Researchers have found that mussels can increase marsh growth through accretion.
Mussels are another animal gaining a reputation for being ecosystem engineers. This means that they directly or indirectly drive habitat construction and control the availability of resources to other organisms. Mussels can be found in freshwater streams, rivers, ponds, lakes, saltwater oceans, and bays.
Both marine and freshwater mussels are filter feeders meaning they feed on plankton, bacteria and other microscopic sea creatures. Mussels are good water quality indicators because they keep the water clean by absorbing heavy metals and filtering silt and particulates. Researchers and scientists use mussels as bio-indicators to monitor the health of aquatic environments. If mussels are dying due to contamination that they are filtering in the water, it’s a good indicator that the water is unsafe for human consumption,
Marshes, one of the habitats mussels depend on, are at risk of disappearing. This happens for several reasons: water drainage, pollution, unsustainable use, invasive species, disrupted flows from dams and sediment dumping from deforestation and soil erosion upstream. However, researchers have found that mussels deposit large volumes of material onto marsh surfaces through their feeding process.
The accumulation of sediment helps marches grow through a process called accretion. When the mussels pile up in mounds around grass stems, they protect the grassroots by improving water storage and reducing soil salinity. With the help of mussels, marshes will be able to recover from drought in less than a decade.
Researchers from the Carbon Containment Lab at the Yale University School of the Environment analyzed 750,000 acres of expansive salt marsh systems in the US along the coastal area known as the South Atlantic Bight. Their goal was to quantify the impact mussels have on protecting coastal regions. One of their biggest experiments involved moving over 200,000 mussels by hand from one landscape to another and measuring changes to the marsh elevation over three years. They found that the areas where the mussels were removed lost about 1.7cm of elevation per year, while the marsh areas where mussels were added gained an elevation of about +0.4 cm.
The researchers stress the need for local conservation and management efforts to include mussels in models of coastal wetland accretion along with large-scale mussel manipulation to promote marsh vertical growth. There is also a need to protect mussel habitats from pollution, pesticides and herbicides and effects caused by climate change, such as sea level rise to enable these marine creatures to continue to help the ecosystems recover and thrive.
Other marine animals helping with ecosystem growth are lugworms and burrowing ghost shrimps, which act as bioturbators and alter sediment cohesion. Purple marsh crabs contribute to accretion through vegetation density, structure, and tissue allocation. Nature can repair itself if we allow it to do so. If we protect animals like mussels, there is a possibility of restoring marshes and recovering ecosystems that are at risk due to climate change or human impact.