June 25, 2014 — The size of the annual summer "dead zone" of low-oxygen water in the Gulf of Mexico along Louisiana's coast will cover between 4,633 and 5,708 miles, about the size of the state of Connecticut, according to a Tuesday forecast announced by the National Oceanic and Atmospheric Administration. That's about average for the size of the low-oxygen area since 1985, but still a significant concern, scientists say. And the prediction means another year when states along the Mississippi River have failed to sufficiently reduce the nutrients that cause the dead zone, as called for in a 6-year-old federal-state dead zone reduction plan.
The dead zone moniker is used to describe water that scientists label as hypoxic, meaning it has oxygen levels below 2 parts per million, or anoxic, meaning it contains no oxygen.
The nutrients feed huge blooms of algae, mostly one-cell plants, that grow quickly, die and sink to the Gulf's bottom near the shoreline. There, the decomposition of the algae uses up oxygen.
The nutrient-laden freshwater tends to lie above saltier water at the bottom, forming a barrier for oxygen to mix into the bottom water until storms or a hurricane cross the area.
Many fish are able to avoid such areas, but others that can't are killed, as are organisms that live on the bottom or in the bottom sediment that are the food supply for fish and other organisms.
"The dead zone in the Gulf of Mexico affects nationally important commercial and recreational fisheries and threatens the region's economy," says a NOAA news release announcing this year's estimate.
Read the full story at NOLA.com | The Times-Picayune