Freshwater Ecosystem

 

Fresh Water Ecosystem 

 

A freshwater ecosystem whose physical nature is dominated by set the of presence of water and supports a distinct producers (plants) and consumers (animals). When the water system is inland from the coast, and surface water as is streams and rivers and is standing waters like in lakes, reservoirs, ponds or wetlands, the ecosystem is a freshwater fre shwater ecosystem. he factors a!ecting the type and number of organisms found in fresh water are"  he amount or concenration concenration of nutrients nutrients  he depth through through which sunlight sunlight can penetrate  he amount of dissolved dissolved o#ygen o#ygen and water temperature •

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$lants

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American Waterweed  Waterweed  (Elodea

canadensis)

 

Bladderworts (Utricularia spp.)

 

%attail  (ypha spp.)

 

Coontail (Ceratophyllum demersum)

 

Animals

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Amazon River Dolphin (Amazon River)

 

Fresh Water urtle

 

!e"on# $iant Freshwater Freshwater Fish  (!e"on# River China)

 

*akes  

 he lake lake is a standing freshw freshwater ater ecosystem. ecosystem.

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&t is formed when water is collected from direct precipitation, surface run o! or ground water 'ow. Water lls the basinlike depression formed from volcanic activity aal *ake*aguna, in +atangas, adlac *ake(e.g., in *os +anos, +ulusan *ake in orsogon, *ake ube in -indanao) glaciation (/reat *akes in 0orth America) and impact featur features es of meteorites (%rater *ake in 1regon).

 

2istinct 3one of *akes 

 

A typical lake has distinct 4ones of biological communities linked to the physical structure of the lake (Figure 56). he littoral littoral 4one  4one is the near shore area where sunlight penetrates all the way to the sediment and allows a8uatic plants (macrophytes (macrophytes)) to grow. *ight levels of about 59 or less of surface values usually dene this depth. he 59 light level also denes the euphotic 4one 4one of  of the lake, which is the layer from the become surface down tofor the depth where light levels too low photosynthesi4ers photosynthesi4ers.. &n most lakes, the sunlit epilimnion.. euphotic 4one occurs within the epilimnion

 

:owever, in unusually transparent lakes, photosynthesis  may occur well below the photosynthesis may thermocline thermocline into  into the perennially cold hypolimnion. hypolimnion. For e#ample, in western *ake uperior near 2uluth, -0, summertime algal photosynthesis and growth can persist to depths of at least ;< meters, while the mi#ed layer, or epilimnion, epilimnion, only e#tends down to about 56 meters. =ltraoligotrophic =ltraoligotrophic *ake  *ake ahoe, %A>0?, is so transparent that algal growth historically e#tended to over 566 meters, though its mi#ed layer only e#tendsinade8uate to about 56 meters in of summer. =nfortunately, management basin since  since about 5@6 has led to a the *ake ahoe basin signicant loss of transparency due to increased algal growth and increased sediment inputs from shoreline erosion.  erosion. stream and shoreline

 

 he higher plants in the littoral 4one, in addition to being a food source and a substrate  for algae and invertebrates, provide provide a habitat for sh and other organisms that is very di!erent from the open water environment.  he limnetic 4one is 4one is the open water area where light does not generally penetrate all the way to the bottom. he bottom sediment, known as the benthic 4one, 4one, has a surface layer abundant with layer of sediments may organisms. be mi#ed byhis theupper activity of the benthic  organisms that live there, often to a depth of ;< cm (several inches) in rich organic  sediments. -ost of the organisms in the benthic 4one are 4one are invertebrates, such as

2ipteran insect 2ipteran  insect larvae (midges, mos8uitoes, mos8uitoes,  

 he productivity productivity of  of this 4one largely depends upon the organic content of the sediment, the amount of physical structure, and in some cases upon the rate of sh predation. andy substrates contain relatively little organic matter (food) for organisms and poor protection from predatory sh. :igher plant growth is typically sparse in sandy sediment, because the sand is unstable and nutrient decient. A rocky bottom hasprotection a high diversity of from potential habitats o!ering (refuge) algae (  ( predators, pre dators, substrate for attached algae periphyton periphyton on  on rocks), and pockets of organic Boo4eB (food). A 'at mucky bottom o!ers abundant food for benthic organisms but is less

protected prote cted and may have a lower diversity of  

2istinct *ayers of *akes

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*akes can be classied into two distinct layers" •

Epilimnion C upper layer of with warm water e#posed to the atmosphere with high level of dissolved o#ygen.

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:ypolimnion C lower layer of colder, denser water, usually with a lower concentration of dissolved o#ygen.

 he main transition 4one 4one separating these two layers is called the thermocline, in which the temperature

drops sharply sharply..  

-aDor ypes of *akes  

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Eutrophic C lake with a low supply of plant nutrients -esotrophic *akes C *ake that fall somewhere between these two e#tremes of nutrient enrichment.

*akes may not always contain freshwater or water with low sanity that is usually associated with lakes.

 

eservoir  

Are fairly large and deep, human created bodies standing water, often built behind of dams. heyfresh are built primarily for water storage.

 

$ond  

Are small, shallow usually humancreated impoundments of freshraising water fres used primarily for watering livestock, freshwater hwater sh or recreation, especially shing.

 

tream  and iver 

$recipitation that does not inltrate into the

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ground remains on the earths surface or as evaporate surface water. treams are relatively small and 'owing bodies of freshwater that empty into rivers.