Context: According to a study published in the journal, Science of The Total Environment more than 90 percent of biologically productive ecosystems Salt Marshes may soon succumb to sea level rise by the turn of the century.

• Salt marshes are coastal wetlands that are flooded and drained by salt water brought in by the tides.

• They are marshy because the soil may be composed of deep mud and peat.

What does the study say?

• According to a study by the Marine Biological Laboratory (MBL) over 90 percent of these salt marshes could disappear due to sea level rise by the turn of the century.

• Scientists have been tracking vegetative cover in Great Sippewissett Marsh in Falmouth, Massachusetts, for the last 50 years in order to analyze the implications of higher nitrogen levels on marsh grass species.

• According to them, increased nitrogen levels favored higher levels of vegetation and accretion of Marsh Surface. But these ecosystems won’t be able to outpace submergence from global sea level rise.

• The only choice for salt marshes is to migrate landward. However, migration to landward can be impacted by anthropogenic activities and other factors.

• Marshes all around the world face "coastal squeeze," in which the sea level rise, anthropogenic activity, and topographical factors (like a hill or a cliff) constrain the potential for landward marsh migration. For example, a seawall that shields a house from flooding will prevent a wetland from naturally moving to a higher location.

What are salt marshes?

• Salt marshes are coastal wetlands that are flooded and drained by salt water brought in by the tides.

• They are marshy because the soil may be composed of deep mud and peat.

• As the salt marshes are frequently submerged by the tides and contain a lot of decomposing plant material

• Salt marshes occur worldwide, particularly in middle to high latitudes.

Ecological significance of Salt Marshes

• Protects the coast: Salt marshes are the “ecological guardians of the coast” that maintain healthy fisheries, coastlines and communities.

• Habitat for Aquatic life: They provide shelter, food and nursery grounds for coastal fisheries species including shrimp, crab and many finfish.

• Buffer against erosion: They also protect shorelines from erosion by creating a buffer against wave action and by trapping soils.

• Protection against floods: In flood prone areas, salt marshes reduce the flow of flood waters and absorb rainwater.

• Maintain Water quality: They also help to maintain water quality in coastal bays, sounds and estuaries by filtering runoff and excess nutrients.

• Carbon sinks: Salt marshes and other coastal wetlands also serve as “carbon sinks,” holding carbon that would otherwise be released into the atmosphere and contribute to climate change.

Threats to Salt Marshes

• Despite their numerous advantages, salt marshes are facing a number of threats that could put their survival at risk. One of the most significant of these threats is sea level rise.

• As sea levels continue to rise due to climate change, salt marshes are at risk of being submerged and disappearing entirely.

• Another threat to salt marshes is the introduction of excess nitrogen, which can alter the balance of plant species and lead to a loss of biodiversity. This excess nitrogen can come from a variety of sources, including fertilizer runoff from agricultural fields and urban areas.

• Anthropogenic activities, such as the construction of seawalls and other structures along the coast, can also prevent salt marshes from migrating landward in response to rising sea levels.

• This can lead to a phenomenon known as “coastal squeeze,” where the marshes are squeezed between rising seas and man-made barriers.

Conclusion

• In a scenario where sea levels rise, plants' only options will be to colonise new areas or move uphill. However, that migration might not be feasible in some places.

• Sea level rise is the most significant threat to salt marshes, as these ecosystems play an important role in stabilizing the environment. Therefore, preventive measures need to be taken to ensure that salt marshes can continue to play their vital role.