Marine scientists estimate the low-oxygen “dead zone” in the Gulf of Mexico covers a record 8,776 square miles, or one-seventh of the basin. “This large dead zone size shows that nutrient pollution, primarily from agriculture and developed land runoff in the Mississippi River watershed, is continuing to affect the nation’s coastal resources and habitats in the Gulf,” said NOAA.
Nutrient runoff “stimulate massive algal growth that eventually decomposes, which uses up oxygen needed to support (marine) life in the Gulf,” said a NOAA release. An unusually large hypoxic zone was forecast this year because of heavy May rainfall in the Farm Belt washed an estimated 2,800 rail cars of nitrogen fertilizer down the Mississippi River. This year’s dead zone is roughly the size of New Jersey.
“We expected one of the largest zones ever recorded because the Mississippi River discharge levels, and the May data indicated a high delivery of nutrients during this critical month which stimulates the mid-summer dead zone,” said professor Nancy Rabalais of Louisiana State University, who led the week-long survey that sampled Gulf waters during the final week of July.
Officials have a target of reducing the dead zone to 1,900 square miles, considerably smaller than the five-year average of 5,806 square miles. The previous record for the dead zone was 8,497 square miles in 2002.