Oceans Are Getting Louder, Posing Potential Threats To Marine Life

An anonymous reader quotes a report from The New York Times: Slow-moving, hulking ships crisscross miles of ocean in a lawn mower pattern, wielding an array of 12 to 48 air guns blasting pressurized air repeatedly into the depths of the ocean. The sound waves hit the sea floor, penetrating miles into it, and bounce back to the surface, where they are picked up by hydrophones. The acoustic patterns form a three-dimensional map of where oil and gas most likely lie. The seismic air guns probably produce the loudest noise that humans use regularly underwater, and it is about to become far louder in the Atlantic. As part of the Trump administration's plans to allow offshore drilling for gas and oil exploration, five companies have been given permits to carry out seismic mapping with the air guns all along the Eastern Seaboard, from Central Florida to the Northeast, for the first time in three decades. The surveys haven't started yet in the Atlantic, but now that the ban on offshore drilling has been lifted, companies can be granted access to explore regions along the Gulf of Mexico and the Pacific. And air guns are now the most common method companies use to map the ocean floor.

Some scientists say the noises from air guns, ship sonar and general tanker traffic can cause the gradual or even outright death of sea creatures, from the giants to the tiniest — whales, dolphins, fish, squid, octopuses and even plankton. Other effects include impairing animals' hearing, brain hemorrhaging and the drowning out of communication sounds important for survival, experts say. So great is the growing din in the world's oceans that experts fear it is fundamentally disrupting the marine ecosystem, diminishing populations of some species as the noise levels disturb feeding, reproduction and social behavior. A 2017 study, for example, found that a loud blast, softer than the sound of a seismic air gun, killed nearly two-thirds of the zooplankton in three-quarters of a mile on either side. Tiny organisms at the bottom of the food chain, zooplankton provide a food source for everything from great whales to shrimp. Krill, a tiny crustacean vital to whales and other animals, were especially hard hit, according to one study.

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