Aquatic Ecosystem:

An Ecosystem Which Consists the Water is the Main Source of the Habitat is Known as the Aquatic Ecosystem.

  1. Fresh Water Ecosystem: The Salt Contains the Fresh Water Bodies is Very Low always than the 5ppt.
  2. Marine Ecosystem: The Water Bodies Contains the Salt Concentration Equal or Above the Sea Level.
  3. Brackish Water Ecosystem: These Water Bodies have Salt in the Content Between 5 to 35 PPT.

Aquatic Organisms:

The Organisms in the Aquatic Organisms Are Unevenly Distributed but can be Classified on the Basis of their Life:

  1. Neuston:
    • They are Unattached Organisms Which Live at the air Water Interface Such as Floating Plants Etc. Some of the Organisms Spend Most of the Lives at the top of the Air Water Surface.
  1. Periphyton:
    • These Organisms Which Remain Attached with the Steams and Leaves of the Rooted Plants or Substances Emerging Above the Bottom Mud.
  1. Plankton:
    • This Group includes all the Microscopic Plants such as Algae and Animals Like Crustaceans and Protozoans.
  1. Nekton:
    • These Group Contains Animals Which Are Swimmers. They are Relatively Large and Powerful. The Animals range in Size from the Swimming Insects to the Largest Animals like Blue whale.
  1. Benthos:
    • The Benthic Organisms are those Found Living in the Bottom of the water Mass.
    • Every Aquatic Organisms Contains Well Developed Benthos.

Filter feeders

  • They could be important for the maintenance of the health of water bodies.
  • They are known to mitigate diseases by removing pathogens hence are presumed that they eliminate specific entities actively for consumption.
  • Filter feeders are a subdivision of suspension-feeding entities which feed by straining suspended matter and food particles from water by passing the water over a specialized filtering structure.
  • Mussels and oysters filter feeders filter tiny particles and toxins out of the water and promote water clarity. Hence, these feeders could play a significant role in clarifying water, and hence are considered ecosystem engineers.

Factors Affecting the Aquatic Habitats:

  1. Sunlight:

Sunlight Penetration Rapidly Diminishes as it Passes down the Coloum of Water. As Based on the Light Penetration and Plant Distribution they are Classifies as Photic and Aphotic Zones.

  1. Photic Zones:

It’s the Layer of the Aquatic Ecosystem, up to Which Light Penetrates and Within Photosynthesis Activity Confined. Both Photosynthesis and Respiration Activity.

  1. Aphotic Zones:

The Lower Layers of the Aquatic Ecosystem Where Light Penetration and Plant Growth Are Restricted forms the Aphotic Zones. Only Respiration Activity took Place.

  1. Dissolved Oxygen:
  • In Aquatic Ecosystem Oxygen dissolved in Water, where it Concentrates Varies Constantly Depending On Factors that Influence the input and Output of Oxygen in Water. Oxygen Enters the Aquatic Ecosystem through air Water interface and by Photosynthetic Activities of Aquatic Plants.
  1. Transparency:
  • It Effects the Extent of the Light Penetration. Suspended Particulate Matters Such as Clay, Slit, Phytoplankton, Etc.
  1. Temperature:
  • The Water Temperature Changes Less Rapidly than the temperature of Air Because Water has a Considerably Higher Specific heat than air. Since Water Temperature Are Less Subject to Change, the Aquatic Organisms have Narrow Temperature Tolerance Limit.

Lake Ecology:

Ageing of Lakes:

Lakes are Born as they Originate by Various Geological and Geomorphic Events and grow with time to time in Various Stages. Over Periods Spanning Millennia Ageing Occurs as the Lakes Accumulate Mineral and Organic Matter and Gradually Filled up.


Eutrophia Means Adequate and Healthy Nutrition. It is a Syndrome of ecosystem response to Addition of Artificial or Natural Substances Such as Nitrates and Phosphorus. Eutrophication is the Enrichment of an Aquatic system by the Addition of Nutrients.

  • Some Algae and Blue Green bacteria thrive on the excess ions and a population explosion covers almost entire surface layer is known as algal bloom.
  • Oxygen is required by all the respiring animals in the water and it is replenished by photosynthesis of green plants.
  • All this eventually leads to degradation of Aquatic ecosystem and death of its organisms.
  • It leads to change in animal and plant population & degradation of water & habitat quality.

Flow chart:

Change in ecosystem:

Eutrophication Eventually create deterius layer in the ponds & lakes and Produces successively shallower depth of surface water.

Decreased biodiversity:

Algal blooms restrict the sunlight to penetrate & effects the photosynthesizing plants.

New species invasion:

Eutrophication may Cause the Ecosystem Competitive by Transforming the Normal Limiting Nutrient to abundant Level


The Algal Blooms when Die or Eaten, Release Neuro & Hepatotoxins Which can kill Aquatic Organisms & Pose threat to Humans. Depletion of Dissolved Oxygen Level and the Coral Reefs So the Affects Navigation due to increased turbidity.


The Interfaces Between a Flowing Body of Water and Land Created Near the Waterways, farms, Roads, Etc. Sediments and Nutrients Are Deposited in the Buffer Zones instead of Deposition in Water. The Successful Method of Minimizing the non-Point Pollution. They are Nitrogen Testing & Modelling.


The Multi-Dimensional in Nature Should include Education & Awareness so Research, Monitoring and Evaluation of Regulations.

Harmful Algae Blooms:

Algae are Microscopic Organisms that can be Found Naturally in Coastal Waters. They Are Major Producers of Oxygen and Food for Many of the Animals. A bloom Often Results in a Color Change in the Water. Algal Bloom can be any Colour, but the Most Common Ones Are Red and Brown.

Wetland Ecosystem:

The Area of Marsh, Fen, Peatland, Whether Natural Artificial Permanent Temporary with Water that is Static Flowing, Fresh, Brackish Salt, Including areas of Marine Water the Depth.

Function of Wetlands:

  • Habitat to Aquatic A Flora and Fauna as Well as Numerous Species of Birds, including Migratory Species.
  • Nutrients Recycling
  • Water Purification
  • Floods Mitigation
  • Maintenance of Stream Flow
  • Ground Water Recharging
  • Provide Drinking Water.


  • Covered by Waterlogged soil for At least Seven Days During the Growing Season.
  • Adopt Plant Life.
  • Hydrilic Soils.
  • Stabilization of Local Climate.
  • Source of Live Hood for Local People.

Reasons for Depletion:

  • Conversion for Lands for Agriculture.
  • Overgrazing
  • Removal of Sands from beds.
  • Aqua Culture.
  • Pollution
  • Domestic Waste.
  • Climate Change.


  • Survey and Demarcation.
  • Artificial Regeneration.
  • Protective Measures.
  • Weed Control
  • Wildlife Conversation
  • Environmental Awareness

Estuary Ecosystem:

They are Located where the River meets the Sea. They are the Water Bodies where the Flow of the Fresh Water from River Mixes with the Salt Water Transported, by tide, from the Oceans.


  • An Estuary is a Semi Enclosed with a Coastal Body of Water with one or More Rivers or Streams Flowing into it.
  • It has Free Connection with a n Open Sea
  • The Complete Salinity Range from 0-35 PPT is seen from the Head to the Mouth of an Estuary.
  • Estuaries ae Typically Classifies by their Geomorphological Features or by Water Circulation Patterns and Can Be Referred by Many Different Names Such as Bays, Harbors, Lagoons, inlets, Etc.
  • Estuaries are Usually Biologically Highly Productive Zones.