Pond Ecosystems

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Pond Ecosystems
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Biotic Zones of a Pond

• A pond is broken up into 4 zones
• Littoral Zone
• Limnetic Zone
• Profundal Zone
• Benthic Zone

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Littoral Zone Emergent

• Emergent plants are those producing biomass above
  and below water level

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Littoral Zone Floating

• Floating plants are those producing biomass at
  and below water level

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Littoral Zone Submergent

• Submergent plants are those producing biomass
  solely below the water level

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Limnetic Zone

• The limnetic zone is an open water area where
  light penetrates and floating algae and plankton
  dominant

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Profundal Zone

• Area of open water where light cant penetrate
• The profundal zone lacks producers but contains
  mobile higher level consumers that are dependent
  on the littoral and limnetic zones

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Benthic Zone

• Area on the bottom of the pond where light cant
  penetrate
• The benthic zone lacks both producers and
  consumers. This zone is dominated by decomposing
  organisms, from microscopic bacteria to
  macroinvertebrates like the crayfish.

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Abiotic Factors Temperature

• Seasonal changes in water temperature in a
  mid-latitude ponds is critical to the ecology of
  the pond
• The changes in temperature are associated with
  important physical properties of water

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Summer Stratification

• As summer peaks, the difference between the water
  temperature at the surface and the bottom of the
  pond increases.
• The warm water at the surface is less dense and
  sits above the colder denser water at the bottom.
  The stratified water reduces mixing between
  layers, epilimnion and hypolimnion.
• The epilimnion develops relatively high levels of
  oxygen through photosynthesis while the
  hypolimnion develops high levels of nutrients
  from decomposition.

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Fall Overturn

• As summer is replaced by fall, the surface waters
  cool and the stratified layers start to
  disappear. At some point the water temperature
  reaches a common value.
• Now, when the wind blows, water circulates within
  the entire pond, allowing surface and bottom
  water to mix.
• Oxygen replenishes the hypolimnion while
  nutrients replenish the epilimnion.

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Winter Stratification

• As winter peaks, the difference between the water
  temperature at the surface and bottom of the pond
  increases.
• In contrast to summer stratification, the surface
  temperature becomes colder than the bottom
  temperature.
• As water freezes, it becomes less dense, floats,
  and insulates the water below, protecting the
  aquatic life from freezing.

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Spring Overturn

• As winter is replaced by spring, the surface
  waters warm. At some part the water temperature
  reaches a common value.
• As the wind blows, the water circulates within
  the entire pond again allowing surface and bottom
  water to mix oxygen and nutrients.

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