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Pond Ecosystems. Biotic Zones of a Pond. A pond is broken up into 4 zones Littoral Zone Limnetic Zone Profundal Zone Benthic Zone. Littoral Zone: Emergent. Emergent plants are those producing biomass above and below water level. Littoral Zone: Floating.
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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
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.