Gulf Hypoxic Zone Found to Be Smaller Than Expected

NOAA-supported scientists announced that this year’s Gulf of America hypoxic zone is approximately 1,332 square miles, making it the 2nd smallest zone on record in 40 years of measurement. Hypoxic areas, also called “dead zones,” are areas with little to no oxygen in the water, which can negatively impact fish, shellfish, corals and aquatic plants by making critical habitat unavailable to bottom species.

The annual hypoxic zone survey was led by scientists at Louisiana State University and the Louisiana Universities Marine Consortium (LUMCON). The survey cruise was conducted aboard the LUMCON research vessel Pelican from July 24-30. Data from the survey is available online for the public.

The measured hypoxic zone is smaller than anticipated this year due to Tropical Storm Bertha passing through the northern Gulf of America on the eve of the cruise. Tropical storm-force winds and high waves churned the water across the cruise area and mixed oxygen-rich surface waters down to the seabed. Although the cruise did not capture the full extent of the zone, years with abnormal weather events help researchers better understand how these events impact the breakup and reformation of hypoxia in the Gulf and ultimately lead to better models and forecasts.