Please select your home edition
Edition
Zhik Dinghy Wetsuits

How dolphins handle 'the bends'

by Woods Hole Oceanographic Institution on 28 Oct 2011
A common dolphin is examined by ultrasound after stranding alive on Cape Cod, Mass. (Image under NOAA Stranding Agreement with International Fund for Animal Welfare (IFAW) WHOI Graphic Services
Scientist are aware that the blood and tissue of some deceased beaked whales stranded in the vicinity of naval sonar exercises are riddled with bubbles. It is also well-known that human divers can suffer from bubble induced decompression sickness, more often referred to as the bends.

What researchers know comparatively little about is how living marine mammals handle the compression of lung gas as they dive deep and then resurface.

Now, in a study published online in the Proceedings of the Royal Society B, a team that includes researchers from the Woods Hole Oceanographic Institution (WHOI) has confirmed that bubbles do form in live, stranded dolphins. But in many cases, those animals are able to 'manage' those bubbles and can resume relatively normal lives of swimming and diving in the ocean.

'Evidence suggests that live dolphins that have been stranded have bubbles that appear not clinically significant,' said Michael Moore, a senior research specialist in biology and director of the WHOI Marine Mammal Center.

The multi-institutional research team, led by Sophie Dennison of the Marine Mammal Center in Sausalito Ca., along with collaborators from WHOI, the International Fund for Animal Welfare (IFAW), and the Chicago Zoological Society, performed ultrasound scans on 22 live stranded and capture-release dolphins. The researchers examined the liver, kidneys, eyes, and blubber-muscle interface.

They found gas in the kidneys of 21 of the live stranded dolphins and in some liver veins of two of the animals. Nine then died or were euthanized, and the presence of bubbles was corroborated by computer tomography and necropsy examinations. Of the remaining 13 that were released, 11 did not re-strand.

The researchers said that off-gassing of supersaturated blood and tissues was the most likely origin for the gas bubbles. 'In contrast to marine mammals repeatedly diving in the wild, stranded animals are unable to recompress by diving, and thus may form bubbles,' they report in their paper. 'Since the majority of beached dolphins released did not re-strand, it also suggests that minor bubble formation is tolerated and will not lead to clinically significant decompression sickness.'


The results, Moore said, 'suggest that dolphins are possibly managing bubbles routinely to avoid decompression sickness, also known as the bends. Humans likewise manage 'silent bubbles.’' Only a minority of human divers that get bubbles, he added, get the bends.

Moore said it was the observation of bubbles in deceased beaked whales that led to the current study. 'In routine decompression, the animal exhibits normal physiology and experiences few bubbles,' he said. 'But acoustic stressors, such as sonar, seem to change normal bubble management.'

'Beaked whales are stranding atypically when exposed to sonar,' Moore said. 'The beaked whale mortality events have led the current generation of marine mammal physiologists to revisit the question of how marine mammals manage the issue of lung gas being compressed as they dive deeper,' he said.

'Above the depth of alveolar collapse, a depth at which the gas-exchange surface of the lung is no longer inflated, increasing pressure with depth can cause gases to dissolve in the body; the gases then come back out of solution as they resurface. If this decompression is uncontrolled, bubbles can form. In humans such bubbles can cause joint pain that is relieved by 'bending' limb joints - hence the popular name. It was thought that marine mammals were immune to such problems, but the beaked whale cases reopened this assumption to fresh scrutiny.'

Moore said the study, which was funded by the U.S. Office of Naval Research and IFAW, is but one piece to the puzzle of possible effects of how human or environmentally induced changes to ocean conditions might affect the health and behavior of dolphins. Nevertheless, he said, 'We have shone a bit more light on bubbles in marine mammals.'

Woods Hole Oceanographic Institution website

The Woods Hole Oceanographic Institution is a private, independent organization in Falmouth, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the ocean and its interaction with the Earth as a whole, and to communicate a basic understanding of the ocean's role in the changing global environment.

