Quantcast
Environmental News for a Healthier Planet and Life

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

Deserted view of NH24 near Akshardham Temple on day nine of the 21-day nationwide lockdown to curb the spread of coronavirus on April 2, 2020 in New Delhi, India. Raj K Raj / Hindustan Times via Getty Images

India is home to 21 of the world's 30 most polluted cities, but recently air pollution levels have started to drop dramatically as the second-most populated nation endures the second week of a 21-day lockdown amidst coronavirus fears, according to The Weather Channel.

Read More Show Less
A Unicef social mobilizer uses a speaker as she carries out public health awareness to prevent the spread and detect the symptoms of the COVID-19 coronavirus by UNICEF at Mangateen IDP camp in Juba, South Sudan on April 2. ALEX MCBRIDE / AFP / Getty Images

By Eddie Ndopu

  • South Africa is ground zero for the coronavirus pandemic in Africa.
  • Its townships are typical of high-density neighbourhoods across the continent where self-isolation will be extremely challenging.
  • The failure to eradicate extreme poverty is a threat beyond the countries in question.
Read More Show Less
Sponsored
The outside of the Food and Drug Administration headquarters in White Oak, Md. on Nov. 9, 2015. Al Drago / CQ Roll Call

The U.S. Food and Drug Administration has approved the use of two malarial drugs to treat and prevent COVID-19, the respiratory infection caused by the SARS-CoV-2 coronavirus, despite only anecdotal evidence that either is proven effective in treating or slowing the progression of the disease in seriously ill patients.

Read More Show Less
Some speculate that the dissemination of the Antarctic beeches or Nothofagus moorei (seen above in Australia) dates to the time when Antarctica, Australia and South America were connected. Auscape / Universal Images Group / Getty Images

A team of scientists drilled into the ground near the South Pole to discover forest and fossils from the Cretaceous nearly 90 million years ago, which is the time when dinosaurs roamed the Earth, as the BBC reported.

Read More Show Less
The recovery of elephant seals is one of the "signs of hope" that scientists say show the oceans can recover swiftly if we let them. NOAA / CC BY 2.0

The challenges facing the world's oceans are well known: plastic pollution could crowd out fish by 2050, and the climate crisis could wipe out coral reefs by 2100.

Read More Show Less