In June scientists said this year’s “dead zone” in the Gulf of Mexico could be the largest ever, and forecast it would cover between 7,450 to 9,668 square miles of the bottom of the continental shelf off Louisiana and Texas.
Fast forward one month and, with the measurements in, the dead zone is actually … 3,000 square miles.
Dead zones occur when excess amounts of nitrogen (often from fertilizers) are carried into the Gulf of Mexico and other bodies of water by rivers. The Gulf’s dead zone is driven primarily by flows from the Mississippi River carrying agricultural byproducts of farming in the Midwest.
Nutrient overloading, and corresponding algal blooms, deplete oxygen levels in the water, which then can support fewer organisms. Hypoxic conditions have been linked to fish kills and other ill environmental consequences.
Nancy Rabalais, Ph.D., from the Louisiana Universities Marine Consortium, says the reason the forecast missed is:
“The winds and waves were high in the area to the west of the Atchafalaya River delta and likely mixed oxygen into these shallower waters prior to the cruise, thus reducing the area of the zone in that region. The variability we see within each summer highlights the continuing need for multiple surveys to measure the size of the dead zone in a more systematic fashion.”
The dead zone this year is the smallest since the year 2000, and only the third time the dead zone has been less than 3,000 square miles since scientists began measuring it in 1985.
My take: This is obviously good news for marine life and fisheries along Texas and Louisiana. But it’s not-so-good news for the scientists who are trying to predict dead zones and environmentalists trying to use the dead zone threat to drive farming reforms in the Midwest.