Powerful Sonar Causes Deafness In Dolphins 323
Hugh Pickens writes "Mass strandings of dolphins and whales could be caused because the animals are rendered temporarily deaf by military sonar, experiments have shown. Tests on a captive dolphin have demonstrated that hearing can be lost for up to 40 minutes on exposure to sonar and may explain several strandings of dolphins and whales in the past decade. Most strandings are still thought to be natural events, but the tests strengthen fears that exercises by naval vessels equipped with sonar are responsible for at least some of them. For example, in the Bahamas in March, 2000, 16 Cuvier's beaked whales and Blainville's beaked whales and a spotted dolphin beached during a US navy exercise in which sonar was used intensively for 16 hours (PDF). 'The big question is what causes them to strand,' says Dr. Aran Mooney, of the University of Hawaii. 'What we are looking at are animals whose primary sense is hearing, like ours is seeing. Their ears are the most sensitive organ they have.' In the experiment, scientists fitted a harmless suction cup to the dolphin's head, with a sensor attached that monitored the animal's brainwaves, and when the pings reached 203 decibels and were repeated, the neurological data showed the mammal had become deaf, for its brain no longer responded to sound. 'We definitely showed that there are physiological and some behavioral effects [from repeated, loud sonar], but to extrapolate that into the wild, we don't really know,' said Mooney."
This probably causes permanent damage. (Score:5, Interesting)
Loud noises tear the cilia in your cochlea out by the roots. In humans, and, as far as I know, other higher mammals, they don't grow back (Can someone who knows confirm that this is true in dolphins as well?).
So the word "temporary" might make this sound less bad than it is: Our sonar may only temporarily cause total deafness, but I suspect it permanently degrades hearing.
Sucks to be a dolphin. Reminds me of Douglas Adams' sympathy for whales, whose songs no longer can be heard across the ocean. (I think Douglas talked about this in Last Chance to See.)
Re:Disarmament (Score:5, Interesting)
you do realize that 99%+ of the time, these terrible nuclear submarines don't even use ANY form of sonar other than underwater microphones don't you?
To a similar (though not as high degree) neither do surface ships.
I didnt think so.
yet another example of a slashtard talking out of their ass with absolutely NO idea what they are talking about.
And yes, I did happen to serve on one of these terrible nuclear submarines.
and in the case of missle subs, it's probably closer to three nines or more.
ssbn subs are holes in the water that strive to make absolutely no noise.
you can hear the original sound wave a lot further off than you can hear the return echo which is always weaker.
and that's before you even throw in the effect of temperature gradients and convergence zones.
another thing to ponder is what was the frequency used?
and does this matter.
the reason i say this is that MOST sonar is low frequency or extremely low frequency, with the exception being high frequency sonar used to search for underwater mines and to penetrate ice fields.
of course, why mention these type things as they will just muddy the waters and potentially invalidate the test.........
(I said potentially, not that they do, i have no idea and based on the report, neither does anyone else)
Excellent (Score:2, Interesting)
Re:We can't stop or the terrorists will win! (Score:4, Interesting)
Our Military superiority, (or inferiority,) dictates how much economic pressure we can apply.
Re:you dont' need to make dolphins deaf. (Score:2, Interesting)
Re:203 decibels? (Score:3, Interesting)
Can sound get THAT loud? According to this [wikipedia.org], 115dB is the threshold of pain for humans. 203 dB is simply 33,000 times louder.
If you account for the high sound sensitivity of dolphins and water being a better sound conductor, just imagine the damage! It's like dropping a bomb on your head.
Couldn't the sonar be replaced by something less damaging? I guess water muffles radio waves, so a water radar is not a good idea. Maybe a very low frequency radar?
Re:203 decibels? (Score:3, Interesting)
Thanks! All I need is a Universal Lobotomiser and some herring.
You know, for the dolphins.
Re:203 decibels? (Score:4, Interesting)
I spent 7 years in the Navy, and we could hear the sonars be tested in port on ships several piers down. The Navy need better listening equipment, not louder speakers. Whales communicate for several hundred miles with whatever their voice boxes can make, and the receiver can hear it and respond. Nature has done it, why can't we?
Re:203 decibels? (Score:3, Interesting)
But considering how sensitive active sonar is, how strong does a ping need to be in order for its reflection to be received by the passive component of the targeting system?
A small problem with the conclusion (Score:3, Interesting)
To the best of my knowledge, SONAR is short bursts of loud noise broken by longer periods of quiet to receive and process the return echos. Two minutes of continuous sound is not going to happen. Even if the effect is cumulative, a cetacean would have to travel with the source for over five minutes which it is unlikely to do if the SONAR is injurious. Would you hang out in an excruciatingly loud environment?
Now, some will point to this:Sound can become trapped if a layer of warm water lies over cold water. When sound created in the warm zone reaches the cold water it can bounce back instead of travelling though it. This, Dr Mooney said, would have the effect of trapping the sound in the warm layer, where it would bounce around "like a ping-pong ball", giving whales and dolphins little chance of escaping it.
But, the thing is, dolphins and whales are mammals. The would leave the noisy layer when they surfaced. Therefore, they would quickly learn how to escape the sound: surface or dive.
The conclusions seem specious to me.
Re:Experiments like these... (Score:3, Interesting)
You gotta catch up with the wingnuttery, dude. These days it's all right-wing whining about FEMA internment camps for Patriots, terror that the gubmint will take away their AK-47s, and the xenophobic "DEY TOOK OUR JAHBS!" ranting about immigrants.
The left sounds positively sane by comparison.
No, 9/11 truthers make everyone look sane by comaparison, and a new assault weapons ban would make obtaining AK-47s difficult, thus not an unrealistic concern. And the crowd yelling, "DEY TOOK OUR JAHBS and sent them oversez" loudest are the leftist/big labor(must pass card check) crowd.
PS captcha=armament /. has become self aware!
Re:203 decibels? (Score:5, Interesting)
> Whales communicate for several hundred miles
That's a pretty lowball estimate (src): [sciencedaily.com]
We now have evidence that they are communicating with each other over thousands of miles of ocean. Singing is part of their social system and community.
Re:We can't stop or the terrorists will win! (Score:1, Interesting)
"Maybe not Terrorists, but our Naval Superiority, , does play a lot into our relationship with China."
Not anymore it doesn't.
http://www.exiledonline.com/the-war-nerd-this-is-how-the-carriers-will-die/ [exiledonline.com]
Re:203 decibels? (Score:2, Interesting)
If you accept that then you have to accept the fact that the Navy needs to practice with it before they need it in an actual shooting war. Sucks that it apparently harms marine life but what can you do?
Not use it. I don't accept that it's needed.
Falcon
saving humans (Score:3, Interesting)
I'd personally kill every Dolphin myself if it would save a human life.
Ah, if you kill every dolphin, you'll also be killing humans. Though rare, dolphins [msn.com] have saved humans, especially from sharks [all-creatures.org].
Falcon
Re:203 decibels? (Score:3, Interesting)