A dead zone is an area where seasonal oxygen levels drop too low to support most life in bottom and near-bottom waters and is caused by nutrient runoff, principally from agricultural activity, which stimulates an overgrowth of algae that sinks, decomposes, and consumes most of the life-giving oxygen supply in the water.
The team is predicting the area could measure between 7,450 and 8,456 square miles – roughly the size of New Jersey. Additional flooding of the Mississippi River may result in a larger dead zone.
Researchers observed large amounts of nitrogen feeding into the Gulf from the Mississippi and Atchafalaya Rivers, which experienced heavy water flow in April and May that were 11 percent above average.
Gene Turner, Ph.D., a lead forecast modeler from Louisiana State University said. “The high water volume flows coupled with nearly triple the nitrogen concentrations in these rivers over the past 50 years from human activities has led to a dramatic increase in the size of the dead zone.”
This forecast helps coastal managers, policy makers, and the public better understand and combat the sources of the dead zones. For example, the models that generate this forecast have been used to determine nutrient reduction targets required to reduce the size of the dead zone. This hypoxic, or low-to-no oxygen area, is of particular concern because it threatens valuable commercial and recreational Gulf fisheries by destroying critical habitat.
Copyright © 2009 by Marine Science Today, a publication of OceanLines LLC