Scientists say Gulf "Dead Zone" misses forecast, but appears to be getting larger

Published on
August 2, 2019

Scientists studying this year’s “dead zone” in the Gulf of Mexico announced on Thursday, 1 August, that the size of this year’s zone is about 6,952 square miles.

That determination ended up being smaller than the 7,829-square-mile forecast NOAA officials announced in June. However, in a press conference to discuss the findings, the scientists added a caveat to their findings.

The survey used to develop the estimated size took place after Hurricane Barry came through the Gulf. That storm, with its heavy winds, brought in salt water to dilute the “dead zone,” also known as a hypoxic zone, which is where chemical and biological factors lead to algae blooms. Through the blooms, oxygen is depleted from the water. Mobile creatures move away from the zone, while stationary animals, such as clams, die out. 

However, the scientists saw signs that it was already reforming.

“I would predict that in one week from now the area will be larger than it is right now,” said Nancy Rabalais, a research professor at the Louisiana Universities Marine Consortium. “But we can only spend so much time on the water.”

NOAA officials said they were pursuing technologies, such as underwater drones, that would allow them to better examine the dead zone and get a more accurate size for the zone, which is considered to be the second-largest such zone in the world.

Even with the scientists’ determination being smaller than the original forecasts, the 2019 dead zone ended up being the eighth-largest in size since scientists began measuring it annually 33 years ago. It also exceeded the rolling five-year average of 5,770 square miles.

The record zone of 8,776 square miles, nearly equal to the size of New Hampshire, occurred two years ago.

The goal is to reduce the size of the dead zone to less than 2,000 square miles, based on a five-year rolling average, by 2035.

“The data from this cruise are used by NOAA and its partners to help refine the models and more accurately simulate how river discharge, nutrient loads and oceanographic conditions influence hypoxic conditions in the Gulf and impact living resources,” said Steven Thur, the director of NOAA’s National Centers for Coastal Ocean Science.

Scientists predicted a large dead zone this year because of the record flooding that took place along the Mississippi River basin earlier this year. That flooding led to significant runoffs of nitrate and phosphorus into the river, which flows into the Gulf.

The flooding became so severe that officials with the U.S. Army Corps of Engineers were forced to open the Bonnet Carré Spillway twice this year. The first-time event poured even more fresh water into the saltwater Gulf.

Fishermen in the Gulf have blamed the flooding for the low harvests of shrimp and oysters in the Gulf. Elected leaders on the state and federal levels from the Gulf states have already sent several letters to U.S. Commerce Secretary Wilbur Ross, asking him to declare a fishery disaster in the region.

Image courtesy of NOAA

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