Download Chapter 6 Marine Macroalgae Marine Algae

Chapter 6
MultiMulti-cellular Primary Producers:
Seaweeds and Plants
Marine Macroalgae
• Important coastal primary producers
(photosynthetic)
• These algae are called by a generic term
“seaweeds”
seaweeds” or more formal term
macroalgae
• algae do not have the same advanced
structures seen in plants such as roots,
stems and leaves
• Lack vascularization
Marine Algae
• The body of a macroalgae is known as a thallus.
• This thallus can be simple or more advanced in
its structure.
• In some algae, there are:
– Blades – leafleaf-like structures
– Stipes – stemstem-like structures
– Holdfast – rootroot-like structures
(these structures lack the advanced conducting tissues
seen in true plants)
Marine Algae
• Some algae also possess pneumatocysts,
gasgas-filled bladders used to keep the
blades near the water’
water’s surface where
more light is available for photosynthesis
• The blades, stipes and pneumatocysts of
the giant kelp ( a brown algae) are shown
in Fig. 6.8
Brown Algae
• Brown algae are the largest and most
complex algae
• All are multicellular, and most are marine
• Brown algae include many species
commonly called seaweeds
• Seaweeds have complex multicellular
anatomy- thallus
Blade
• But lack true roots,
leaves and stems
Stipe
Holdfast
• Giant seaweeds
called kelps live in
deep parts of the
ocean
• Up to 60m (120ft)
Human Uses of Seaweeds
• Important commodities and many are
harvested for food
Alginate
• http://www.youtube.com/watch?v=FUfA3W6
2PEk&feature=fvsr
• Alginic acid (alginate) is used as a thickener
in the food industry as well as getting fats
into suspension in water (emulsifier)
• Alginate is a polysacharide from kelps that
absorbs lots of water. When it is exposed to
calcium it forms fibers that separate from
water.
– i.e. youtube video, “apple caviar”
Figure 06_01
Marine Algae
• Can exhibit extremely fast growth rates
• Can reside in areas favorable for growth, do not
get washed around like phytoplankton
• Important habitat and food source of other
marine organisms.
• Three general types based on photosynthetic
pigments: green, red, and brown.
Green algae-Ulva sea lettuce
Green algae-Enteromorpha
Brown algae: Nereocystis bull kelp
Figure 06_05
Red algae:
Gigartina turkish
towel
Figure 06_10
Trichodesmium
Sargassum
Advanced Primary ProducersProducersPlants
• Angiosperms are true plants.
• Over 250,000 species exist worldwide,
however, only a few of these exist in the
marine community.
• Those plants that do exist there must have
mechanisms for dealing with salinity.
• These plants have true leaves, stems,
roots and conducting tissues.
Advanced Primary ProducersProducersPlants
• Seagrasses
– About 60 species exist in temperate and
mainly tropical locations.
– Flowers are small and inconspicuous in most
species.
Advanced Primary ProducersProducersPlants
• Seagrasses
– They also provide habitat for countless organisms
that hide among the blades in seagrass beds (large
collections of seagrass plants)
– Eelgrass is the most widely distributed of the
seagrasses where it is widely distributed in shallow
water bays and estuaries.
Advanced Primary ProducersProducersPlants
• Salt marsh PlantsPlants- plants bordering shallow bays and
tidal creeks.
– Cordgrass, Spartina, the predominant salt marsh plant is in the
grass family.
– Spartina is only exposed to saltwater at high tide.
– Spartina is extremely important as habitat to young marine
animals such as juvenile invertebrates and fish.
Advanced Primary ProducersProducersPlants
• Mangrove trees
– About 80 species of mangroves exist only in tropical
and subtropical areas.
– They cannot withstand freezing temperatures.
– Like Spartina,
Spartina, they only tolerate partial salt water
submergence.
– Mangroves have a thick network of prop roots that are
heavily exposed at low tide (Fig. 6.14, pg. 112
displays the roots of the red mangrove tree)
Willapa Bay
• Spartina
alterniflora
• 10,000 to 25,000
acres affected
• Nearly 4000 solid
acres
Living at the interface
between reduced and
oxidized conditions - oxygen
transport is an important
physiological capability
Oxidized zone
No hydrogen sulfide
Anoxic zone
Hydrogen sulfide-rich