Underwater noise pollution threatens marine life

Credit: University of St Andrews

A groundbreaking study by a specialist European research team, including scientists from the University of St Andrews, shows that human-made underwater noise pollution is picked up by whales in the same way they perceive predators nature, explaining why certain species are particularly sensitive to disturbance.

The report, led by a team of behavioral ecology experts including Professor Patrick Miller and Dr Saana Isojunno of the University’s Marine Mammal Research Unit (SMRU), says cetaceans – whales, dolphins and porpoises – are faced with the choice of “life over dinner” and that their responses to the sounds of man-made noise such as military sonar systems are shaped by how they have evolved to respond to natural predators like killer whales. While some cetaceans may be able to fight off or flee from predators when they believe they are under attack, human-created underwater sound disturbances also cause them to stop feeding and therefore become more vulnerable in impacting their energy budgets.

The findings were part of a project involving European colleagues, including oceanographer Dr. Frans-Peter Lam of Acoustics & Sonar at TNO in the Netherlands; Dr. Petter Kvadsheim, senior researcher in sensing and surveillance systems at the Norwegian Defense Research Establishment; Charlotte Curé of the Joint Environmental Acoustics Research Unit of Cerema, Gustave Eiffel University; and SMRU Ph.D. student Eilidh Siegal, within the 3S team (Marine Mammals, Sonar and Safety).

The S3 research team found that navy sonar caused all four whale species studied – northern beaked whales, humpback whales, sperm whales and long-finned pilot whales – to stop searching for food. all rely on acoustic signals to assess the risk of predation as well as to find food themselves.

Professor Miller, co-lead author of the report with Dr Isojunno, said: “The fact that whales and dolphins can be adversely affected by sonar sounds has come to public attention due to events of High profile strandings in which large numbers of whales stranded in association with military sonar activities.

“During the early to mid-2000s, several different research groups, including our 3S group which authored this most recent work, established new procedures to directly study how the behavior of free-ranging whales is affected by exposure to sonar sounds.”

Since 2006, the team has documented the behavioral responses of six cetacean species off the coast of Norway, while other species have been studied by research groups working primarily in the United States.

He explained that data from the latest study, obtained in Arctic waters around Norway, shows that when marine mammals tagged with temporary transmitters played 1 to 4 kilohertz naval sonar or killer whale sounds, the time during which 43 whales belonging to one of four foraging species declined at about the same rate.

The data varies from species to species, with the northern snout stopping feeding altogether, while sperm whales only showed a 50% reduction in foraging time.

Professor Miller added: “As human activities impact virtually all animal habitats on the planet, identifying species at risk from disturbance is a priority. Measuring the reduction in intense foraging activities during reading killer whale sounds showed a strong correlation between species close to 1:1 line.

“In our study, the corresponding responses from naval sonar and predatory killer whale sounds indicate that whales that are both predator and prey but rely on hearing to find food and detect danger do not have not adjusted their threat response by learning to differentiate between noise that does not pose a risk of predation versus that which does.

“Indeed, they must choose life over dinner when they hear of a potential threat in the sea. This is of particular concern for Arctic cetaceans, with killer whales and humans increasingly able to access arctic waters due to melting sea ice marine mammals use cryptism and flight to avoid being victimized by killer whales and similar responses have been reported to the noise of icebreakers and air guns tablet used in oil and gas exploration. increased numbers of true predators as well as perceived threats from increased human noise under the sea.”

New sonar still deters sperm whales from feeding

More information:
Patrick JO Miller et al, Behavioral responses to predatory sounds predict cetacean sensitivity to anthropogenic noise in a fear soundscape, Proceedings of the National Academy of Sciences (2022). DOI: 10.1073/pnas.2114932119

Provided by the University of St Andrews

Quote: Underwater Noise Pollution Threat to Marine Life (2022, March 23) Retrieved May 3, 2022 from https://phys.org/news/2022-03-underwater-noise-pollution-threat-marine.html

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