When talking about the Chesapeake Bay's woes, we often focus on the huge "dead zone" in the middle of the estuary, where oxygen levels are so low that fish, crabs and shellfish can't breathe.
But those critters actually tend to spend more time in shallower waters than in the deep middle, and the shallows can have problems of their own, with oxygen levels plunging at night, only to rebound in daytime.
Now, a team of scientists, led by the Smithsonian Environmental Research Center in Edgewater, plans to take a closer look at how those repeated dips in oxygen, or hypoxia, in the shallow waters may be affecting the likes of summer flounder, strilped bass, white perch and oysters - not to mention the little fish that bigger fish feed on, such as weakfish and mummichog.
Smithsonian senior scientist Denise Breitburg already has begun testing how oysters fare, exposing them in tanks to repeated fluctuations in oxygen levels that mirror the drops seen at night and in early morning. For more on her work, go here.
The National Oceanic and Atmospheric Administration is providing $634,000 for the study now, with a total of $1.6 million planned over the next five years. Scientists from the University of Delaware and Louisiana State University will be part of the research.
(Denise Breitburg with oysters from Choptank River to be used in hypoxia study: 2010 Baltimore Sun photo by Amy Davis)