Hypoxia Issues in the Gulf of Mexico

By ScienceDaily.com
24 October 2013

The Mississippi River Basin is home to much of the United States’ fertile crop land. Though we need our food and energy crops, their production has led to an increase in the levels of nutrients such as nitrogen and phosphorus in our water sources. Increasing nutrient levels affects our rivers, lakes, and oceans. Single cell plants, called phytoplankton, feed off the increased nutrients, and in doing so start a cascade of events that leads to low oxygen levels in the water bodies. This low oxygen condition is called hypoxia. The result is dying fish and a poor ecosystem, called a "dead zone."

The dead zone in the Gulf of Mexico, where the Mississippi meets the ocean, has received much attention in the last decade, and led to the creation of the Mississippi River/Gulf of Mexico Watershed Nutrient Task Force.

"We need to see an increase in the rate of implementing practices that lower nutrient export," says Matt Helmers, PhD, of Iowa State University, and member of the Soil Science Society of America. "Cover crops not only decrease the amount of nitrogen and phosphorus leaving the fields, but they improve the soil in other ways. Subsurface drainage bioreactors — often called wood chip trenches — and specialized wetland systems also reduce nutrient export."

Helmers admits the "challenges are more complex than changing the inputs to our crops," such as corn and soybean. And, because there are not short-term financial gains to most of the practices that reduce nutrient export, the industry may be slower to adopt change. "If we don’t show reduced nitrogen and phosphorus export, we may see regulation."