Noise pollution traumatizes aquatic fauna

Far from being the “world of silence” of Jacques Cousteau’s famous documentary, the ocean is rather full of natural sounds. From the acoustic vibrations of the shell of the American lobster to the small grunts of the Atlantic cod, passing through the high-frequency echolocation clicks of the killer whale and the deep vocalizations of the immense blue whale, the sounds of the ocean form a veritable symphony. Since it travels five times faster in water than in air, sound is the most effective means of communication for marine species. But their musical notes are lost, slowly buried under an increasing amount of noise caused by human activities.

Following the growth of ocean industrialization in recent decades – expansion of ports, increased shipping, mining and gas exploration and development – ​​the noise of human activities is beginning to overtake the natural soundscape of the ocean. The impacts of this phenomenon are now documented in all marine ecosystems, from whales to plankton. Underwater noise pollution has been linked to disruption of normal behavior and communication, deterioration of diet, and increased stress levels. It can even cause permanent injury or death. The combination of existing stressors like overexploitation, chemical pollution and changing ocean conditions contribute to species decline and ecosystem degradation. Such losses are felt almost immediately by indigenous and coastal communities who depend on the resources of the sea for their health and livelihoods.

It was in 2001, following a mass stranding of giant squid off Asturias, Spain, that the problem was brought to light. The study of the dead animals has made it possible to discover a lesion of the sensory organ which allows them, among other things, to maintain their balance. These lesions were caused by scientific experiments, which in the same region, used air guns under water. In these aquatic invertebrates, the structure of the sensory organs is similar to that of the inner ear of mammals and birds, specifies the biologist. When these species are exposed to an intense sound source, the traumas observed at the cellular level are identical. The scientist recreated in the laboratory situations similar to those existing at sea.

Economic impact

The impact of human noise on the oceans could have serious economic consequences, with marine wildlife being a major food source globally. What can be done to avoid a massacre of these resources? The Marine Strategy Framework Directive, a project of the European Commission, aims to help member states ratify ocean protection laws. Eleven parameters qualifying the state of health of the oceans have been established, including noise pollution. Michel André’s laboratory participates in the collection of data aimed at defining a limit to the rate of authorized noise pollution. A difficult job, given the number of sound-sensitive species. Each species tolerates noise pollution at a different threshold. Therefore, which indicator species of acceptable noise levels should be chosen? Much work remains to be done to better understand the impact of noise pollution on marine fauna. For the time being, sound mapping of the oceans continues aboard the sailboat Fleur de passion. “We are now diving into the unknown,” enthuses Michel André. This new route (note: the crossing of the Pacific) is really unknown from an acoustic point of view.

How to lower the volume to benefit marine species

Bordered by three oceans, Canada has a global responsibility to be a bold leader in preventing underwater noise pollution and fostering technological innovations that create environmental, economic and social benefits. Recognizing this need, the federal government has begun to develop an Ocean Noise Strategy that will guide and coordinate underwater noise management efforts for the next decade.

However, to effectively reduce underwater noise pollution, a combination of management efforts with defined targets is required. Here are some of the priorities we identified in our submission to the Canadian government when developing its strategy.

Establish thresholds based on biological limits and indigenous and local knowledge. If we try to minimize noise without considering both types of knowledge, we will not necessarily achieve what nature and communities need.

Promote quieter technologies. Industry has an important role to play in accelerating the development and adoption of quieter technologies, and we can remind them of this regularly.

Develop noise targets according to ships and according to areas. If we are to limit noise emissions from ships, we must also consider that different areas may need different approaches, such as slowing down activities in high traffic habitats where Southern Resident Killer Whales live or beluga whales, or to preserve the Arctic soundscape from the region’s rapid development.

Ensure strategies are in place. Marine protection legislation very rarely includes navigational restrictions and never includes noise restrictions. Unless the Ocean Noise Strategy becomes legally binding through regulations or ministerial authority, we are unlikely to see a biologically significant region free from noise pollution.

WWF-Canada continues to participate in the Ocean Noise Strategy process to ensure that Canada creates quiet spaces that allow the natural rhythm of the ocean to return.