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Northern Gulf of Mexico Hypoxic Zone

2015 Gulf of Mexico Hypoxic Zone Size

The 2015 "Dead Zone" measured 16,760 square kilometers (= 6,474 square miles). This size is larger than the predicted range made in June as described below. The 2015 dead zone size is above the five-year average (14,024 sq km). It is also three times larger than the Hypoxia Task Force goal of 5,000 square kilometers. Researchers suggest that heavy rains in June and high river discharges in July may provide an explanation for the larger zone measurement. You can read the Louisiana Universities Marine Consortium (LUMCON) press release here Exit EPA Disclaimer and the National Oceanic and Atmospheric Administration (NOAA) press release here Exit EPA Disclaimer.

2015 Forecast: Summer Hypoxic Zone Size, Northern Gulf of Mexico

NOAA and USGS released their 2015 forecast for the summer hypoxic zone size in the Northern Gulf of Mexico on June 17, 2015. You can find the full press release here Exit EPA Disclaimer. Scientists are expecting the 2015 area of low oxygen, commonly known as the 'Dead Zone,' to be approximately 5,483 square miles or about the size of Connecticut –the same as it has averaged over the last several years. 

2014 Gulf of Mexico Hypoxic Zone Size

2014 Dead Zone SizeThe 2014 "Dead Zone" measured 13,080 square kilometers (= 5,052 square miles) as of Aug 1, 2014. This size fell within the predicted range made in June described below. The 2014 dead zone size is below the five-year average (14,353 sq km), but still well above the Hypoxia Task Force goal of 5,000 square kilometers. You can read the LUMCON press release here Exit EPA Disclaimer and the NOAA press release here Exit EPA Disclaimer.

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 hypoxiaExit EPA Disclaimer.

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.

Information about the size of the hypoxic zone can be obtained from NOAA’s Gulf of Mexico Hypoxia Watch and the Louisiana Universities Marine Consortium (LUMCON), which is supported by NOAA’s NGOMEX.Exit EPA Disclaimer

The Gulf of Mexico Hypoxia Watch Exit EPA Disclaimerevolved 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.Exit EPA Disclaimer

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.

Gulf Hypoxic Zone 1985-2013

Size of the Gulf of Mexico hypoxic zone from 1985 to 2013. Source: N. Rabalais
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2013 Hypoxic Zone Measurements

2013 Hypoxic Zone Measurements.
Source: NOAA Gulf of Hypoxia Watch
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The following links provide information regarding the 2012 hypoxic zone and relation to the Summer 2012 drought:

NOAA scientists: Midwest drought brings fourth smallest Gulf of Mexico 'Dead Zone' since 1985 Exit EPA Disclaimer

Louisiana University Marine Consortium Shelfwide Cruise 2012 Website Exit EPA Disclaimer

Louisiana University Marine Consortium Shelfwide Cruise 2012 Press Release (4pp, 563K, About PDF)

The New York Times Green Blog: Big Drought Makes for a Small 'Dead Zone' Exit EPA Disclaimer

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).

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Graphic created from hypoxic zone measurements available from NOAA Gulf of Hypoxia Watch.

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