The problem is caused in part by fertilizer run-off from agricultural activities in the
"The oxygen-depleted water at the bottom is not replenished because of the lack of circulation," Dale said. "The more water that flows into the Gulf and the more nutrients in the water, the worse the hypoxia becomes."
While scientists initially believed nitrogen was the major culprit, the assessment team for the Science Advisory Board of the Environmental Protection Agency realized that phosphorus also plays a significant role. The team is recommending a 45 percent reduction in phosphorus and nitrogen from the 1980-1996 average flux during the spring (April, May and June) on a five-year running average….The delta of the Atchafalaya River on the Gulf of Mexico. View is upriver to the northwest. Photo by Arthur Belala, U.S. Army Corps of Engineers, Wikimedia Commons