Ocean Dead Zones: Arabian Sea Region the Size of Florida Doesn't Have Enough Oxygen

More than half a century ago, scientists realized there was something wrong in the Gulf of Oman, part of the Arabian Sea: There wasn't enough oxygen in the water, which means fish were struggling to breathe.

But since then, the story has gotten much grimmer, according to a new paper published in the journal Geophysical Research Letters. The new study finds that an area of water about the size of Florida has little or no oxygen—which scientists call an oxygen minimum zone and which is often nicknamed a dead zone.

"[Dead zones] are a disaster waiting to happen—made worse by climate change, as warmer waters hold less oxygen, and by fertilizer and sewage running off the land into the seas," lead author Bastien Queste, a marine scientist at the University of East Anglia in the U.K., said in a press release.

The dead zone at the Gulf of Oman, which is one of four large oxygen minimum zones in tropical waters, has been particularly difficult for scientists to study because of political instability and piracy. The new research avoided the lingering challenges of those problems by using two remote-controlled aquatic drones, which spent eight months traveling throughout the gulf taking measurements of the amount of oxygen dissolved in the water.

Seagulls and fishermen seek their meals on the coast of the Gulf of Oman, which contains a large low-oxygen zone that could suffocate fish. Karim Sahib/AFP/Getty Images

Then, the scientists used that data to construct the most detailed picture ever of how bad oxygen levels in the Gulf of Oman have gotten. That's where the comparison with Florida—63,700 square miles of oxygen-starved water—comes from. (The dead zone's depth varies, particularly as the seasons change.)

"Our research shows that the situation is actually worse than feared—and that the area of dead zone is vast and growing," Queste said in the press release. "The ocean is suffocating. Of course all fish, marine plants and other animals need oxygen, so they can't survive there. It's a real environmental problem, with dire consequences for humans too who rely on the oceans for food and employment."

The team was also able to look for changes in oxygen level over time, showing how weather patterns like the monsoon affect the dead zone. In addition, Queste told Gizmodo that he and his colleagues want to try to pinpoint whether the problem is actually less oxygen in the water, or if the problem is too many living things like fish consuming that limited supply.