In the Gulf of Mexico off the south-eastern US, meanwhile, the water demands of Atlanta and other cities mean river flows are down, making estuaries more salty and allowing invading marine predators to feast on native oysters.The good news is that oyster reefs can bounce back, if managed with care.Article continues: http://www.newscientist.com/article/mg20227094.300-shellfish-reefs-more-imperilled