Seaweeds come in many shapes, sizes, colors and have unique structures depending on their phylum. The three main phyla of seaweeds are green algae (Chlorophyta), red algae (Rhodophyta), and brown algae (Phaeophyta). Salt marsh plants, sea grasses, and mangroves are flowering plants found in estuaries and coastal areas that play important ecological roles through primary production, habitat provision, and sediment stabilization.

1. Chapter 7
Multicellular Primary Producers

2. Seaweeds
Seaweeds!!!
Come in all kinds of interesting
Shapes and sizes!
• some are delicious!
• some are poisonous
• Some have weird names
• Come in all sorts of colors

3. Seaweed Structure
• Thallus-body
• Lack vascular tissue -Do not
have roots, stems, or leaves
• Holdfast -The structure
that attaches the seaweed
to the substrate
• Stipe-stem-likestructure

4. Phylum Chlorophyta (green algae)
• Contain chlorophylls a and b for photosynthesis
• Most are freshwater
• Ecologically important
– food source
– Contribute to coral reef formation
– Some are invasive

5. Green algae structure
• Most unicellular
• Marine species have coenocytic thallus-
containing more than 1 nucleus
– Occurs by cell growing
– nucleus divides
but cell never
divides

6. Reproduction of Algae
• Sexual
• Gametes released from gametophyte 2 flagella
• spores released from sporophyte- 4 flagella

7. Representative species
• Halimeda
• Caluerpa-invasive

8. CFU: Green Algae
• Are green algae unicellular or multicellular
• Autotrophic or heterotrophic
• What is an important organelle in
photosynthesis
• How does green algae grow in length?
– Same cell, division of nucleus
• What is the function of the Stipe?

9. Red Algae

10. Phylum Rhodophyta (red algae)
• Primarily marine
• Most diverse among seaweeds
• Cholorphylls a and d, pigments:
phycoerythrins and phycocyanins
• Not always red in color- can appear yellow to
black

11. Structure
• Multicellular and less than 1 meter long
• Wide variety of shapes and organization
among species

12. Reproduction
• Can vary from simple
to complex…but 2
unique features………..
1. Lack flagella on
spores and gametes
2. 3 multicellular stages
1. Carpospore-unique
to red
algae

13. Ecological Roles
• Porphhra- used as food in oriental dishes
• Seasonal food source for
urchins, mollusks, fish, and crustaceans
• Some grow on other plants or animals
• Help form base of coral reef
• Agar- used as a thickening agent in foods such
as ice cream, pudding, and salad dressings
• Used in cosmetics for creamy foundations

14. CFU: Red Algae
• Heterotrophic or Autotrophic?
• Multicellular or unicellular
• What are the two unique stages?
• What organisms feed on red algae?

15. Brown Algae

16. Phaeophyta (brown algae)
• Mostly marine
• Higher diversity than green but less diverse
than red
• Size: from microscopic to kelps (100 meters)
• Chlorophylls a and c and pigment fucoxanthin
• Mostly in high latitudes
• Large flat leaf-like blades with bladders help
bouy plant toward light
• Representative species Sargassum, Fucus

17. reproduction
• Gametophyte is
eliminated from
life cycle (difference
from Chlorophyta and
Rhodophyta)
• Egg develops
root-like
structures
(rhizoids) after
fertilization

18. Ecological role
• Habitats for a variety of marine life
• Harvested for thickening agents used in
dentistry, cosmetic, and food industries
• Previously iodine was extracted and put into
table salt (iodized salt) to prevent a goiter

19. • Excessive nutrients
– Runoff from fertilizer Human Impacts
• Causes huge algae
blooms!
– When algae dies off
decomposers consume
majority of the oxygen in
the environment
– Eutrophication
• Kills off fish and marine
life

20. CFU: Algae
• What macromolecule allows algae to live in
marine environments without swelling?
• What causes algae blooms?
• What is this process called?
• What are the harmful effects of algae blooms?

21. Sea grasses, salt marsh plants,
mangroves

22. Salt Marsh Plants and Sea Grasses
• Salt marshes are in Estuaries
– The kidneys of the coasts
• Nursery for small fish
– 75% of commercial fish are hatched in estuaries
• Estuaries are severly affected by humans
– Coastal development
– Pollution
– Eutrophication
• Protect us from storms

23. Phylum Anthophyta
• Seagrasses, salt marsh plants, mangroves
• Ecological Roles- Primary
producers, habitats, stabilizing sediments
• Help slow down erosion
• Have to deal with extreme changes in salinty
and oxygen
Mixing of salt and fresh water
Eutrophication

24. Sea grasses (marine flowering plants)
• Related to lilies
• Reproduce by pollination of seed; Male and female flowers on
separate plants contain pollen
• Literally look like grass
• Food for manatees and sea turtles
• Can live up to 100 meters below sea level

25. Sea Grasses in Florida
• 12 genra
– Genra native to Florida
• Syringodium -
manateegrass
• Halophila-paddlegrass
• Thalassia- turtlegrass
• Ruppia-
• Halodule- shoalgrass

26. Salt Marsh Plants
• Adapted to high levels of salinity and tidal action
• Found in estuaries – level of succession based on salinity and tidal
tolerance
• Species native to Jacksonville
– SpartinaAlternaflora
– BatisMaritima
– Spartina patens
– Juncus
– Salicorniavirginica

27. Mangroves
• Found in south of St. Augustine to Key West
• 3 genra local to Florida
– Rhizophora mangle –red mangle-----prop roots
– Avicennia germinans – black mangle---
pneumatophores
– Laguncularia racemosa- white mangle
• Distinctive by their root system and pods

28. Mangroves: Highly adaptive
• Use active transport to
regulate water levels in
their roots
• Live in anaerobic mud
– Why they stand above
the water
• Protect coral reefs from
eutrophication
– Filter, kidney

29. Help Protect Coastal Development
2004 Indian Ocean
Tsunami

30. Mangrove reproduction
• Flowers pollinated by wind or bees
• Embryo grows on the plant in a propagule
(similar to seed)
• Propagule eventually falls from parent and is
carried by current until it settles and takes
root

31. Red Mangrove
Black Mangrove
Red, White, and Black mangrove White Mangrove
leaves