Gulf of Mexico : Largest “dead zone” ever recorded this year
www.gizmodo.co.uk reports, 5th August 2017: Measuring 8,776 square miles, this year’s dead zone in the Gulf of Mexico is the largest ever recorded.
A recent expedition to the Gulf of Mexico has yielded the largest “dead zone” ever recorded in the area. Measuring 8,776 square miles, this massive patch of oxygen depleted water is wreaking havoc on the Gulf’s marine life — a consequence of unchecked agricultural run-off pouring down from North America’s Mississippi River.
Distribution of bottom-water dissolved oxygen, 24th July – 30th July, 2017. Black line denotes 2 mg l-1.
Data source: N. N. Rabalais, Louisiana State University & Louisiana Universities Marine Consortium; R. E. Turner, Louisiana State University. Funding: National Oceanic and Atmospheric Administration, National Centers for Coastal Ocean Science.
Note: Louisiana Universities Marine Consortium states: The entire area was not mapped because of insufficient days on the ship, and that Quality Control/Quality Assurance standards for processing the data may change the overall estimate and other environmental parameters.
The average size for the last five years, including this year, is 15,032 square kilometers (= 5,806 square miles). The 31-year average (less 1989 and 2016) is 14,042 square kilometers (5,424 square miles). This year’s ‘Dead Zone’ is the size of New Jersey.
Gizmodo.co.uk continues: Dead zones appear in the Gulf every summer, and the typical size is around 5,800 square miles.
Back in 2002, scientists detected an unusually large dead zone stretching for 8,497 square miles, but this new one, detected just last week, is now the largest ever recorded. At a whopping 8,776 square miles (22,730 sq km), it’s 4.6 times larger than the target size set by the Gulf Hypoxia Task Force.
In the words of the National Oceanic Atmospheric Administration, this finding shows that “nutrient pollution, primarily from agriculture and developed land run-off in the Mississippi River watershed is continuing to affect the nation’s coastal resources and habitats in the Gulf.”
Hypoxia is a fancy term for low oxygen, and it’s primarily a problem for estuaries and coastal waters. These dead zones have dissolved oxygen concentrations of less than two to three parts per million, and they’re triggered by a variety of factors.
In the case of the Gulf of Mexico, excess nutrients stream down the Mississippi river, stimulating massive algal growths that eventually decompose — a process that depletes the oxygen required to support marine life. Sources of these nutrients include fertilizers from agriculture, golf courses, and suburban lawns, erosion of soil packed with nutrients, and sewage discharge from treatment plants.
Dead zones can cause a loss of fish habitat, or force fish to migrate to other areas to survive. They can also cause reproductive issues among marine animals. Studies suggest that dead zones in the Gulf are leading to fewer large shrimp, for instance. There are over 400 hypoxic zones in the world, but the Gulf of Mexico dead zone is the largest in the US, and one of the largest globally.
Note: Mightyearth.org advises that the primary source of this pollution is meat production up-river in the USA, and also states, July 2017: Fertilizer pollution is also the leading cause of annual toxic algae blooms that cause waterways across America to collapse into Dead Zones, which are toxic to marine life and unhealthy for recreationalists.
While fertilizer pollution starts in the Midwest, it flows down the Mississippi River until it finally dumps out into the Gulf of Mexico, which collapses into one of the world’s largest Dead Zones each year as a direct result.
Approximately 1.15 million metric tons of nitrogen pollution flowed into the Gulf of Mexico in 2016 alone,22 which is around 170 per cent more pollution than was dumped into the Gulf by the BP oil spill. While the BP spill was recognized as a major industry disaster on a national scale, fertilizer spills into the Gulf every year with little scrutiny or accountability.
This year’s Dead Zone is projected to be one of the largest ever, due to record levels of nitrate pollution flowing down the Mississippi River. The EPA calls water pollution from excess nitrogen and phosphorus “one of America’s most widespread, costly, and challenging environmental problems.”
Current estimates indicate that two thirds of the coastal rivers and bays in the United States are moderately to severely degraded from excess nitrogen pollution.
Opinion: To see an opinion on this issue provided by Callum Roberts, Professor of Marine Conservation, York University, UK — see www.theguardian.com/commentisfree/2017/aug/04/meat-industry-gulf-mexico-dead-zones-pollution
