A scientist-led research cruise has found that the Gulf of Mexico’s “dead zone” is now measuring at 6,334 square miles, the National Oceanic and Atmospheric Administration (NOAA) announced on Tuesday, which is roughly the size of Connecticut. This is approximately four million acres of habitat that is unusable for underwater species.
The “dead zone” describes an area of bottom water in the Louisiana coast that is hypoxic, or low-oxygen, which renders the area uninhabitable for wildlife. Hypoxia occurs there when excess nutrients from surrounding cities and areas drain into the Gulf and stimulate algae growth during the spring and summer. When the algae dies, it sinks to the bottom of the Gulf and is decayed by oxygen-consuming bacteria. This process results in low oxygen levels in the bottom water.
The investigation was led by researchers from the Louisiana State University and the Louisiana Universities Marine Consortium, with support from NOAA. The scientists also found that surface waters in the area were low in salinity due to freshwater runoff from the Mississippi River. This, combined with warm surface waters, reduces the rate at which surface water oxygen can diffuse to the bottom layer. Winds from the south also maintained the surface water’s low salinity.
These conditions can alter the diets, reproduction and growth rates of fish. Researchers also warned that hypoxic waters can also affect the availability of harvestable shrimp which could impact local economies.
According to a press release from the researchers, wind speed and direction as well as hurricane conditions will continue to impact the area’s hypoxia.
“This year, we have seen again and again the profound effect that climate change has on our communities—from historic drought in the west to flooding events. Climate is directly linked to water, including the flow of nutrient pollution into the Gulf of Mexico,” Radhika Fox, assistant administrator for water at the U.S. Environmental Protection Agency, said in a press release from the NOAA. “As we work to address the Gulf of Mexico hypoxic zone, we must consider climate change and we must strengthen our collaboration and partnerships to make needed progress.”
Scientists have measured the area annually since 1985 on research cruises funded by the National Oceanic and Atmospheric Administration. Their annual measurements of the area help track progress towards their 2035 goal of 1,900 square miles or smaller. This year’s measurement is on the higher end of recent years’ findings.
Efforts are being made to alleviate these conditions in the Gulf by groups such as the Hypoxia Task Force, which works with federal partners, states, and farmers to reduce excess nutrients in the area. Other federal efforts such as the U.S. Department of Agriculture’s Mississippi River Basin Healthy Watersheds Initiative will further support conservation investments by agricultural workers in the area.
“The efforts need to continue and intensify as we face many societal and environmental knowns and unknowns in both the watershed and in offshore waters,” the researchers’ press release reads. “We, as citizens of the watershed, need to lessen our consumption of nitrogen-based products and reduce other activities that contribute reactive-Nitrogen to the environment.”