One issue with introducing the lemon sharks is that the loggerhead is still somewhat passive competing for food, while the lemons are aggressive towards everything edible. The sharks are trained with tongs just as the turtle was (see pics below) , but the turtle has not yet established its position (with regards to feeding) in the big tank.
Before they go in, the turtle needs to be able to fend off attempts to take food from it. Sea turtles can inflict serious damage when they want to, but they also need a little attitude and training. The Chesapeake Bay exhibit is over 30 times the size of any previous enclosure it has been in and is filled with many large fishes so as usual it takes a little time before getting comfortable. But it “gets it” a little more each day.