Emerging Ocean Listening Network Will Study Seas Uniquely Quieted by Covid

The Covid-19 pandemic left the oceans quieter than ever in 2020, allowing scientists to analyze the effect human-generated sound has on marine life.

This map from the IQOE-endorsed JOMOPANS project shows the difference between the total noise level and the natural noise level with differences up to 30 decibels (dB). While 30 dB on its own is not loud, the superimposition raises the level significantly higher than natural noise. (Credit: JOMOPANS)

(CN) — A unique new study has taken advantage of the momentary pause in human activity in the ocean during the Covid-19 pandemic, as scientists around the world listen for how human-generated noise in the water and a lack thereof affects marine life.

In the past year, an international group of scientists identified and collected recordings from over 200 non-military hydrophones throughout the world’s oceans and consolidated the data into their 2020 quiet ocean assessment. Hoping to increase that number to 500, their goal is to observe what happens to the animals, like whales, in response to human noise levels. They also hope to combine their data with other ocean conservation efforts, including animal tagging, to achieve the most complete demonstration of how sound can affect marine life.

For years, scientists have questioned how human-generated noise in the ocean affects marine animals. According to the National Oceanic and Atmospheric Administration, too much human noise in the ocean can interfere with a sea creature’s own ability to listen to its environment, which is essential for survival.

In 2011, scientists from all over the world came together to form the International Quiet Ocean Experiment (IQOE), which was released in 2015 with the International Quiet Ocean Experiment Science Plan. They wanted to create a time series measuring the changes in ambient sound throughout different regions in the ocean to characterize marine “soundscapes.” 

In other words, by observing and establishing normal sound levels of an area, harmful noise levels can be more easily identified. In this plan, the year 2022 was going to be designated as “the Year of the Quiet Ocean.”

Hydrophones became the most important tools in this project’s arsenal, capable of picking up even faint noises from miles away. They are extremely sensitive and therefore highly utilized by navies for ocean surveillance. A great number of these hydrophones are used exclusively by militaries, but some regions contain many that are not, including the North American Coasts, Hawaii, Europe, Antarctica and some select areas of the Asia-Pacific region.

On the other hand, many marine animals use natural sonar to communicate with each other and detect underwater objects. For example, some dolphins and whales use echolocation, emitting sounds and analyzing the echoes as they bounce off surrounding objects, allowing them to find food and avoid predators.

Using hydrophones, the team wanted to investigate just how much sound can affect marine animals, especially those highly sensitive to sound.

“Measuring variability and change in ambient, or background, ocean sound over time forms the basis for characterizing marine ‘soundscapes,'” said collaborator Peter Tyack, professor at the University of St Andrews in Scotland.

“Assessing the risks of underwater sound for marine life requires understanding what sound levels cause harmful effects and where in the ocean vulnerable animals may be exposed to sound exceeding these levels,” Tyack said. “Sparse, sporadic deployment of hydrophones and obstacles to integrating the measurements that are made have narrowly limited what we confidently know.”

In early 2020, the Covid-19 virus erupted into a global pandemic and human activity reached an all-time low. Travel, transportation and ocean exploration all stood still when governments began enforcing lockdowns and putting extensive safety precautions in place. Because of this, the IQOE decided they wouldn’t find a better time to create their ambient soundscapes than when people were in the water less than ever. 

“The COVID-19 pandemic provided an unanticipated event that reduced sound levels more than we dreamed possible based on voluntary sound reductions,” said project originator Jesse Ausubel, director of the Program for the Human Environment at The Rockefeller University, in a statement.

“IQOE will consider 2020 the Year of the Quiet Ocean and is focusing project resources to encourage study of changes in sound levels and effects on organisms that occurred in 2020, based on observations from hundreds of hydrophones deployed by the worldwide ocean acoustics community in 2019-2021,” said Ausubel.

The IQOE began encouraging the deployment of civilian hydrophones, and thanks to their efforts there are now a significant number of these hydrophones in North America, Europe and other places around the world. The deployed hydrophones give the team excellent coverage of shallow coastal areas where human activity is high. They also have hydrophones in deep stations that allow them to record low-frequency sounds in open waters.

As of February 2021, there are 231 non-military hydrophones sharing data with the IQOE, with hopefully more to come. Most of the identified hydrophones are in U.S. and Canadian waters, with the second most in Europe, and the team adds they hope to see more in the Southern Hemisphere soon.

The IQOE is now working on making a complete data record of ocean soundscapes and animal vocalizations, with the help of several organizations helping them achieve this goal. Among these groups are researchers from the University of New Hampshire (MANTA), who plan to release a new software that will allow collaborators to share their raw data into a system that will standardize the quality of their ocean recordings.

Additionally, researchers at the Alfred Wegener Institute in Bremerhaven, Germany, are testing an Open Portal to Underwater Sound to allow easy access to MANTA-processed data for the public to analyze.

Lastly, the scientists at IQOE are hopeful that their burgeoning network will provide invaluable contributions to the Global Ocean Observing System, a collaborative system of ocean observation methods documenting various factors affecting ocean health.

“To observe a return to normal conditions as the pandemic subsides, the intensive acoustic monitoring by many existing hydrophones must continue at least through 2021,” said Edward Urban Jr., IQOE project manager, of the Scientific Committee on Oceanic Research.

The team adds that opportunities for such research as a result of historical events are few and far between and that there has never been a more opportune time to collect quiet data in the ocean, especially amidst climate change. Covid-19 has immensely slowed down human activity in the water, and as society slowly recovers from its year in the pandemic odds are the oceans are as quiet as they’re going to be for a long time.

“Let’s learn from the Covid pause to help achieve safer operations for shipping industries, offshore energy operators, navies, and other users of the ocean,” said Ausubel. “We are on the way to timely, reliable, easily understood maps of ocean soundscapes, including the exceptional period of April 2020 when the Covid virus gave marine animals a brief break from human clatter.”

“We invite parties in a position to help to join this global effort on the variability and trends of ocean sound and the effects of sound on marine life. The shocking global effect of Covid-19 on human additions of noise to the oceans can spur maturation of regular monitoring of the soundscape of our seas,” Ausubel said.

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