As unlikely as it may seem, your drive to the supermarket is responsible for a lot of noise pollution in our oceans – and a lot of stress to marine life as a result.
Of course, it’s not the specific sound of your car trundling along the street that the fish and whales hear. But many of the products that feature in your weekly shop – from the goods you buy, to the petrol you burn, to your car’s component parts – contribute to marine noise pollution.
Let’s start with the oil. Before we can drill the oil or turn it into fuel to drive our cars, oil companies have to discover it.
Companies look for oil using high-pressure airguns. These machines are towed across the surface of the ocean, firing off sounds to determine the make-up of sediment layers in the seafloor. These are some of the loudest human-created sounds – researchers working in the middle of the Atlantic Ocean have been able to record the sounds produced from coastal oil surveys.
These sounds are problematic for marine life. Whales and other animals that rely heavily on sound for communicating and finding food are most affected. Hearing is to these animals much the same as vision is to humans. Unusually loud sounds can disturb whales’ behaviour and, if they are close enough, can damage their hearing. There is even some suggestion that the airguns can cause whale strandings, although this is not yet completely certain.
Currently, one-third of all oil comes from offshore sources and this proportion is expected to increase. This can only mean more bad news for our marine life.
What about the metal box that consumes all the oil? Parts for the car are sourced from all over the world and have to be shipped across our oceans. In turn, the raw materials needed to make these parts are usually shipped in from yet more places. The commercial shipping needed for all this represents another problematic source of ocean noise.
The contributions of individual ships may seem trivial in comparison to the loud noise from airguns. However, the world merchant fleet includes around 52,000 ships. Collectively, these increase the ambient noise levels in our oceans. In fact, the amount of low-frequency sound in some parts of our oceans has doubled each decade over the past 60 years.
Humans perceive only some of this sound, because of the very low pitches involved. But these sounds are well within the frequency range used by baleen whales. Recent work suggests that this constrains the communication ranges in whales, causing chronic stress and potentially interrupting mating behaviour.
Oh, and most of your groceries are shipped around the world at some point too, as are many other consumer items – including the battery in your hybrid car, if you have one. Around 90% of world trade is carried by commercial ships at some stage. Not all of this ends up in your shopping bag, but a large proportion enters the consumer market at some point.
Certain grocery items, such as fish, originate from the oceans themselves. Like cargo ships, fishing vessels produce noise from their engines and propellers, but they also have noisy fish-finding sonars and winches as well.
The good news is that noise pollution, unlike chemical pollution, dissipates quickly. This means that the future for underwater noise remains bright. If you want to give the whales a break, just drive a little less, or support higher efficiency standards for vehicles. This will not only reduce oil consumption, but also the wear and tear on your car, meaning that fewer replacement parts will need to be shipped in.
You can also buy locally produced items and support the local economy too. That way everyone wins.
No matter how connected we think everything is, the situation is generally even more complicated than we can imagine. So next time you walk to the shops and buy an apple grown in your state, you should allow yourself a moment to feel good about yourself, safe in the knowledge that you have helped to make the oceans a tiny bit quieter.
Air guns used for marine oil and gas exploration are loud enough to affect humpback whales up to 3km away, potentially affecting their migration patterns, according to our new research.
Whales’ communication depends on loud sounds, which can travel very efficiently over distances of tens of kilometres in the underwater environment. But our study, published today in the Journal of Experimental Biology, shows that they are affected by other loud ocean noises produced by humans.
As part of the BRAHSS (Behavioural Response of Humpback whales to Seismic Surveys) project, we and our colleagues measured humpback whales’ behavioural responses to air guns like those used in seismic surveys carried out by the offshore mining industry.
Air guns are devices towed behind seismic survey ships that rapidly release compressed air into the ocean, producing a loud bang. The sound travels through the water and into the sea bed, bouncing off various layers of rock, oil or gas. The faint echoes are picked up by sensors towed by the same vessel.
During surveys, the air guns are fired every 10-15 seconds to develop a detailed geological picture of the ocean floor in the area. Although they are not intended to harm whales, there has been concern for many years about the potential impacts of these loud, frequent sounds.
Although it sounds like a simple experiment to expose whales to air guns and see what they do, it is logistically difficult. For one thing, the whales may respond to the presence of the ship towing the air guns, rather than the air guns themselves. Another problem is that humpback whales tend to show a lot of natural behavioural variability, making it difficult to tease out the effect of the air gun and ship.
