Sea
Important for nursery and transport communities

18. Laminaria Sea palms, feather boa kelps, etc. Up to 3m in length
Single or small group of large blades attached to a single stipe.
Important food source

19. Nereocystis Bull kelps Whip-like stipe that is up to 30m long
Large spherical pneumatocyst at one end

20. Macrocystis Giant kelps Enormous holdfasts that anchor multiple stipes
Elongate blades branch from stipes, each with a gas-filled (CO) pneumatocyst
Grow up to 100m (up to 20 cm/day)
Form dense forests or ‘kelp beds’
Among most productive marine ecosystems
Are harvested for several natural products

21. Red Algae - Rhodophyta
Most numerous (~4,000 species) in marine environment
Contain a red pigment (phycobilins)
Harvested for food and other natural products
Most are filamentous
Some are heterotrophic and parasitic on other algae
Examples:
Ceramium
Chondrus
Nemalion
Porphyra
Corallina

22. Ceramium Small, filamentous algae Epiphytic
Produce chemicals that make them distasteful

23. Chondrus Irish moss Ranges across the North Atlantic
Shape varies with changes in temperature, salinity, and light availability

24. Nemalion Grows as a branched ‘worm’ on rocks in the intertidal zone.
Softly cartilaginous

25. Porphyra
Common on rocky shores
Polar to tropical distribution

26. Corallina Coralline algae
Deposit calcium carbonate within their cell walls
Can be an important reef building species in tropical waters
Can grow branching or encrusting

27. Life History
Refers to the series of growth, metamorphoses, and reproductive stages in an organism’s generation.
A little review:
Sexual vs. asexual reproduction
Diploid vs. haploid
Gametes
Mitosis vs. Meiosis
What’s a spore?

28. Algal Generations
Sporophyte – diploid (2n) , spore producing generation
Gametophyte – haploid (n), gamete producing generation
Alternation of generations – life histories in which two generations, a sporophyte and a gametophyte, exist
Can take four basic patterns

29. Life histories of various seaweeds

30. Halimeda Life History

31. Economic Importance of Seaweeds
Harvested for food (mariculture)
Produce phycocolloids
used in food processing & manufacturing as thickeners or gels

32. Algin produced from giant kelp (Macrocystis) and bull kelp (Laminaria)
Stabilizer and emulsifier in dairy products
Prevents drying of frostings and toppings
Pharmaceuticals
Shampoo
Plastics
Pesticides
Used in textiles as a thickener for printing paste
SPHERICAL MANGO RAVIOLI Blend the Citras with 250g of water, add the Algin and blend once more.
Bring to a boil, allow to cool and mix with the mango puree. Blend 1000g of water with Calcic.
Pour the contents of a dosing spoon full of the mango and Algin mixture into this
Calcic bath, leave for 2 minutes and wash in cold water. Repeat until all of the ravioli are made.

33. Carageenan Produced from red algae such as Chondrus
Used as an emulsifier especially in dairy products, soy milk, processed foods, and puddings
Toothpastes and other beauty products
Used in vaccines against HPV and other sexually transmitted Link
Ingredients: skim milk, partially hydrogenated soybean oil, disodium phosphate, carrageenan, Vitamin A Palmitate, and Vitamin D3

34. Agar
Extracted from several red algae including (Gelidium, Gelidiella, and Pterocladiella)
Uses:
protect meats during canning
low-calorie (diet) foods
thickener
laxatives, cosmetics, and pharmaceuticals
as a medium for bacteria and mold growth
Sugar Coated Pills: Each sugar coated pill contains: sennosides USP 15 mg. Nonmedicinal ingredients: acacia, alginic acid, calcium phosphate, carnauba wax, cellulose, iron oxide, magnesium stearate, sodium benzoate, sodium lauryl sulfate, starch, stearic acid, sucrose, talc and titanium dioxide. Blister packs, boxes of 10, 30 and 60.

35. Flowering Plants Have true leaves, stems, and roots
Structures to transport water, nutrients, and food
Reproduce sexually with the production of spores in flowers
Three types of marine plants;
Seagrasses – completely submerged in seawater
Salt-marsh plants – roots only covered at high tide
Mangroves – trees and shrubs that live along shores, roots adapted to salt

36. Salt Marshes, Mangroves and Seagrasses….Oh My!

37. Marsh Metaphors

38. Salt-Marsh Grasses Cordgrasses are true members of the grass family
Not marine species; land plants tolerant of salt – cannot tolerate complete submergence in seawater
Inhabit soft-bottom, coastal areas partially submerged by sea water at high tide – leaves are always partially exposed to air
Salt glands in their leaves excrete excess salt

41. Mangroves Trees and shrubs adapted to live along tropical shores
Salty environment means water loss from leaves is high and soil sediment is poor in oxygen
Leaves are thick to reduce water loss
Seeds germinate while on parent tree and begin to grow before falling to soft sediment

43. SeaGrasses
Truly marine and spend their lives entirely submerged by water
Not grass; more closely related to the lily family
Horizontal stems call rhizomes that grow under sediment; roots and shoots grow from stem
Small flowers (no need to attract pollinators)
Examples:
Eelgrass – widely distributed in temperate and tropical water; inhabits shallow, well protected coastal waters
Surf grass – inhabit rocky coasts exposed to heavy wave action

44. Do we have Seagrass Beds in the Chesapeake Bay?