Phytoplankton Diversity

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Phytoplankton Diversity
Phytoplankton Diversity Abundance
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Key Facts

• Phytoplankton (planktos wandering, phyton
  plant)
• Photosynthesizers
• Produce 40 of O2 food on earth each year
• Mostly single celled, about 15µm (10-6 m)
• Most important base of marine food chain

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3 Categories of Phytoplankton

• Diatoms
• Dinoflagellates
• Picoplankton

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Diatoms

• Diatoms are most dominant and abundant
  photosynthesizer in the world!
• Evolved 100 million years ago (age of Dinosaurs)
• 5,600 species identified
• They are the key phytoplankton during upwelling,
  and are also responsible for Fossil Fuels

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Diatoms

• This is a side view You can see two halves of
  the frustule
• The frustule is made from SiO2 (glass)

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Diatoms

• This is a stack of diatoms
• 55 of the sunlight is converted to sugar
• Stacks grow very quickly.
• Diatoms may split 3x per day.

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Diatoms

• This is a pennate (elongated) diatom
• It is about 15µm long

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Diatom Reproduction
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Dinoflagellates

• Ahhhh! Aliens!
• Some species are symbiotic (like in coral)
• Most live singly
• Most have flagella to move vertically in the
  water column
• Their shells are made from Cellulose
• They are the dominant phytoplankton during
  relaxation

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Dinoflagellates are also responsible for

• Red Tides
• Bioluminescence in the water when you swim

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Dinoflagellate Skeleton

• The armored plates that surround and protect them
  are called a theca.

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Dinoflagellate

• Another theca this is an image from an scanning
  electron microscope
• You can easily see the groves in the armor where
  the flagella lie

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Phytoplankton Challenges

• Q How do phytoplankton prevent themselves from
  sinking below the photic zone? (200m)
• A1 Their strange shapes that increase surface
  area. Also they luck out because of the
  thermocline that isolates the surface zone.

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Diatom Adaptations

• Diatom chains often have extensions to prevent
  sinking

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Dinoflagellate Adaptations

• Dinoflagellates do too
• This specimen is in the genus Ceratium and is
  about .5 mm across

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Upwelling during summer 2004
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Upwelling during summer 2004
http//www.phys.tue.nl/colloq/colloq/2004a/Clercx/
Clercx.htm
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Compensation Depth

• Productivity the use of sunlight to make carbon
  compounds
• Respiration burning carbon compounds for cell
  requirements

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Summer Thermocline
temp

• In the summer, a strong thermocline can develop,
  keeping the plankton near the top.

depth
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Winter Thermocline
Temp

• In the winter, storms mix the top layer deeper,
  the sun is lower angle, so the thermocline is
  deeper and less dramatic.

Depth
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Question

• The next picture is of a slide from a plankton
  tow in the San Francisco Bay.
• How many different species can you see?
• Hint There are at least 8!

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This slide is about 10 mm across. Each
milliliter of water can contain thousands of
phytoplankton.
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The average depth of the ocean is 2000m! But
phytoplankton need light (cannot photosynthesize
in less than 1 sunlight lt 200m deep) so they
live mostly in the top 10 m of water.
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Phytoplankton Abundance

• The following slide shows a satellite image of
  the ocean with false color.
• Red represents the most phytoplankton, purple is
  the least.
• Note the areas where most of the phytoplankton
  live.
• Why is this?

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