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Role of Sunlight and Dissolubility of Oxygen in Aquatic Ecosystem

Role of Sunlight and Dissolubility of Oxygen in Aquatic Ecosystem

Aquatic Ecosystem

  • An aquatic ecosystem is an ecosystem in a body of water.
  • The two main types of aquatic ecosystems are marine ecosystems and freshwater ecosystems.
  • Important factors affecting the productivity of aquatic ecosystems are as follows.

SUNLIGHT

  • Sunlight is the most important factor determining the productivity of all the ecosystems.
  • In an aquatic ecosystem, sunlight diminishes rapidly as it passes down the water body.
  • Based on availability of sunlight, aquatic body is divided into photic and aphotic zones.
  • A photic zone refers to the part of water body, where light penetrates.
  • An aphotic zone refers to the part of water body, where there is no penetration of light.
  • Penetration of light depends upon the transparency of water body and the extent of sunlight available.
  • Photic zones are larger in the tropical regions as compared to polar regions because of larger availability of sunlight in the tropical regions.
  • Within photic zones, both photosynthesis and respiration occur.
  • In apthotic zones, only respiration occurs because sunlight is not available to carry out photosynthesis.
  • Sometimes, especially during winters, water body is covered with ice.
  • Ice has high reflectivity. Thus, less sunlight penetrates into these water bodies.
  • Consequently, photosynthesis cannot be carried out in these water bodies, leading to lack of oxygen. This further leads to the death of many aquatic species.
  • This phenomenon is called winterkill.                              Role of Sunlight and Dissolubility of Oxygen in Aquatic Ecosystem

DISSOLUBILITY OF OXYGEN

  • In the aquatic ecosystem, concentration of oxygen varies depending upon various factors.
  • In freshwater, the average concentration of oxygen is 10 parts per million (ppm).
  • Oxygen enters the aquatic ecosystem through air-water interface and due to the photosynthesis carried out by aquatic plants.
  • Dissolved Oxygen (DO) escapes the water body through air-water interface and due to respiration by the aquatic animals.
  • Temperature of water also influences the amount of oxygen retained.
  • In warm water, oxygen is less soluble and the rate of decomposition is also high.
  • Therefore, increase in the temperature of a water body leads to depletion of oxygen.
  • When the level of dissolved oxygen falls below 3-5 ppm, many aquatic organisms are likely to die.

ALSO READ : https://www.brainyias.com/medical-oxygen/

Environment & Biodiversity

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