Once again, this summer could be a tough one for the Chesapeake Bay's critters.

There are indications that the oxygen-deprived "dead zone" is starting to make its annual appearance.

While it's not surprising, it's yet another bad sign for the bay.

"All living resources - crabs, fish, oysters, clams - they need oxygen to survive," said Bruce Michael of the Maryland Department of Natural Resources.

When there's not enough oxygen, crabs and fish scuttle and look for better places to live. They can become susceptible to illness.

And critters that live at the bottom and can't move, such as oysters, can die from...