Human Activity Is Making Oceans Louder, Putting Wildlife at Risk

right_wale_calf
Right whales breaching / NOAA

Jacques Costeau famously called the planet’s oceans “The Silent World.”

“Unfortunately, that was not really an accurate description,” says Dr. Jason Gedamke. “To the animals that live in the ocean, it is an incredibly noisy and loud place.”

Gedamke should know – he is the director of the Ocean Acoustics Program at the National Oceanic and Atmospheric Administration (NOAA).

What’s more, Gedamke says that the world’s oceans are getting noisier still thanks to human activity. At a recent round-table discussion hosted by the Renewable Natural Resources Foundation, Gedamke discussed his team’s research on this significant but overlooked impact of human activity on the not-so-silent world.

Water, it turns out, is an excellent conductor of acoustic energy.  “Sound travels incredibly efficiently underwater,” said Gedamke. He pointed to the 1991 Heard Island Feasibility Test, in which sounds emitted from underwater speakers off the coast of Australia were heard by researchers on the other side of the planet.

Whales and dolphins have adapted to exploit this property of water to communicate over large distances, but these adaptations also make them vulnerable to adverse effects from human sounds.

For example, there is evidence to suggest that beaching behavior – when a whale or dolphin becomes stranded on the ocean shore – may be related to acute ocean noise events such as loud pings from underwater sonar equipment.

Gedamke’s team, however, is most interested in the chronic effects of years’ worth of sound pollution on marine mammal life. “We’re trying to shift our focus from the acute – the immediate, loud sound that causes an animal to change its behavior – to the broader effects of all this introduced sound changing their habitat.”

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A young monk seal / NOAA

Part of the challenge Gedamke and his team face in their research is a lack of consistent data. The historic record of ocean noise levels is piecemeal, meaning it is difficult to make direct comparisons over time. The researchers are trying to address this with a new system of recorders that were deployed in 2014. These will allow for more accurate assessments of how the ocean’s sonic landscape is changing over time.

Gedamke’s team is also using GIS to map areas of high-noise intensity. When those are overlaid with maps showing areas of wildlife population, they could help identify areas and populations most at risk from harmful noise pollution.

There are many risks of a noisier habitat for marine life. Ambient noise could mask sounds that allow certain species to detect their predators, or vice versa, which could lead to food chain disruptions and ecological imbalance. It could also make it more difficult for individual animals to communicate with members of their own species, interfering with behaviors like hunting and mating. Proximity to loud sources of sound could lead to injury or hearing loss.

Oil and gas exploration and maritime shipping are primary contributors to our increasingly noisy oceans. Gedamke said that the Gulf of Mexico, the source of 17 percent of total U.S. crude oil production, is “an incredibly loud environment, one of the most heavily impacted on Earth.”

oil_rig
An oil rig at the mouth of the Mobile Bay / Andrew Wright

In January of this year, Interior Secretary Ryan Zinke proposed opening all US coastal areas to offshore oil exploration, sparking widespread pushback from many coastal states and environmental groups. Recent reports suggest that industry demand for such a move is tepid, however.

Conventional industrial activity is not the only contributor, however. The installation of offshore wind turbines also contributes to ocean noise.

According to Project Drawdown, offshore wind turbines are an important tool for reversing global warming, with the potential to reduce atmospheric CO2 by 14.1 gigatons by 2050.

Wind turbines, both on and offshore, have also drawn criticism from environmental groups in the past for their potential impacts on wildlife, especially birds.

The risk of rising ocean noise fits into a larger pattern of disregard for the impact of human activity on marine habitat. From warming water temperatures to toxic chemical spills to swirling islands of plastic garbage, the world’s oceans are bearing the brunt of some of the most harmful industrial practices of the 20th and early 21st century.

The recent BBC nature documentary series Blue Planet II illustrated the scope of these impacts in its final episode, “Our Blue Planet.” In the episode, narrator David Attenborough warns that “the health of our oceans is under threat now as never before in human history.”

Among the harmful impacts of human behavior are overfishing, plastic entering the food chain, and yes, noise. “Man-made noise is now everywhere in the ocean, and it has an effect on marine creatures of all kinds,” says Attenborough.

The Blue Planet team follows marine biologist Steve Simpson, who researches how fish use sound to communicate, as well as how man-made sound interferes with that ability.

While it seems to be a complicated issue, for Simpson, the way forward is clear: “We can choose where we make the noise, we can choose when we make the noise. We can directly control the amount of noise that we make, and we can start doing that today.”

Learn more about NOAA’s research on ocean noise: Cetacean & Sound Mapping.

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