An ecosystem is composed of a biological community of organisms and their environment. Ecosystems are influenced by a variety of factors including the availability of resources such as light, food and water. Other factors that shape an ecosystem are topography, soil composition and climate. There are many types of ecosystems with unique environmental characteristics and species that live there.

Two Types of Ecosystems

Ecosystems can be classified into two main categories: terrestrial ecosystems and aquatic ecosystems. Terrestrial ecosystems are located on land masses and cover approximately 28% of Earth’s surface. Examples of terrestrial ecosystems include desert, tundra, rainforest and alpine regions.

Aquatic ecosystems are located within a watery environment (aquatic environment) and cover more than 70% of Earth’s surface. Examples of aquatic ecosystems include lakes, ponds, bogs, rivers, estuaries and the open ocean.

Information About Aquatic Ecosystem

Some basic, important information about aquatic ecosystems is that there are two types: marine ecosystems and freshwater ecosystems. The main difference between these two types of aquatic ecosystems is the salinity (saltiness) of the water present in the ecosystem. The amount of salt in water greatly impacts the types of species that can live in a particular aquatic environment.

Marine ecosystems are located in oceans and seas around the world and provide habitat for a wide variety of specialized organisms from tiny plankton to huge whales. Marine water (salt water) is present in the vast majority of aquatic environments. Marine ecosystems are greatly impacted by water depth, temperature and light availability.

Freshwater ecosystems are characterized by non-saline water (water without salt). Freshwater ecosystems such as rivers and lakes cover less than 1% of the surface of Earth but are home to many vulnerable species of plants and animals, including 41% of all species of fish.

Freshwater Ecosystems

One fact about aquatic ecosystems is that freshwater ecosystems are home to more than 100,000 species of living things. Shallow water bodies such as ponds and bogs are more biologically productive because of the availability of sunlight and nutrients sequestered within the ecosystem and can support a wide variety of organisms. Examples of freshwater animals include a variety of invertebrates such as worms, mollusks, crayfish and insects. Freshwater ecosystems also provide habitat to vertebrates like fish, frogs, newts, turtles, beavers, herons, gulls and egrets.

Freshwater ecosystems exist in all regions of the world. Topography, wind, temperature and gravity have a large effect on the movement of water over land and therefore there are many possibilities for the shapes and sizes of freshwater ecosystems. Freshwater ecosystems can be divided into three categories: lotic ecosystems, lentic ecosystems and wetland ecosystems.

Lotic ecosystems are characterized by rapidly flowing water that is moving in one general direction. Examples of lotic ecosystems are rivers and streams. Organisms that live in lotic ecosystems have to withstand the force of moving water and include insects, fish, crayfish, crabs and mollusks. Mammals such as river dolphins, otters and beavers as well as a variety of birds also live in lotic ecosystems.

Lentic ecosystems are characterized by still water. Examples of lentic ecosystems include lakes and ponds. Organisms that live in lentic environments have a more protected habitat and can become more established than those in lotic environments. Plants that live in lentic ecosystems include water lilies, algae and other rooted or floating plants. Ponds and lakes are also home to birds, frogs, snakes, newts, salamanders and many invertebrates.

Wetland ecosystems include areas with shallow water and saturated soils. Examples of wetlands include mashes, bogs and swamps. Wetland ecosystems are very vulnerable to disturbance and are disappearing rapidly due to human activity. Organisms that live in wetland ecosystems include sphagnum moss, black spruce, tamarack, sedges, insects, reptiles and amphibians.

Marine Ecosystems
Marine ecosystems are located in or around salt water and include both coastal habitats and open ocean habitats. The marine biome is the largest biome and covers two-thirds of the surface of Earth. A fact about aquatic ecosystems is that while only 7% of marine environments are coastal environments, they provide more than . 50% of the food for ocean ecosystems through primary productivity.

Marine ecosystems are greatly impacted by the availability of sunlight. Sunlight cannot penetrate more than a few hundred feet below the surface of the ocean, therefore coastal habitats where the water is shallower are some of the most biologically productive on the planet because photosynthesis can occur there. Deep ocean environments are devoid of light and rely on nutrients raining down from the surface of the ocean.

Marine environments are constantly being formed and reshaped by natural processes. Certain species of organisms such as mangroves, coral, kelp and seagrasses can significantly impact the shape of the landscape as well. The major marine environments include intertidal zones, estuaries, coral reefs, open ocean, kelp forests, mangroves and seagrass meadows.