MonitorMyOcean.com: Measuring the acoustic impact of the COVID-19 lockdown on underwater ocean noise

Abstract

Low-frequency noise from marine shipping is an underwater acoustic pollutant. The noise spectrum overlaps with frequencies marine mammals use to communicate, leading to stress and behavioural disruptions. This research established a model to measure the effects of anthropogenic activities on underwater noise. The COVID-19 lockdown led to a decline in marine traffic. The model quantified the reduction in noise levels before and during the lockdown in the Arctic, Atlantic, Pacific Oceans, and the Mediterranean Sea. Underwater ocean sound peaks between 10 and 100 Hz and is dominated by noise from shipping traffic. Hydrophones data from seven ocean observatories were analyzed at 1-Hz spectral and 1-minute temporal resolution. Power spectral densities were calculated, aggregated into monthly long-term spectral averages, and noise levels in the 63 Hz third-octave band were compared. The analysis revealed that global oceans quietened by an average of 4.5 dB during the lockdown period. The maximum decrease was at locations close to major shipping channels and cruise tourism destinations. The study proved that strategic “anthropauses” could reduce underwater noise levels. A web application MonitorMyOcean.com endorsed as a UN Ocean Decade Activity, was created to provide updated anthropogenic ocean noise levels.