Turning down the volume on human noise pollution for marine life
JUDY WOODRUFF: There's a growing problem for marine life in the world's oceans and waterways, manmade noise.
This week, the National Oceanic and Atmospheric Administration released a new decade-long plan to try to deal with the way it's affecting life underwater.
Special correspondent Cat Wise has our report. It's part of our weekly series covering the Leading Edge of science and technology.
CAT WISE: Beachgoers are drawn to the water this time of year to relax and enjoy some peace and calm. And that's what many describe it's like under the water, too.
WOMAN: I would say it sounds beautiful, relaxing.
WOMAN: I think it sounds, like, so peaceful, like, I mean, just calm.
CAT WISE: But the calm near the surface often belies what it actually sounds like deep beneath the waves, especially if that's where you live.
Over the last hundred years, as humans have increasingly used the world's waterways for shipping, defense, and natural resources, among other things, the level and the amount of manmade noises in marine environments has increased.
But many species of mammals, fish, and even invertebrates rely on sound to communicate under the water to find food, mates, and stay safe.
And those vital communications, in some areas, are being drowned out.
MARLA HOLT, NOAA Fisheries: People don't really realize how noisy it is. Sound travels very well underwater compared to air. So it can travel very long distances.
CAT WISE: Marla Holt is a wildlife biologist for the National Oceanic and Atmospheric Administration in Seattle. She and other NOAA scientists have been studying the impacts of noise pollution on marine life from big to small.
It's been shown that noise can cause behavior changes, hearing loss, and it can even be fatal. Holt's research focuses on orcas, also known as killer whales, and how they amplify their calls when they are in noisy waters, especially around container ships.
MARLA HOLT: OK, so here are orca calls with minimal boat noise. And here are their calls with lots of boat noise.
CAT WISE: There's quite a difference, and you see it visually here too.
MARLA HOLT: Yes, so, they really have to pump up the volume of their calls in order to hear each other.
CAT WISE: Many of the orcas Holt studies spend a lot of their time in Washington state's Puget Sound. They and hundreds of other marine species have a lot more than just container ships to contend with. More than four million people live around the Sound.
The beautiful waterways of Puget Sound are what draw so many people to this area, but all the boating and shoreline development make this a very noisy place to be for marine life. It's an issue that the state of Washington has been trying to deal with for quite some time.
RHONDA BROOKS, Washington State Dept. of Transportation: Any time we touch anything with water, we try to deploy practices that aren't harmful.
CAT WISE: Rhonda Brooks is works for the Washington State Department of Transportation. She says the state's many ferry terminals and bridges require a lot of work that is often quite noisy, especially when it comes to driving foundation piles in the water.
RHONDA BROOKS: I think it's only really been in the last decade or so that we have become concerned about the sound that it makes underwater as it's being struck from above the water, and what that sound does to the species that are not only in the vicinity of the pile, but also miles and miles away.
CAT WISE: While marine pile driving is a relatively small slice of the overall noise pollution problem, it is one of the loudest and most distressful manmade noises for marine life.
Documented fish kills around marine pile driving projects in the early 2000s led to more state and federal noise mitigation requirements. One of the main ways to reduce the noise with pile driving has been through the use of bubble curtains, which are large rings that surround the pile, and the bubbles that are pumped out reduce the sound waves, but sometimes not very much, as little as 30 percent. They also can cause construction delays, according to Brooks.
RHONDA BROOKS: As we know, time is money in construction. And so we began to look at practical, innovative ways to attenuate that sound.
CAT WISE: So Brooks and other transportation officials sought help from engineers around the state. And they eventually got that help from this man.
PER REINHALL, University of Washington: Once we understood the principles of how sound was created, then the solution was pretty simple.
CAT WISE: Per Reinhall is the chair of the mechanical engineering department at the University of Washington. Over the years, he has developed a number of products, including a next-generation football helmet.
But this was his first foray in marine construction, and what he came up with was a double-walled pile. Reinhall showed me how the system works on a model.
PER REINHALL: So, what we have done is, we have taken the ordinary pile and then we have put another pile inside it. And, as you can see here, there's an airspace in between where the water can not get to. And what we do is, we strike the inside pile. Now we have a bulge going down.
But now it's acting against the air, not the water. So, essentially, no sound, or very little sound gets developed.
CAT WISE: The other key part of the design is the connection at the bottom of the two piles, seen in this testing prototype, which prevents the sound from traveling into the seafloor.
PER REINHALL: And that's really the secret sauce of this concept, is the flexible coupling at the bottom. See, it's essentially a spring, a very, very stiff spring, between the outside pile and the inside pile.
CAT WISE: Reinhall has turned his innovation into small start-up. The company, called Marine Construction Technologies, has done several tests with the state Department of Transportation.
And the results, says Reinhall, have confirmed the design works. At this test, done in 2014, there was a 21-decibel noise reduction. To understand what that means, you really need to hear it.
PER REINHALL: So, this is a regular pile. And this is our new pile. So, it's a dramatic difference.
CAT WISE: It is a big difference. How much of a difference?
PER REINHALL: It's a reduction of about 90 percent of the volume.
CAT WISE: Ninety?
PER REINHALL: Ninety percent of the volume, so, yes, it's a big deal if you're a fish.
CAT WISE: One hurdle, though, is the cost. The double-walled piles are about 20 percent more than a standard single pile. But Reinhall says those costs should be mitigated by the effectiveness of the technology.
PER REINHALL: The goal of this is to actually save money, if you include everything, if you include monitoring, the time of the projects, permitting, et cetera, et cetera. So, overall, the projects should be cheaper with this technology.
CAT WISE: The Reinhall piles have yet to be used commercially, but the state is now evaluating them now for future projects.
As for the marine life in Puget Sound, there was no comment, but we expect any noise reductions in their waters would be a welcome development.
For the "PBS NewsHour," I'm Cat Wise in Seattle, Washington.
JUDY WOODRUFF: Yes, it would.
Cat's report is also part of our Breakthroughs coverage of invention and innovation.
Whale and killer whale footage in this report provided by NOAA was filmed under NMFS ESA/MMPA Permit No's 16163, 0932-1489-9 and 781-1824.