Ecosystems are biological systems that are formed by all the organisms that live in a community and by all the abiotic or non-biological factors (climate, relief, luminosity…) with which they interact. On our planet there is a great variability of ecosystems that are classified into aquatic, terrestrial and mixed or transition ecosystems. For example, aquatic ecosystems encompass many environments and we can distinguish between marine and inland water ecosystems, which develop on the surface of the continents, whether they are fresh or salt water.
In this AgroCorrn article we delve into a type of inland water ecosystem : freshwater aquatic ecosystems, their examples and characteristics .
What are freshwater aquatic ecosystems
The inland water ecosystems , which are freshwater, are systems of great importance that provide very different services: they are a source of food and water, regulate climate, maintain biodiversity and soil, stores and eliminate contaminants and participate in the nutrient recycling process.
The aquatic freshwater ecosystems are classified as:
- Lotus systems: as examples of freshwater ecosystems considered lotics we have rivers, streams, streams and springs.
- Lentic systems: as examples of sweet aquatic ecosystems considered lentic we have lagoons and lakes, ponds, ponds, swamps, swamps …
- Wetlands and estuaries.
So, if you were wondering which are the two main types of freshwater ecosystems, these are the lotic and lentic ecosystems. However, wetlands deserve a separate mention for their condition. To expand this basic information about this type of ecosystem, we encourage you to read this other post about What is an aquatic ecosystem .
Characteristics of freshwater ecosystems
After learning briefly what a freshwater ecosystem is, we will now mention that among the general characteristics of freshwater ecosystems, apart from having a low density of salt in their waters, we highlight the following:
Biotope of the freshwater ecosystem
Among the characteristics of the biotope or area in which these aquatic spaces are, we can mainly indicate these:
- The climate in freshwater ecosystems is highly variable, as it depends on how close or far you are from coastal areas, as well as at what altitude you are. Thus, the higher the ecosystem is, for example on top of a mountain, the colder the climate will be.
- Where are freshwater ecosystems found? As we have clarified before, the location of these is one of its main characteristics. These are areas of continental waters, that is, they are on land, either on the earth’s surface or under it.
Biocenosis of the freshwater ecosystem
Among the characteristics of the biocenosis or flora and fauna of the freshwater ecosystem we highlight:
- Flora of aquatic ecosystems: these are freshwater plants and algae. Among the plants that inhabit these waters or on their shores we can highlight the water hyacinth, water lilies, coves, reeds, reeds, water lettuce, etc. Discover +50 aquatic plants, their names, characteristics and images in this other post.
- Fauna of aquatic ecosystems: among the aquatic animals in these areas there are both fish and mollusks, amphibians, insects and mammals. Some examples are salmon, trout, piranhas, otters, beavers, manatees, swans, ducks, ibis, alligators, lizards, frogs, toads, leeches, crayfish, etc. Here you can meet +35 freshwater animals .
Freshwater ecosystems: example of lotic systems or rivers
Rivers are streams of water that persist over time and flow continuously in one direction. The characteristics of the river basin together with the climate (temperature and rainfall) will determine the vegetation of the riverbank. The main primary producers of biomass in rivers are algae ( phytoplankton if they live in suspension in the water column, and periphyton or biofilm if they live on sediments), mosses, lichens and vascular plants .
Rivers change throughout their journey. The upper, middle and lower reaches of the rivers present different characteristics and, therefore, will present different communities of species and processes.
- Upper section of the river: near its source the rivers have a steep slope, shallow depth, width and flow, thick substrates and a turbulent flow (the water particles move chaotically). In many high sections the light is scarce due to the riverside vegetation, which makes primary production difficult.
- Middle and lower sections of the river: as we descend in its course the river will gain in depth, will have more width and more flow, the substrates will become finer and the flow will become laminar (all the water particles move in the same direction ). In these sections the temperature of the river increases, since the waters have received more solar radiation as its channel widens, with which the lighting conditions for primary production improve. However, in lower reaches there is too much depth and conditions get worse again, as the river also carries a large amount of sediment, not reaching the bottom of the basin.
An important characteristic of rivers, since it will determine the communities that will be found in their surroundings, is the hydrological regime; that encompasses all the temporal variability of the amount of water in the river ecosystem , that is, the frequency of floods, droughts, their magnitude and duration, their predictability, etc.
It should also be noted that the state of these rivers has a direct and indirect impact on the ecosystem. An example of this is groundwater , which is of great importance, since its waters can also be used, but they are not independent of the state of conservation of the rivers.
We advise you to expand this information with this other AgroCorrn post about lotic ecosystems: what they are and their characteristics .
Lentic systems, another example of freshwater ecosystems
Lentic systems such as lakes, ponds, ponds, ponds, swamps, swamps, etc. , are closed bodies of water without flow or currents that persist over time. In them we can differentiate three zones: epilimnion (most superficial layer of the water column), metalimnion (intermediate layer, with very changing physical and chemical characteristics) and hypolimnion (deepest layer).
The environments present in freshwater aquatic ecosystems that are called lentic systems can be classified into three zones:
- Littoral zone: near the edge, there is vegetation present and the light reaches the bottom of the lake.
- Pelagic zone : open water zone where the survival of phytoplankton is possible.
- Deep zone: the survival of plant species such as phytoplankton, macrophytes (plants that we see with the naked eye) or periphyton is not possible as light does not reach the bottom of the lake.
Volume and depth are two very important factors in these systems. By increasing both, the volume of water in contact with the atmosphere (main source of oxygen) and sediments decreases (the entry of nutrients into the water column is hindered), and the water renewal time increases (time that must pass so that all the water in the system is replaced).
These freshwater ecosystems can be temporary if water does not flow out through rivers and are often home to poor communities, although some organisms are highly abundant due to the drought-flood cycle and the scarcity of predators.
In deep lakes , thermal stratification occurs, a phenomenon by which the layers of the water column differ due to changes in their density, causing the most superficial layer to float on the deeper ones without mixing with them, making it difficult for the nutrients to rise from the bottom.
If you want to delve into these knowledge, here is a summary post on Lentic Ecosystems: what they are and examples .
Wetlands and estuaries, large freshwater aquatic ecosystems
Wetlands are mixed or transition ecosystems between inland water ecosystems and terrestrial ecosystems. They have characteristics similar to lentic ecosystems and terrestrial ecosystems , since they occur in places where at least once a year the soil is saturated with water. When this happens, the soil is deprived of oxygen and an intermediate ecosystem is generated. For all these reasons, the communities of these environments are neither purely terrestrial nor purely aquatic; the fauna is usually endemic and differentiated from neighboring areas, such as large families of birds and reptiles.
According to the RAMSAR convention (the Convention Relative to Wetlands of International Importance, especially as Habitat for Waterfowl), wetlands are vital for humans as they are one of the most productive environments on the planet, being sources of water and places of great biological diversity and primary productivity. Thus, countless species, both animal and plant, depend on wetlands to survive. However, the surface and quality of these environments continue to decrease, among other causes, due to their transformation for the exploitation of agriculture or aquaculture.
Get to know these sweet aquatic ecosystems better by reading this other post about Wetlands: what they are, types and characteristics . Other ecosystems similar to wetlands are estuaries , which are also mixed. Of these two types of aquatic areas there are some with sweeter waters and others with brackish waters, since they are transition ecosystems, although the waters of estuaries tend to be more brackish than those of other types of wetlands.
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