The noise we make

CODCAST E3 The Noises We Make

SPEAKERS

Francis Juanes, Craig Radford, Mathew Pine, John Last

John Last 00:04

Imagine you're a whale coasting on currents in the deep blue ocean, calm as can be, far above you. You hear a faint sound an approaching ship, and then out of nowhere, you... an explosion of sound. It's a seismic survey vessel, and every 10 seconds, they'll be sending a pulse of sound down beneath the waves to map the seabed for oil. Seismic surveying is just one of the ways humans are putting more and more noise into the water. Dredging underwater construction, small craft fisheries all produce novel sounds that the creatures of the deep have never had to hear before.

Mathew Pine 00:57

It's really fascinating, if you take it from the perspective of like a long lived whale.

John Last 01:01

This is Matthew pine. He's an expert in underwater acoustics, and for a while now, he's been studying the spread of human made noise in the sea.

Mathew Pine 01:09

You know, you're up there in the High North Atlantic. You go back 50 to 100 years, and we had a frozen, you know, sea ice that was far thicker and more expensive than it is today, and ships were wind powered, sort of you know, your 1960s you're seeing orders of magnitude every decade of sound increasing in the deep oceans because the shipping channels you know so frequented now in all the trading routes by ship, and They're all motorized shipping. You've got oil and gas exploration, so drilling and things like that, seismic surveying, and they produce huge amounts of noise.

John Last 01:51

And all this noise doesn't just stay in one place. Sound moves faster and further underwater than in air.

Mathew Pine 01:58

That's the thing with sound that travels 1500 meters a second underwater, on average. Because of that speed and the low frequency of them as well, they can travel 10s of kilometers very easily. So it traverses habitat boundaries, all the activities that we do on the water, shipping, construction, exploration, like seismic exploration or oil and gas or offshore wind farm construction and all the renewables are changing that Sonic World, and it's causing almost like a fog.

John Last 02:31

I'm John last this is the codcast, and this is a story about the quest to understand this tiny sound. It's the noise of an Arctic cod recorded for the first time just a few years ago. And while we have some good guesses, we still don't know exactly why cod make it, but we do know that in today's ocean environment, such a small and delicate sound may be harder than ever to detect. Today on the codcast, we're talking about anthropogenic noise, noise made by all of us, why it's become such a big problem, and how it's affecting all the creatures of the sea, including our friend the Arctic cod. Let's get started. I'll begin by introducing you to Francis juanes.

Francis Juanes 03:22

Well, I'm the Liber Ero, as in Liber Ero, Professor of fisheries.

John Last 03:28

Juanes has been researching fish sounds for decades, first at the University of Massachusetts and now at the University of Victoria. He's the principal investigator, a kind of lead coordinator on the research project at the center of our story, trying to understand the sounds of Arctic cod. Juanes says when he first started this work, there was even less known about the sounds of the sea than today, but still, it was hard to get people interested in the subject.

Francis Juanes 03:56

There were very, very few people working on it, and nobody cared.Unfortunately, we wrote all kinds of proposals about doing work on acoustics, and nobody wanted to fund it. Nobody thought it was interesting.

John Last 04:10

That started to change. One has told me, when people started to realize just how important sound was underwater,

Mathew Pine 04:16

Yeah. I mean, the silent world is sort of, you know, our bug is perception of it.

Francis Juanes 04:16

one of the things is, of course, we don't hear well underwater as humans, so we don't have an appreciation of how noisy or un noisy or quiet it is, but we've come to think that that acoustics and sound and noise are really critical for species that live in aquatic environments. So light doesn't travel very fast or very far underwater, chemicals, signals don't travel very far, but yet, sound, not only does it travel very far in the water, but it does so really, really fast. So it makes sense in an environment that after very few meters, is essentially dark, that a sensory systems such as hearing and sound production would be really important. So even for species that don't make sounds, sound is going to be really important for them to perceive their environment, to navigate and to presumably detect predators and even their prey.

