The Ocean Is Losing Its Breath. Here’s the Global Scope.

BATON ROUGE – Oxygen is essential for life in the ocean. When oxygen is limited, the habitats of fish, shrimp, crab and other animals are diminished or lost. Some animals suffocate and die while others cannot fully grow or reproduce. These low-oxygen areas in coastal waters, including estuaries and shorelines, have increased more than 10-fold since 1950. Climate change is a key culprit as warmer waters hold less oxygen. As the Earth warms, oxygen is expected to decrease beyond coastal zones and throughout the world’s oceans. An international team of scientists asserts in a new paper published in the journal Science that the world needs to rein in both climate change and nutrient pollution to halt the decline of oxygen in the ocean.

“Dramatic changes are needed in human consumptive habits that require excess use of fossil fuels and forms of agribusiness that over use and waste fertilizers,” said LSU Department of Oceanography & Coastal Sciences Professor and co-author Nancy Rabalais.

Rabalais is a member of a team of scientists from the Global Ocean Oxygen Network, or GO2NE, a working group created in 2016 by the United Nation’s Intergovernmental Oceanographic Commission, which is part of the United Nations Educational, Scientific and Cultural Organization, or UNESCO, that has authored this paper. The group’s review paper is the first to take a sweeping look at the causes, consequences and solutions to low oxygen worldwide in both the open ocean and coastal waters.

Rabalais leads studies of low oxygen levels in the northern Gulf of Mexico in the shadow of the Mississippi River plume as it moves westward along the Louisiana shore. The area of low oxygen called the “dead zone” in the northern Gulf of Mexico is the second largest human-caused low oxygen area in the coastal ocean. Excess nitrogen and phosphorus loads from the Mississippi River caused and has exacerbated the dead zone since the 1950s. Solutions to this lack of oxygen, or deoxygenation, are not simple but will require addressing climate change and excess nitrogen and phosphorus inputs to coastal waters. Individuals can help diminish this global problem.

“Personally, I consciously eat a low corn-based diet with little meat, drive a fuel efficient vehicle, use non-ethanol gasoline and contribute to the necessary research and public education,” Rabalais said.

Winning the War: A Three-Pronged Approach

            To keep low oxygen in check, the scientists said the world needs to take on the issue from three angles:

  •  Address the causes: nutrient pollution and climate change. While neither issue is simple or easy, the steps needed to win can benefit people as well as the environment. Better septic systems and sanitation can protect human health and keep pollution out of the water. Cutting fossil fuel emissions not only cuts greenhouse gases and fights climate change, but also slashes dangerous air pollutants like mercury.

  • Protect vulnerable marine life. With some low oxygen is unavoidable, it is crucial to protect at-risk fisheries from further stress. According to the GO2NE team, this could mean creating marine protected areas or no-catch zones in areas animals use to escape low oxygen, or switching to fish that are not as threatened by falling oxygen levels.

  • Improve low-oxygen tracking worldwide. Scientists have a decent grasp of how much oxygen the ocean could lose in the future, but they do not know exactly where those low-oxygen zones will be. Enhanced monitoring, especially in developing countries, and numerical models will help pinpoint which places are most at risk and determine the most effective solutions.


Additional Links:

Declining oxygen in the global ocean and coastal waters, Science:

Hypoxia In the Northern Gulf of Mexico:




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LSU Media Relations


Ernie Ballard
LSU Media Relations