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The Gulf of Mexico’s ‘ Dead Zone ’ could double in size this year

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An oxygen-poor area in the Gulf of Mexico is expected to grow as runoff from American farms drastically increase the levels of Nitrogen in the water. Usually only about 13,700 square kilometres (5,300 square miles), Louisiana State University predicts the dead zone could stretch to almost 26,000 square kilometres (10,000 square miles). Federal agencies have tried to downplay the number, with their estimate of this year’s dead zone closer to 20,000 square kilometres (8,000 square miles) – that is still enough to make it the third largest dead zone since records began in 1985.

Gulf of Mexico Dead Zone MAP NASA_NOAA
Gulf of Mexico Dead Zone MAP (2011); soruce wikimedia.org; author NASA_NOAA

Named because of the lack of sea-life in a designated zone due to poor oxygen levels, dead zones are usually caused by a chemical imbalance – in this case the runoff of nitrogen rich fertilizer used by farms. When the runoff exits the Mississippi River, it creates an imbalance within the ocean, killing everything within the zone. Dead zones aren’t a new phenomenon and have been around roughly since the industrial era began.

World's Aquatic Dead Zones
World’s Aquatic Dead Zones; source wikimedia.org and NASA Earth Observatory; author Robert Simmon & Jesse Allen

Whilst heavy pollution from industry is no longer a major issue, the chemicals used in pesticides in fertilizers are. Major dead zones can be found stretching from the Gulf of Mexico to the rest of the United States’ eastern seaboard, as well as the southern tip of the Korean Peninsula and the Baltic Sea. The Gulf of Mexico however, is the longest and largest recurring event on record.

Natural Dead Zone caused by decay of algae,
Natural Dead Zone caused by decay of algae, La Jolla California “La Jolla Red Tide”; source wikimedia.org; author Alejandro Díaz

A large dead zone like the one expected to happen would wreak havoc with local fisheries and tourism, therefore negatively affecting the area’s economy. Farmers have been involved in efforts to try reduce the size of the dead zone, either by swapping to different types of fertilizer or techniques, but low interest from their part has led to little success in cutting back nitrogen runoff, as LSU professor of marine ecosystems Nancy Rabalais explains:

“There’s a federal-state task force to come up with recommendations state-by-state to reduce nutrients. If you read the details of the forecast and the changes in flows over time, you can see there hasn’t been much of a change. Which means the few really concerted efforts to reduce nutrients have been overwhelmed by the usual way of big agribusiness in the watershed.”

A research cruise carried out this month will be able to form a consensus as to the total size of the dead zone affecting the Gulf, as well as any ecological issues that may arise from the temporary drop in oxygen levels.

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