John Last 05:26

This is Matt pine, again,

Mathew Pine 05:27

it's only really in the last sort of 10 to 20 years that it's now becoming pretty understood that the ocean is a Sonic World. What vision is to humans or land animals, sound is to them

John Last 05:41

As an expert in underwater acoustics over the years, pine has lent his services to dozens of labs who are trying to get a better picture of life at sea by starting with its sounds. Yeah, the first step basically, in any kind of research study is, of course, trying to understand what the existing soundscapes are, right and how we go about that is, of course, using underwater microphones called hydrophones, we put them on the sea floor, and they stay there for pretty long periods of time.That enables us to visualize the underwater world, you know, through sound, just as fish or whales or dolphins would, we're able to tap into this, the sensory world of sound. I like to think of it as like CCTV for the ocean, because light doesn't work underwater. Your your cameras, if you like, and now these, these underwater microphones, when you pull the instruments out, you will have an awesome record of what's been there, how long they've been there, what it was that they were doing when they were there, and they being fish, marine mammals or humans. Yes, what these records show is the growing Sonic presence of humans along virtually every coastline, around every island and every inlet. There is the unmistakable sound of human activity, the tinny revving of small craft motors, the endless grinding of sea floor dredging and the deep rumble of container ships. Underwater, these deep sounds can travel vast distances, and every year there are more of them. So what does all this noise mean for the sea's original inhabitants? Well, to know the answer to that question, we need to dive into how these animals use sound, and not just how they talk, but how they listen too.

Craig Radford 07:52

You know, there's something like 30,000 different species fish, and we only really know a small fraction of how well these animals hear.

John Last 08:04

This is Craig Radford. He's a marine scientist at the University of Auckland. For the past few years, he's been looking into the brains of fish to see exactly how and what they hear.

Craig Radford 08:14

You just place two little electrodes under the skin, and you can play pones. So we're playing, I think, six different tones ranging from 60 up to about 800 Hertz. And then at each one of those tones, you decrease the sound level. The electrodes on the head pick up the brain activity, and as that sound gets quieter, the signals get smaller, and the last time you see a signal is where you would determine the hearing threshold at

John Last 08:56

Radford, studies have produced some interesting results, though the mechanism is similar fish hearing isn't like human hearing, for one thing, for some species, like our friend the Arctic cod, it may actually change from season to season.

Craig Radford 09:09

Actually just started analyzing the data now. So this first round of tests we did is outside the breeding season, and their bandwidth is quite narrow. We were testing down to about 60 hertz, and the fish weren't hearing much above 700 to 800 Hertz. But the real interesting aspect will come in when we do the tests in the breeding season, because it is thought that they use this the sounds that they produced and reproduction. So I wouldn't be a bit surprised that during the breeding season, the hearing becomes a lot more sensitive.

John Last 09:47

That has big consequences for how we humans use the ocean, because when we use the water, we often produce a lot of noise, and it could be having major impacts on species like the midshipmen that rely on subtle sound. For reproduction. Here's Francis Juanes again.

Francis Juanes 10:02

So midshipmen are particularly interesting because they are deep sea fish. We have no idea what they do when they're in the deep sea, and they're not a species that is fished. So nobody knows much about them. But in the spring they come up to the intertidal zone. The males build nests. They sit in the nest and they call out to females, and females are attracted to these sounds. The males also produce aggressive sounds, so whenever there's a potential egg predator, for example.

John Last 10:35

and it's not just the midshipmen that rely on sound this way, our friend, the cod, does as well.

Mathew Pine 10:40

Cod is part of the gadidae family, are probably the most prolific sound makers out there.

