2026 Gulf ‘dead zone’ is second smallest on record. But not for the reason you think.

Mobile Real-Time NewsA map of the "dead zone" off the coast of Louisiana, as recorded by researchers from the Louisiana Universities Marine Consortium. The zone was much smaller this year because Tropical Storm Bertha passed just before researchers took off for their annual survey. (Map by Coastal Mapping & Sciences, LLC, courtesy Louisiana Universities Marine Consortium)Louisiana Universities Marine ConsoritumBy Margaret Kates | mkates@al.comEvery summer, a large area of low-oxygen water forms in the Gulf of Mexico off the coast of Louisiana. This area is called the “dead zone” because marine life there dies. Scientists have been measuring the dead zone for 40 years, but thanks to a tropical storm, this year’s dead zone is the second smallest on record. “Measuring the hypoxic zone provides more than just a score card of the Gulf’s ocean oxygen levels — it helps us better understand the interconnectivity of our nation’s land, waterways and ocean,” said Timothy Petty, assistant secretary of commerce for oceans and atmosphere and deputy administrator of the National Oceanic and Atmospheric Administration. The dead zone forms every year due to high volumes of nutrients draining from the Mississippi-Atchafalaya River Basin that runs through the Midwest, primarily runoff from farmland and developed areas. In the Gulf, the nutrients create an algal bloom that later die and decompose. As the algae are eaten and sink to the bottom, dissolved oxygen is consumed, a process known as “eutrophication.” Any sea creature that can leave the dead zone does, and those that can’t move die. A “dead zone” also typically forms off the coasts of Mississippi and Alabama every year, though it is usually much smaller than the Louisiana dead zone. It is far less studied and less understood. Researchers with the interagency Hypoxia Task Force have only surveyed the dead zone east of the Mississippi River three times. This year’s Louisiana dead zone was around 1,332 square miles, the second smallest ever recorded, according to a press release from the Louisiana Universities Marine Consortium (LUMCON), which surveys and measures the dead zone every year. But it may just be a fluke: two days before researchers set out on their six-day cruise of the dead zone, Tropical Storm Bertha made landfall in Louisiana. The storm followed the southern edge of Louisiana before making its final landfall in Texas the following day. The storm’s winds and waves churned up oxygen-rich waters, causing them to mix with the low-oxygen waters and break up the dead zone, the news release said. The total area in the Gulf where the water was "hypoxic," meaning it lacks oxygen, each summer from 1985 to 2026. The year's "dead zone," or hypoxic area, is the first to be smaller than the goal set by federal agencies since 2000. (Graph courtesy Louisiana Universities Marine Consortium)Louisiana Universities Marine ConsortiumThe “Hypoxia Task Force” that works both with researchers on the coast and upriver in the Midwest has set a goal of reducing the dead zone to around 1,900 square miles. According to LUMCON data, this is the first year since 2000 that the dead zone has fallen below that threshold. In June, forecasters with NOAA predicted that the dead zone off the coast of Louisiana would be larger than average this year, around 7,027 square miles, slightly bigger than the dead zone in 2024 and around the size of New Jersey. The forecast was based on estimates of nutrient loading into the Mississippi river basin from farther north. But even though surveyors did not get to see what the dead zone may have looked like prior to the storm, researchers can still learn from this trip, the release said, helping scientists to understand how abnormal weather events can affect dead zones. “The data we’ve gathered from 40 years of measurements in the region will help inform the development of better management strategies upstream as part of our ongoing efforts to mitigate future impacts in the Gulf,” Petty said in the release. Margaret “Maggie” Kates is the environment and natural resources reporter for AL.com. Based in Mobile, she reports on Alabama's diverse environment and its effect on people. She covers stories related to the...