Extreme Weather Threatens Wild Gulf Coast Oysters

LaDon Swann of the Mississippi-Alabama Sea Grant Consortium says the shellfish require water that’s salty, but not too salty.

“So it’s kind of like Goldilocks. … You know, an oyster’s really looking for that perfect location,” he says. “When they find that water that’s just right, that’s where they make their home.”

But climate change is throwing off that balance. When heavy rain falls, too much freshwater may flow from the Mississippi River into the oyster reefs.

“Oysters can survive that for a short period of time, but if it goes beyond just a few days, then it affects their health, and ultimately you see mass mortalities of oysters because of the freshwater inflow,” Swann says.

On the other hand, when there’s not enough rain, the water around oyster beds gets too salty. That allows saltwater predators – such as a snail called the oyster drill – to enter oyster habitat.

This snail can make a hole in the oyster’s shell, suck it out, and digest it.

So Swann says as climate change causes precipitation extremes at both ends of the spectrum, wild Gulf Coast oysters may lose the “just right” Goldilocks zone they need to thrive.