Toxic Algal Bloom Forces Mississippi to Close All Its Mainland Beaches

Experts think nutrient-rich freshwater, diverted into the Gulf of Mexico during recent flooding, is fueling the algae overgrowth


Mississippi has closed all 21 of its mainland beaches due to a toxic algal bloom that has been creeping along the Gulf Coast. The Mississippi Department of Environmental Quality said that those inclined to visit the beach can safely stay on the sand, but cautioned that humans and pets should steer clear of the water and avoid any seafood sourced from the algae-affected areas.

As Ben Kesslen reports for NBC News, the Department of Environmental Quality began shuttering beaches in late June. By Sunday, the spread of blue-green algae had prompted the department to close the last two remaining mainland beaches. Beaches on Mississippi’s barrier islands, which run parallel to the mainland, are still open, but are being monitored for any signs of harmful algae.

The source of the toxic bloom can be traced back to spring-time flooding of the Mississippi River, which was caused by heavy rains and lasted several months. To mitigate the flooding and prevent the waters from hitting New Orleans, officials opened the Bonnet Carré Spillway, which diverts water to Lake Pontchartrain, and then on to the Gulf of Mexico. But according to the Center for American Progress, recent floods had washed millions of tons of fertilized topsoil into the Mississippi River—and when that fertilizer-laden water, rich in nutrients like nitrogen and phosphorous, flowed into the brackish water of the Gulf, it created the perfect environment for a harmful algal bloom.

The blue-green algae contaminating Mississippi’s coast is in fact comprised of bacteria—known as cyanobacteria—that grow in many types of water and are usually too small to be seen. Sometimes, however, algae colonies can grow out of control and become harmful; cyanobacteria produces toxins that can cause abdominal pain, headaches, fever, vomiting and a host of other symptoms, according to the Environmental Protection Agency. A number of conditions can lead to harmful algal blooms, among them “overfeeding,” which occurs when “nutrients (mainly phosphorus, nitrogen, and carbon) from sources such as lawns and farmlands flow downriver to the sea and build up at a rate that 'overfeeds' the algae that exist normally in the environment,” explains the National Oceanic and Atmospheric Administration.

But climate change may also play a role in feeding the overgrowth of harmful algae. For one, climate change has been linked to extreme precipitation events and floods, which move nutrient-rich fertilizers into the water. Toxic blue-green algae also prefer warmer waters, and warm temperatures prevent water from mixing, in turn allowing algae to grow thicker and more quickly.

“As the earth gets warmer, you can get more and more blooms,” Larry Brand, a marine biologist at the University of Miami, tells Kesslen.

In Mississippi, recent flooding and the algal bloom are having a devastating effect on humans and wildlife. Christine Hauser of the New York Times reports that the surge of freshwater released into the Gulf of Mexico has killed off the state’s oyster beds—and it could take up to five years for them to recover. And those who work in the local tourism industry were hit hard by the closure of the state’s beaches over the Fourth of July weekend. James Barney Foster, who owns the Life’s a Beach watersports rental service on the Mississippi coast, told Hauser that he bought dozens of new Jet Skis in preparation for the summer season, only to find that the coastal waters had been closed.

“We are down here today trying to rent umbrellas,” Foster said, “and we haven’t made a dime.”

Now that the bloom is in full swing, there is not much officials can do to make it dissipate. As Brand tells NBC’s Kesslen, “You're going to have to wait for the tides to flush it away.”

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