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Sonar Side Effect
The long-held
assumption that whales and dolphins cannot get the bends just got bent.
According to marine
biologists, it appears that not only can these aquatic animals suffer
the same type of decompression sickness that has long plagued human scuba
divers, but that nautical sonar can directly provoke the illness.
In October researchers
published results from a study of stranded whales and dolphins in the
journal Nature. The study reported that the scientists found tiny
nitrogen bubbles throughout the mammals’ tissues similar to those
that cause the bends. Scientists further reported finding “evidence
of acute and chronic tissue damage in stranded cetaceans, challenging
the view that these mammals do not suffer decompression sickness.”
It was the first time the illness had been linked to mammals, and scientists
speculate that sonar is the culprit. Military vessels often use sonar
to detect submarines. The sound blasts, which are far more intense that
those used by recreational boaters to measure depth, have already been
found to affect the migration routes of whales and dolphins.
“It is widely accepted
that there is a link between naval sonar use and mass strandings, predominantly
of big whales,” the researchers state. The theory is that strong
sonar blasts confuse and frighten the marine mammals, causing them to
dart to the surface more quickly than they should. They then apparently
undergo a rapid decrease in pressure of both the water and air in their
bodies, which causes the formation of deadly nitrogen bubbles in the bloodstream
that is consistent with decompression sickness.
The evidence is abundant.
A mass stranding occurred last year in the Canary Islands immediately
following a large naval drill. Another in the Bahamas in 2000 was linked
to a sonar system.
Now, for the first time,
sonar use may prove fatal to the largest animals on the planet. Or, as
the scientists put it, “Acoustic factors could be important in the
aetiology of bubble-related disease and may call for further environmental
regulation of such activity.”
Things We Like
If you get embarrassed
pulling out a big ol’ map while on a cruise or simply dislike lugging
around a 300-page tour book, check out the InsideOut Guides. On one side
a map unfolds like an accordion, while on the other a booklet has the
crucial info you need about that city. Available for cities around the
globe, the guide also comes with a pen and a compass. PMY managing
editor Eileen Mansfield recently gave the Barcelona edition a good trial
run and decided it was the next best navigational device after her chartplotter.
They’re perfect for cruises and boat shows, and they fit right in
your back pocket. Published by Compass Maps, the guides are available
at Rand McNally and Brookstone, among other stores and Web sites.
502
Average number
of people that attend a Coast Guard Boating Safety Course each day. Source:
U.S. Coast Guard
January Calendar
Dec. 27-Jan. 4. The New York National Boat Show in New York City.
(212) 984-7000. www.discoverboating.com/newyork.
8-11. The
Boat Show in San Diego, California. (858) 274-9924. www.discoverboating.com/sandiego.
14-18.
The Boat Show in Atlanta, Georgia. (770) 951-2500. www.discoverboating.com/atlanta.
17-25.
Boot 2004, the 35th-Annual International Boat Show in Düsseldorf,
Germany. (312) 781-5180. www.mdna.com.
22-25.
Central Florida Boat Show in Orlando, Florida. (407) 298-1167. www.boatshowflorida.com.
24-31.
Chesapeake Bay Boat Show in Baltimore, Maryland. (212) 984-7000. www.discoverboating.com/chesapeake.
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