What is the Difference Between Estuary and Salt Marsh

The main difference between estuary and salt marsh is that an estuary is a place where a river/stream opens into the sea, whereas salt marsh is a coastal wetland that is frequently flooded by saltwater brought in by the tides.

Estuaries and salt marshes are landforms that are common in coastal areas. Estuaries and salt marshes are usually located close to each other. This is why a lot of confusion about the difference between these two landforms.

Key Areas Covered

1. What is an Estuary 
     – Definition, Features
2. What is a Salt Marsh
     – Definition, Features
3. Similarities – Estuary and Salt Marsh
     – Outline of Common Features
4. Difference Between Estuary and Salt Marsh
     – Comparison of Key Differences

Key Terms

Estuary, Salt Marsh, Bar-built Estuaries, Coastal Plain Estuaries, Fjord Estuaries, Tectonic Estuaries

Difference Between Estuary and Salt Marsh - Comparison Summary

What is an Estuary

An estuary is a partially enclosed coastal water body where freshwater from rivers mixes with the saltwater from the ocean. Both seawater and freshwater constantly circulate in and out of estuaries. The blend of seawater and freshwater creates brackish water, which is somewhat salty but not salty as seawater. Landforms like barrier islands and peninsulas protect estuaries from the full force of waves and winds.

There are many types of habitats in and around estuaries, including rocky shores, river deltas, sandy beaches, shallow open water, salt marshes, and tidal pools. In addition, estuaries are home to unique plant and animal species that thrive in brackish waters.

Estuary and Salt Marsh - What's the Difference?

We can categorize estuaries into four different types. In fact, this classification is on the basis of their formation.

  1. Coastal plain estuaries
  2. Tectonic estuaries
  3. Bar-built estuaries
  4. Fjord estuaries

Coastal plain estuaries are the estuaries that form when sea levels rise and fill in an existing river valley. The Chesapeake Bay in the United States is an example of a coastal plain estuary. California’s San Francisco Bay, on the other hand, is an example of a tectonic estuary. Such estuaries form due to tectonic activity, i.e., shifting together and rifting apart of the Earth’s crust.  Moreover, when a barrier island separates an estuary from the sea, we call it a bar-built estuary. Fjord estuaries are a form of estuaries glaciers create. They occur when glaciers carve out a deep, steep valley and then retreat while the ocean rushes in to fill the narrow, deep depression.

What is a Salt Marsh

Salt marsh is a coastal wetland that is frequently flooded by saltwater brought in by the tides. We can usually find salt marshes close to estuaries and bays. The plant diversity in salt marshes is relatively low since plants that grow there have to be salt-tolerant.

Estuary vs Salt Marsh

The soil in salt marshes consists of deep mud and spongy peat. Since these marshes are regularly submerged by tides, they contain many decomposing plant materials, and the oxygen content in the peat tends to be very low. Furthermore, salt marshes occur everywhere in the world, nearly on every coast. In fact, they help to save the shoreline from erosion and play an important role in the marine food web.

Similarities Between Estuary and Salt Marsh

  • Estuaries and salt marshes are usually located close to each other.
  • High tides and low tides affect both these landforms.
  • Moreover, they are home to unique plant species that are salt-tolerant.

Difference Between Estuary and Salt Marsh

Definition

An estuary is a partially enclosed coastal water body where freshwater from rivers mixes with the saltwater from the ocean, while a salt marsh is a coastal wetland that is frequently flooded by saltwater brought in by the tides.

Nature

An estuary is mainly a body of water, but a salt marsh is basically an area of coastal grassland that is regularly flooded by seawater.

Conclusion

In general, estuaries and salt marshes are landforms that are common in coastal areas. The main difference between estuary and salt marsh is that an estuary is a place where a river/stream opens into the sea, whereas a salt marsh is a coastal wetland that is frequently flooded by saltwater brought in by the tides.

Reference:

1. “Estuary.” National Geographic Society, 9 Oct. 2012.
2. “What Is a Salt Marsh?” NOAA’s National Ocean Service, 1 June 2013.

Image Courtesy:

1. “Estuary, river, coast, nature, sea” (CC0) via Pixabay
2. “Salt Marsh at Rye Harbour” By Ethan Doyle White – Own work (CC BY-SA 4.0) via Commons Wikimedia

About the Author: Hasa

Hasa has a BA degree in English, French and Translation studies. She is currently reading for a Masters degree in English. Her areas of interests include literature, language, linguistics and also food.

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