The Disappearance of Tidal Marshes Caused by Sea-Level Rise – Featuring Sergio Fagherazzi

New England is one of the few regions of the world that still has expansive wetlands–in fact, the Boston University campus was partly built on a marsh. However, wetlands are disappearing all over the world at alarming rates due to sea-level rise. In the Northeast, wetland boundaries erode at a rate of tens of centimeters per year. The loss of salt marshes will have detrimental impacts on the environment and potentially contribute to the worsening effects of climate change. 

Aside from their intrinsic beauty, salt marshes provide various ecosystem services to our society and planet. They sequester carbon, purify water, and protect infrastructure against storms. Not only that, salt marshes are home to many commercial fish species. 

“Wetlands provide an aesthetic value because they allow for recreational purposes like boating, kayaking, and fishing. Houses with a view of wetlands are very valuable,” Earth and Environmental Science Professor Sergio Fagherazzi said. 

Fagherazzi’s research centers around understanding coastal processes and modeling creeks and channels developing on salt marsh surfaces. In Massachusetts, marsh soils are composed of 30% organic matter, which is mostly dead roots and rhizomes, called “blue carbon.” Organic matter helps to reduce the amount of carbon dioxide in the atmosphere.

“Per square meter, marshes are probably the most effective ecosystem in sequestrating carbon,” Fagherazzi said.  

The vegetation and sediment of salt marshes are essential in purifying the water. Vegetation can extract nutrients such as nitrogen and phosphorus. Sediment can absorb pollutants and metals. Fagherazzi said he once saw nuclear waste disappear in a salt marsh, which provides a testament to their purifying abilities. 

Wetlands are also living coastlines, meaning they act as a natural seawall preventing land and homes from being eroded away in the event of storms. However, too much flooding is harmful to wetlands. Marshes in New England are turning into ponds, causing the vegetation to drown and lose its ability to purify water and sequester carbon, further amplifying the effect of greenhouse gasses on the climate. 

In New England, wetlands pose the threat of invading neighboring areas. Marshes border many forests and agricultural farms, so when sea levels rise, they expand and replace trees and crops. Fagherazzi explained this in terms of BU’s campus– if the Charles River, which was once part of a marsh, expands, it could flood parts of BU. 

Ultimately, restoration and preservation of wetlands come down to government policy. However, protecting wetlands often means realigning the coast, or allowing wetlands to migrate inland. This can cause political problems if the land converted is of considerable value. To counteract this, Fagherazzi said a change in mindset needs to happen in order to preserve wetlands. 

“I think as a society we need to believe that the shoreline is very dynamic–it is not permanent.  We need to understand that it is normal for the shoreline to change, and we need to embrace this change,” Fagherazzi said. 

Fagherazzi encourages the public to learn about the functions of wetlands so they are more accepting of policies. 

“The public should know it’s okay to do some restoration project that adds more sediment and protects vegetation,” Fagherazzi said. “The goal is to preserve what we have and make sure that marshes are not going to erode or disappear.” 

New England is lucky to still have marshes; in Mississippi, salt marshes are disappearing by an area equivalent to a football field every hour. In Europe, there are efforts to restore marshes. In a paper titled Biogeomorphic modeling to assess the resilience of tidal-marsh restoration to sea level rise and sediment supply, Fagherazzi worked to realign salt marshes in Belgium to protect their vital functions. This project in Europe is reactionary, whereas the work in New England is more proactive. Without the preservation of marshes, there is a great risk that many coastal areas will experience erosion and more flooding. 

Fagherazzi made it clear that this would be far in the future, but his research provokes awareness in the seemingly mundane aspects of the land we live on and are surrounded by. 


Rhodes, L., McHugh, M., & Gruszkos, T. (2019, March). Inland and coastal wetlands of Massachusetts status and Trends. MassDEP. Retrieved November 30, 2022, from 

Gourgue, O., van Belzen, J., Schwarz, C., Vandenbruwaene, W., Vanlede, J., Belliard, J.-P., Fagherazzi, S., Bouma, T. J., van de Koppel, J., & Temmerman, S. (2022, June 7). Biogeomorphic modeling to assess the resilience of tidal-marsh restoration to sea level rise and sediment supply. Earth Surface Dynamics. Retrieved November 30, 2022, from 

Dr. Sergio Fagherazzi

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