Bay Oxygen Levels Looking Up

Chesapeake Bay oxygen levels rise to second-highest since 1985

Samples taken in late June revealed than the area of water at the bottom of the bay that contains little or no oxygen has shrunk to about 40 percent of its long-term average, at less than half a cubic mile of volume, according to the state Department of Natural Resources. That was the second-smallest volume for late June since scientists started closely monitoring the data in 1985.

"We're kind of dialing things back about 30 years," said William Dennison, vice president for science applications at the University of Maryland Center for Environmental Science.

While the abundance of seafood or underwater grasses are visible signs of the bay's rebounding health, oxygen levels are an unseen yet imperative part of its ecosystem. "Dead zones" devoid of oxygen kill fish, crustaceans, bivalves and even phytoplankton.

Oxygen levels are "a truly integrative kind of measure," Dennison said. "When that's getting better, that's really the ultimate good news story."

I'm starting to get cautiously optimistic about the Bay's recovery. We've had two or three pretty good years (from an anoxia standpoint). However, those have also been fairly favorable weather years, with no major spring flood (which bring in the extra nutrients that fuel the algae that die and rot and use up the oxygen), and no major tropical storms or hurricanes, which stir up the bay and bring the nutrients in the bottom water back up. The true acid test of the recovery will be when the Bay starts to survive events like that and still has good years.