Salt Water Marsh
Saltmarsh, also known as saltwater marsh, coastal salt marsh, or tidal marsh is an area of low, flat, poorly drained ground subjected to regular or occasional flooding by saltwater or brackish water and is covered by salt-tolerant plants such as grasses, herbs, or low shrubs. Saltmarsh plays an important role in the aquatic food web and provides nutrients to the coastal waters. Salt marsh also reinforces terrestrial animals and arrange coastal protection.
Salt Marsh Evolution
Saltmarsh or coastal marsh evolve from young marshes to old marshes. In the eastern USA, the natural young marshes are vegetated for the major part with low marsh cordgrass known as Spartina alterniflora. Nutrients are carried by tidal currents through tidal channels. This enabled grasses to grow thick and lavish, so weakening the effect of tidal currents and waves accelerated the deposition rate of mud.
Erosion is minimized by the root and rhizomes of the plant. During that time, the marsh surface builds up above the high water level, high marsh species captured, defeated, and substitute the low marsh. The most stressed tolerant plant species occupy the lower reaches of the marshes while the competitive influencer occupies the upper elevation that is less stressful. While the size of low marsh and high marsh is about equal, the ecosystem reaches the mature stage of development.
The ongoing deposition of mud transforms the low marsh into the high marsh. Minimum water flows through the tidal channel of these elevated “ old marshes''. Accumulation of sand and mud on the high marshes metamorphose into dry land that is detached from the ocean effects. Lateral channel migration and wave attack at the bottom of the marsh cliffs are the main instruments for the erosion of mature salt marshes and their succeeding rejuvenation cycle.
Salt Marsh Development Requirements
Saltmarsh requires coarse-grained sediments.
There may be no tidal currents or strong waves.
They need salty conditions to grow.
They need a temperate or cool temperature. Incidental frozen temperatures do not destroy the plants.
They demand a wide tidal range. This is crucial because it limits erosion, makes deposition of sediments possible, and causes a transparent zonation.
Where Does Salt Marsh Found?
Saltmarsh is generally found along the bank of lagoons, shallow sea cut from the open sea, or along the bank of estuaries where rivers join the sea. In these areas, plants can easily take roots in the mud as water is calm. Saltmarsh is home to various coastal wildlife.
Salt Marsh Grass
Saltmarsh grass or cordgrass makes up the vast majority of plants in the salt marsh ecosystem and is invaluable to humans. Smooth cordgrass forms a great swaddle of vegetation that preserves tidal, coastal muds and protects the coastline from erosion. Saltmarsh cordgrass is widely used to produce salt meadow hay. The other species in these groups form smaller colonies within the salt marsh ecosystem generally in the area covering up the marsh which receives lesser saltwater flooding.
Saltmarsh grasses or cord-grass are found abundantly along both Atlantic back bays and shores of Delaware bays. Some species are rarely found at inland sites, especially along roadsides where salt is used in winters or on areas where evaporation exceeds precipitation, creating a high water content in the soil.
Did You Know?
The salt marsh trail is a part of the deserted Musquodoboit railroad that has been transformed into a part of the TransCanada rail. The trail offers relaxed adventures to similar hikers and bikers.
The salt marsh trail of Cole Harbour, Nova Scotia is a renowned walk constructed within the Halifax regional community. This salt marsh trail offers delightful views of the salt marsh as the visitors walk along former railway turner walking tracks that cross through Cole Harbour.
The grasses, sedges, and rushes that describe salt marsh are halophytic. It means that they are specially modified to survive in a saline habitat.
One acre of salt marsh can approximately absorb 1.5 millions gallon of floodwater which is equivalent to more than 2.25 Olympic size swimming pools.
The US has approximately 3.8 million acres of salt marshes. Three-quarters of them are in the Southeast, including vast interconnected 1 million acres stretched from North California to Florida.
Saltmarsh protects the shoreline from excessive erosion caused by wind, water, and ice.
Saltmarsh helps in maintaining water quality by filtering runoff and excessive nutrients.
