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Overview
Brief description of the ecosystem:
Definition:The ecosystem, Lake, is a large physical feature of freshwater, which forms a depression on the surface. The freshwater usually is supplied by a drainage of a extended area. Compared to a pond, the lake is said that it is larger and deeper.
(picture of lakes)
Where can Lakes be found?
Majority Of the Lakes can be found in areas with lots of mountains, rift zones which are volcanic like structures and areas which have large amount of ice moving very slowly. However, some are found at drainage basins. This applys to all lakes that they are temporary over geologic time scales, as the lakes will slowly fill in with sediments.
Formation Of various Lakes
When a mountain range is lifted, it creates a bowl-shaped depression and water will be accumulated to form lakes. The formation and melting of glaciers creates a depression for water to accumulate and will also form lakes. Lakes are also formed when landslides happen. The first lake is the salt lakes are fprm when water evaporates quickly and the drainage surface of the water and atmosphere pressure is higher than the salt level. Second is the oxbow lakes where it is formed due to the outer side meandering more than the inner side. Lastly, Crater Lakes are formed in the calderas of volcano which fill the precipitation more than the rate of evaporation.
(Picture showing formation of lakes)
Examples Of Types Of Lakes:
Crater Lakes, Fjord Lakes and Seasonal Lakes.
Left Side: Crater Lake Right Side: Fjord Lake
Level of human activity
The level of human activity is usually low majoritily as humans just use lakes as a source of hydro for hydro electric power stations to be runned to produce electricity. It is also use in humans for navigation around the lake for tourist attractions which will bring in income for the country. The only negative impact is that some humans use lakes for irrigation and causes the lake to be gone. So,the level of human activity is mainly low.
Disappearance Of Lakes:
A lake will become a swamp if too much sediments are deposited. Large water plants like the water lily will acclerate ths process as they will decompose to form peat soils. Peat soils can burn and recreate a shallow lake. A disappearing lake has many floating plants on the water edges and becomes a habitat for them and some aquatic animals. Day by day, the lake will close and form young peats as a fen. One day, the lake would have been closed until it cannot be seen. Lakes can also disappear due to the shifting of soil and human activities.
(Satellite Image showing the lake in blue and plants in green. As seen from this, the river is disappearing due to the domination of plants.)
Physical Factors
In an ecosystem, there are basically 5 physical factors. They are light, temperature, water air and mineral salts and pH salinity. Now let us find out how this 5 factors affect a lake.
Light
The amount of light within the water column is the most important condition as it controls the temperature and rate of photosynthesis by plants. Light also affects wind and water movements and the amount of dissolved oxygen in water. The amount of light received by the lake depends on how much the clouds are being covered and how deep the water is. If more like is reflected into the lake, aquatic plants will be able to make more food.
Temperature
When the temperature is high, lakes tend to seperate distinct layers. The larger a lake, the deeper it will form in layers. In late summer when the temperature is starting to get cold, the surface of the lake will be cold, the cooler water sinks and is replaced by warmer water and the temperature is about 4.C. When it is winter which means the temperature is very cold, it will affect the amount of light entering the lake and reduce the rate of photosynthesis in plants as the surface of the lake turns into solid ice. When the temperature is high, the water will become hot also and affects the amount of dissolved oxygen to decrease as the lake has formed in layers.
Water
The water from the lake basically accumulates in a depression of a land by rainfall and melting of glaciers. It is made up of fresh water by suspended materials. The water in the lake affects the lake itself and the living organisms living in it. If the quality of the lake is polluted, it will prevent aquatic plants which are submerged from making food and the aquatic animals from breathing in enough dissolved oxygen. Therefore, it is a must to ensure the quality of a lake is to be maintain clean and pure.
Air
In the lake, it contains dissolved oxygen for the aquatic organisms to breathe in. With this, they can survive. However, if there is water pollution, there will be a lack of oxygen and the aquatic organisms will not be able to survive in the water as there is far too little that what they need and eventually, they will die out.
