A humpback whale's tail emerges from the waters of the Pacific Ocean at Contadora Island, Panama, July 13, 2019. -
Luis ACOSTA / AFP
For thirty years, bioacousticist Michel André has listened to the seas and oceans, with particular attention to the impact of noise pollution generated by human activities on marine biodiversity.
"With the initial idea that cetaceans would be the first species affected by these noises," he told
20 Minutes
.
But the more we advance in our research, the more we realize that other animals undoubtedly suffer even more from this noise pollution.
"
A scourge that tends to increase as our activities at sea intensify.
But Michel André remains optimistic.
Solutions are at work to make future boats less noisy.
An oil spill or a soup of plastic waste… These are often the first images that come to mind when we talk about “marine pollution”.
What about the noise?
For thirty years, Michel André, director of the Laboratory of Applied Bioacoustics at the Polytechnic University of Catalonia, has listened to the seas and oceans.
The LIDO (Listen to the Deep-Ocean) program, which he coordinates, has made it possible to install 150 underwater acoustic sensors in the main oceans, a network he continues to grow.
From this, the bioacoustician, winner of the Rolex Entrepreneurship Awards, focuses in particular on how noise pollution generated by human activities affects marine biodiversity.
Starting with the whales, of which this Friday is the international day.
"But not only", insists Michel André, who answers the questions of
20 Minutes.
Bioaccousticist Michel André, director of the Applied Bioacoustics Laboratory of the Polytechnic University of Catalonia.
- / @ JoshForwood
Are the seas and oceans ultimately much less silent than we think?
The marine environment has never been a world of silence.
Since the existence of the Earth, it has been crossed by sounds and noises.
They already come from natural physical processes.
Earthquakes, waves, rain… Then came the marine organisms.
In seas and oceans there is no light except very close to the surface.
Consequently, the only way for these organisms to communicate, to exchange information, is through sounds and noises… These acoustic codes, of incredible diversity, govern all the life of the oceans.
But our ears are not made to hear underwater, so they escape us.
Are the sounds and noises generated by human activities increasingly tending to cover these natural sounds?
This noise pollution is as old as plastic pollution or oil spills.
All of them appeared a little over a century ago, when we began to exploit the sea industrially.
But because it is invisible and practically inaudible, noise pollution has been ignored for a long time even though it is as much a scourge for the seas and oceans.
We have only been able to measure it for about twenty years.
These noises are already those of boat engines.
More than 100,000 container ships ply the seas every day.
But these are also the acoustic loads used by gas and oil prospecting to try to discover deposits in the seabed, military maneuvers or the construction of wind farms at sea.
Does this noise pollution mainly impact whales?
We thought so in view of the importance of the acoustic signals that cetaceans exchange to communicate, orient themselves, reproduce, seek their prey ... The idea was even to study the sensitivity of all cetacean species * to this pollution, to define tolerance thresholds that would apply both to these large whales but also to the rest of the marine food chain.
But the more we advance in our research, the more we realize that other animals suffer, probably even more, from these nuisances.
This is the case with marine invertebrates, which group together thousands of species (crustaceans, cephalopods, jellyfish, corals, etc.).
They may be without ears, they are able to pick up the mechanical components of sound thanks to sensory organs.
When they are exposed to artificial sound sources, trauma is observed to the point, no doubt, of impacting their ability to eat, move, manage gravity ... However, for the most part, these invertebrates do not have the ability of cetaceans to quickly flee a polluted area, so that they can be subjected to much higher doses of artificial sounds.
Can we even say that cetaceans have ended up adapting to this noise pollution?
They have no doubt learned to manage it because their lives depend on it.
Species continue to live in areas of intense human activity, in the Mediterranean or in Southeast Asia, for example.
Like us, in the end, cetaceans are able to live in a noisy space as long as this does not completely prevent them from orienting themselves, feeding themselves ... But there are limits.
When the noise pollution gets too much, they end up leaving, which puts the whole food chain off balance.
Are there spared areas?
The physical properties of the oceans mean that sound travels there five times faster than in the air and at much greater distances.
Up to hundreds of kilometers.
As a result, there are hardly any areas free from noise pollution today.
Of course, the different levels.
The closer we are to human activities, the more intense the noise pollution.
Conversely, in the seas of the South Pacific, near French Polynesia, we noted the lowest levels of noise pollution, probably close to zero.
But even Antarctica is no longer spared.
The continent is however legally protected from human activities, but cruise ships remain authorized there for part of the year.
This activity may well be very framed on the environmental side, no measures are taken to limit the noise pollution it creates.
The Antarctic and the Arctic are very interesting case studies.
We launched the “Listening to the poles” mission last March.
It aims to set up six acoustic observatories in each of these two regions to study the impact of climate change on noise pollution.
Melting ice allows new species to gain access to these areas and to new human activities to develop, which can upset the soundscape and therefore the balance of polar biodiversity.
Are solutions being implemented to reduce this noise pollution?
We can hope that boats will be quieter in the future.
Until then, we mainly thought of isolating the engine rooms for the comfort of humans on board.
More and more, hulls are being isolated to protect marine life.
While turning, the propellers of ships also generate pressure variations which cause the appearance of gas bubbles.
When they explode, they produce loud noises.
Improvements have been made to reduce this phenomenon of cavitation.
More difficult to eradicate: deliberate noise pollution emitted by oil exploration or during military maneuvers.
But even there, there are areas for improvement.
In 2002, for example, we developed a real-time acoustic localization system for cetaceans.
The idea inspired the “Repcet” device, which today equips ships in the Mediterranean with the aim of avoiding collisions with these marine animals.
We are also working to equip oil rigs or military boats with acoustic devices so that they can stop their activities when they spot cetaceans nearby.
Planet
Mediterranean: A sea coyote, to avoid whales, soon imposed on French boats?
Planet
The stranding of dolphins even more numerous in 2021 on our coasts… and still no solution in sight?
Planet
Wed
Pollution
Ocean
Whale