7 Examples of Marine Ecosystems and their Characteristics
Examples of marine ecosystems are; oceans, estuaries, mangrove forests, salt marshes, sandy beaches, coral reefs, and saltwater lakes.
This article discusses the examples of marine ecosystems and their characteristics, as follows;
1). Oceans (as one of the Examples of Marine Ecosystems)
Ocean ecosystems are most common and prominent among the examples of marine ecosystems.
The geographic coverage of oceans in the world is broad, spanning across all major continental zones.
Facts about the ocean as a marine ecosystem include;
1. Oceans cover approximately 70 percent of the Earth's surface
2. A large portion of Earth's biodiversity is in the ocean
3. Climate-regulation is one of the functions of oceans
4. The ocean serves as a major natural carbon sink, and a source of atmospheric oxygen 
5. Oceans can be vertically delineated into various depth-zones with different characteristics
Ocean ecosystems can be distinguished into various zones or habitats including coastal and open ocean ecosystems .
In the deep sea, organic activity is very low due to cold temperatures and lack of solar radiation for photosynthesis. This zone includes the ocean floor, which has notable topographic features including ridges and trenches.
An estuary is a coastal marine ecosystem that is partially enclosed, and signifies the confluence of saltwater and freshwater bodies from oceans, streams and rivers .
Examples of estuary ecosystems in the world include; Drigg in England, Tampa Bay along the Gulf Coast, Hudson Rover Estuary, Delaware Bay and Chesapeake Bay in the United States.
Because they occur where salt and freshwater masses meet; estuaries are transitional aquatic ecosystems, that share characteristics with both marine and freshwater zones. This has implications toward the biodiversity of an estuary, which must adapt to estuarine conditions.
Marine plants and animals that live in an estuary are those which are capable of surviving in brackish water; including invertebrates like oysters, shrimps, clams, mud crabs, blue crabs; vertebrates like seahorses; and plants like red algae, eelgrass, saltbrush, and Douglas aster.
Various types of estuaries can also be distinguished, based on factors like origin, sediments, water flow trend, and morphology. The types of estuaries are tectonic, coastal-plain, bar-built, and fjord estuaries .
3). Mangrove Forests (as one of the Examples of Marine Ecosystems)
A mangrove forest ecosystem is a coastal marine ecosystem that is dominated by saltwater-tolerant shrubs, trees, and other small plants. Mangrove forests are commonly located between the land and sea, in intertidal zones of sub-tropical and tropical marine regions .
Characteristic features of mangrove forest ecosystems include; brackish saline water, humid climate, halophytic vegetation, and water-saturated soil .
The role of mangrove trees in a marine ecosystem comprises of soil stabilization, nitrogen fixation, carbon sequestration, and water quality-regulation. There are up to 80 species of these trees, meaning that mangrove forest have significant species richness and diversity.
Mangroves are often viewed as the most biologically-productive marine ecosystems . This can be attributed to the fact that mangrove forests are fairly stable and not subject to extreme conditions like those that may occur in other marine ecosystems.
4). Salt Marshes
Salt marshes are coastal wetland ecosystems that are waterlogged or inundated with saline water from the ocean.
The introduction of saline water into a salt marsh occurs due to the action of tidal currents . This is possible because salt marshes generally occur in intertidal zones that demarcate the land from the open sea. Saltwater that is retained in soil from tidal flooding events, is what leads to the development of a salt marsh.
This water saturated and clogs the pores of coastal soils, triggering the formation of peat and mud by slow biodegradation of organic matter.
Types of salt marshes include; estuarine, open, deltaic, high marsh, low marsh, and mud flat types; which are distinguished based on their areal coverage and associated marine systems.
Examples of salt marshes are; Morecambe Bay in Britain, and the Drowned Land of Saeftinghe, in the Netherlands .
Salt marshes usually share close proximity with other marine ecosystems like beaches and estuaries.
5). Sandy Beaches (as one of the Examples of Marine Ecosystems)
Sandy beaches, or sandy shores, are marine ecosystems formed by the continuous weathering, erosion and deposition of sediments on nearby landmasses by ocean waves.
The characteristics of sandy beach ecosystems include continuous wash-and-swash wave processes, gentle-sloping geomorphology, and distinctive biodiversity.
Sandy beaches are a widespread feature of marine regions around the world, and are subject to the environmental impacts of economic development, due to their accessibility .
Marine organisms that are found on sandy shores or beaches include sub-terrestrial groups like mollusks and crustaceans, with examples including shrimps and crabs; as well as some algae and vascular marine plants.
Compared to other marine ecosystems, the biodiversity of beaches is low, so that they may be described as the deserts of the marine biome. This means that their biological attributes are not studied as often as other ecosystems.
The food chain of a sandy beach ultimately derives its bioenergy from plants and phytoplankton , a major portion of which comes from the open ocean.
6). Coral Reefs
A coral reef is a marine ecosystem formed by the carbonate secretions of corals, which cluster in colonies.
The coral polyps of individuals that form a coral reef are described as reef-building or stony corals, and the carbonate secretions serve as skeletal components of these organisms. These skeletal components comprise of carbonate compounds like Aragonite , and do not undergo biodegradation even after the death of the organism.
Zones where coral reef ecosystems can be found include coastal, underwater regions in the Indian, Atlantic and Pacific oceans . Coral reefs are important for their role as a habitat for marine organisms, as a source of scientific information, as well as food, employment, and raw materials.
Marine organisms that live in coral reef ecosystems include; clams, oysters, sea urchins, sponges, fish and algae. These organisms share a symbiotic relationship with reefs, so that the coral reef ecosystem is arguably the most diverse and biologically-active subsection of the marine biome.
Coral reefs also contribute to the role of the ocean as a natural carbon sink and climate-regulator.
7). Saltwater Lakes (as one of the Examples of Marine Ecosystems)
A saltwater lake, also known as marine or saline lake; is an enclosed aquatic ecosystem that contains saline water by reason of narrow links to the ocean.
Saltwater lakes are unique as marine ecosystems because they exist in physical seclusion from the sea. The saline water in these lakes usually comes from small, sea-bound tributaries that may occur in the subsurface water column.
The level of salinity of a saltwater lake depends on the hydrodynamic and climatic conditions of its environment. Higher amounts of precipitation may dilute these water bodies, thereby reducing their salinity, and vice-versa.
An example of a saltwater lake is the Great Salt Lake in northern Utah, United States.
Examples of marine ecosystems are;
3. Mangrove Forests
4. Salt Marshes
5. Sandy Beaches
6. Coral Reefs
7. Saltwater Lakes
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