Mineral Salts and salinity
The mineral salts in the lake plays a very important role to all the aquatic living organisms in there for the survival of the aquatic organisms in the lake. The aquatic plants need the mineral salts to gain nutrients to be able to survive. The aquatic animals then gain energy from the food they eat in the lake which contains mineral salts. The nutrients which the mineral salts contain nutrients like sodium, potassium, calcium chloride, phosphate, sulphate,etc...
pH
The pH of the lake determines the type of living organisms that will live there as some organisms cannot live in environments which are too acidic or too alkaline. Aquatic orgainisms are very sensitive to the acidity or alkalinity of the water they live in. Thus, orgainisms living in lakes must live in water with pH range of about 7. If they live in waters with pH range above 7, they will most probably die out.
Classification of Living Organisms
An ecosystem is classified into 3 groups. Producers, Consumers, Decomposers.
Starting with the producers.
1) Floating Plants
eg. Water Lily
(Water Lily)
2)Submergent
eg.Bladderwort
(Bladderwort)
3)Emergent
Eg.Cattail
(Cattail)
4)Exotics
Eg.Eurasion Water Milfoil
(Eurasion Water Milfoil)
Next, welcome the consumers.
1)Frogs
2)Kingfishers
3)Piscivorous Fish
(Frogs)
(Kingfishers)
(Piscivorous Fish-a type of carnivore fish)
Lastly for the decomposers.
The Algae and bacteria in the lake.
(Close Up view of the Algae)
Food Web
Here is the food web of a lake ecosystem.
Click on this link to view it!!!
Lake Ecosystem Food Web.pptx
Interrelationship in Ecosystem
In an ecosystem, there is a biotic environment for the organisms to live in. This leads to the formation of 3 relationships in the ecosystem Predator-prey relationship, Parasitism and Mutualism.
Predator-prey relationship
In this relationship, there is a predator which is the animal that lives by killing and eating other animal. The animal that is killed and eaten by other animals is called the prey.
An example showing a lion as the predator and the zebra as the prey.
The predator-prey relationship in a lake can be madde up of lots of them. Example, the kingfisher being the predator, eating the fishes which are the prey. The frogs which is the predator will eat the dragonflies flying above the lake surface. The carnivorous fishes being the predator eating the small fishes being the prey.
The Ringed kingfisher eating fish....What a pity..T_T for the fish
Parasitism
The definition of Parasitism is a relationship between two organisms in which one (the parasite) benefits at the expense of the other (the host or the source). A parasite usually doesnt harm its host.
Picture showing example of parasitism where the fungus gets to benefit by extracting the nutrients out from the suffering log.
In the lake ecosystem, parasitism happens like when the fishes in the lake eat the algaes. This benefits the fish as there is food supply for the fish. However, the algaes will slowly be eaten and eventually die.
Mutualism
The definition of mutualism is a relationship between two organisms in which both benefit from it.
Mutualism is shown as the bees help to pollinate the flower and the flower provides nectar for the bees.
In a lake ecosystem, mutualism is shown like when the duckweeds photosynthesize, they give out oxygen and is dissolved into the lake and changes to dissolved oxygen for the fishes to breathe. The fishes in return give out carbon dioxide which goes up to the surrounding air for the plants to use to photosynthesize.
Useful Links
Include the links of websites you took information from.
For example:
Wild World @ nationalgeographic.com ( http://www.nationalgeographic.com/wildworld/terrestrial.html )
Image by FlamingText.com
Image by FlamingText.com
Comments (5)
2E1group6 said
at 10:39 pm on Mar 27, 2009
Hurray Overview is done
-Nicholas-
2E1group6 said
at 2:39 pm on Mar 28, 2009
Haha i agree...
-Kevin-
nazrul_hadi_jamali@... said
at 3:22 pm on Mar 31, 2009
Hi group 6, good job on the quick upload so far. Keep it up! You may wish to check the facts on mineral salts under 'Physical Factors' - do mineral salts actually contain nutrients like vitamins and proteins?
2E1group6 said
at 5:06 pm on Mar 31, 2009
ok we will try to work on that
2E1group6 said
at 9:13 pm on Mar 31, 2009
Finally completed..We edited the food web pls view at it again...
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