Lentic Systems Lakes and Ponds. Formation of Lakes Glacier lakes Glacier lakes Oxbow lakes Oxbow...

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Transcript of Lentic Systems Lakes and Ponds. Formation of Lakes Glacier lakes Glacier lakes Oxbow lakes Oxbow...

  • Slide 1
  • Lentic Systems Lakes and Ponds
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  • Formation of Lakes Glacier lakes Glacier lakes Oxbow lakes Oxbow lakes Playas Playas Man-made lakes Man-made lakes
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  • Glacier Lakes Carved out by glaciers (glaciation), which fill with water Carved out by glaciers (glaciation), which fill with water Northern U.S. and Canada Northern U.S. and Canada
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  • How Does Glaciation Work? As the glaciers move they act as scouring pads on the ground underneath them. As the glaciers move they act as scouring pads on the ground underneath them. Near the end of the last glacial period, roughly 10,000 years ago, glaciers began to retreat Near the end of the last glacial period, roughly 10,000 years ago, glaciers began to retreat A retreating glacier often left behind large deposits of ice in hollows between hills which later melted to create lakes. A retreating glacier often left behind large deposits of ice in hollows between hills which later melted to create lakes. Rocks are eroded and mineral deposits become sediments at the bottom of the lake Rocks are eroded and mineral deposits become sediments at the bottom of the lake Some suspended minerals are used by algae for growth, making the water appear green Some suspended minerals are used by algae for growth, making the water appear green
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  • The Great Lakes in northern U.S. are the largest glacial lakes in the world.
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  • The Seven Rila Lakes in Rila, Bulgaria Lake Jokulsarlon, in Iceland.
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  • Oxbow Lakes Formed by meandering rivers Formed by meandering rivers Loops of river gets cut off Loops of river gets cut off Lakes are long and narrow, and usually U-shaped Lakes are long and narrow, and usually U-shaped Common in low valleys and flat coastal areas Common in low valleys and flat coastal areas
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  • Oxbow Lake An oxbow in the making: meanders and sandbank deposition on the Nowitna River, Alaska An oxbow in the making: meanders and sandbank deposition on the Nowitna River, Alaska
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  • How Does an Oxbow Lake Form? (1) On the inside of the loop, the river travels more slowly leading to deposition of silt.
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  • (2) Meanwhile water on the outside edges tends to flow faster, which erodes the banks making the meander even wider. (3) Over time the loop of the meander widens until the neck vanishes altogether.
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  • (4) Then the meander is removed from the river's current and the horseshoe shaped oxbow lake is formed. -- Without a current to move the water along, sediment builds up along the banks and fills in the lake.
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  • Oxbow Lake Oxbow lake and the Chippewa River in Eau Claire, Wisconsin. Oxbow lake and the Chippewa River in Eau Claire, Wisconsin.
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  • Playas Formed from multiple things that leave a depression Formed from multiple things that leave a depression Soil erosion, wind, animal herds Soil erosion, wind, animal herds Small, shallow, and circular Small, shallow, and circular Common in dry plains areas Common in dry plains areas These lakes are ephemeral, and only form at certain times of the year These lakes are ephemeral, and only form at certain times of the year
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  • Playas are important habitat for migratory birds and waterfowl. Playas are important habitat for migratory birds and waterfowl. The Red-winged Blackbird, Blue-winged Teal, and the Mallard can all be found in playa lakes at some time of the year. The Red-winged Blackbird, Blue-winged Teal, and the Mallard can all be found in playa lakes at some time of the year.