As per NOAA, salt marsh absorbs floodwaters and wave energy during the storm, which minimizes property damage in adjacent communities by up to 20%.
FAQs on Salt Marsh
1. What exactly is a salt marsh?
A salt marsh is a unique coastal wetland ecosystem that is regularly flooded and drained by saltwater tides. Its ground is typically composed of deep mud and peat, which is a spongy, waterlogged layer of decomposing plant matter. This environment is characteristically found in sheltered coastal areas like estuaries and bays, where it is protected from high-energy waves.
2. How are salt marshes formed?
Salt marshes form through a gradual process. It begins in sheltered coastal areas where slow-moving water allows fine sediments like mud and silt to settle and build up, creating a mudflat. Over time, as the elevation of the mudflat rises, it gets flooded less frequently. This allows salt-tolerant plants (halophytes) to colonise the area, whose roots trap more sediment and further raise the land, eventually creating the stable marsh environment.
3. What are the main functions and importance of a salt marsh?
Salt marshes are incredibly important for several ecological and economic reasons:
Coastal Protection: They act as a natural barrier, absorbing wave energy and reducing the impact of storms on the coastline.
Water Filtration: They improve water quality by filtering pollutants, excess nutrients (like nitrates and phosphates), and sediments from the water.
Biodiversity Hotspot: They provide critical habitats, food, and nursery grounds for a wide variety of animals, including fish, shellfish, and migratory birds.
Carbon Sink: Salt marshes are highly effective at capturing and storing atmospheric carbon in their deep peat soils, helping to mitigate climate change.
4. Why is the ground in a salt marsh spongy and sometimes smelly?
The ground is spongy because it is made of peat—a thick layer of waterlogged, partially decomposed plant material. Because the soil is constantly saturated with water, there is very little oxygen available (a condition called hypoxia). This low-oxygen environment slows down full decomposition and instead promotes the growth of anaerobic bacteria. These bacteria release sulphur compounds as a byproduct, which creates the characteristic "rotten egg" smell associated with marshes.
5. What types of plants and animals are adapted to live in a salt marsh?
Life in a salt marsh must be specially adapted to salty and wet conditions. Key examples include:
Plants: The flora is dominated by salt-tolerant species known as halophytes. Common examples include various types of cordgrass (Spartina), salt hay, and pickleweed, which can excrete or manage excess salt.
Animals: The ecosystem supports a rich variety of life, including crabs (like fiddler crabs), snails, mussels, and shrimp. It also serves as a crucial nursery for many species of commercial fish and is a vital feeding ground for wading birds such as herons, egrets, and ibis.
6. How does a salt marsh differ from a mangrove swamp?
The main difference between a salt marsh and a mangrove swamp lies in the dominant vegetation and their geographical location. A salt marsh is a coastal wetland dominated by low-lying, salt-tolerant grasses and shrubs, and is typically found in temperate and sub-arctic climates. In contrast, a mangrove swamp is dominated by salt-tolerant trees and shrubs (mangroves) and is exclusively found in tropical and subtropical coastal regions.
7. Where are some major salt marshes located in India?
In India, salt marshes are found along the coastlines of several states. The most significant area is the Great Rann of Kutch in Gujarat, which is one of the largest salt deserts in the world and exhibits marsh characteristics during the monsoon season. Other notable salt marsh ecosystems are found in coastal areas of Maharashtra, Tamil Nadu (e.g., Pichavaram), Andhra Pradesh, and the Andaman & Nicobar Islands.
8. What are the biggest threats facing salt marsh ecosystems today?
Salt marshes are highly vulnerable ecosystems facing numerous threats from human activities and environmental changes. The major threats include:
Urban and industrial development leading to direct habitat loss.
Pollution from industrial wastewater and agricultural runoff.
Sea-level rise due to climate change, which can submerge and drown the marshes faster than they can build up sediment.
Invasive species that can outcompete and displace native marsh vegetation.
Altered hydrology from the construction of dams, dykes, and channels.
