Noise pollution is the harmful levels of noise that result from things like industry and airplanes. It is currently occurring underwater, and is proving harmful to marine life.
There are three main causes of ocean noise pollution:
- General shipping traffic
Ships and boats used for shipping purposes are known to cause a lot of noise. The propellers and other machinery generate a noise called cavitation: noise that occurs at propeller blade tips. This noise is produced when rotating blades cause the local pressure in water to drop below a critical value and bubbles to form. Most of the noise is low-frequency, which travels long distances underwater.
- The oil industry
For offshore drilling, pressurized air guns are used by ships to form a three-dimensional map of where oil and gas most likely lie. The noise that is produced is extremely loud to allow the waves to penetrate the deep levels of the ocean and bounce off the seafloor. They are said to cause “[impairment of] animals’ hearing, brain hemorrhaging and the drowning out of communication sounds important for survival, possibly killing certain species.
- Military activity
The US Navy has been using rail guns—a kinetic energy weapon used to fire projectiles at targets in the sea or in the air. The models that the Navy has produced estimates temporary and permanent hearing loss for thousands of marine animals. There have been incidents in the past that link dead animals with military experiments such as in Greece, where over a dozen dolphins washed up ashore near massive Turkish naval exercises in the area. Similarly to the air guns, the sonar from rain guns interfere with the animals’ means of communication. Scientists also fear that the noise will change the animals’ behavior and their ability to hear in certain ranges. The Navy has also recently submitted a request for a permit to “incidentally harass” marine animals as collateral damage.
Fortunately, there have been measures taken to fight against ocean noise pollution. In 2016, the federal government introduced an outline of a ten-year strategy called the Ocean Noise Strategy Roadmap to reduce the harmful impacts of noise on marine animals.
There have also been recent wins such as a coalition of environmental groups that have filed suit against the National Marine Fisheries Service, a division of the National Oceanic and Atmospheric Administration, claiming that the agency is violating several federal laws protecting wildlife, including the Endangered Species Act, by allowing the blasts. Several governors have also teamed up to create laws to regulate offshore drilling. Another area where action is taking place is in gulf, where there are plans to create a major international port to improve transport routes to Asia. To combat the problems that will be caused for marine species such as the humpback whale, “researchers are becoming acoustic prospectors”, and are “searching for quiet zones and noisy habitats in efforts to chronicle what exactly happens when sound levels change.” Efforts range from natural experiments on the effects of a plan to reroute shipping lanes in the Baltic Sea, to investigating the impact of a trial scheme in Canada to reduce ship speeds in coastal waters off Vancouver.
Last month, there was widespread backlash to the Navy’s recent plans to carry out drills and research with underwater guns and explosives in the Pacific Northwest, which would lead to major harm for many marine animals. Organizations like the Washington Environmental Council prepared petitions, the mayor of Seattle filed a letter of protest, and many citizens provided comments to the navy to urge them to maintain peaceful and quiet waters for the animals.
Although we are still far from the goal of silent waters, research on noise pollution has been expanding. Much is being done in an effort to understand the struggles that marine animals are facing, and this will help lead to action.