Robots have found the world's biggest underwater "dead zone" in the Gulf of Oman—yet another sign that such oxygen-depleted regions are only increasing worldwide, ZME Science reports. Scientists sent the remote-controlled submarines underwater for eight months and uncovered roughly 63,000 square miles with little to no oxygen in waters that link the Persian Gulf to the Arabian Sea. "Our research shows that the situation is actually worse than feared—and that the area of dead zone is vast and growing," research leader Bastien Queste says in a statement. "The ocean is suffocating. Of course all fish, marine plants and other animals need oxygen, so they can’t survive there." Such dead zones can happen naturally, the CBC notes, but they're becoming bigger and more common, mostly due to wastewater and chemical fertilizers.
The run-off feeds algae blooms that suck up much-needed underwater oxygen. They also clog the gills of fish, which drain more oxygen when the fish decay and die. Climate change plays a role too, Queste says, because "warmer waters hold less oxygen." The Weather Network explains that warmer water floats on top of colder water, so the layers can't mix and allow oxygen from the air to reach down below. The latest find only adds to alarming data that the number of coastline dead zones has gone from 50 to 500 since 1950. Large dead zones are also hard to fix, and Queste doesn't sound too optimistic. "It's a real environmental problem, with dire consequences for humans too who rely on the oceans for food and employment," he says. (Meanwhile, the dying Gulf Stream could trigger a global nightmare.)