This past summer, the Chesapeake Bay's dead zone was among the worst on record. Scientists blame heavy rains and high temperatures. But things may be getting better over the long term.
Dead zones are giant areas of water in the center of the Chesapeake Bay where there isn't enough dissolved oxygen to support much life. Massive numbers of bottom dwelling creatures suffocate to death every year, caused by nutrient pollution from fertilizer, exhaust, and sewage. But since 1980, the size of late-summer dead zones -- or hypoxia -- has decreased by about 20 percent, according to researchers at Johns Hopkins and the University of Maryland.
"We were surprised," says Michael Kemp, with UMD. He says that the shrinking of late summer dead zones correlates with reductions in nutrient pollution since the 80's.
"The lesson is yes indeed the bay will respond to reduced nutrient loading," says Diaz.
Bob Diaz, with the Virginia Institute of Marine Science, reviewed the research and says it needs further investigation, but notes one thing is clear.
"It will require a much greater reduction than what we've seen in the last 20 years for the hypoxia in the bay to really be reduced," he says.
The Chesapeake Bay Foundation says that efforts to curb nutrient reduction are under threat both in the courts and in Congress.