Drought's Positive Effect: Smaller Gulf Dead Zone

Low levels of oxygen dissolved in the water is often referred to as a “dead zone” (in red above) because most marine life either dies or leaves. Habitats that would normally be teeming with life become, essentially, biological deserts.

(Image credit: NOAA)

Though the parched conditions have wreaked havoc on natural habitat and agricultural crops, drought may have one upside, bringing the fourth smallest dead zone in the Gulf of Mexico since mapping of this annual oxygen-free zone began in 1985.

Scientists estimate the 2012 Gulf of Mexico dead zone spans an area of 2,889 square miles (7,482 square kilometers), or just larger than the state of Delaware.

Latest Videos From

Watch full video here:

The lack of oxygen results from nutrients, particularly nitrogen, that run off the land, from agricultural and other human activities, down the Mississippi River and into the Gulf of Mexico. These nutrients are food for algae, which grow as a result, before dying, sinking to the sea bottom and decomposing. It's this decomposition that sucks all the life-giving oxygen from the surrounding waters. [Mightiest Floods of the Mississippi River]

Two groups of researchers had forecast earlier this summer two very different potential sizes for this hypoxic zone, one on the small side and the other more in line with an average-size dead zone. The more conservative prediction, which involved researchers at the University of Michigan, took into account the nutrient-rich agricultural run-off from the Mississippi River watershed this spring. The "average" prediction accounted for leftovers from the prior year's nutrient pollution, called a carryover effect.

Jeanna Bryner is managing editor of Scientific American. Previously she was editor in chief of Live Science and, prior to that, an editor at Scholastic's Science World magazine. Bryner has an English degree from Salisbury University, a master's degree in biogeochemistry and environmental sciences from the University of Maryland and a graduate science journalism degree from New York University. She has worked as a biologist in Florida, where she monitored wetlands and did field surveys for endangered species, including the gorgeous Florida Scrub Jay. She also received an ocean sciences journalism fellowship from the Woods Hole Oceanographic Institution. She is a firm believer that science is for everyone and that just about everything can be viewed through the lens of science.