Drowning in noise
17 July 2018
The Arctic is undergoing dramatic and radical changes, most obviously in the loss of sea ice and the associated rise in temperature. Some see these changes as opportunities for year-round commercial shipping and ready access to massive fields of oil and gas beneath the seafloor. This could also lead to acoustic industrialization—the loss of one of the most pristine marine environments on this planet—and threaten its magnificent marine life. But as scientist Christopher W. Clark notes, one solution is to create acoustic sanctuaries: places that are still naturally quiet and in which noise-generating activities that perturb that quiet are forbidden.
Whales and seals who were calves and teenagers during the First World War knew the sounds of that quiet ocean, learned to interpret the subtle roars of coastal currents and grew up to understand the tell-tale signs of shifting ice fields and summer calms.
A hundred years ago, whales and seals roamed the ice-cold waters of the Arctic without fear of seismic explosions from oil exploration or the growing roar of shipping traffic. Around this time, the commercial slaughter of bowhead whales ended, and the Arctic entered a period of relative acoustic tranquility. Whales and seals who were calves and teenagers during the First World War knew the sounds of that quiet ocean, learned to interpret the subtle roars of coastal currents and grew up to understand the tell-tale signs of shifting ice fields and summer calms. They used these cues to recognize opportunities for feeding or mating and to find safe places for giving birth. Listening to and producing sounds in an ocean with little human-induced noise was an essential tool for survival. Unfortunately, those days are long gone.
The natural acoustic soundscape has been blown apart by a crescendo of noise that drowns the calls and songs of whales and seals, that turns their quilted world of precise sound into acoustic static and renders their exquisite listening abilities useless.
Each of the marine mammals endemic to the Arctic has remarkable adaptations that provide distinct advantages for living in the Arctic’s harsh environment. Many of these are associated with auditory perception and sound production. That is to say, Arctic marine mammals possess exceptional and delicate bioacoustic abilities. They “see” their underwater world through sound. This underscores the adaptive importance of listening to and producing sounds for survival.
All Arctic whales and seals use passive and/or active acoustics for life’s basic functions: communicating, detecting predators, foraging and navigating. So, for example, they can navigate by passively attending to the sounds of ice grinding, cracking, sliding and exploding, or by actively listening to the reverberations and echoes of their calls, songs and echolocation clicks off ocean ice features. We know from Arctic acoustic research that there are subtle differences in the acoustic environments of multi-year ice, young ice and open water, as well as myriad combinations of these conditions. All Arctic whales, even adult bowheads, can get trapped or die in ice, so there is clearly a selective advantage for specialized attributes that enable marine mammal to sense such threats. A naturally occurring ocean soundscape is essential for these mammals to take full advantage of their adaptations for listening to and producing sounds.
But today, the Arctic’s acoustic environment is under siege from civilization’s advancing progress. Seismic airgun explosions from surveys conducted off northern Greenland penetrate the coastal waters near Barrow, Alaska, 3,000 km away. The shipping route through the Northwest Passage is becoming readily available as multi-year ice melts, allowing nearly constant noise from propeller cavitation.
There is no ambiguity about the reality of this rising tide of anthropogenic din. Yes, there are and will be disagreements about how much and how fast and what is biologically tolerable and what is not. But those are only debatable waypoints along a continuum of threats that are unambiguously increasing the density and distribution of human noise.
Nor is there ambiguity about the extraordinary uniqueness of Arctic marine mammals’ bioacoustic capabilities. There is still much we don’t know, so there will continue to be scientific revelations about how well they hear and how remarkably they call, sing and echolocate. Those are beautiful waypoints along the trail of discoveries that could further demonstrate life’s remarkable and seemingly endless inventiveness and capacity.
But pause for a moment and think about the implications of these two star-crossed trajectories: that is, marine life’s continued existence and our exploitation of the Arctic’s resources.
Back away as best you can from the temptation to slip into reductionism and determinism, and simply consider the overall situation: the Arctic environment is changing radically, both physically and biologically, in terms of temperature, ice, primary productivity and life. Humans are moving expeditiously to take advantage of the opportunities created by climate change. Will we take into consideration the lost opportunities for the life that’s already there? What happens when Arctic life has nowhere to go? Do we care enough to change our ways of life to allow the Arctic’s to continue?
Let’s agree to leave the natural Arctic soundscape as we found it. Let’s establish acoustic sanctuaries in which human noise-making activities are restricted, motorized vehicles are not allowed, and naturally occurring levels of noise are respected. We have learned that restrictions on human-made toxins lead to better lives. Let’s apply this same principle to noise by restricting the release of noisy by-products that are harmful to marine life and to our future. I contend that the Arctic requires special attention in the form of protection: a moratorium on exploitation and the unambiguous recognition that its existence as a healthy, frozen, unaltered habitat is critical.
Christopher W. Clark is a research professor and senior scientist in the department of neurobiology and behavior at Cornell University.
This predominantly Arctic species is associated with ice floes. Its movement patterns are therefore influenced by the melting and freezing of the ice. The bowhead has suffered from severe over-exploitation that has seen its range shrink considerably since the 17th century.
As the Arctic's ice melts, the world is eyeing the shipping routes and natural resources of the Arctic Ocean.