Efforts to restore eastern oyster (Crassostrea virginica) populations along the Atlantic coast of the US by returning oyster shells to the sea also benefit other marine animal species. Oyster shells from the gourmet seafood industry are returned to coastal waters to create reefs where juvenile oysters and other marine animals find protection from larger predators.
Restored oyster populations then contribute to improved water quality and the prevention of coastal erosion. Healthy native oysters are once again harvested for the gourmet seafood market, replacing introduced shellfish species, which reduces the risk of parasitic and bacterial infections carried by non-native species.
Eastern Oyster Losses Affect Marine Biodiversity
Approximately 85% of oyster reefs worldwide have disappeared with North American coasts being particularly hard hit. Chesapeake Bay in Maryland, for example, has lost more than 90% of its historic reef area, largely from a combination of overharvesting and sedimentation caused by runoff from the land.
The eastern oyster has been devastated all along the Atlantic coast by overharvesting, habitat loss and water pollution. As numbers dropped, non-native oysters were introduced to supplement the shellfish harvesting industry. Parasites and diseases brought in by those non-native shellfish species have also had a negative impact on the native eastern oyster.
The Importance of Oysters in the Coastal Ecosystem
Oyster shells provide habitat for other marine animals, which improves coastal biodiversity. Important recreational and commercial species such as southern flounder (Paralichthys lethostigma), striped bass (Morone saxatalis) and blue crab (Callinectes sapidus) find shelter in clumps of oyster shells.
A variety of worms, other mud crabs and shrimp, which provide food for other marine animals, also find shelter in the recycled oyster shell reefs. Oysters are also important water filterers, processing between 15 and 30 gallons per day. This filtering activity helps reduce water pollution and improve visibility.
How Oyster Shell Recycling is Helping Restore Coastal Ecosystems
Oysters, an intertidal keystone species, are a popular food shellfish, with thousands of pounds being harvested every day for the upscale food market. But, until recently the shells from the oysters harvested as gourmet seafood were ground up for calcium supplements or crushed for use in driveways and decorative paths.
Today there is ongoing research into the restoration of oyster reefs along the Eastern Seaboard. Recycling of oyster shells to make these reefs has proven to be one of the safest and most effective methods for improving eastern oyster production.
Oyster shells are collected and returned to the intertidal and subtidal seabeds in narrow ridges, which provide a basic reef structure. Mesh bags filled with shells are then placed in a border around the ridges to provide stability until the reef is more developed. The reefs provide a place for juvenile oysters to attach as they develop. The shells also provide hiding places for fish and other marine animals.
Oyster shell recycling is being used in Massachusetts, Maryland and North Carolina on the US Atlantic coast with some initial success. As the oyster shell reef communities continue to develop the added benefits of reduced coastal erosion and improved water quality will contribute to healthier intertidal and subtidal ecosystems.
Dawn M. Smith - A vet nurse, Dawn has worked in wildlife rehabilitation and conservation around the world in addition to her veterinary hospital ...
Join the Conversation