Brown Algae

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Brown Algae
Sargassum wightii

• Phaeophyta

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Introduction to Algae

• Algae are grouped as photosynthetic organisms
  that are not quite plants.
• They belong to the Sub-Kingdom Thallophyta
• They lack organized tissues, like leaves, roots
  and the complex vascular structure of higher
  plants.

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• Algae are divided into several phyla on the basis
  of several characteristics
• There are three groups that are distinguished
  based on their color.
• Green algae Phylum Chlorophyta
• Red algae Phylum Rhodophyta
• Brown algae Phylum Phaeophyta

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Characteristics of the Group
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Brown Algae (Phaeophyta)

• are the largest and most complex of algae.
• are multicellular.
• are macroscopic with no unicellular or colonial
  forms.
• belong to a very large eukaryotic group of
  organisms that are distinguished by having
  chloroplasts surrounded by four membranes called
  Heterokontophyta.

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• Almost all brown algae are attached.
• Phaeophytes contain the requisite photosynthetic
  pigments, chlorophyll a and c.
• They are characteristically brown due to the
  accessory carotenoid pigment fucoxanthin.

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Characteristic Structures
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• - Thallus refers to the whole algal body
• - Holdfast attaches the thallus to the
  substrate like the root
• - Stipe flattened, erect stem-like stalk

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• - Blades leaf-like structures
• - Frond leaf-like structures
• - Bladders gas-filled swellings which float and
  keep the algae upright in water

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Habitat
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Habitat

• Brown algae have adapted to a wide variety of
  marine ecological niches including the tidal
  splash zone, rock pools, the whole intertidal
  zone and relatively deep near shore waters.

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Habitat

• Most brown algae are marine, commonly found in
  cool, shallow coastal waters of temperate of
  arctic areas.
• Many brown algae grow along rocky seashores.

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Nutrition
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Nutrition

• Brown algae are photosynthetic.
• They absorb nutrients from the water.

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Reproduction
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Reproduction

• Brown algae do not produce flowers, which is why
  they reproduce instead through variations on
  alternating between generations of sexual and
  asexual spore reproduction
• alternation of generations
• They reproduce by means of flagellated spores and
  gametes that closely resemble cells of other
  heterokonts.

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•  Ectocarpus life cycle

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Ecology
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Ecology

• They stabilize the captive environment by
  introducing beneficial microbes, absorbing
  nutrients, and producing metabolites that mediate
  systems biologically.
• They are good as bio-indicators, showing signs of
  degrading water quality.

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Ecology

• Food almost all fishes and invertebrates eat
  algae.
• They play the role of producers in many marine
  ecosystems.
• They may serve as habitat/ornament to break up
  the environment physically, providing hiding
  space and beauty.

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Three Species
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Ascophyllum nodosum

• Rockweed/Norwegian Kelp/Knotted Kelp/Knotted
  Wrack/Egg Wrack

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Ascophyllum nodosum

• - is a large common brown alga in the family
  Fucaceae
• - is the only species in the genus Ascophyllum
• - is seaweed of the northern Atlantic Ocean
• - has long fronds with large egg-shaped
  air-bladders set in series at regular intervals
  in the fronds and not stalked.

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Durvillaea antarctica

• Cochayuyo

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Durvillaea antarctica

• - is a large bull kelp species
• - is the dominant seaweed in southern New Zealand
  and Chile
• - is found on exposed shores, especially in the
  northern parts of its range

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Durvillaea antarctica

• - attaches itself with a strong holdfast
• - does not have air bladders, but floats due to a
  unique honeycomb structure within the algas
  blades

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Macrocystis pyrifera

• Giant Kelp/Giant Bladder Kelp

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Macrocystis pyrifera

• - a species of kelp
• - one of four species in the genus Macrocystis
• - perhaps the largest, fastest growing organism
  on the planet
• - up to two hundred or so feet long
• - grows up to two feet more a day

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Trivias
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• The legendary Sargasso Sea in the middle of the
  North Atlantic is characterized by the presence
  of brown algae from the genus Sargassum that
  floats in masses on the surface.

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• Sargasso Sea

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• The oldest examples of fossilized brown algae
  date back to the Mesozoic Era (251 to 180 million
  years ago).
• The 1,500 species of brown algae are almost
  exclusively found in marine habitats.
• The brown algae include the largest of the
  seaweeds, Durvillea and the kelps, found in cold
  waters. 

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Sources

• http//en.wikipedia.org/wiki/Brown_algae
• http//www.wetwebmedia.com/brnalgae.htm
• http//en.wikipedia.org/wiki/Ascophyllum
• http//en.wikipedia.org/wiki/Durvillaea_antarctica
  
• http//www.mbari.org/staff/conn/botany/flora/brown
  s.htm
• http//www.aquaticcommunity.com/algae-control/brow
  n.php
• Biology by Miller and Levine