As Arctic warming accelerates, the underwater acoustic environment in the Arctic Ocean is rapidly changing. We present the first results of passive acoustic monitoring in the marginal ice zone of the East Siberian Sea (ESS). A high sea ice concentration (SIC) and seasonal variations in ice cover make the ESS an ideal region to verify how ambient sound levels respond to natural physical processes and anthropogenic activities during summer. Our observations show that the sound level in the ESS exhibits a strong negative correlation with SIC, and the sound level in September, which was higher than that in other months, was 16 dB higher than the annual average. This increase resulted from geophony and anthrophony with the reduction in the SIC, and sound level increased by 13 dB without anthrophony. Our results indicate that ambient sound level in the Arctic Ocean may increase as climate change accelerates sea ice melting.

Offshore wind power plants are under construction worldwide, and concerns about the adverse effects of underwater noise generated during their construction on the marine environment are increasing. As part of an environmental impact assessment, underwater noise generated by impact pile driving was measured during the construction of an offshore wind farm off the southwest coast of Korea. The sound exposure levels of impact pile driving noise were estimated as a function of distance and compared with those predicted by a damped cylindrical spreading model and broadband parabolic equation simulation. Source level at 1 m was estimated to be in a range of 183–184 dB re 1μPa2s in the sound exposure level based on the model predictions and it tended to decrease by 21log⁡r as the distance increased. Finally, the spatial distribution of impact pile driving noise was predicted. This result, if combined with noise-induced damage thresholds for marine life, may be used to assess the effects of wind farm construction on marine ecosystems.

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