AQUATIC ECOSYSTEM

 Aquatic ecosystem is an ecosystem in the body of water. They are the living things that depend on the water for survival, such as fish, plants, and micro-organisms. They are very fragile and easily disturbed by the pollution. It includes ocean, lakes, river, wetland, streams and estuaries. It includes a group of interacting organisms which are dependent on one another and their water environment for nutrients and shelter. There are two types of aquatic ecosystem: marine ecosystem and fresh water ecosystem.

1.      Fresh water aquatic ecosystem

                     They cover only a small portion of earth nearly 0.8 per cent. Freshwater involves lakes, ponds, rivers and streams, wetlands, swamp, bog and temporary pools. Freshwater habitats are classified into lotic and lentic habitats. Water bodies such as lakes, ponds, pools, bogs, and other reservoirs are standing water and known as lentic habitats. Whereas lotic habitats represent flowing water bodies such as rivers, streams.

2.      Marine ecosystem

                   Marine ecosystem covers the largest surface area of the earth. Two third of earth is covered by water and they constitute of oceans, seas, intertidal zone, reefs, seabed, estuaries, hydrothermal vents and rock pools. Each life form is unique and native to its habitat. This is because they have adaptations according to their habitat. In the case of aquatic animals, they can’t survive outside of water. Exceptional cases are still there which shows another example of adaptations (e.g. mudskippers). The marine ecosystem is more concentrated with salts which make it difficult for freshwater organisms to live in. Also, marine animals cannot survive in freshwater. Their body is adapted to live in saltwater; if they are placed in less salty water, their body will swell (osmosis).

 Aquatic ecosystems perform many important environmental functions. For example, they recycle nutrients, purify water, attenuate floods, recharge ground water and provide habitats for wildlife. It is also used for human recreation, and are very important to the tourism industry, especially in coastal regions. The health of an aquatic ecosystem is degraded when the ecosystem's ability to absorb a stress has been exceeded. A stress on an aquatic ecosystem can be a result of physical, chemical or biological alterations of the environment.

·         Physical alterations include changes in water temperature, water flow and light availability.

·         Chemical alterations include changes in the loading rates of bio-stimulatory nutrients, oxygen consuming materials, and toxins.

·          Biological alterations include over-harvesting of commercial species and the introduction of exotic species.