As over 80% of our global trade by volume happens through marine shipping, humans are introducing different kinds of pollution into oceans ranging from ballast water, biocides (chemicals used in antifouling paints), sewage, oil spills, and noise. The noise from propellors of over 60,000 container ships and ocean tankers traversing the oceans at any given time is an underwater acoustic pollutant. They overlap with sounds produced by marine mammals to communicate and navigate. And these noises are of lower frequency; they can carry hundreds and even thousands of kilometres, causing stress, hearing loss, or even an increase in marine mammals and ship collisions.
My research used the COVID-19 lockdown that brought a dip in global trade and movements as a research opportunity. The lockdown period and the associated decline in marine traffic provided a baseline for “quieter oceans” or underwater noise levels in the absence of human activities. This baseline data was obtained from a network of hydrophones (or underwater microphones) in the Arctic, Atlantic, Pacific Oceans, and the Mediterranean Sea. Analyzing hydrophone data before, during, and after the lockdown, it was possible to quantify the contribution of human activities to the underwater ocean noise levels. Underwater ocean sound peaks between 10 Hz – 100 Hz and is dominated by noise from shipping traffic. Hydrophones (underwater microphones) 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 compared to previous years.
The analysis revealed that global oceans quietened by an average of 4.5 dB, or the peak sound intensity decreased 2.8 times during the lockdown period. The maximum decrease was at locations close to major shipping channels and cruise tourism destinations. The findings were validated by comparing shipping traffic using the satellite-based Automated Identification System (AIS).
The study proved that strategic “anthropauses” could reduce underwater noise levels and give marine mammals a chance to reverse the decline in their population. A web application https://wwwMonitorMyOcean.com was created to provide updated anthropogenic noise levels in global oceans. Policymakers can determine if measures such as shifting shipping channels or moratoriums on new shipping routes lead to “Quieter Oceans.”
It was a wonderful experience delivering this webinar and engaging with ocean professionals working on this issue. I plan to expand my research to cover more oceanic regions and better understand the impact of underwater ocean noise on the health of the marine mammal population. I particularly like researching the issue of ocean noise as it is one of the easier pollutants to remove: simply switching off the noise removes the pollutant.
Best of the Fair Award and Gold Medal, Canada Wide Science Fair 2022. RISE 100 Global Winner, Silver Medal, International Science and Engineering Fair 2022, Gold Medal, Canada Wide Science Fair 2021, NASA SpaceApps Global 2020, Gold Medalist – IRIC North American Science Fair 2020, BMT Global Home STEM Challenge 2020. Micro:bit Challenge North America Runners Up 2020. NASA SpaceApps Toronto 2019, 2018, 2017, 2014. Imagining the Skies Award 2019. Jesse Ketchum Astronomy Award 2018. Hon. Mention at 2019 NASA Planetary Defense Conference. Emerald Code Grand Prize 2018. Canadian Space Apps 2017.