Nice write-up by Dave Sigworth of my talk at the Norwalk Maritime Aquarium.
Wreckage from the tsunami off the coast of Japan last year is slowly making its way to American shores, and beachcombers say the debris has begun to reach land.
SCUBA divers know about the danger of decompression sickness, commonly referred to as “the bends.” Depending on the depth and duration of the dive, divers must follow a prescribed method during ascent known as decompression. If the ascent is too rapid, gases that were absorbed by the body during the dive will not be released, potentially creating bubbles inside their body, resulting in joint pain and even death.
In 2010, the Woods Hole Oceanographic Institution’s Marine Mammal Center (MMC) convened a meeting to discuss how marine mammals survive frequent dives and ascents.
Just yesterday, Dec. 21, 2011, the resulting paper was published online, “Deadly diving? Physiological and behavioral management of decompression stress in diving mammals.”
Michael Moore, the MMC Director stated “Until recently the dogma was that marine mammals have anatomical and physiological and behavioral adaptations to make the bends not a problem.” “There is no evidence that marine mammals get the bends routinely, but a look at the most recent studies suggest that they are actively avoiding rather than simply not having issues with decompression.”
”Researchers began to question the conventional wisdom after examining beaked whales that had stranded on the Canary Islands in 2002. A necropsy of those animals turned up evidence of damage from gas bubbles. The animals had stranded after exposure to sonar from nearby naval exercises.
This led scientists to think that diving marine mammals might deal with the presence of nitrogen bubbles more frequently than previously thought, and that the animals’ response strategies might involve physiological trade-offs depending on situational variables. In other words, the animals likely manage their nitrogen load and probably have greater variation in their blood nitrogen levels than previously believed.”
Moore noted that technology is helping scientists understand, e.g. CT scanners are being used to examine marine mammal cadavers at different pressures to better understand the behavior of gases in the lungs and “get some idea at what depth the anatomy is shut off from further pressure-kinetics issues.” Moore and his colleagues have also used a portable veterinary ultrasound unit to study the presence or absence of gas in live, stranded dolphins.
An important open question regards noise and whether it impairs the marine mammal’s ability to manage through “situational variables”. After a dolphin surfaces it will normally again dive but if disoriented it may enter deadly shallow water and be beached.
- Whereas when we as human divers encounter a variable, we extend decompression by having a spare tank lowered down the line, or artificially enter a recompression chamber.
Calypso’s recompression chamber in actual use (diver inside).
Proceeding of The Royal Society Biological Sciences
WHOI Marine Mammal Center (MMC)
This is my first blog posting on tumblr. My intent is to write about all things SCUBA, with a bent toward conservation and Jacques Cousteau. Your comments, questions, and any content you wish to contribute are all very welcome. I have a different blog on wordpress, which is focused more on marine biology, still with a bent toward Jacques Cousteau.
Here’s a question for you. What’s the most outrageous ocean debris you have seen and where and when did you see it?
Ocean debris is not a new problem but unfortunately it’s ever increasing.
Yesterday I listened to a webinar about marine debris and the anticipated arrival of Japanese tsunami marine debris in the Northwestern Hawaiian Islands in early 2012.
It was hosted by Marine Affairs Research and Education (MARE) http://marineaffairs.org/marinedebris.html, publisher of MPA News and founder of www.marinedebris.info, an online community and discussion forum on research, management, and prevention of marine debris. Hosting partners included Blue Ocean Sciences http://blueoceansciences.org and the EBM Tools Network http://www.ebmtools.orgwww.marinedebris.info, an online community and discussion forum on research, management, and prevention of marine debris. Hosting partners included Blue Ocean Sciences http://blueoceansciences.org and the EBM Tools Network http://www.ebmtools.org
I saw satellite imagery of the vast amounts of debris in the Pacific Ocean resulting from the Japan tsunami.
I’m reminded of Jacques Cousteau’s early collaboration with NASA. - For a time this year NASA’s satellite imagery was successfully tracking the debris but unfortunately as the debris disbursed satellites could no longer track it. Now the scientists are dependent up on computer models to track the debris.
Particular concerns regard hazardous materials, larger structures like the aforementioned shipping containers and ships themselves, which run aground and damage coral reefs, and invasive species like vermin, insects, and seeds, which can all be very problematic and take years if not decades to eradicate.
These organizations are interested in hearing from sailors (and divers) traveling between Hawaii and Japan who see debris. They request you provide specific information regarding the debris seen and very importantly accurate position coordinates.
Thanks for reading,
Richard E. Hyman