INTRO: Noise is a natural part of life in the oceans, but human activities have cranked up the volume. Doug Schneider has more in this week's Arctic Science Journeys Radio.
STORY: The oceans are noisy places. Waves and wind create background noise, and ocean creatures use sound to communicate and navigate. There are even rumbling underwater earthquakes and the boom of volcanic eruptions. But over the past century, the volume of human-caused sounds in the oceans has gone up.
Darlene Ketten is part of a special National Research Council panel that looked into human-caused noise in the world's oceans. (Courtesy Woods Hole Oceanographic Institution)
Darlene Ketten is a senior researcher at the Woods Hole Oceanographic Institution. She served on a National Research Council panel that reported on the noise and its impacts on ocean creatures. Ketten says noise levels in the oceans have been on the rise since the early to mid-1900s.
KETTEN: "There are a lot of figures that have been bandied about for that increase, some of them very large. What the panel concluded was there's actually about a three decibel per decade increase of noise going on. "
Ketten says sound levels are measured on a different scale in water than they are in air, but three decibels per decade adds up to a significant increase.
KETTEN: "Three db is my going from about this level to about this level. So that three db difference would be somebody simply raising their voice a bit. If they get excited they might go up three to five db, say. Ten db starts to get a little noisier. When it gets over sixty, seventy db, that's in a crowded noisy room. When it gets up to a hundred db, that's very noisy. "
Most of the added noise in the oceans comes from large engine-driven ships, but navigational sonars, underwater construction, and oil exploration all add to the sound total. Darlene Ketten says the three decibel increase is an average over all the oceans. But in busy shipping lanes, near harbors, and along coasts, the sound increase has been much greater. Ketten says more research is needed to understand how all this human noise affects marine mammals and other sea creatures.
Thanks this week go to Earthwatch Radio at the University of Wisconsin
Sea Grant Program. This is Arctic Science Journeys Radio, a production
of the Alaska Sea Grant Program at the University of Alaska Fairbanks
School of Fisheries and Ocean Sciences. I'm Doug Schneider.
Audio version and related websites
Thanks to the following individual for help preparing
Darlene Ketten, Senior Scientist, Biology
Woods Hole Oceanographic Institution
Woods Hole, MA 02543
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Darlene Ketten profile
Release: "Impact of Noise on Marine Mammals Remains Unclear"
(National Academies Press/National Research Council)
Reference to NRC report titled "Ocean Noise and Marine Mammals"
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