Solutions on the half shell.

After that oyster slides into your mouth, and you’ve tossed another empty shell onto your plate, do you ever think about where those shells end up?

Probably not. Yet that pile of mollusk shells contributes to more than 7 million tons of “nuisance waste” discarded every year by the seafood industry that mostly winds up thrown into landfills or dumped into the ocean. Researcher James Morris calls the practice “a colossal waste of potentially useful biomaterials.”

He and his colleagues have a better idea, one that could reap huge ecological benefits. They propose using shells to restore damaged oyster reefs or crushing them for applications in agriculture and engineering. Both require little time and money.

“Reusing shell waste is a perfect example of a circular economy, particularly as shells are a valuable biomaterial,” Morris said. “Not only does it improve the sustainability of the aquaculture industry moving forwards, but it can also provide secondary economic benefits to shellfish growers and processors as well.”

Morris and a team of CACHE (Calcium in a Changing Environment) scientists from the Royal Belgian Institute of Natural Sciences have been studying environmental and economically sustainable options for mollusk shells, and recently presented their findings to a meeting of the Society for Experimental Biology.

Mollusk shells are rich in calcium carbonate — which makes up about 95 percent of their composition. The shells are the perfect material for repairing damaged oyster reefs, according to the scientists.