Thursday, October 31, 2013

Aquatic ecosystems - Lakes

LAKE ECOSYSTEM
Lakes are large shallow water bodies. They are used for various purposes and are supplied with water from rainfall, streams and melting snow.

TYPES OF LAKES
Some important types of lakes are:
  1. Oligotrophic lakes: They have low nutrient concentrations.
  2. Eutrophic lakes: They are over-nourished by nutrients like N and P.
  3. Dystrophic lakes: They have low pH, high humic acid content and brown waters
  4. Volcanic lakes: They receive waters from magma after volcanic eruption
  5. Meromictic lakes: They are rich in salts
  6. Artificial lakes: They are created due to construction of dams
ZONES OF LAKES
Depending on the depth and distance from the shore, lakes consist of the following four distinct zones:
  1. Littoral zone: It is the top layer of the lake. It has shallow water.
  2. Limnetic zone: Next to the littoral zone is the limnetic zone, where effective penetration of solar light takes place
  3. Profundal zone: It is the deep open water where it is too dark
  4. Benthic zone: This zone is found at the bottom of the lake.
CHARACTERISTICS OF THE LAKE ECOSYSTEM
  1. Lake is a shallow freshwater body
  2. It is a permanent water body with large water resources
  3. It helps in irrigation and drinking
STRUCTURE AND FUNCTION OF LAKE ECOSYSTEM
Abiotic components
Ex: Temperature, light, proteins and lipids, turbidity, oxygen and carbondioxide.
Biotic components
  1. Producers: They are green plants which might be freely floating, submerged or amphibious in nature. Ex: Phytoplanktons, algae and flagellates
  2. Consumers: Primary consumers (zooplanktons) feed on phytoplanktons. Ex: Ciliates, Protozoans, etc. Secondary consumers (carnivores) feed on zooplankton. Ex: Insects and smaller fish. Tertiary consumers feed on smaller fish. Ex: Large fish like game fish feed on small fish.
  3. Decomposers: They decompose dead plants and animals. Ex: Bacteria, Fungi and actinomycetes

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