However, it is a massive and costly undertaking to deploy enough devices to sufficiently cover entire ocean basins. Each recording device may collect highly detailed data for a given location, such as noise, temporal and spatial abundance trends in vocalising animals and generalised biodiversity indices.
Monitoring acoustic habitats over large spatiotemporal scales can be performed using passive acoustic monitoring (PAM) where autonomous acoustic loggers are deployed to record for months or even years 24, 25, 26, 27. It is therefore critical to establish sufficient acoustic monitoring in the Arctic to track the predicted changes in ambient noise levels and thus allow for mitigation and legislation development on an informed basis 14, 17, 18. Consequently, human exploitation, tourism and geopolitical interests are likely to increase shipping, survey activity, construction, and human presence in the Arctic region 22, 23 with increased noise pollution as an expected side effect. Further, the Arctic is rich in natural resources, it is home to unique wildlife, and its location is strategically important for the world’s superpowers and coalitions. However, sea ice coverage in the Arctic is reducing rapidly 19, with established and potential Arctic shipping routes now likely to stay open for longer each season, which will likely result in a marked shift in global shipping 20, 21. The Arctic is a geographic region that is still relatively unaffected by anthropogenic noise pollution compared to other lower-latitude regions, which is mainly explained by extended seasonal periods of inaccessibility due to sea ice formation 14, 17, 18. Such monitoring can inform managers of the magnitude of the problem, the relative contribution of individual sources and, most importantly, provide feedback on the effectiveness of mitigation measures. Paramount to managing any environmental pressure factor, such as underwater noise, is the ability to monitor its development in time and space. Consequently, legislation aimed at regulating underwater noise has been passed, with underwater noise targeted most directly by the European Union Marine Strategy Framework Directive (descriptor 11) 16. Several intergovernmental organisations have recognised anthropogenic underwater noise as an environmental pollutant with the potential for significant adverse effects on marine life 12, 13, 14, 15. Some regions have seen increases in low frequency ambient noise levels of 1–3 dB per decade in the 30–300 Hz range 7 while activities such as seismic surveying and pile driving may periodically raise the noise floor by tens of decibel over hundreds of square kilometres 8, 9, 10, 11. As a consequence, underwater noise levels are on the rise globally due to human activities such as shipping, seismic surveys, sonar, and construction 5 and are predicted to continue to increase in the future 6. In the last century, marine soundscapes have faced substantial and increasing contributions from anthropogenic sources due to increased human encroachment in the marine environment 1, 2, 3, 4. We encourage additional research to quantify proportional noise contributions from geophysical, biological, and anthropogenic sources in Arctic waters. Biological activity was more readily identified using detectors rather than band levels.
These three regions also had similar tonal detection patterns that peaked in May/June, likely due to bearded seal vocalisations. Consistent seasonal noise patterns occur in Melville Bay, Baffin Bay and Greenland Sea, with noise levels peaking in late summer and autumn correlating with open water periods and seismic surveys. Ambient noise levels partly overlap with previous Arctic observations, however we report much lower noise levels than previously documented, specifically for Melville Bay and the Greenland Sea. Ambient noise was analysed in third octave and decade bands and further investigated using generic detectors searching for tonal and transient sounds. Here we present long-term underwater sound recordings from 26 deployments around Greenland from 2011 to 2020. Many Arctic marine mammal species depend on sound for communication, navigation, and foraging, therefore quantifying underwater noise levels is critical for documenting change and providing input to management and legislation. A longer Arctic open water season is expected to increase underwater noise levels due to anthropogenic activities such as shipping, seismic surveys, sonar, and construction.