Dolphin Deaths Possibly Due to Navy Deco

diver42 · April 30th, 2006, 08:15 AM

Did Navy sonar kill Zanzibar's dolphins?
Biologists investigate mystery of mammals washing up on shore
Saturday, April 29, 2006; Posted: 6:50 p.m. EDT (22:50 GMT)

"Some scientists surmise that loud bursts of sonar, which can be heard for miles in the water, may disorient or scare marine mammals, causing them to surface too quickly and suffer the equivalent of what divers call the bends -- when sudden decompression forms nitrogen bubbles in tissue."

http://www.cnn.com/2006/WORLD/africa....ap/index.html

GoDiva · April 30th, 2006, 09:33 AM

Sounds a bit strange as Dolphins do not breath in under water. Same as free divers. As they do not add more gas to there bodies, I do not see why they should get bends.
I can imagine that the sonar might disorientate them or that they have difficulty hunting.

GLOC · April 30th, 2006, 10:10 AM

There was an article recently in one of the science/nature journals which examined the bones of whales and noted that there was some 'bubbling' in the bones, the same sort that occured in saturation divers, and this might be what they are referring to.

However, I am not an expert (in anything

), but then again neither are the newspaper editors. I cringe when I read so called 'defence experts' giving their view on how some aircraft system works, or why it crashed following an accident....

Again, don't believe all you read....http://www.scubaboard.com/archive/in...p/t-38498.html

Geo · May 1st, 2006, 08:38 AM

Contrary to popular believe, free divers can get the bends. I know of one local spear fisher who got the bends during a compo and had to be received decompression treatment. In that instance I think it was the number of dives and relative depth which was the contributing factor. His dive profile was some like 45min at 30m.

In pure free diving, the divers often go way deeper than that which can then become a factor. Similarly the dolphin dives much deeper and a uncontrolled accent might just lead to bubble formation even though not breathing a depth the gas will still be forced into the tissue, there would be just a lot less of it and therefore the rarity of bends in free divers.

diver42 · May 1st, 2006, 04:19 PM

From National Geographic:

Military Sonar May Give Whales the Bends, Study Says

This physical effect of sonar on whales was proposed by Dorian Houser of the Navy Marine Mammal Program and colleagues in San Diego, California, in 2001.

Houser and colleagues devised a mathematical model that shows low-frequency sound waves can rapidly compress and then expand microscopic bubbles of gas in the tissue. Each sound wave causes the bubble to absorb more and more of the gas dissolved in the bloodstream, eventually making the bubbles big enough to rupture tissues.

But...

Roger Gentry, a scientist with the National Marine Fisheries Service in Silver Spring, Maryland, who studies marine mammal strandings, said the connection between the beaked whale strandings and the military sonar exercises is clear, but he is not certain the sonar causes an ailment similar to decompression sickness, as reported in Nature.

"None of the authors is an expert on decompression sickness and none of the results have been seen by anyone who is an expert on decompression sickness," he said.

The fisheries service is trying to set up a workshop before the end of year where the authors of the Nature paper can present their findings to experts on decompression sickness. Similar research was presented at a workshop organized by the fisheries service in 2002 and it remains a valid hypothesis, said Gentry.

http://news.nationalgeographic.com/n...halebends.html

acqua · May 3rd, 2006, 03:23 PM

80 % of the dolphin where pregnant female .at least 2 miscarried fetus where
found on the beach I V got some photos ( 30 -40) before the fisherman
start to butcher , I know normally dolphin have cut on the skin but to me seems is to many cut .

we V waiting for somebody of the oceanographic institute to come and get
some animals but . nobody came

April 30th, 2006, 08:15 AM	#1 (permalink)
diver42(Offline) New Member Join Date: Dec 2005 Location: Durham, NC Posts: 107	Dolphin Deaths Possibly Due to Navy Deco Did Navy sonar kill Zanzibar's dolphins? Biologists investigate mystery of mammals washing up on shore Saturday, April 29, 2006; Posted: 6:50 p.m. EDT (22:50 GMT) "Some scientists surmise that loud bursts of sonar, which can be heard for miles in the water, may disorient or scare marine mammals, causing them to surface too quickly and suffer the equivalent of what divers call the bends -- when sudden decompression forms nitrogen bubbles in tissue." http://www.cnn.com/2006/WORLD/africa....ap/index.html

