Aquatic ecosystem: Meaning, Characteristics, Types and Importance

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Aquatic ecosystem: Meaning, Characteristics, Types and Importance

What is an aquatic ecosystem?

An aquatic ecosystem is an ecosystem that is water based. The word ‘aquatic’ comes from the Latin word for water. An ecosystem is a distinct community of organisms in a specific environment.

So, we can say that an aquatic ecosystem is a community of organisms that live together, interact, and to an extent depend on each other in a water based environment.

There are various different types of aquatic ecosystem and this article explains all about four main types of aquatic habitats for animals. So, read on to find out all about them.

Characteristics of aquatic ecosystems.

Characteristics of aquatic ecosystems include:

  • Being underwater, or
  • Being based around water.
  • Being a community of organisms.
  • Being a distinct community that is more or less self contained.

Types of aquatic ecosystems.

Let us now look at the key types of aquatic ecosystems: marine ecosystem and freshwater ecosystem – pond ecosystems, lake ecosystems and river ecosystems.

A. Marine ecosystems – salty water.

Marine is a word that comes from the Latin word for sea – mar. So, a marine ecosystem is any ecosystem that exists within the sea. Our seas and oceans are vast bodies of salt water and so – while it may be argued that the whole ocean is one giant ecosystem – it may be also argued that several different ecosystems can coexist within a single ocean. A whole host of different organisms live in marine ecosystems. When it comes to plant life, for example, we have seaweeds and marine algae. Invertebrates that live in the marine ecosystem include jellyfish and crustaceans. Meanwhile, there are fish such as sharks and eels, and mammals such as whales and seals. There are also various sea birds in all parts of the sea: they feed off the fish and other organisms that live there. Humans may also form part of the marine ecosystem if they fish in the sea for food.

B. Freshwater ecosystems.

Contrary to the marine water ecosystem that contains salty water, freshwater ecosystem has little or no salt. The major types of freshwater ecosystem includes pond ecosystem, lake ecosystem and river ecosystem.

Pond ecosystems.

A pond is discernibly a closed, self contained environment which houses a community of organisms. Ponds are usually freshwater ecosystems, however they can also be made up of brackish (salty or briny) water. Many different plants, fish and animals can live in these types of ecosystems. Frogs, newts, water weeds and water lilies are all examples of pond creatures. In addition, various types of fish can live in a pond. Ponds can be natural or human made ecosystems; if human made, it is not uncommon for goldfish or ornamental carp (such as koi carp) to live in a pond ecosystem. In addition, certain birds and insects may visit the pond ecosystem with regularity. For example, we might see dragonflies or herons around the pond. It may be up for debate whether these visitors are truly part of the ecosystem as they may also visit other ecosystems. But, it is certain that they have an impact on the ecosystem – and that it has an impact on them.

Lake ecosystems.

Because they tend to be physically enclosed by the earth, rock or mountains around them, freshwater lakes are also identifiable as a distinct habitat that is inhabited by a distinct community of organisms. In a freshwater lake ecosystem, we can find all kinds of different organisms, including crustaceans (such as shrimp and crayfish), fish (like carp, trout and pike) and many birds, reptiles and amphibians. Freshwater lakes can be home to some beautiful plant life, such as tall purple irises, and the flora and fauna that abound within them may also change with the seasons. Some animals may only use lakes for looking after their offspring in, such as frogs that may leave frogspawn in a lake before leaving to inhabit other ecosystems.

Freshwater river ecosystems.

River ecosystems are slightly different to ponds and lakes because whilst the latter two ecosystems offer stagnant (static) water, river water is always flowing. That means that these river ecosystems are the homes of animals and plants that are best adapted to living in flowing water. Salmon are a key example, as they use the flowing motion of a river to help them with their annual migration. And, in general, organisms that prefer to migrate – whether to seek food or to seek a partner – are often to be found in freshwater river ecosystems because the motion of the river suits their style of life (whilst they, in their turn, have evolved to suit a flowing environment). Rivers tend to flow into the sea, and in this way river ecosystems and marine ecosystems meet each other. It may well, therefore, be up for debate to what extent river ecosystems are closed systems. But it is definitely clear that these are distinct types of fresh water ecosystems.

The importance of aquatic ecosystems.

The health of aquatic ecosystems is crucial to the health of the planet as a whole. Our earth is not called the blue planet for nothing: the seas with their fish, weeds, invertebrates and mammals and the rivers, lakes, streams, swamps and ponds of this world are all precious repositories of biodiversity. The seas help to regulate the world’s temperature, too, and to lock carbon away from the atmosphere. Though we should all try and cut down on fish as a food source, there is no denying that fish and other aquatic organisms are irreplaceable links in the food chain for many terrestrial animals (i.e. animals that live on earth) as well.


There are many wonderful kinds of aquatic ecosystems in the world, all of them home to some truly amazing creatures. In fact, scientists believe that they have only mapped about 10 % of the creatures that live in the ocean – so vast and mysterious are our marine ecosystems. However, these aquatic ecosystems are under serious threat from pollution, carbon emissions and over fishing. We can already see the Great Barrier Reef, one of the natural wonders of the world, dying before our eyes. It is vital that we all act now to preserve our world’s aquatic ecosystems for future generations. We can do this by reducing our emissions, stopping using harmful chemicals that can leach into the oceans and rivers, and by cutting fish out of our diet.

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