The spill had a devastating effect on Louisiana’s oyster crop, destroying about half of the state’s oyster beds. Ironically, it wasn’t the oil that killed the oysters. In the vast majority of cases, it was fresh water from the Mississippi River, poured into the coastal estuaries to keep the oil from reaching shore, that killed millions of oysters. To survive, oysters require a delicate balance of salt water and fresh water. The fresh water brought in to keep the oil from reaching the coast disrupted that fragile balance. The change in the water’s salinity destroyed thousands of oyster beds.