By Jennifer Grimes
If you’re celebrating National Oyster Day today by rapidly devouring copious amounts of delicious bivalve meat (but obviously not before posting it to Instagram), you may want to consider saving that shell after you’re done consuming its erstwhile host.
Oysters are a keystone species and their numbers are dwindling.
This statement shouldn’t come as a surprise considering that if you’re reading an article about a marine animal these days that animal is assuredly experiencing some form of devastation precipitated by humans’ unrestrained imposition of their will upon the environment. Accordingly, overfishing, habitat destruction, pollution, and disease have led to the loss of 85% of the world’s oyster reefs. As keystone species, oyster reefs provide habitat for numerous other animals, produce cleaner water by acting as filtration systems for algae and pollutants, and serve as a buffer against shoreline erosion. Moving on.
Oyster shells function as critical habitat for the free floating oyster larvae that require these types of hard surfaces to latch onto and mature. Without a surface like this to latch onto, they die. This is clearly not a positive outcome for oyster lovers, but it’s also detrimental for the surrounding ecosystem. Successful colonies of inter-tidal reefs not only serve to replenish oyster populations, they provide habitat for fish, crabs, and shrimp that is critical for every life stage of those creatures. An individual adult oyster can filter pollutants out of 50 gallons of water per day; that’s more water than the average person will drink in 70 days. Furthermore, the scarcity and diminished size of the reef habitat that is increasingly becoming the norm can lead to overcrowding of larvae and poorly developed adult oysters, as well as reduced ecological resilience and eventual population collapse.
Additionally, the reefs serve as important buffers against shoreline erosion. High energy wave activity combined with the negative impacts of human development can lead to erosion and habitat loss. Oyster reef breakwater installations are now being included in some coastal protection plans as a means to attenuate wave activity and protect the shoreline while simultaneously increasing habitat for oysters. As sea levels rise and coastal lands become more vulnerable to storm surge damage, natural buffers such as oyster reefs will become increasingly important in developing sustainable strategies to protect our coasts.
Oyster shells, as well as many other shells, also contain high levels of calcium carbonate. This is the same main ingredient found in acid reducing medications like Tums. This produces an alkalizing, or acid reducing, effect on their marine habitat. This is of notable interest considering the increasing acidification of the oceans presently occurring due the uptake of excessive levels of carbon dioxide from the atmosphere. The mere presence of oyster shells can even improve the growth of some types of shellfish.
Yet shells are rarely returned to the water.
To make things worse, few restaurants or individuals ever think to return the shells to their places of origin. But some organizations are doing their part. In Georgia, an oyster restoration project coordinated by the University of Georgia, called G.E.O.R.G.I.A. (Generating Enhanced Oyster Reefs in Georgia’s Inshore Areas), has a handful of donation drop-off locations and will even organize shell collections for you. So why not celebrate oysters by giving back? Literally. Give them back their shells. They need those.
Jennifer Grimes has a Masters Degree in City and Regional Planning with a Specialization in Environmental Planning and Geographic Information Systems (GIS) from Georgia Tech. She currently works with the Urban Honey Bee Project in the School of Science at Georgia Tech. She can be reached at firstname.lastname@example.org