There is also the question of whether any response by the whales is influenced more by the loudness of the air gun, or how close the air blast is to the whale (although obviously the two are linked). Previous studies have assumed that the response is driven primarily by loudness, but we also looked at the effect of proximity.
We used a small air gun and a cluster of guns, towed behind a vessel through the migratory path of more than 120 groups of humpback whales off Queensland’s sunshine coast. By having two different sources, one louder than the other, we were able to fire air blasts of different perceived loudness from the same distance.
We found that whales slowed their migratory speed and deviated around the vessel and the air guns. This response was influenced by a combination of received level and proximity; both were necessary. The whales were affected up to 3km away, at sound levels over 140 decibels, and deviated from their path by about 500 metres. Within this “zone”, whales were more likely to avoid the air guns.
Each tested group moved as one, but our analysis did not include the effects on different group types, such as a female with calf versus a group of adults, for instance.
Our results suggest that when regulating to reduce the impact of loud noise on whale behaviour, we need to take into account not just how loud the noise is, but how far away it is. More research is needed to find out how drastically the whales’ migration routes change as a result of ocean mining noise.
As transportation networks expand and urban areas grow, noise from sources such as vehicle engines is spreading into remote places. Human-caused noise has consequences for wildlife, entire ecosystems and people. It reduces the ability to hear natural sounds, which can mean the difference between life and death for many animals, and degrade the calming effect that we feel when we spend time in wild places.
Protected areas in the United States, such as national parks and wildlife refuges, provide places for respite and recreation, and are essential for natural resource conservation. To understand how noise may be affecting these places, we need to measure all sounds and determine what fraction come from human activities.
In a recent study, our team used millions of hours of acoustic recordings and sophisticated models to measure human-caused noise in protected areas. We found that noise pollution doubled sound energy in many U.S. protected areas, and that noise was encroaching into the furthest reaches of remote areas.
Our approach can help protected area managers enhance recreation opportunities for visitors to enjoy natural sounds and protect sensitive species. These acoustic resources are important for our physical and emotional well-being, and are beautiful. Like outstanding scenery, pristine soundscapes where people can escape the clamor of everyday life deserve protection.
“Noise” is an unwanted or inappropriate sound. We focused on human sources of noise in natural environments, such as sounds from aircraft, highways or industrial sources. According to the Environmental Protection Agency, noise pollution is noise that interferes with normal activities, such as sleeping and conversation, and disrupts or diminishes our quality of life.
Human-caused noise in protected areas interferes with visitors’ experience and alters ecological communities. For example, noise may scare away carnivores, resulting in inflated numbers of prey species such as deer. To understand noise sources in parks and inform management, the National Park Service has been monitoring sounds at hundreds of sites for the past two decades.
Noise is hard to quantify at large-landscape scales because it can’t be measured by satellite or other visual observations. Instead researchers have to collect acoustic recordings over a wide area. NPS scientists on our team used acoustic measurements taken from 492 sites around the continental United States to build a sound model that quantified the acoustic environment.
They used algorithms to determine the relationship between sound measurements and dozens of geospatial features that can affect measured average sound levels. Examples include climate data, such as precipitation and wind speed; natural features, such as topography and vegetation cover; and human features, such as air traffic and proximity to roads.
Using these relationships, we predicted how much human-caused noise is added to natural sound levels across the continental United States.
To get an idea of the potential spatial extent of noise pollution effects, we summarized the amount of protected land experiencing human-produced noise three or 10 decibels above natural. These increments represent a doubling and a 10-fold increase, respectively, in sound energy, and a 50 to 90 percent reduction in the distance at which natural sounds can be heard. Based on a literature review, we found that these thresholds are known to impact human experience in parks and have a range of repercussions for wildlife.
The good news is that in many cases, protected areas are quieter than surrounding lands. However, we found that human-caused noise doubled environmental sound in 63 percent of U.S. protected areas, and produced a tenfold or greater increase in 21 percent of protected areas.
Noise depends on how a protected area is managed, where a site is located and what kinds of activities take place nearby. For example, we found that protected areas managed by local government had the most noise pollution, mainly because they were in or near large urban centers. The main noise sources were roads, aircraft, land-use conversion and resource extraction activities such as oil and gas production, mining and logging.
We were encouraged to find that wilderness areas – places that are preserved in their natural state, without roads or other development – were the quietest protected areas, with near-natural sound levels. However, we also found that 12 percent of wilderness areas experienced noise that doubled sound energy. Wilderness areas are managed to minimize human influence, so most noise sources come from outside their borders.
