Sea Sounds and Survivability

By C. MacDonald

Explorocean
Newport Beach, California
explorocean.org

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Newport Beach, CA--Few of us hear or even think about underwater sounds, but a lot can be learned by studying ocean noise, according to Dr. Ana Sirovic, Ph.D., a researcher at UC San Diego's Scripps Institution of Oceanography, who spoke recently in the ExplorOcean Lecture Series.

"There's increasing evidence of rising ocean noise levels and this affects marine life, who rely on sounds for food, mating, guarding their territory and other factors," said the scientist who has logged more than 300 days of sea time. "By studying these sounds, using non-lethal acoustic methods and technology, we can gain a much better understanding of highly exploited and endangered marine species."

She said increasing underwater noise from ships, sonar, pile drivers, industrial activity and other things impacts sea life. Sirovic and her colleagues use special sound equipment that's lowered and left in the water. "We don't have access to the data until we pick it up," said the member of the Acoustical Society of America. "Once, equipment we had near Antarctica somehow broke loose and went all the way to New Zealand, where people found it and contacted us."

Dr. Sirovic played the recordings of several ocean sounds, including a snapping shrimp (sounded like "crackle"), Sperm whales (click-click-click), Baleen whales (produce the loudest noises), ships (propellers could be heard) and even an earthquake (sounds like thunder down under).

She noted that the oceans were noticeably quieter right after 9-11, as much shipping was halted. "Also, during the economic downturn, people purchased less, causing less demand for shipping, dropping the ocean noise level and there was less stress in some sea life."