Lake Ecosystem : 

 Lakes are include depressions. There are
Lake Ecosystem
the standing water bodies formed by flowing water, pre- cipitations and runoff water. The depth ranges from few feel to 5000 feet. The gradation of oxygen light and temperature effect the life in the lake. Circulation of nutrients and distribution of organisms are influenced by currents. Lakes have different zonations like ponds and provide a number of ecological─▒riches and habitats to the organisms. 

   Lakes consists of abiotic and biotic component.

1. Abiotic components : It includes light, heat, inorganic and organic compounds such as carbon dioxide, oxygen, nitrogen, phosphorus, calcium and amino acids etc. Climatic factors are also part of abiotic components.

2. Biotic components : It includes producers, consumers and decomposers.

    (i) Producers: Producers are the auto topers and includes photo plankfous such as diatoms (Naricula, Cyclotella) blue green (comaarium,algae, (Micro cystics, Occillationa) green algae (comaarium, Starurastreum) and halophytic flagellates and dinophycean flagel-lates.

    (ii) Consumers : They are heterotrophies and depend on producers for the food. Most of the consumers depend on producers for the food. Most of the consumers are herbivores. Here consumers includeBoranchiura sowerbicoligochaetes, Autodrilus., Pluriseta, Hirudinea species, Molluscs and Crustaceous etc.

   (iii) Decomposers : These are also known as micro-consumers because they absorb only a small emenent of decomposed. Organic matter, These include bacteria and fungia that feed on dead. Organic matter of consumer. They also play an important role in cycling of nutrients.

     River or Stream Ecosystem :

     Rivers : Rivers include moving water.

River ecosystem
They are available and raning in size from Ganga, Yamuna, Kalinandi, Sutlej, Gomti and sob on. considerably over its length, as it charige from a mountain brook to a large river.

     Stream : Stream are open ecosystem with high energy input Coming from outside source. Stream may begin as outlets of ponds or take or they may arise from springs and seepage areas. Tempera-terture affects the composition of stream community, shallow watesstreams are not good for many organisms streams.

(i) Fast streams : It has high velocity of water excellant trounurceriees.

(ii) Slow streams: It has low velocity of water still and decayinoorganic matter accumelates on the bottom. The running water of a stream or a river is usually well. It has a large surface area to absorb oxygen from the air. The various components of river orstream ecosystem are as follows: 

   Abiotic components : These include inorganic substances andclimatic factors. The river or stream water has lesser mineral con-tent and greater penetration of light. In the lower reaches water is usually muddy cutting down the light at the river bed.

 Briotic components :

   (i) Producers : In slow moving water of banks, ktous, phytop deatoms, blue green, algae like cladophor ulothres, water grasses and other amphibious plants are the producers. In swift w er float in populations, plankfor are generally absent.

  (ii) Consumers : These include flatworms, leaches, water insects, snails, fishes and crocodiles. lephalojhlerye, Felder, Phalachucera, Gammarns etc are the main species present. Many birds and anammals also get their food from rivers and streams.

(iii) Decomposers : Several bacteria and fungi which fecd on dead organic matter represent this group.