News and ResourcesWetlands of Delmarva - February 12, 2017
There are an estimated 7-9 million square kilometers of wetlands on the planet today. However, due to construction, sea level rise, and a variety of other factors, this area is decreasing each year. Currently, wetlands take up 4 to 6 percent of the terrestrial environment, but they are among the most productive and fundamental ecological zones on the globe. Each and every wetland varies depending on latitude and longitude, hydrology, flora and fauna present, and many other environmental aspects.
Here on Delmarva, we have five different types of wetlands: tidal freshwater marshes, tidal brackish marshes, saltwater marshes, cypress swamps, and riparian wetlands. Each of these distinctive wetlands provide different benefits to our local ecosystem and help to maintain a healthy level of biodiversity here on the Eastern Shore.
When people come to Ocean City or Assateague Island, they often find salt marshes along the edge of the coastal bays. These marshes are characterized by tidal action and inundation of salt water and large patches of hardy grass with very few trees. Saltmarshes are extremely productive areas that serve as habitat for not only terrestrial animals, but also many bird species and marine animals. Salt marshes, like every other kind of wetland, have multiple stressors that dictate what animals and plants can live there. Salinity in both the water and plants living there, constant exposure to wind and rain, and high risks of flooding are some of the factors that influence what can and cannot live in this harsh environment.
Tidal brackish marshes can be found in places like the St. Martin River and other rivers and streams where salt water mixes with fresh water. Tidal brackish marshes are difficult to distinguish because they share many of the same species of plants and animals with freshwater and saltwater marshes. The biggest stressor for tidal brackish marshes is salinity. Unlike salt marshes where animals and plants have to deal with high salinity every day, organisms living in brackish marshes have to be able to cope with sudden increases and drops in salinity as either more saltwater or freshwater inundates the marsh. While most animals can leave the marsh if the salinity gets too high or low, plants living in this environment must be able to deal with this erratic change in salinity.
Moving into the more upland areas of Delmarva, we find large areas of tidal freshwater marshes. The name can be a bit confusing. These marshes experience tidal action, but because they are so far removed from the ocean and coastal bays, they do not get inundated with saltwater but instead fresh or brackish water. Again, flooding and anaerobic soils are a major stressor on the organisms that live in freshwater marshes, but they do not have to deal with high levels of salinity, which allows for a different plant regime compared to other marshes.
In places like Furnace Town, Pocomoke River State Park, and Pemberton Park, we find forested wetlands made up of cypress swamps. These more upland wetlands are easily distinguished by the presence of cypress trees and areas of standing water with very wet organic soils. Unlike marshes found along Delmarva, Cypress swamps are not exposed to tidal action; therefore, one of the biggest stressors in this environment is the low amount of nutrients that enter the swamp.
The most upland wetlands found on Delmarva are the riparian wetlands. These ecosystems tend to be adjacent or close to freshwater streams and rivers. However, they still are mostly composed of large trees and shrubs as opposed to swatches of sturdy grasses. Unlike the cypress swamps, riparian wetlands tend to have more nutrients available due to nutrient loading from the stream or river. While organisms that live in the cypress swamp must adapt to deal with low nutrient levels, organisms that live in riparian ecosystems must compete to uptake the available nutrients quickly.
Each of these types of wetlands provides different benefits for the local environment and ecosystem. It is vital that we learn about each of these wetlands and the differences between them so we can continue conservation and restoration efforts successfully.
Jackson is the former Education Coordinator for Maryland Coastal Bays Program.
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