The continuing study of coastal salt marshes reveals a wealth of information about these unique habitats. This diverse ecosystem has long been revered for its productivity with an astonishing range of grass species, and other plant life that thrive in high levels of salt. However, new research uncovers the alarming threat of sea level rise to these thriving ecosystems.
Understanding Coastal Salt Marshes
Located between the land and the sea, salt marshes are coastal wetlands that undergo regular cycles of flooding and draining due to tidal movements. The dominant plant life of these marshes is a mix of grasses, sedges, rushes, and other plant species that can survive in highly salty environments.
The terrain of salt marshes is marshy, often composed of deep mud and peat, which is decomposed plant matter in several feet thickness, rendering a characteristic sulfurous rotten-egg smell. This is due to hypoxia, a condition of extremely low oxygen levels caused by flourishing bacteria growth on frequently submerged plant matter.
Coastal Protection and Biodiversity: The Value of Salt Marshes
Salt marshes offer indispensable contributions to the planet’s biodiversity and coastal health. Regarded as the “ecological guardians of the coast,” they harbor a diverse array of wildlife, including numerous fish and bird species. Additionally, they serve as nurseries for over 75% of coastal fisheries species, encompassing shrimp, crab, and many types of finfish.
Beyond animal life, salt marshes protect shorelines from erosion and act as buffers against wave surges. They trap soils and slow floodwater circulation, absorbing rainwater efficiently. They also help conserve water quality in neighboring bays, sounds, and estuaries by filtering runoff and excess nutrients.
In the larger picture, salt marshes are key carbon sinks, which means they have an essential role in combating climate change. They absorb and store copious amounts of atmospheric carbon dioxide, helping to regulate greenhouse gases and mitigating climate change effects.
The Looming Threats to Salt Marshes
Despite these critical benefits, salt marshes face serious threats that endanger their existence. Chief among these is the rise of sea levels due to climate change, putting the marshes at risk of being completely inundated and disappearing.
Furthermore, the introduction of excess nitrogen, whether from fertilizer runoff from agricultural fields or urban areas, can disrupt the plant species balance, leading to a loss of biodiversity.
Human activities, like building seawalls and other coastal structures, add another layer of threats. By blocking the natural landward migration of salt marshes in response to rising sea levels, such activities can create a “coastal squeeze” situation. This phenomenon results in the marshes being trapped between the climbing seas and human-made barriers, compromising their ability to adapt and survive.