Finally, we found that many endangered species, particularly plants and invertebrates, experience high levels of noise pollution in their critical habitat – geographic areas that are essential for their survival. Examples include the Palos Verdes Blue butterfly, which is found only in Los Angeles County, California, and the Franciscan manzanita, a shrub that once was thought extinct, and is found only in the San Francisco Bay area.
Of course plants can’t hear, but many species with which they interact are affected by noise. For example, noise changes the distribution of birds, which are important pollinators and seed dispersers. This means that noise can reduce the recruitment of seedlings.
Noise pollution is pervasive in many protected areas, but there are ways to reduce it. We have identified noisy areas that will quickly benefit from noise mitigation efforts, especially in habitats that support endangered species.
Strategies to reduce noise include establishing quiet zones where visitors are encouraged to quietly enjoy protected area surroundings, and confining noise corridors by aligning airplane flight patterns over roads. Our work provides insights for restoring natural acoustic environments, so that visitors can still enjoy the sounds of birdsong and wind through the trees.
Ask most people about pollution, and they will think of rubbish, plastic, oil, smog, and chemicals. After some thought, most folks might also suggest noise pollution.
We’re all familiar with noise around us, and we know it can become a problem – especially if you live near an airport, train station, highway, construction site, or DIY-enthusiast neighbour.
But most people don’t think that noise is a problem under water. If you’ve read Jules Verne’s Twenty Thousand Leagues Under the Sea you might imagine that, maelstroms excepted, life is pretty quiet in the ocean. Far from it.
When we put a hydrophone (essentially a waterproof microphone) into the water, no matter where in the world’s oceans, it’s never quiet. We hear wind blowing overhead and rain dropping onto the ocean surface – even from hundreds of metres deep. In Australian waters we can also detect the far-off rumbles of earthquakes and the creaking of Antarctic ice thousands of kilometres away.
Water is much denser than air, so its molecules are packed tighter together. This means that sound (which relies on molecules vibrating and pushing against one another) propagates much further and faster under water than in air.
This also applies to human-produced sound. Under water we can hear boats and ships and even aeroplanes. Large vessels in deep water can be detected tens of kilometres away. We can be far offshore doing fieldwork, the only people around, with nothing in sight but water in any direction. Yet when we switch the engines off and put a hydrophone into the water, we hear ship noise. Sometimes, whole minutes later, the vessel we heard might appear on the horizon.
Seafarers have known about another source of sound for thousands of years: marine life. Many animals produce sound, from the tiniest shrimp to the biggest whales. Many fish even communicate acoustically under water – during the mating season, the boys start calling. Whales do it, too.
Light doesn’t reach far under water. Near the surface, in clear water, you might be able to peer a few metres, but in the inky depths you can’t see at all. So many marine animals have evolved to “see with sound”, using acoustics for navigation, for detecting predators and prey, and for communicating with other members of their species.
The thing is that man-made sound can interfere with these behaviours.
The effects of noise on marine animals are similar to those on us. If you’ve ever been left with ringing ears after a rock concert, you’ll know that loud noise can temporarily affect your hearing or even damage it permanently.
Noise interferes with communication, often masking it. Can you talk above the background noise in a busy pub? Long-term exposure to noise can cause stress and health issues — in humans and animals alike.
Excessive noise can change marine creatures’ habits, too. Like a person who decides to move house rather than live next door to a new airport, animals might choose to desert their habitat if things get too noisy. The question is whether they can find an equally acceptable habitat elsewhere.
There is a lot more research still to be done in this field. Can we predict what noises and vibrations might be released into the marine environment by new machinery or ships? How does sound propagate through different ocean environments? What are the long-term effects on marine animal populations?
One positive is that even though noise pollution travels very fast and very far through the ocean, the moment you switch off the source, the noise is gone. This is very much unlike plastic or chemical pollution, and gives us hope that noise pollution can be successfully managed.
We all need energy, some of which comes from oil and gas; most of our consumer goods are shipped across the seas on container vessels; and many of us enjoy eating seafood caught by noisy fishing boats, some of which even use dynamite to catch fish. We want to protect our borders, making naval operations a necessity. Then there’s the ever growing industry of marine tourism, much of it aboard ever-bigger cruise ships which need large ports in which to berth.
There are a lot of stakeholders in the marine environment, and all speak a different language, all make different claims, and all make noise. Knowing precisely how much noise they make, and how it affects marine life, will help to ensure our oceans and their resources last well into the future.
September 3-11 is SeaWeek 2016, the Australian Association for Environmental Education Marine Educators’ national public awareness campaign.
The link below is to an article that reports on the decline of city birds, due to noise pollution.