1. Multicellular Primary Producers Seaweeds and Plants
Chapter 6

2. All photosynthetic?
Most are photosynthetic but of course there are exceptions Some are not photosynthetic and are actually parasites of other seaweeds!
Almost all the seaweeds and marine plants discussed in this chapter are photosynthetic. There are always exceptions, and a few seaweeds are not primary producers but parasites of other seaweed!

3. The role of seaweeds
Transform solar every to chemical energy in the form of organic matter
Energy is then available for consumption
Habitat
Oxygen producers
Seaweeds play an important role in many coastal environments. Seaweeds transform solar energy into chemical energy in the form of organic matter and make it available to a long list of hungry creatures. Some organisms live on or even in the tissues of seaweeds
Organisms on land as well as those living in the ocean utilize some of the oxygen seaweeds produce.

4. Structure of seaweeds Seaweeds are eukaryotic
Seaweeds still lack the specialized structures and reproductive mechanisms characteristic of terrestrial plants
Wide range of variation among seaweeds
The structure of seaweeds or macrophytes or macroalgea are much more complex than those of unicellular algae.

5. Variation Rocky shore- small and sturdy to withstand waves
Some delicate ones live on other seaweeds
Kelps- found offshore in cold waters (giants)
The multicellular condition of seaweeds allows many adaptations not available to unicellular forms. The ability of seaweeds to grow tall and rise off the bottom provides new opportunities as well as challenges, particularly that of wave action.

6. General Structure
Seaweeds lack true leaves, stems, and roots of plants.
Thallus- Complete body
Blades- Leaf-like flattened portions of the thallus, large surface area, photosynthesis
Pneumatocysts- Gas-filled bladders that can keep blades close to sea surface
Stipe- Stem-like structure for support, blades originate
Holdfast- Attaches the thallus to the bottom and well developed in kelps
Lots of variation among seaweeds. Unifying features are worth mentioning.
Blades- The have a large surface area and are the main photosynthetic region though all portions of the thallus are able to photosynthesis as long as they have chlorophyll. The upper and lower surfaces of the blades are identical to each other.
Most seaweeds cannot anchor in soft sediments and are restricted to hard bottoms.
Water and nutrients bathe the entire thallus and are picked up directly across the surface without the need of roots as in land plants.

7. Structure

8. Types of Seaweeds Three types 1) Green 2) Brown 3) Red
It is not easy to recognize the groups by their color in nature since the proportion of chlorophyll and other pigments can vary. Chemical analysis, however, reveals the characteristic pigments of each group.

9. Green Algae Most are freshwater and terrestrial
10% of the 7,000 species are marine
Most have a simple thallus compared to the other 2 groups
Thought that land plants evolved from green algae
Pigments and food reserve are the same
Most of the marine species are unicellular but that does not mean that multicellular green algae are uncommon in the sea.
The chlorophyll is not masked by other pigments so they are typically bright green in color

10. Where do green algae live?
Common on rocks in shallow water
Rocky shore tide pools

11. Types of green seaweeds
Filamentous types may be branched or unbranched
Enteromorpha- thin thallus in the form of a hollow tube
Ulva- Sea lettuce is paper thin
Valonia- forms large spheres or curious spherical clusters.
Caulerpa- Single giant cell with many nuclei
Codium- Deadman’s fingers
Halimeda- Calcareous green algae (coral reefs)
Valonia forms large spheres or clusters in the tropics and subtropics.
Codium- multinucleated filaments woven into a spongy, often branching thallus.

