Wetlands are natural land areas where water dominates. At this meeting of earth and water, there is a wide variety of living species.
The biodiversity found there is not only essential to nature, but also to human beings. Its soil, mostly made up of decomposed organic matter, is a great space for life, for filtering pollutants from the water and for capturing carbon, contributing to a healthy living environment for all.
There are several types of wetlands. They differ in terms of their species composition, natural history and geographic location. These include freshwater marshes, swamps, bogs and salt marshes, which dominate the coast of our watershed.
Salt marshes are a meeting point between the land and the sea, mostly created by sediments and organic matter transported by rivers. Often accompanied by a coastal dune that protects it, the salt marsh fulfills several functions that we will list on this page.
First, the structure of each marsh in our region is similar, since it is determined by the height of the salt water which is influenced by the tides.
Here is an infographic that explains it.
The boundaries of the different sections of the saltmarsh can be distinguished by the typical plant species (Cordgrass/Spartina) that dominate them. There are also many other species, whose diversity changes depending on the salinity of the soil.
Beyond where the salt water regularly flows, there are debris brought in by storms, as well as shrubs, and finally trees, human constructions, or a freshwater marsh.
Salt marshes fill so many roles in the coastal zone that it is difficult to make a complete list. However, it is possible to group them into broad categories for better understanding. Here are three ways to think about salt marshes:
Tidal streams in salt marshes act as nurseries for certain species of fish and other marine organisms. They are thus an essential component of the health of the entire coastal ecosystem. This is where many species lay their eggs, which makes salt marshes important for commercial fishing. Many of the commercially caught fish depend on food and organic matter from the marshes.
These same young fish feed on organic matter from the salt marsh during the tides. This abundance of food attracts large numbers of insects and other invertebrate species, providing important food for shorebirds and larger fish. Some mammals, such as raccoons, otters and deer, come here to find food.
Humans have long used the marshes for food and health through the harvesting of medicinal plants. For native people, salt marshes have been a place to harvest resources such as sweetgrass, a sacred medicinal herb, for thousands of years. The Acadians collect samphire greens, plants traditionally eaten in the summer. In the marshes is also found the spreading spartina, historically called the "meadow hay" (foin de pré), to feed the livestock.
Today, it is also a good place to observe the fauna and flora. It is an ideal place for education and scientific research, since the salt marshes are a diverse and varied ecosystem, populated by many interesting life forms. Waterfowl hunting is also practiced here, as ducks nest and feed in abundance in these areas.
Salt marshes are like a sponge, as the organic soil and plants in the marshes will absorb water from floods. The marsh will also filter pollutants that flow to the sea.
Damage caused by storm surges is reduced by salt marshes by reducing wave energy, which in turn reduces erosion. It has been proven that these natural environments (called “green” infrastructure) are much more efficient than the "gray" infrastructure, which is built by humans. Their preservation is therefore an economic advantage for the municipalities that have them in their territory.
Marshes are one of the most effective terrestrial environments in the world for capturing carbon from the atmosphere in its organic soil, thus mitigating the effects of the climate crisis.
Salt marshes are a living system that evolves over time. The retreat of the marshes is a normal process, which occurs naturally with erosion, but the rise in sea level caused by climate change accelerates the process.
One example of this retreat is the ghost forest, which runs along the edges of salt marshes. These stands of dead trees are not haunted, as one might think. Rather, it is the result of saltier groundwater as the marshes recede, killing the trees.
As sea levels rise, this phenomenon is likely to become more pronounced.
It is for these reasons that we need to make room for marshes in our community planning. A marsh must have room to retreat, otherwise it will disappear against infrastructure such as roads, in a phenomenon called Coastal Squeeze.
All these reasons make the protection of salt marshes very important.
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