Multi-cellular Primary Producers: Seaweeds and Plants

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Multi-cellular Primary Producers Seaweeds and
Plants

• Multi-cellular algae are commonly referred to as
  seaweeds
• Seaweeds belong to Kingdom Protista, and are
  further classified into divisions (or phylum)
  according to their characteristic color
  (pigmentation)
• Like unicellular algae, all multi-cellular algae
  are eukaryotic

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Three Domains of Life
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Multi-cellular Algae Seaweeds

• Seaweeds are more formally referred to by
  biologists as macrophytes or macroalgae
• Seaweeds are not plants and so lack true leaves,
  stems, and roots
• The complete body is known as
  the thallus whether it is a
  filament, a thin leafy sheet, or
  a giant kelp

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General Structure

• All portions of the thallus are capable of
  photosynthesis
• The leaf-like, flattened portions of the thallus
  are known as blades
• large surface area main photosynthetic region
• Gas-filled bladders known as pneumatocysts help
  keep the blade close to the sea surface
• Some seaweeds have a distinctive, stem-like
  structure, the stipe, which provides support

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Plant
Algae
http//atlasveg.ib.usp.br/English/focara.html
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General Structure

• A structure resembling roots, the holdfast,
  attaches the thallus to the bottom
• NOT involved in any significant absorption of
  water and nutrients
• Does not penetrate through sand and mud as true
  plant roots do
• Restricts seaweeds to hard bottoms not found in
  sandy, soft bottom habitats
• Water and nutrients are transferred directly
  across the surface of the thallus

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Types of Seaweeds

• There are three types of seaweeds
• The green algae
• The brown algae
• The red algae

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Green Algae Phylum Chlorophyta

• Green algae belong to phylum (or division)
  Chlorophyta
• Most green algae live in freshwater and
  terrestrial environments only 10 of the
  estimated 7,000 species are marine
• Nonetheless, many species of green algae dominate
  bays and estuaries and isolated tidal pools on
  rocky coasts

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Green Algae Phylum Chlorophyta

• Chlorophyll in both green algae and plants are
  not normally masked by other pigments
• Land plants are believed to have evolved from
  green algae considered by many taxonomists as
  belonging to Kingdom Plantae!

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Common Long Island Chlorophytes
Codium fragile (Dead Mans Fingers)
Ulva lactuca (Sea lettuce)
Enteromorpha sp. (Gutweed)
http//www.ubcbotanicalgarden.org/potd/2007/10/cod
ium_fragile_subsp_tomentosoides_1.php
http//www.biopix.dk/Photo.asp?LanguagelaPhotoId
11271
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Brown Algae Phylum Phaeophyta

• Brown algae belong to phylum (or division)
  Phaeophyta
• Color varies from olive green to dark brown, but
  are classified by having a preponderance of
  yellow-brown photosynthetic pigments,
  particularly fucoxanthin
• Nearly all 1,500 species are marine
• Include the largest and most complex seaweeds

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Brown Algae Phylum Phaeophyta

• Many species have gas-filled floats
  (pneumatocysts) e.g., rockweeds or wracks,
  Sargassum weed

http//www.physorg.com/news100350969.html
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Brown Algae Phylum Phaeophyta

• The kelps are the most complex and largest of all
  brown algae
• Consist of a single, or numerous large blade(s)
• The stipes of giant kelp, Macrocystis can reach
  lengths of 100 m and
  grow 1 ft per day!
• Provides food and
  shelter for many other
  marine organisms

http//www.rmrs.nau.edu/usamab/general20descripti
on20channel20islands.htm
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KELP!!!
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Kelp community with sea otters
http//www.otterproject.org/atf/cf/7B1032ABCB-19F
9-4CB6-8364-2F74F73B30137D/Otter_image4.jpg
Kelp community without sea otters
http//sbc.lternet.edu/sites/biome_kelpforest.html
http//blackcormorant.blogs.com/photos/uncategoriz
ed/kelpurchins_415_030.jpg
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Red Algae Phylum Rhodophyta

• Red algae belong to phylum (or division)
  Rhodophyta
• There are more species of marine red algae than
  green and brown algae combined!
• The chlorophyll of red algae is masked by large
  amounts of red pigments called phycobilins
• Nearly all 4,000 species are marine
• Dominate in tropical and subtropical regions

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Common Long Island Rhodophytes
Chondrus crispus (Irish moss)
Palmaria palmata (Dulce)
Porphyra sp. (Laver)
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Multi-cellular Primary Producers The Plants

• Worldwide, there are 5,000-6,000 species of
  seaweed and only 55 species of seagrass!
• Seagrasses are flowering plants belonging to the
  kingdom Plantae
• Not actually a grass
• Related to lilies evolved
  from land plants!
• True leaves, stems, and
  roots

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Seagrasses

• Underground roots and rhizomes (horizontal stems)
  extract nutrients from the sediment and hold the
  plant in its place
• Seagrasses have cell walls made out of cellulose
  (a characteristic of all plants) which provide
  support for the plant and keep the plant vertical
  in the
  water column

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Seagrasses

• Seagrass provides important shelter and food for
  many marine inhabitants
• Because of the protection they provide, seagrass
  communities serve as important nursery grounds
  for developing fish shellfish

http//www.flickr.com/photos/19727876_at_N00/41536831
8/
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Common seagrass of Long Island
Zostera marina (Eel grass)
http//www.ceoe.udel.edu/cms/jgallagher/tigani/kt_
index.html
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How NOT to drive your boat through seagrass...
http//www.dep.state.fl.us/COASTAL/images/habitats
/seagrasses/Aerial1.jpg