Aquatic Ecosystems

• Aquatic ecosystems include plant and animal species found in bodies of water. Aquatic ecosystems are classified based on salinity into following two types: (i) Freshwater (ii) Marine

Freshwater aquatic ecosystem covers only 0.8 percent of earth. Freshwater is further classified into lentic and lotic habitats.

Lentic Ecosystem

Standing water bodies such as ponds, lakes, bogs, pools and other reserve waters are known as lentic habitats. A lot of aquatic insects such as crabs, amphibians , shrimps and frogs etc. are the species of lentic ecosystem.

Lotic Ecosystem

On the other hand, flowing water such as rivers and streams are known as lotic habitats. Lotic ecosystem mainly refers to flowing water that moves in an unidirectional way. A lot of aquatic insects such as mayflies, beetles and stoneflies etc. are the species of the lotic ecosystem.

Components of Aquatic Ecosystems:

• Abiotic Components

• • • Light: Solar radiation provides the energy that keeps the system running. The amount of dissolved or suspended particles in water, as well as the number of plankton, all influence light penetration. An aquatic environment can be classified into euphotic (eu=true, photic=light), mesophotic, and aphotic zones based on the extent of light penetration. In the euphotic zone, plants and animals have plenty of light. In the aphotic region, there is no light
    • Inorganic substances: These are carbon, water, phosphorus, nitrogen, calcium, and other elements like sulphur depending on the location of the ecosystem. The inorganic substances like carbon dioxide and oxygen are dissolved in water. Both plants and animals rely on water for food and gas exchange. Phosphorus, nitrogen, sulphur, and other salts of inorganic nature are present in the bottom bed and within living organisms as reserves. A very small percentage of these salts can be dissolved

• Organic compounds: Amino acids, humic acids, as well as the broken down products of dead animals and plants, are some of the natural organic compounds of the aquatic environment. They are partially dissolved and partially suspended in water

• Biotic Components

• • Producers or autotrophs: These synthesize food for all the heterotrophs of the aquatic ecosystem. We can classify them into two segments:
    • Floating microorganisms and plants: These are called phytoplankton (“Phyto”- plants, “plankton” –floating). They are microscopic organisms. Sometimes, they are so abundant in the water body that they make it look green in color; e.g., Spirogyra, Ultrix, Cladophora, Diatoms, Volvox
    • Rooted plants: From the periphery to the deeper layers, these are organized in concentric zones. With increasing water depths, three distinct zones of aquatic plants can be seen in the following order:
      • Zone of emergent vegetation: e.g., Typha, Bulrushes and Sagittaria
      • Zone of rooted vegetation with floating leaves. e.g., Nymphaea
      • Zone of submergent vegetation: For example, the pond weeds such as Hydrilla, Rupia, musk grass etc
    • Consumers/Heterotrophs: Consumers are those organisms that derive their nutrients either directly or indirectly from the autotrophs i.e the producers, for e.g., Tadpole, snails, sunfish, bass etc. These animals can be classified into the following groups:
      • Unattached creatures that live at the air-water interface, such as floating plants, are known as Neuston. For example, Beetles and back-swimmers
      • Periphyton are organisms that cling to the stems and leaves of rooted plants or substances that emerge above the mud’s surface, such as sessile algae and their associated group of animals
      • Zooplanktons are floating animals. For example, Cyclops, Cypris.
      • Nektons are creatures that have the ability to float and navigate at will. For example, Fish
      • Benthic species are those that live at the bottom of the ocean, e.g., Molluscs, mites, beetle, and some crustaceans
    • Decomposers: They are distributed throughout the entire aquatic ecosystem but  live at the water body’s bed. These are bacteria and fungi, e.g., Rhizopus, Penicillium, Curvularia,  that feed on the dead and decomposing lives

Conclusion

In this article, we have discussed the aquatic ecosystem and its components. Aquatic ecosystems include plant and animal species found in bodies of water. Aquatic ecosystems are classified based on salinity into the following two types, one is freshwater and the other is Marine. Freshwater aquatic ecosystem covers only 0.8 percent of earth. Freshwater is further classified into lentic and lotic habitats. Standing water bodies such as ponds, lakes, bogs, pools and other reserve waters are known as lentic habitats. A lot of aquatic insects such as crabs, amphibians , shrimps and frogs etc. are the species of lentic ecosystem. On the other hand, flowing water such as rivers and streams are known as lotic habitats. Lotic ecosystem mainly refers to flowing water that moves in an unidirectional way. A lot of aquatic insects such as mayflies, beetles and stoneflies etc. are the species of the lotic ecosystem.