Ecology of Freeliving Nematodes

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Ecology of Free-living Nematodes
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Phylum Nematoda

• Body form worm-like
• Slender, tapered at ends
• Mostly less than 2.5 mm long, 0.1 mm wide

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Phylum Nematoda

• Primarily aquatic or marine, some terrestrial
• Many parasitic
• Mostly very small
• Meiofauna
• Live in spaces between grains of soil, sediments

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Phylum Nematoda

• Largest pseudocoelomate phylum
• estimated 20,000 species
• Worldwide in all imaginable habitats
• Deep sea to mountain tops
• Glaciers to hot springs
• Feed on all kinds of organic materials

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Humus

• Partially decayed organic matter
• Formed by bacteria, fungi, earthworms, and other
  soil organisms, including some nematodes
• Consumed by nematodes

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Hypothesis 1

• H1 Where soil contains more humus, there are
  more nematodes.
• More food (humus) more nematodes.

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Hypothesis 2

• Nematodes require water in soil
• Move in water films covering soil particles
• Die or become dormant if soil dries out.
• H2 Where soil is moister, there are more
  nematodes.
• More water more nematodes.

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Hypothesis 3

• Soils differ in particle sizes and shapes
• Clay soils have tiny flat particles with little
  space
• Sandy soils have larger irregular particles with
  more space
• Nematodes can move more easily where there is
  more space
• Find food, mates, etc.

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Hypothesis 3

• H3 Where there is more space, there are more
  nematodes.
• But, how can we measure space?

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Hypothesis 3

• How can we measure space?
• We cant, but
• Density of rock (soil particle) 3 g/ml
• Density of water 1 g/ml
• Density of air 0.001
  g/ml
• Soils with more rock less space (water air)
  are denser so . . .

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Hypothesis 3

• H3 Where soil is more dense (less space), there
  are fewer nematodes or where soil is less dense
  (more space), there are more nematodes
• Less density more nematodes.

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3 Hypotheses

• H1 Where soil contains more humus, there are
  more nematodes.
• More food (humus) more nematodes.
• H2 Where soil is moister, there are more
  nematodes.
• More water more nematodes.
• H3 Where soil is less dense (more space), there
  are more nematodes.
• Less density more nematodes.

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Methods