April 30th, 2006, 10:10 AM	#3 (permalink)
GLOC (Online) Moderator Join Date: Nov 2005 Location: Fleet, Hants Posts: 1,950	There was an article recently in one of the science/nature journals which examined the bones of whales and noted that there was some 'bubbling' in the bones, the same sort that occured in saturation divers, and this might be what they are referring to. However, I am not an expert (in anything ), but then again neither are the newspaper editors. I cringe when I read so called 'defence experts' giving their view on how some aircraft system works, or why it crashed following an accident.... Again, don't believe all you read....http://www.scubaboard.com/archive/in...p/t-38498.html __________________ Gareth Images of Life Photography DIR Team Foxturd Travels Underwater and Further Afar If you don't have the time to do something right, where are you going to find the time to fix it? - Stephen King

May 1st, 2006, 04:19 PM	#5 (permalink)
diver42(Offline) New Member Join Date: Dec 2005 Location: Durham, NC Posts: 107	Military Sonar May Give Whales the Bends, Study Says From National Geographic: Military Sonar May Give Whales the Bends, Study Says This physical effect of sonar on whales was proposed by Dorian Houser of the Navy Marine Mammal Program and colleagues in San Diego, California, in 2001. Houser and colleagues devised a mathematical model that shows low-frequency sound waves can rapidly compress and then expand microscopic bubbles of gas in the tissue. Each sound wave causes the bubble to absorb more and more of the gas dissolved in the bloodstream, eventually making the bubbles big enough to rupture tissues. But... Roger Gentry, a scientist with the National Marine Fisheries Service in Silver Spring, Maryland, who studies marine mammal strandings, said the connection between the beaked whale strandings and the military sonar exercises is clear, but he is not certain the sonar causes an ailment similar to decompression sickness, as reported in Nature. "None of the authors is an expert on decompression sickness and none of the results have been seen by anyone who is an expert on decompression sickness," he said. The fisheries service is trying to set up a workshop before the end of year where the authors of the Nature paper can present their findings to experts on decompression sickness. Similar research was presented at a workshop organized by the fisheries service in 2002 and it remains a valid hypothesis, said Gentry. http://news.nationalgeographic.com/n...halebends.html

May 3rd, 2006, 03:23 PM	#6 (permalink)
acqua(Offline) New Member Join Date: May 2006 Location: Maldives Posts: 17	mdd and dolphin 80 % of the dolphin where pregnant female .at least 2 miscarried fetus where found on the beach I V got some photos ( 30 -40) before the fisherman start to butcher , I know normally dolphin have cut on the skin but to me seems is to many cut . we V waiting for somebody of the oceanographic institute to come and get some animals but . nobody came

April 30th, 2006, 09:33 AM	#2 (permalink)
GoDiva(Offline) New Member Join Date: Dec 2005 Location: Belgium Posts: 540	Sounds a bit strange as Dolphins do not breath in under water. Same as free divers. As they do not add more gas to there bodies, I do not see why they should get bends. I can imagine that the sonar might disorientate them or that they have difficulty hunting.

May 1st, 2006, 08:38 AM	#4 (permalink)
Geo(Offline) New Member Join Date: Dec 2005 Location: Cape Town, South Africa Posts: 9	Contrary to popular believe, free divers can get the bends. I know of one local spear fisher who got the bends during a compo and had to be received decompression treatment. In that instance I think it was the number of dives and relative depth which was the contributing factor. His dive profile was some like 45min at 30m. In pure free diving, the divers often go way deeper than that which can then become a factor. Similarly the dolphin dives much deeper and a uncontrolled accent might just lead to bubble formation even though not breathing a depth the gas will still be forced into the tissue, there would be just a lot less of it and therefore the rarity of bends in free divers.