12. Enteromorpha

13. Ulva

14. Valonia

15. Caulerpa

16. Codium

17. Halimeda

18. Brown Algae Coloration – varies from olive green to dark brown
Fucoxanthin over chlorophyll
Almost all of the 1500 species are marine
Often the dominant primary producers on temperate and polar rocky coasts.
Largest and structurally most complex (Include the kelps)
The variation in color is due to yellow-brown pigments Fucoxanthin over chlorophyll

19. Types of Brown Algae Ectocarpus- Finely filamentous thallus
Dictyota – thallus is flat and branched
Padina- Fan-shaped and lightly calcified
Desmaretia- branched
Some are exposed at low tides at the middle and upper levels of rocky shores
Gas-filled floats – rockweeds or wracks
Ectocarpus is widely distributed
Desmaretia – found in cold waters
Those exposed at low tides have thick leathery thalli that can withstand exposure to air.

20. Sargassum
Brown algae found in warm waters (Gulfs of Mexico and California)
Sargasso weed has spherical air bladders to keep small leaf like blades afloat
Most grow on rocks
Offshore in huge masses
Sargasso Sea
Area in Atlantic

21. Sargasso Sea

22. Sargassum Sea

23. Kelps Most complex and largest of all brown algae
Great importance – provide food and shelter for many organisms.
Laminaria- species of kelp where a single large blade can be up to 10 ft
Agarum and Alaria – Rib runs along the middle of a single blade
Egregia- Feather boa kelp
Eisenia- Southern sea palm
Nereocystis- Bull kelp
Pelagophycus- Antler like branches
Found in great abundance below the low tide level in temperate and sub-polar latitudes
Laminaria is harvested for food in some parts of the world

24. Brown Algaes kelp.gifkelp.gif Padina Agarum Egregia Dictyota
Ectocarpus
Laninaria
Desmarestia
Alaria
Nereocystis
Eisnia
Pelagophycus

25. Macrocystis Largest of kelps Massive holdfast attaches to the bottom
At the base of each blade a gas-filled pneumatocyst
Can grow 20 in per day in optimal conditions
Form kelp beds or forests
Among the richest, most productive environments in the marine world

26. Kelp Forest http://www.youtube.com/watch?v=GcbU4bfkDA4
What coast of North America can they be found?
What do kelps consist of?
What do young kelp compete for?
What do fish use the kelp forest for?
Why does the canopy make a good nursery environment?
Youtube: Underwater Kelp Forests usoceangov

27. Red Algae More red algae that green and brown combined
Red pigments known as phycobilins
Essentially marine
Of the 4000 species, only a few are fresh water or soil
Live in most shallow-water marine environments
Phycobilins mask chlorophyll.

28. Structure of Reds
Simplified in structure by becoming parasites of other seaweeds
A few have lost all chlorophyll and are heterotophs
Most are filamentous
Thickness, width, arrangement of filaments varies
A few have lot all chlorophyll and are heterotrophs depending entirely on their host for nutrition.

29. Types of Reds Gelidium Gracilaria
Endocladia – wirey clumps on rocky shores from Alaska to S. Ca.
Gigartina- Most massive of the red algae
Porphyra-Common on rocky shores above the lowest tide mark
Rhodymenia –Common in North Atlantic
Chondrus –Irish moss and can tolerate wide ranges in temp, light and salinity
Gelidium and Gracilaria are found worldwide, there are many species of Gelidium and Gacilaria

30. Red Algae en Gelidium Gracilaria Porphyra Rhodymenia Endocladia
Gigartina
Chondrus

31. Coralline Algae (Corallina)
Red algae that deposit calcium carbonate in their cell walls
Important in several marine environments
Calcified thallus takes a variety of shapes
Color varies from light to intense reddish-pink
Warm-water coralline algae are actively involved in formation and development of coral reefs

32. Bingo Thallus Blades Pneumatocysts Stipe Holdfast Green algae
Red algae
Brown algae
Enteromorpha
Ulva
Valonia
Caulerpa
Halimeda
Gigartina
Chondrus
Fucoxanthin
Ectocarpus
Dictyota
Padina
Desmarestia
Rockweeds
Sargasso Sea
Laminaria
Nereocystis
Pelagophycus
Macrocystis
Kelp forest
Phycobilins
Coralline algae
Gracilaria
Porphyra