John Last 10:46

Matt pine again, they've got the swim bladder and sonic muscles. They can vibrate this muscle around the swim bladder, amplifying the sound, and it can generate a whole sort of repertoire of various sounds, croaks and drumming and that sort of thing. And they use those to coordinate all kinds of behavior. So, you know, when we think of Atlantic cod, being a very famous fish that everybody likes to order in restaurants, they can use, you know, they'll communicate with one another and mediate their reproductive behaviors and spawning behaviors using sound. And they can locate spawning grounds form aggregations and then peel off outside the breeding season. If fish are really using sounds to communicate all these things, then it's really important that this sound isn't drowned out by all our activity.But the fact is, we know that humans are terrible at keeping quiet, as Matt's hydrophones reveal, we're producing a ton of noise at sea, and that noise is traveling all over the ocean. So what does that do to fish and their sensitive little hearing? Well, buckle in, because the answer is not great.

Francis Juanes 12:00

It can, it can kill organisms. So we know that, but we think that's fairly rare. If it doesn't kill them, it can have a variety of other effects. They could just move away from an area. Perhaps that's important, and that's been seen in a lot of wind farms, for example.

John Last 12:19

Noise might also cause physical effects, a kind of hearing loss that comes from repeated exposure to loud noise. And with that may come a kind of psychological trauma as well,

Mathew Pine 12:29

in a general sense, startle responses for impulsive noises, kind of giving them a fright, and that increases, you know, sort of stress hormones within them and fight or flight responses, which do that too many times. It's not great. You can have swimming behavior changes, migration route changes, so schools can break down and they end up forming smaller groups, makes them easier for predators to pick off.

Francis Juanes 12:59

And then there's a whole aspect of their sound production and how it is masked, so not only in their ability to hear other important sounds, but their ability to be heard.

John Last 13:13

This is what's known as the cocktail party effect, what happens when you go to a loud party, you tend to speak much louder. So fish do the same. Not only do they do, they speak louder, but often they speak at a different frequency than the noise so that can be heard above the din. And ultimately, those kinds of effects can affect their ability to court and therefore reproduce. We know that it can affect their parental care as well, and their ability to nest guard. So lots and lots of effects that we're uncovering the more we look None of that is good news, because the fish our ecosystems rely on are suffering from all sorts of other human caused stress, as well climate change and pollution, overfishing, invasive species and all this brings us back to our friend the Arctic cod. Remember him? He's the one who produced this delicate little sound. So what'll happen to the Arctic cod if humanity's noisy footprint reaches even to his icy home.

Francis Juanes 14:24

This is a key species in the Arctic. There's a lot of concern about it, because a lot of species depend on it.

Mathew Pine 14:30

The Arctic is a rapidly changing place. Couple of short decades time, we're going to have a completely ice free North West Passage in the summer months, thereby opening it up to transcontinental shipping. So it's going to go from a near pristine environment to a completely different soundscape.

John Last 14:48

But pine says that soundscape doesn't have to be a worse one. For our little friend, research projects like the ones led by Junaes may help fill the gaps in our knowledge just in time to create the protection they need so their quiet conversations can still be heard beneath the waves.

Mathew Pine 15:05

We've got loads of regulations and rules for airborne noise in the human world, where we have construction sites right next to to residential dwellings or places of work or hospitals, things like that, but we don't have any of that for the underwater world. Great thing with it is, if you understand the sounds that fish make, right? If you know what that optical sounds like, you put hydrophones throughout a habitat, you can then monitor where they go, or where the fish are, and their densities and and that sort of stuff, all the way up to how the ocean sort of changes in its soundscape as well, and how their behaviors change. So once you know that if you can establish areas that are really important to the fish, really important to the predators, then you know what areas to protect. In order to do all of that, or establish those areas, then you obviously need to understand what the Arctic cod is saying to each other.

John Last 16:11

In our next episode, we'll dive into exactly how the team led by Juanes plans to crack that code, what their research has uncovered so far, and what potential it might have for protecting the future of a keystone species for now, though, it's time to say goodbye. I'm John last this is the Codcast See you next time. The Codcast is produced with the support of the North Pacific Research Board. Music was provided by Blue Dot sessions. Ocean sounds were provided by the University of Rhode Island Sound in the sea project. The Arctic cod was recorded by Amalis Reira. I produce this podcast. If you like it. Tell your friends. You can read more about this project on The North Pacific Research Board website, www.nprb.org.

The noise we make
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