Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.
Benefits of registering include
Braunbehrens once bubbled...
Again, I urge you to help by going to
https://www.nrdc.org/joinGive/join/lfa.asp right now and making an online
emergency contribution.
"Mid-frequency sonar" - not LFA. As noted in previous posts, SURTASS LFA has not been used since April 1998 and was not the cause of these beachings.The NRDC, via Braunbehrens, once bubbled...
Two years ago, the mere testing of high-intensity Navy sonar in mid-frequency range caused a mass stranding of whales in the Bahamas. Whales from at least three different species died, their inner ears bleeding from the explosive power of the sonar signal.
Just last month, a group of biologists off the coast of Washington state witnessed a "stampede" of distressed marine mammals as a U.S. destroyer, operating a powerful mid-frequency sonar system, passed through. Over the next several days, ten porpoises were discovered stranded on nearby beaches.
One diver out of 87 test subjects and 437 tests. Based on these results, there will be a 145 dB limit if used in the presence of known commercial and recreational diving. One problem with this quote - the sound level will be limited to 180 dB, not 235 dB. Also note that these test divers were subjected to a duty cycle over twice that of the actual system operation.]The NRDC continued... And the dangers go beyond marine mammals. In preparing for the upcoming trial, NRDC has uncovered the shocking results of the Navy's own LFA research on human scuba divers. One Navy test subject was exposed to 14 minutes of LFA noise at 160 decibels -- far below the level of 235 decibels at which the actual LFA system will be operating. The diver experienced uncontrollable shaking in his limbs and lapsed into a seizure-like state that recurred periodically for days. The Navy's report described him as a "casualty."
Ah, the smoking gun. I don't think anyone ever said LFA was harmless but that there is minimal risk to survival or reproduction, particularly with the mitigation measures that will be implemented as a result of the studies. In fact, the EIS states that "the potential for injury exists at very high received levels. This risk is confined to a relatively small area very close to the LFA vessel." Could it be that the US Navy is actually trying to balance the environmental impact with national security needs?Garibaldi once bubbled...
So if the Navy themselves agreed that LFA was so harmless it is very ironic that they themselves follow the following protocals established by the NOAA:
- LFA Sonar to be shutdown whenever marine mammals and marine turtles are detected within a 1.1 nautical mile range of the sonar
- The US Navy is prohibted from using SURTASS LFA Sonar within 12 nautical miles of all coastlines
Braunbehrens once bubbled...
As for the Sonar, I just read a well researched paper that has given me even more cause for concern. The conclusions were that:
The sonar does cause marine mammals to change their migration patterns.
The sonar has caused marine animals to die.
I am also looking forward to the outcome of the trial. Unfortunately we all know what will happen if this goes to the supreme court, they have demonstrated their allegiance in the last election.
I'm certain this sonar business is making a lot of money for someone. [/B]
vicky once bubbled...
But most sonars (and to some extent the phased array/towed ones) produce a spherical sound field. Thus, acoustic energy decreases as 1/r ("r"=distance/range from sonar). So what is considered a high level at several meters away is usually harmless from a distance of several hundred meters and unnoticeable from large distances. I am skeptical whether the LFA is responsible to all the phenomena you'be described. Tomorrow someone will accuse "El Ninio" as the responsible for killing the whales.
It is perhaps popular and eay to blame Naval activities for all Nature's mishappens, but not always true.