Connecticut-Sized Dead Zone Expected in Gulf of MexicoBy JoAnna Wendel, Staff Writer, EOS
June 19, 2015
An ensemble of four computer models evaluated river runoff, wind patterns, and other factors affecting the extent of oxygen-poor waters near the Mississippi River’s mouth.
A visualization of how nutrient runoff from farms (green) and cities (red) in the Mississippi River Basin influences algal blooms in the Gulf of Mexico. The warmer colors represent a higher concentration of algae. NOAA scientists predict that the size of the 2015 Gulf of Mexico dead zone, which is caused by the decomposition of these blooms, will be about the size of Connecticut. Credit:
By 18 June 2015
The National Oceanic and Atmospheric Administration (NOAA) released on Wednesday its prediction of the size of the annual Gulf of Mexico dead zone, which the agency forecasts to span about 14,200 square kilometers—about the area of the state of Connecticut. The actual size of this summer’s dead zone will be studied and announced in early August.
This huge expanse of oxygen-depleted Gulf waters just beyond the Mississippi River Delta forms after nutrients from wastewater and vast amounts of fertilizer used by farmers wash down the river and run off the Louisiana and Texas coasts during the rainy spring. The extra nutrients—mainly chemical compounds containing nitrogen or phosphorous—nourish huge blooms of algae.
When the algal blooms eventually die, they fall to the sea bottom and decompose, soaking up the available dissolved oxygen. As oxygen levels fall too low to sustain most marine life, bottom-dwelling animals like crabs and shrimp cannot thrive and often flee the area, which can the Gulf’s seafood industry. Other, less mobile species may not survive.
“What we’re trying to do is better understand the variability in size