pond ecosystems
Post on 07-Jan-2016
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Pond Ecosystems
Biotic Zones of a Pond
• A pond is broken up into 4 zones
1. Littoral Zone
2. Limnetic Zone
3. Profundal Zone
4. Benthic Zone
Littoral Zone: Emergent
• Emergent plants are those producing biomass above and below water level
Littoral Zone: Floating
• Floating plants are those producing biomass at and below water level
Littoral Zone: Submergent
• Submergent plants are those producing biomass solely below the water level
Limnetic Zone
• The limnetic zone is an open water area where light penetrates and floating algae and plankton dominant
Profundal Zone
• Area of open water where light can’t penetrate
• The profundal zone lacks producers but contains mobile higher level consumers that are dependent on the littoral and limnetic zones
Benthic Zone
• Area on the bottom of the pond where light can’t penetrate
• The benthic zone lacks both producers and consumers. This zone is dominated by decomposing organisms, from microscopic bacteria to macroinvertebrates like the crayfish.
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
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.
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.
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.
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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