Salt Marshes

Salt marshes are coastal wetlands that are filled and drained by the tide. These habitats can be found in coastal areas in nearly all climates with a range of flora and fauna. Salt marshes are areas of transition as they are located in the intertidal zone. This means that the plants and animals that live here must be able to withstand a variety of salinity and water conditions. Many of these organisms have specific adaptations that allow them to live in this transition zone. 

Image Source: RI Coastal Resources Management Council

Though salt marshes are incredibly important ecosystems, they have a reputation for not smelling so great. The combination of relatively slow moving water, decomposing material and low oxygen levels yields an odor that has been characterized as smelling like rotten eggs. However, the many birds, fish, and crustaceans that make their home in salt marshes don’t seem to mind the smell. Many fish and crustacean species use salt marshes as nurseries to raise their young. 

In addition to an unpleasant smell, salt marshes also happen to have very low levels of oxygen. This means that organisms that make their homes in salt marshes often are adapted to low oxygen environments. For example many species of roundworms that live in salt marshes can live without any oxygen at all for long periods of time. Another example of species that has adapted to living in a salt marsh is the rat-tailed maggot which has a tail breathing tube that it extends to the surface of the water for air. 

For some organisms, the main challenge they encounter is the changing of the tides. The Marsh Periwinkle, a type of snail, has specifically adapted its behavior to the intertidal environment. At low tide, the snails like to graze the mud that has been exposed by the retreating water. As the tide water comes back into the marsh, the snails climb up grasses to be safe from the water where they may drown and from predators like crabs and conch snails. 

Image Source: Chesapeake Bay Program 

As you can see, the organisms that live in the salt marsh are specifically adapted to the constantly changing conditions of the salt marsh environment. However human activity is changing these ecosystems in destructive and challenging ways. Sea level rise driven by climate change, polluted runoff, coastal development, and invasive species all threaten the existence of salt marshes and the organisms that live in salt marsh ecosystems. 

Climate change, as a result of human activity, is driving the melting of the polar ice caps which is responsible for rising sea levels. A change in sea level can result in a change in the distribution of plants and animals in the salt marsh which disrupts the delicate balance of the marsh ecosystem. One of the main challenges of sea level rise is that it messes with the natural process of sediment accumulation and causes marsh plants to drown. In addition to sea level rise, climate change also causes increased temperatures which increase evaporation which causes salinity to increase. Changes to salinity can adversely affect many plants and animals in marshes. 

Coastal development and polluted runoff are both major causes of salt marsh destruction. In some places, salt marshes are developed to make room for waterfront property. In addition, development along the coasts leads to a greater presence of impervious surfaces, surfaces that don’t absorb water. This causes a greater amount of runoff to enter local waterways like salt marshes. This water is often polluted by fertilizers, pesticides, and other chemicals used on the land. 

Salt marshes are extremely important ecosystems and provide many ecosystem services to local communities. They provide a habitat for commercially valuable species of fish and shellfish. In addition salt marshes provide wave protection, erosion control, flood protection, and carbon sequestration. These services are vital to coastal ecosystems and communities. However, in order to continue to enjoy these services salt marshes must be protected from the effects of coastal development, pollution, and climate change. One way to do this is to establish protected areas of salt marshes where activities like development, fishing, and recreation are limited. Other ways to protect salt marshes include restoration projects, improvements to runoff management, and mitigating the impacts of climate change.

Sources: 

http://www.oceanhealthindex.org/methodology/components/salt-marsh-area

https://oceanservice.noaa.gov/facts/saltmarsh.html

https://www.nps.gov/subjects/oceans/salt-marshes.htm

https://www.britannica.com/science/salt-marsh

https://wildernessclassroom.org/wilderness-library/marsh-periwinkle/

https://www.saltmarshguide.org/guide/threats-protection/

About the Author: Emma Gamble is a junior at the George Washington University majoring in Environmental Studies and minoring in public policy. Emma is passionate about incorporating greater sustainability into our food systems in order to create a greener future for people and the planet. Emma enjoys sailing, kayaking, and paddle boarding.