Northern Gulf of Mexico Hypoxic Zone
Measuring the Hypoxic Zone
The hypoxic zone in the northern Gulf of Mexico is an area along the Louisiana-Texas coast, where water near the bottom of the Gulf contains less than 2 parts per million of dissolved oxygen, causing a condition referred to as hypoxia.
Each summer, the size of the hypoxic zone is measured. The size of the zone is an important indicator of how much progress is being made to reduce nutrient inputs into the Gulf of Mexico. Sometimes the size of the zone is influenced by other factors, such as droughts or hurricanes that can reduce the size of the zone, or floods that can increase the size.
The Gulf of Mexico Hypoxia Watch evolved as a cooperative project among NOAA’s National Marine Fisheries Service (NMFS), the National Coastal Data Development Center (NCDDC), and the CoastWatch - Caribbean/Gulf of Mexico - Regional Node. The objective of Hypoxia Watch is to develop new near-real time data and map products using shipboard measurements of bottom-dissolved oxygen and disseminate them over the Internet. Access measurements taken from 2001 to the current season.
2013 Hypoxic Zone
The 2013 area of low oxygen in the Gulf of Mexico, commonly known as the hypoxic zone or ‘Dead Zone,’ was 15,120 square kilometers (= 5,800 square miles), which was smaller than predicted. Researchers suggest that winds may have contributed to more mixing and a smaller zone measurement. The size of this year’s hypoxic zone is about double the measured size of the zone in 2012, when summer drought conditions in the Mississippi River Basin contributed to greatly reduced nutrient outputs into the Gulf of Mexico. This year’s zone of oxygen-depleted bottom-water was above both the long-term average and also the five-year average.
The following links provide information regarding the 2012 hypoxic zone and relation to the Summer 2012 drought:
Hypoxic Zone over the Years
The Flash animation below shows a comparison of how the hypoxic zone has changed over the last 5 years (2009 to 2013).