Quantcast

Connecticut-Sized Dead Zone Found in Gulf of Mexico

Ocean Conservancy

By Alexis Baldera

Imagine if all of the animals throughout the entire state of Connecticut left or died. This is what happens every year in the Gulf of Mexico. The size of the dead zone varies—sometimes it’s as big as New Jersey or only the size of Rhode Island, but the problem always persists.

Researchers from the Louisiana Universities Marine Consortium just spent a week measuring dissolved oxygen concentrations off the coasts of Louisiana and Texas to determine how big the dead zone is this year. And they found that it is about 5,800 square miles, or roughly, the size of the state of Connecticut.

This area is called “the dead zone” because dissolved oxygen levels are too low to support life. Animals that can move out of the area, like fish and shrimp, will leave, and animals that can’t, like brittle stars and mussels, will become stressed and eventually die.

The dead zone forms every summer because nutrient-rich water from the Mississippi River basin flows into the Gulf and causes algal blooms. Nutrients, like nitrogen and phosphorus, are helpful when used to fertilize gardens and crops, but like most other things, the best rule for nutrients is moderation. While these nutrients are naturally occurring in the Gulf and all ecosystems, levels that are too high can cause problems.

In the Gulf of Mexico, the nutrient-rich waters, fueled by agricultural runoff fed down the Mississippi River, create explosive algae blooms. Photo credit: eutrophication'hypoxia/Flickr

The Mississippi River basin drains 41 percent of the contiguous U.S. and as water runs off fields, yards and pavement, it collects nutrients. These nutrients are carried to the Gulf where they “fertilize” coastal waters and cause algal blooms. As algae die, they sink to the seafloor where they are decomposed by bacteria, a process that uses oxygen.

During most times of the year, bottom waters and surface waters mix frequently, so oxygen levels are replenished regularly. However, during the summer there is an abundance of warm fresh water in the Gulf due to seasonal warming and freshwater river outflows. This water is less dense than the cold salty water near the bottom of the seafloor.

The densities are different enough that the two layers of water will become separated (think oil and water) and prevent mixing of the oxygen-poor bottom waters with the oxygen-rich surface waters. This is called stratification. When stratification occurs, low-oxygen waters are trapped at the bottom, and as more algae are decomposed, the oxygen levels continue to drop until they get low enough to cause a dead zone.

While the dead zone off the coast of Louisiana is the largest and most recognized example of coastal hypoxia in the Gulf, this problem is a Gulf-wide issue. The Ocean Conservancy has mapped the documented cases of low-oxygen areas in the extensive report, Gulf of Mexico: A Marine and Coastal Atlas.

What is the best way to reduce the size of the dead zone? Reduce the amount of nutrients that reach the Gulf.

The two best ways to do this are:

  1. Reduce nutrient inputs into coastal and upriver water bodies
  2. Increase the watershed’s capacity to retain excess nutrients

 

As consumers of agricultural goods, we can contribute to reducing nutrients by supporting farming practices that promote sustainable, responsible agriculture. For example, one practice called crop rotation can reduce fertilizer application by rotating plants like legumes that add nitrogen to the soil with plants like corn that take it up. And the practice of adding stream buffers to drainage ditches can capture nutrients before they enter waterways.

In our own yards, the best way to reduce excess nutrients is to use fertilizers carefully and slow storm water runoff by using techniques such as rain gardens.

Visit EcoWatch’s WATER page for more related news on this topic.

——–

EcoWatch Daily Newsletter

Scanning electron micrograph of Yersinia pestis, which causes bubonic plague, on proventricular spines of a Xenopsylla cheopis flea. NIAID / Flickr / CC BY 2.0

A middle-aged married couple in China was diagnosed with pneumonic plague, a highly infectious disease similar to bubonic plague, which ravaged Europe in the middle ages, as CNN reported.

Read More Show Less
Milk made from almonds, oats and coconut are among the healthiest alternatives to cow's milk. triocean / iStock / Getty Images Plus

Dairy aisles have exploded with milk and milk alternative options over the past few years, and choosing the healthiest milk isn't just about the fat content.

Whether you're looking beyond cow's milk for health reasons or dietary preferences or simply want to experiment with different options, you may wonder which type of milk is healthiest for you.

Read More Show Less
Sponsored
Greta Thunberg stands aboard the catamaran La Vagabonde as she sets sail to Europe in Hampton, Virginia, on Nov. 13. NICHOLAS KAMM / AFP via Getty Images

Greta Thunberg, the teenage climate activist whose weekly school strikes have spurred global demonstrations, has cut short her tour of the Americas and set sail for Europe to attend COP25 in Madrid next month, as The New York Times reported.

Read More Show Less
The Lake Delhi Dam in Iowa failed in 2010. VCU Capital News Service / Josh deBerge / FEMA

At least 1,688 dams across the U.S. are in such a hazardous condition that, if they fail, could force life-threatening floods on nearby homes, businesses, infrastructure or entire communities, according to an in-depth analysis of public records conducted by the the Associated Press.

Read More Show Less

By Sabrina Kessler

Far-reaching allegations about how a climate-sinning American multinational could shamelessly lie to the public about its wrongdoing mobilized a small group of New York students on a cold November morning. They stood in front of New York's Supreme Court last week to follow the unprecedented lawsuit against ExxonMobil.

Read More Show Less
Sponsored

By Alex Robinson

Leah Garcés used to hate poultry farmers.

The animal rights activist, who opposes factory farming, had an adversarial relationship with chicken farmers until around five years ago, when she sat down to listen to one. She met a poultry farmer called Craig Watts in rural North Carolina and learned that the problems stemming from factory farming extended beyond animal cruelty.

Read More Show Less
People navigate snow-covered sidewalks in the Humboldt Park neighborhood on Nov. 11 in Chicago. Scott Olson / Getty Images

Temperatures plunged rapidly across the U.S. this week and around 70 percent of the population is expected to experience temperatures around freezing Wednesday.

Read More Show Less
A general view of the flooded St. Mark's Square after an exceptional overnight "Alta Acqua" high tide water level, on Nov. 13 in Venice. MARCO BERTORELLO / AFP / Getty Images

Two people have died as Venice has been inundated by the worst flooding it has seen in more than 50 years, The Guardian reported Wednesday.

Read More Show Less