Freshwater biomes


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Freshwater biomes

  1. 1. FRESHWATER BIOMES<br />Freshwater biomes are usually characterized by a salt concentration of less than 1%.<br />Freshwater biomes are closely linked to the soils and biotic components of the terrestrial biomes through which they pass or in which they are situated.<br />The particular characteristics of a freshwater biome are also influenced by the patterns and speed of water flow and the climate to which the biome is exposed.<br />
  2. 2. LAKES and PONDS<br />
  3. 3. Lakes and Ponds<br />Large(Lakes) and Small(Ponds), natural bodies of standing fresh water<br />Formed when depressions in earth’s surface are filled with:<br />Precipitation<br />Runoff<br />Groundwater<br />Large lakes may have many of same characteristics as oceans<br />
  4. 4. Classification <br />Depending on the amount of organic matter produced.<br />
  5. 5. OLIGOTROPHIC<br />deep<br />cold<br />small surface area relative to depth<br />nutrient-poor<br />phytoplankton are sparse, not very productive<br />don’t contain much life<br />waters often very clear<br />sediments low in decomposable organic matter<br />
  6. 6. MESOTROPHIC<br />moderate nutrient content<br />moderate amount of phytoplankton<br />reasonably productive<br />
  7. 7. EUTROPHIC<br />shallow<br />warm<br />large surface area relative to depth<br />nutrient-rich<br />phytoplankton more plentiful and productive<br />waters often murky<br />high organic matter content in benthos<br />leads to high decomposition rates and potentially low oxygen<br />
  8. 8. EUTROPHICATION<br />Oligotrophic lakes may develop into eutrophic lakes over time. <br />Runoff from surrounding terrestrial habitats brings in mineral nutrients and sediments. <br />Human activities increase the nutrient content of runoff due to lawn and agricultural fertilizers; municipal wastes dumped into lakes dramatically enriches the nitrogen and phosphorus concentrations which increases phytoplankton and plant growth. <br />Algal blooms and increased plant growth results in more detritus and can lead to oxygen depletion due to increased decomposition.<br />
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  10. 10. ZONATION IN A LAKE<br />The lake environment is generally classified on the basis of three criteria:<br />LIGHT PENETRATION<br /><ul><li>Photic Zone
  11. 11. Aphotic Zone</li></ul>DISTANCE FROM THE SHORE AND WATER DEPTH <br /><ul><li>Littoral Zone
  12. 12. Limnetic Zone</li></ul>OPEN<br /><ul><li> Pelagic Zone </li></ul>BOTTOM<br /><ul><li>Benthic Zone</li></li></ul><li>Littoral Zone<br />shallow, well-lit, close to shore.<br />rooted and floating plants flourish<br />Limnetic Zone<br />well-lit, open surface water, farther from shore, extending to depth penetrated by light<br />occupied by phytoplankton, zooplankton, higher animals<br />produces food and oxygen that supports most of lake’s consumers<br />Profundal Zone<br />consists of deep, aphotic regions<br />too dark for photosynthesis<br />oxygen levels are low<br />inhabited by fish adapted to cool dark waters<br />Benthic Zone<br />bottom of lake<br />inhabited by organisms that can tolerate cool temperatures and low oxygen levels<br />
  13. 13. WETLANDS<br />areas of standing water that support aquatic plants<br />among the richest biomes for its diverse communities<br />marshes, swamps, and bogs are considered wetlands<br />can be freshwater or saltwater<br />plant species adapted to the very moist and humid conditions are called hydrophytes<br />
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  15. 15. RIVERS and STREAMS<br />bodies of water that move continuously in one direction<br />water changes from their point of origin (headwaters) to where they empty into a larger body of water (mouth)<br />In the headwaters, the water is cold and clear, carries little sediment, and has few mineral nutrients.<br />Near the mouth, water moves slowly and is more turbid due to sediment entering from other streams and erosion; the nutrient content is also higher.<br />
  16. 16. <ul><li>Source Zone</li></ul>contains headwaters (headwater streams)<br />often begins as springs or snowmelt<br />cold<br />clear<br />carries little sediment<br />contains relatively few nutrients<br />channels usually narrow<br />current is swift<br />substrate is rocky<br />
  17. 17. <ul><li>Transition Zone</li></ul>contains wider, lower elevation streams<br />streams join to form tributaries<br />warmer<br />less clear<br />carries more sediment<br />contains more nutrients<br />channels usually wider<br />current is slower<br />substrate begins to accumulate silt<br />
  18. 18. <ul><li>Floodplain Zone</li></ul>tributaries join to form rivers<br />which empty into oceans at estuaries<br />warmer still<br />murky<br />carries substantially more sediment<br />contains substantially more nutrients<br />channels wider, wide mouth<br />current relatively slow<br />substrate silty from deposition of sediment<br />