Human activity is drowning out the natural sounds of the ocean, putting marine life at risk. A new study showed that industrial noise from shipping, construction, and resource extraction is disrupting how animals communicate, navigate, and survive in the Anthropocene era. This growing threat spans across all oceans and adds to the pressures of climate change, overfishing, and pollution. Researchers stress that restoring the ocean’s natural soundscape is essential to protecting marine ecosystems for the future.
In water, sound travels farther than light, making it a reliable indicator of one’s surroundings. Over the past years, the ocean soundscape has been changing drastically, with anthropogenic noise masking naturally occurring sounds.
What is the soundscape?
With sounds coming from waves, rain, wind, and bubbles, the ocean is naturally noisy. The sound of ice breaking, underwater volcanoes, or seismic activity can travel for kilometers, alerting local fauna. Marine animals rely on noise for many things: orientation, finding a mate, locating their habitat, or deterring potential competitors. The information contained in the ocean soundscape can be vital for the residents of the sea. Thus, evaluating the anthropogenic effect on ocean noise (named anthropophony) is essential to understanding the preservation of marine biodiversity.
Anthropophony – factors and impacts
Anthropophony originates from two types of sources: deliberate and unintended noise production. Examples of deliberate noise include scanning the seafloor in search of petroleum, while unintended noise includes low-flying airplanes or traffic on bridges crossing the sea. In addition, while anthropophony has increased, naturally produced sound is decreasing. The reduction of kelp forests, seagrass beds, and coral reefs has led to fewer vocalizing animals.
Furthermore, the effect of anthropophony is amplified by climate change. Over the past years, the ocean has warmed and its pH has decreased (becoming more acidic). Unfortunately, noise travels farther in warmer, more acidic water.
In short, anthropogenic noise is taking over our oceans—and this noise resonates louder and further than ever before.
The effects of anthropophony
Anthropogenic noise can interfere with naturally produced sound by overlapping, in a phenomenon called “masking.” Noise from ships has been identified as interfering with foraging, traveling, and socializing behaviors in marine animals. Due to noise, young fish struggle to detect and avoid predators, leading to increased mortality. They also have difficulty settling in habitats and caring for larvae.
Determining the effects of anthropophony is difficult. It requires complex equipment, long-term studies, and the lack of standardization in this field makes it even harder to assess long-term impacts. Some marine mammals have been observed coping with anthropophony by producing sounds at different frequencies or by avoiding noisy areas. However, the long-term effects on marine life remain unclear.
What now ?
Scientists call for pro-environmental organizations to recognize anthropophony as a pollutant that must be addressed in marine guidelines, laws, and policies.
On a personal note, I would like to attract attention to the International Quiet Ocean experiment (IQOE) which advocates for research on the marine soundscape.
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Sources :
Paula Rey Baquero, M., Parcerisas, C., Seger, K. D., Perazio, C., Botero Acosta, N., Mesa, F., Luna-Acosta, A., & Botteldooren, D. (2021). Comparison of Two Soundscapes. 34(4), 62–65.link
Duarte, C. M., Chapuis, L., Collin, S. P., Costa, D. P., Devassy, R. P., Eguiluz, V. M., Erbe, C., Gordon, T. A. C., Halpern, B. S., Harding, H. R., Havlik, M. N., Meekan, M., Merchant, N. D., Miksis-Olds, J. L., Parsons, M., Predragovic, M., Radford, A. N., Radford, C. A., Simpson, S. D., … Juanes, F. (2021). The soundscape of the Anthropocene ocean. Science. 371(583). link