Macrophytes ENVI 121

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MacrophytesENVI 121
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Photosynthetic Protists Multicellular Algae

• General Structure
• More complex than unicellular algae
• Lack the highly specialized structures and
  reproductive mechanisms of land plants
• Whole body thallus
• Leaf-like structures blades
• Pneumatocysts gas floats at bases of blades
• Stem stipe
• Holdfast anchors body to bottom

Fig. 6.1
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General Structure, cont.

• Pneumatocysts float the blades (most
  photosynthetic region of thallus) close to the
  water surface to maximize light exposure
• Holdfast attaches thallus to hard or rocky ocean
  bottom. Three-dimensional structure serves as
  habitat for many organisms
• Nutrients absorbed through entire thallus surface
  entire thallus can photosynthesize
• Commonly called seaweeds, but theyre not weeds.

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Phylum Chlorophyta Green Algae

• Bright green chlorophyll. No other pigments mask
  green color
• Most are freshwater only 700 marine species
• Most are unicellular
• Ulva popular ingredient in seaweed salad
• Codium Dead Mans Fingers. Spongy thallus
• Enteromorpha

Ulva sp.
Codium fragile
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Class Phaeophyta Brown Algae

• Dominant primary producers on temperate and polar
  rocky coasts
• Fucoxanthin is main pigment (gives algae an olive
  green, brownish color. Same pigment as diatoms)
• Includes the largest and most complex of
  macrophytes the kelps

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Kelp Brown Algae

• Can grow as long as 100 m, and in water as deep
  as 40 m
• Grow quickly up to 50 cm/day
• Dont like heavy wave action
• Sea urchins are biggest predators of kelp
• Kelp grows well where sea otters hang out (why?)

Morgan
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Pelagophycus
Pelagophycus
Macrocystis Giant Kelp
Egregia Feather Boa Kelp
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Phylum Rhodophyta Red Algae

• Most abundant marine algae
• Red pigments called phycobillins mask
  chlorophyll
• Some are parasites of other seaweeds
  (heterotrophs)
• Some deposit calcium carbonate (CaCO3) in their
  cell walls makes them stiff, protects against
  wave action and predators

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Pelagophycus
Halimeda
Porphyra
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World Seaweed Production
1994-1995 data from Pacific Seaweeds by Louis
Druehl (2000)
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Economic Importance of Macrophytes

• Phycocolloids (ex algin produced from kelp) used
  as stabilizers in dairy products (ice cream,
  cheese, frosting)
• Algin used as thickener in shampoo, shaving
  cream, cosmetics
• Carrageenan from red algae used to emulsify dairy
  products and instant pudding
• Porphyra nori for sushi
• Nereocystis pickles

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More Economic Importance

• Some studies suggest that substances extracted
  from macrophytes are potent antitumor agents in
  cancer therapy (Druel 2000)
• Other studies suggest that substances extracted
  from macrophytes aid in the treatments of high
  blood pressure, stroke, and diabetes
• Kelp products may have anti-inflammatory effects

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Even More Economic Importance

• Methane gas can be produced by the anaerobic
  digestion of raw kelp by specialized bacteria
  species
• The use of this biogas produced from Giant Kelp
  (Macrocystis) has been explored as an alternative
  to oil

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Flowering Plants Angiosperms

• Angiosperms have true leaves, stems, roots, and
  veins to transport water and nutrients throughout
  the plant
• Kingdom Plantae (not Protista, like seaweeds)
• Seagrasses live fully submerged in seawater and
  are only true marine flowering plant
• Salt marsh plants and mangroves only partially
  submerged

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Seagrasses

• Stems grow horizontal beneath surface, roots and
  vertical shoots grow from stems
• Stabilize soft sediment, leaves cut wave action
• High rates of primary production
• Phyllospadix (surf grass) and Zostera (eel grass)
  common in San Diego
• Not many grazers turtles and manatees

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Salt Marshes

• Dominant grasses are Spartina (cord grass) and
  Salicornia (pickleweed)
• Environmental importance in salt marshes

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Salt Marsh in San Quintin, Baja California
Salicornia
Spartina
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Salt Marshes

• A transition area of bound sediment between
  terrestrial and aquatic ecosystems
• Fill during high tide, drain during low tide
• Salt marsh plants are halophytes grow in soils
  with high salt content
• Spartina a salt excreter. Salt glands in leaves
  excrete excess salt
• Salicornia a salt sequesterer. Sequesters salt
  in terminal joints
• Threatened environments human destruction

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Mangroves
Red mangrove Rhizophora, common in Florida and
the Caribbean
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Mangroves

• Trees and shrubs adapted to live along tropical
  and subtropical shores
• Mangrove forests called mangals
• Live in anoxic mud
• Pneumatophores vertical extensions of roots
  which absorb extra oxygen
• Aerial prop roots roots that descend from
  branches and absorb extra oxygen
• Prevent erosion and serve as biochemical filters
• Osmoregulators