Research Findings on Marine Noise Made Headlines in 2022
Human activity in global marine habitats—from fishing to transport to mining—is under increased scrutiny as scientists work to understand how noise impacts all marine animals, from invertebrates to great whales.
Recent studies are showing that man-made, or anthropogenic, noise travels farther through ocean water and has wider impacts than previously thought. From deep sea floors to coastal harbors, a cacophony of unnatural sounds are disrupting marine feeding patterns and causing general stress to animals.
In 2015, the International Quiet Ocean Experiment Science Plan was launched, with the goal of obtaining a series of sound measurements over defined time intervals at a variety of ocean locations. The research aims to learn how human activities affect the global ocean soundscape, how sound levels are trending, and what the current and future effects on marine animal populations might be. The plan included designating 2022 “the Year of the Quiet Ocean.”
Interestingly, due to COVID-19, the oceans were quieter in April 2020 than they had been—or likely will be—for decades. This circumstance allowed an additional new focus for study: a comparison of observations prior to 2020 with observations made after 2020.
Drowning in Noise Pollution
For decades, studies have been conducted on the anthropogenic impacts on the oceans' soundscapes. Typically, these studies focus on one part of an ocean and one or a few species of marine mammals, birds, reptiles, invertebrates, or fishes. However, when looked at as a whole, the available data contains overwhelming evidence that anthropogenic noise negatively affects a wide swath of marine animal life.
Dangers of underwater anthropogenic noise pollution may derive from seafaring vessels, seismic surveys, sonar, shoreline construction, military activity, deep-sea mining, extraction of oil or gas, or recreation.
This noise pollution, sometimes described as “sensory smog,” affects marine species because hearing is the primary sense they use to communicate, interact, breed, navigate, detect predators, and find food. Given that sound waves can travel quickly and for thousands of miles through the ocean, this “smog” drowns out the natural soundscape that sea creatures need to hear in order to survive.
In a study from the Sea Mammals, Sonar and Safety team in Europe, researchers found that if a whale or dolphin is feeding and hears a man-made sound that it interprets as a natural predator, the animal may flee in fear instead of foraging. Looking at beaked northern bottlenose whales, humpback whales, sperm whales, and long-finned pilot whales off the Arctic waters surrounding Norway, all were found to stop foraging when they heard navy sonar. Dr. Saana Isojunno, of the University of St. Andrews’ Sea Mammal Research Unit, said that this is causing these animals to choose “life over dinner.” [Listen to the sonar signature of a whale.]
Beaked northern bottlenose, humpback whales, sperm whales, and long-finned pilot whales were found to stop foraging when they heard navy sonar.
Scientists at Woods Hole Oceanographic Institution conducted the first study to show that aquatic turtles are vulnerable to hearing loss after exposure to loud noise. Hearing loss after noise exposure has been observed in a range of other marine life, such as squids, fishes, and whales, but now it is known that turtles can also temporarily be incapacitated by noise pollution. This is particularly significant because, according to Sea Turtle Conservation Bonaire in the Caribbean Netherlands, six out of the seven species of sea turtles are already classified as threatened or endangered.
Familiarity with the efforts to save the whales or protect the sea turtles is common, yet the sea floor remains mysterious. An environmentally healthy sea floor has crustaceans, worms, mussels, and other animals burrowing, feeding, aerating, and fertilizing the sediment. Their life actions are essential to nutrient cycling in the ocean. Without them, fishes would suffer, and the food web could be disrupted.
A research team from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research in Germany has shown in a study published in the journal Environmental Pollution that the rise in anthropogenic noise pollution stresses invertebrates. Even though these bottom dwellers do not have ears for hearing, they are sensitive to vibrations created by blasting and resource extraction on the ocean floor, along with sounds from cargo ships and recreational boats at the surface.
Year of the Quiet Ocean
During 2020, much of the world was on lockdown. The reduced traffic on land, air, and sea allowed people to see wildlife respond to less noise and intrusion by machines. Birds and other wildlife were seen and heard more often as they ventured closer to areas that had suddenly become much quieter. Many ocean animals came closer to shore.
As the number of shipping vessels on the ocean dropped significantly, scientists used the opportune quiet to study the soundscape using 200 underwater microphones. Professor Jennifer Miksis-Olds, an ocean acoustics expert from the University of New Hampshire in the US, pointed out that listening to this quieter ocean allowed scientists to gain insight on the proper balance between human activity and the ocean’s natural processes. Prof. Miksis-Olds has a goal to map the global ocean soundscape so that the patterns of sounds, whether of migrating whales or shipping routes, can be seen.
Scientists relay whale locations to ships, asking them to slow and avoid the whales.
Mapping the sounds of the ocean could potentially protect ocean life from excessive noise. It’s already being used off the West Coast of the US to reduce whale deaths due to ship collisions. Whale Safe is a tool that displays both visual and acoustic whale detections using AI software on buoys to monitor whale sounds. Scientists relay whale locations to ships, asking them to slow and avoid the whales. Cooperation is voluntary, but Whale Safe tracks compliance and grades each company.
Turning Down the Volume
In 2021, the World Register of Marine Species released a census stating that the total number of known marine species is about 240,000.
Scientists at the National Oceanic and Atmospheric Administration estimate that 91% of ocean species have not yet been classified, which could be due to the fact that more than 80% of the oceans are unmapped, unobserved, and unexplored. Even so, human noise pollution is reaching into these vast regions of the largest habitat on Earth and doing undetermined harm.
There is a great deal of work to be done to ensure that the environmental impacts of anthropogenic noise are mitigated before they do irreparable harm to life, known and unknown.
Some solutions have been identified and are beginning to be tested and put forth as suggested guidelines, rules, or laws. The International Maritime Organization, a United Nations agency headquartered in London, is developing guidelines to reduce underwater noise from shipping with expected thresholds to be established soon. How these thresholds will be met is unknown, but there are possibilities in the works.
Researchers at the University of British Columbia, Canada, are striving to engineer quieter ship propellers. Changes in propeller rotation could also have the added benefit of more efficient propulsion, thereby reducing carbon emissions.
A 10% reduction in speed across the global fleet of shipping vessels would reduce noise emissions by 40%.
The faster and larger ships are, the more noise they make. Simply reducing vessel speed is a no-technology-needed solution to reduce underwater noise. Whale researcher Russell Leaper noted in his 2019 study, published in Frontiers in Marine Science, that a 10% reduction in speed across the global fleet of shipping vessels would reduce noise emissions by 40%.
OceanCare is an international marine conservation organization based in Switzerland that holds Special Consultative Status on marine issues with the Economic and Social Council of the United Nations. Part of the organization’s mission is to protect marine life by reducing ocean pollution, including noise pollution. The group says, for instance, that the loud blasts produced by airguns used to prospect for oil and gas are a significant threat to marine life.
OceanCare has key demands to prohibit new fossil fuel exploration in the ocean along with reducing shipping speeds by 75% in order to dramatically reduce noise pollution. In addition, the group is calling for the creation of quiet zones. Addressing and adhering to these demands, OceanCare asserts, would not only quiet the seas but contribute to climate protection.
Even with new technologies and awareness of undersea noise pollution, it is complicated to enlist action from every country and company that has a part in creating the clatter. Advocates call for people everywhere to become more aware of the issues and work to implement and support international policies that will diminish marine noise. Human stewardship of ocean soundscapes is integral to ensuring a healthy ocean for future generations.
*Julie Peterson is a freelance journalist based in the Midwest region of the US who has written hundreds of articles on natural approaches to health, environmental issues, and sustainable living.