Barz Optics - San Juan Worlds Best EyewearWildwind 2016 660x82T Clewring J-class

Related Articles

WHO statement on Zika virus
The third meeting of the EC convened by the Director-General under IHR 2005 regarding microcephaly and Zika virus The third meeting of the Emergency Committee (EC) convened by the Director-General under the International Health Regulations (2005) (IHR 2005) regarding microcephaly, other neurological disorders and Zika virus was held by teleconference on 14 June 2016, from 13:00 to 17:15 Central European Time.
Posted on 16 Jun
Atlantic Cup 2016 - a race with an environmental commitment
The Atlantic Cup continues to further its mission for the 2016 race by examining the global economic impact of the ocean The Atlantic Cup continues to further its mission for the 2016 race by examining the global economic impact of the ocean and how an unhealthy ocean can affect the economy.
Posted on 7 Apr
Zika virus situation report
From 1 January 2007 to 16 March 2016, Zika virus transmission was documented in a total of 59 countries and territories. From 1 January 2007 to 16 March 2016, Zika virus transmission was documented in a total of 59 countries and territories. Cuba and Dominica are the latest to report autochthonous (local) transmission of Zika virus on 14 and 15 March, respectively. Five of these countries and territories reported a Zika virus outbreak that is now over.
Posted on 2 Apr
Have Norway scientists solved the Bermuda Triangle mystery?
The Bermuda Triangle has been said to have claimed numerous ships and aircraft over the years The Bermuda Triangle has been said to have claimed numerous ships and aircraft over the years, and everything from aliens to remnants from the lost island of Atlantis have been fingered as the culprits.
Posted on 15 Mar
Cyclone Winston Relief Fund – Help the people of Fiji
Sea Mercy is sending volunteer fleet of small and large vessels, loaded with shelter, food and medical supplies to Fiji. Sea Mercy is once again sending our volunteer fleet of small and large vessels, loaded with shelter, food, water and medical supplies and teams to Fiji.
Posted on 27 Feb
Flying Scot Atlantic Coast Champs - Hanson Medals awarded for rescues
US Sailing Safety at Sea Committee awarded the Arthur B. Hanson Rescue Medals to eight boats for their heroic efforts The US Sailing Safety at Sea Committee awarded the Arthur B. Hanson Rescue Medals to eight boats for their heroic efforts when a microburst storm hit the 2015 Flying Scot Atlantic Coast Championship, hosted by the Blackbeard Sailing Club, in New Bern, NC on September 12.
Posted on 2 Feb
Eco-warriors Sea-Bin crowd sharing critical stage with nine days to go
The automated marina cleaning SeaBin project has raised 86% of their target with 9 days left. The automated marina cleaning SeaBin project has raised $198,020 of $230,000.00 with nine days left on their Indiegogo crowdfunding platform, but they need more help now.
Posted on 29 Dec 2015
Higher levels of Fukushima Cesium detected offshore
Scientists monitoring the spread of radiation in the ocean from the Fukushima nuclear accident report Scientists monitoring the spread of radiation in the ocean from the Fukushima nuclear accident report finding an increased number of sites off the US West Coast showing signs of contamination from Fukushima. This includes the highest detected level to date from a sample collected about 1,600 miles west of San Francisco.
Posted on 6 Dec 2015
Don’t be a Tosser – Not your usual environmental article!!
The word ‘Tosser’ in the Oxford English dictionary means – ‘a person or thing that throws something’. The word ‘Tosser’ in the Oxford English dictionary means – ‘a person or thing that throws something’. There is no need for me to tell you the other meaning that is commonly used around the world. However in this article it will refer to both at the same time as someone who tosses trash into the ocean, truly is a tosser.
Posted on 3 Dec 2015
Warming ocean worsened Australia’s fatal 2010/2011 floods
Researchers shows that warming of Indian and Pacific oceans played a role in increasing the risk of floods in 2010/2011 A study by a team of U.S. and Australian researchers shows that long-term warming of the Indian and Pacific oceans played an important role in increasing the risk of the kind of devastating floods that struck Australia in 2010/2011.
Posted on 21 Nov 2015