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  • Sandhill cranes winter in playa lakes Sandhill cranes winter in playa lakes
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  • Playa lakes in Kansas agricultural area
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  • Man-Made Lakes Lake Mead is formed as a result of damming the Colorado River by the Hoover Dam in Nevada Water reservoirs formed from Water reservoirs formed from Damming rivers Damming rivers Old rock quarries or mines Old rock quarries or mines Stock ponds on farms and ranches Stock ponds on farms and ranches
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  • Zipingpu Dam on the Min River in China
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  • Lentic Habitats Characterized by Characterized by The shoreline The shoreline The sides of the basin The sides of the basin The surface of the water The surface of the water The bottom sediments The bottom sediments
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  • Zones of Lentic Habitats Littoral zone Littoral zone Limnetic zone Limnetic zone Profundal zone Profundal zone
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  • Littoral Zone Along shore where light can penetrate to the bottom Along shore where light can penetrate to the bottom Rooted plants can grow Rooted plants can grow Shores have coarse sediments from action of waves Shores have coarse sediments from action of waves Sheltered areas have finer sediments (silt and clay) plant growth in this zone Sheltered areas have finer sediments (silt and clay) plant growth in this zone Animal life includes Animal life includes Invertebrates common to lotic habitats Invertebrates common to lotic habitats Small fish Small fish
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  • Limnetic Zone Upper open water area of a pond or lake Upper open water area of a pond or lake Lack of rooted plants because light cant penetrate the bottom Lack of rooted plants because light cant penetrate the bottom Plankton and fish are common Plankton and fish are common
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  • Profundal Zone Deep, bottom-water area Deep, bottom-water area No light penetration No light penetration No photosynthetic organisms or rooted plants No photosynthetic organisms or rooted plants Sediments are silt and clay mixed with organic matter that settles to the bottom Sediments are silt and clay mixed with organic matter that settles to the bottom Organisms living here are tolerant of little or no light or oxygen. Organisms living here are tolerant of little or no light or oxygen.
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  • Biological Productivity The amount of plankton, algae, aquatic macroinvertebrates and fish that a body of water can produce and sustain The amount of plankton, algae, aquatic macroinvertebrates and fish that a body of water can produce and sustain Usually limited to the depth of light penetration Usually limited to the depth of light penetration Light penetration is limited by color of the water and amount of suspended solids Light penetration is limited by color of the water and amount of suspended solids
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  • Ponds vs. Lakes Pond = body of water where light penetrates all the way to the bottom Pond = body of water where light penetrates all the way to the bottom Lake = depth of light penetration varies from several inches to several feet Lake = depth of light penetration varies from several inches to several feet
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  • Determining the Trophic State Total Plant Nutrients Total Plant Nutrients Phosphorous and nitrogen are needed for plant growth and maintenance Phosphorous and nitrogen are needed for plant growth and maintenance Certain level is needed (too much or too little is not a good thing) Certain level is needed (too much or too little is not a good thing) If nutrients are too high, algae blooms occur If nutrients are too high, algae blooms occur Increase the turbidity of the water Increase the turbidity of the water Decrease the oxygen levels Decrease the oxygen levels
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  • Chlorophyll A Chlorophyll A Measure of the algae population Measure of the algae population Influenced by the amount of nutrients Influenced by the amount of nutrients Water Clarity (turbidity) Water Clarity (turbidity) Water clarity determines how far light can penetrate Water clarity determines how far light can penetrate Phytoplankton and plants need light to grow, so they wont grow if light is limited Phytoplankton and plants need light to grow, so they wont grow if light is limited Algae blooms cause lower water clarity Algae blooms cause lower water clarity
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  • Characteristics of Biological Productivity 4 categories of lake classification based on biological productivity 4 categories of lake classification based on biological productivity Oligotrophic Oligotrophic Mesotrophic Mesotrophic Eutrophic Eutrophic hypereutrophic hypereutrophic
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  • Oligotrophic Lakes Nutrient level and productivity is low Nutrient level and productivity is low Water is clear Water is clear Low aquatic plants and plankton Low aquatic plants and plankton Few fish Few fish Sandy bottoms with little organic material Sandy bottoms with little organic material
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  • Mesotrophic Lakes Nutrients and productivity is moderate Nutrients and productivity is moderate Some aquatic plants Some aquatic plants Water clarity is becoming somewhat cloudy Water clarity is becoming somewhat cloudy
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  • Littoral habitat in a mesotrophic lake Littoral habitat in a mesotrophic lake
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  • Eutrophic Lakes Nutrient level and productivity is high Nutrient level and productivity is high Large populations of algae, plankton, fish, plants, and macroinvertebrates Large popu