Coastal Champion: Nancy Rabalais is unstoppable in her pursuit to protect the Gulf of Mexico

By Christine Wendling

For coastal communities along the Gulf of Mexico, its waters represent the cultural and economic lifeblood of the region. Many families have worked in the fishing industry for generations and are very attuned to changes to the Gulf. According to LSU Professor Nancy Rabalais, local shrimp trawlers in the northern Gulf began noticing a mysterious decline in their catch rates as early as the 1970s. By the 1980s, fishers and scientists knew the marine life there was suffocating from low oxygen but did not yet understand the causes and what could be done to solve this problem. Rabalais was determined to find out.

For more than three decades, Rabalais has studied the hypoxic zone, a large region of water in the Gulf of Mexico where oxygen levels are so low that marine organisms cannot survive in it. As a marine ecologist and professor in the LSU Department of Oceanography & Coastal Sciences, Rabalais’ collaborative research has documented and tracked the links between deoxygenation, or hypoxia, in the Gulf of Mexico and agricultural practices that are increasing the amount of harmful nitrogen and phosphorus in the Mississippi River. Her findings have led to federal legislation concerning the diminished water quality.

Early Research 

The daughter of a mechanical engineer who worked for an oil company, Rabalais spent much of her early life in Texas. She earned bachelor’s (1972) and master’s (1975) degrees from Texas A&I University in Kingsville and a doctorate (1983) from the University of Texas. 

By 1983, Rabalais had moved to Louisiana and begun working for the Louisiana Universities Marine Consortium, or LUMCON. In 1985, LUMCON received a grant to study low oxygen in the Gulf and Rabalais was put in charge of a team that included highly respected LSU professors Gene Turner and Bill Wiseman. On their first summer research cruise, which spanned the Mississippi River Delta to Texas and beyond, they found and measured a sizable area of low oxygen that covered the broad expanse of the Louisiana continental shelf.

“ It was a big deal because nobody had actually measured it that way before. ”

“It was a big deal because nobody had actually measured it that way before. Other researchers had monitored from Mobile Bay to the Atchafalaya, but we did the whole Louisiana inner shelf and determined the area of the low oxygen zone,” she said.

But what was causing it?

Rabalais and her team discovered that this coastal deoxygenation was being caused primarily by agricultural fertilizer runoff flowing down the Mississippi River and into the sea.

“Agriculture is the major driver because you have ag on so many millions of acres with runoff ending up in the Mississippi, and with infiltration and leaching, fertilizers affect both groundwater and surface water,” said Erin Meier, a sustainable agriculture expert and director of Green Lands Blue Waters, an organization based in Minnesota in which LSU is a founding partner.

The nitrogen and phosphorous from the fertilizer flow into the ocean, which fuels an explosive plant growth in the form of algal blooms. When the algae die, the decomposition process chokes the oxygen supply, making the area uninhabitable for bottom-dwelling marine organisms, such as shrimp, crabs, burrowing worms, and clams. If the organisms can swim away, they will. Organisms that cannot escape eventually suffocate and die. The loss of these bottom-dwellers means less food for larger marine organisms, such as fish, reducing their population growth and forcing them to alter migration patterns away from the area. And, the process is accelerating.

In 1985, the “Dead Zone” measured 3,800 square miles, making it one of the world’s largest coastal hypoxic zones. Between 1985-2020, the “Dead Zone” averaged 5,300 square miles, nearly the size of Connecticut. In July 2017, it grew to 8,800 square miles, the largest ever measured. Since then, the size of the dead zone continues to fluctuate based on nutrient loads and tropical storms.

Gaining Traction 

However, the momentum from the government to tackle the problem of hypoxia seems to have waned. In 2001, The Mississippi River/Gulf of Mexico Watershed Nutrient Task Force established a national strategy to reduce the size of the hypoxic zone to 1,900 square miles by 2015. As that date neared, the taskforce extended it to 2035. Unfortunately, as of 2021, the forecasted size of the “Dead Zone” was 4,800 square-miles, still two and a half times larger than the Hypoxia Task Force goal.

Furthermore, in years past, Rabalais was able to take continuous measurements of oxygen, salinity, temperature, and currents within the “Dead Zone.” Now, due to reductions in funding, she is limited to station-by-station data collected during her research cruises each July. Nonetheless, her work continues.

“ I have to keep hoping…All I can do is try to keep educating. ”

“I have to keep hoping," Rabalais said. "All I can do is try to keep educating."