15 Salt Marsh Facts: Learn About These Coastal Wetlands

A salt marsh is a coastal wetland in the upper coastal foreshore or intertidal zone between open brackish water or salt water and land, often flooded by tides. Its ecology consists of complex food webs containing primary producers, primary consumers, and secondary consumers.

A salt marsh is also called a tidal marsh or a coastal salt marsh.

It has a lush population of salt-tolerant plants like low shrubs, grasses, or herbs, and these terrestrial plants help create stability by sediment trapping and binding in the salt marsh.

Salt marshes are essential in giving nutrients to the coastal waters and aquatic food web, and they also offer coastal protection to terrestrial animals. These coastal wetlands are found on low-energy shorelines in high-latitude and temperate regions.

However, this dynamic coastal ecosystem is susceptible to the dangers of sea level rise. Due to poor implementation of coastal management, salt marshes have been endangered for a long time.

In 2017, salt marshes were found across 99 countries, with the most expansive salt marshes around the world occurring outside the tropics, particularly in the estuaries of the North Atlantic, bays, and low-lying coasts. Keep reading to learn more about the formation, history, significance, and ecosystem of salt marshes in the world.

History & Formation of Salt Marshes

Salt marshes covered up to 80% of today's land as far back as 1500. However, due to sea trade development, around 2500 crystallization ponds were built between 1560-1660, causing a decrease in naturally-occurring saltwater marshes. 

Its formation starts when a tidal flat surface gains elevation by sediment accretion in relation to sea level, and this exposed surface is later taken over by the duration and rate of tidal flooding decline and vegetation.

The range of salinity depends on runoff from rain and the height of the tide, which is between virtually fresh and very salty.

The development of suitable conditions and the arrival of species like rhizome or seed portions further the colonization process. Tides bring salt water that floods and drains coastal wetlands, which creates salt marshes. The soil may contain peat and deep mud, which makes the salt marshes marshy.

Salt marshes occur in varying landforms depending on geomorphological and physical settings. Such marsh landforms include open-coast, back-barrier, and deltaic marshes. They are found along the southeastern coast, where tides flood and drain.

These marshes are divided into low and high marsh zones due to variations in elevation and flooding and are famous among humans as they have a wide area with low topography. Salt marshes are highly fertile habitats and are also photosynthetically active.

They contain a lot of decomposition and act as storehouses for much organic matter. This matter, in turn, serves as food for many organisms, including mammals and bacteria.

Importance or Significance of Salt Marshes

Salt marshes, also known as tidal wetlands, are important as they maintain shorelines, aid coastal economies, support the marine ecosystem's health, and protect our communities. They also provide habitat, refuge, and food to over 75% of fish and aquatic species like blue crabs and shrimps. In other words, salt marshes are the ecological protectors of the seaside.

These marshes segregate and store carbon around 10 times more than grown tropical forests. This helps to moderate climate change.

They also contribute to recreational activities like sailing, camping, and bird watching. Salt marshes soak wave energy and flood waters in storms, thereby decreasing up to 20% of damage in adjacent societies. They also filter excess nutrients and runoff to retain the water quality of estuaries, coastal bays, and sounds.

Salt marshes buffer wave action to trap sediments, which protect shorelines from erosion and are also rarely a part of lagoons like Italy's Venetian Lagoon. The salt marshes located in flood-prone regions soak rainwater and decrease the flow of flood water.

As animals do not feed on halophytic plants like cordgrass, they die and decompose, becoming feed for micro-organisms, which in turn provide food for the birds and fish in salt marshes.

Animal & Plant Life in Salt Marshes

Salt marshes act as nursery grounds for many recreationally and commercially essential organisms. Marsh snails and fiddler crabs tear dead plants while feeding, which helps in decomposition.

Several bird species in turn feed on these invertebrates and small fishes in salt marshes. Mammals like minks and raccoons also forage in salt marshes and search for aquatic prey like shrimps and crabs.

Sometimes even bottlenose dolphins leave deeper waters to find food in small creeks. As salt marshes regularly and rapidly transit between fresh and salty, dry and wet, and hot and cold, they have a limited number of animal and plant organisms.

Mussels and oysters filter the dead plant material in salt marshes. Animals close up into shells or burrow into the mud when marshes are exposed to low tide.

The young offsprings of species such as red drum, marine fish, white shrimp, and blue crabs use salt marshes as nurseries. Some aquatic creatures remain in the creeks all through the tidal cycle, while many travel on and off the marsh surface with tidal changes.

Only a few reptiles live in salt marshes, one of which is the diamondback terrapin that moves above the high tide mark to lay eggs and forage in high tide. Even alligators, which usually avoid high-salinity marshes, sometimes travel through these brackish marshes.

Halophytic plants like herbs, shrubs, and grasses dominate salt marshes. Globally, there are more than 500 plant species in salt marshes.

FAQs

What predators live in salt marshes?
Predators found in salt marshes are raccoons, herons, rails, and killifish, sometimes alligators as well.

What grows in a salt marsh?
Saltwort, saltgrass, beach tea, woody glasswort, and saltmarsh bulrush grow in salt marsh.

What is the climate of salt marshes?
Salt marshes have temperate and sub-tropical climatic conditions.

What lives in salt marshes?
Worms, crabs, mussels, snails, and many other fish and aquatic organisms live in salt marshes.

How is a salt marsh formed?
A salt marsh forms in shallow basins where stream currents and tidal flooding deposit sediment particles, which form the bottom of the marsh.

What do salt marshes do for humans?
Salt marshes protect our towns and cities from coastal flooding, absorb carbon, and provide a wide range of seafood.