What makes some oysters more resilient than others?

Oysters live and grow in saltwater. However, the saltiness of their habitat can change dramatically, especially where the mighty Mississippi River flows into the Gulf of Mexico. Louisiana oysters from the northern Gulf of Mexico may experience some of the lowest salinity in the world due to the influx of fresh water from the Mississippi River. In addition, increased rainfall and large-scale river diversions for coastal protection will bring more fresh water that does not bode well for the eastern oyster.