Navigation Links
How diving leatherback turtles regulate buoyancy
Date:11/12/2010

Leatherback turtles are remarkably versatile divers. Routinely diving to depths of several hundred meters, leatherbacks are occasionally known to plunge as deep as 1250m. The animals probably plumb the depths to avoid predators, search for prey and avoid heat in the tropics. However it wasn't clear how these mammoth reptiles regulate their buoyancy as they plunge down. Sabrina Fossette from Swansea University explains that no one knew how the turtles descended so far: do they swim down or become negatively buoyant and plummet like a stone? Curious to find out how nesting leatherbacks plumb the depths, Rory Wilson and his long time collaborator, Molly Lutcavage, decided to deploy data loggers containing triaxial accelerometers on leatherback females as they nested on beaches on St Croix in the US Virgin Islands. They found that leatherbacks probably regulate their buoyancy by varying the amount of air they inhale just before submersion and publish their discovery on Nov. 12, 2010 in the Journal of Experimental Biology at http://jeb.biologists.org/cgi/content/abstract/213/23/4074.

'When you first see a leatherback turtle coming out of the water it's like a dinosaur it's really impressive,' says Fossette, having just returned from collecting data in the Indian Ocean. According to Fossette, Andy Myers, Nikolai Liebsch and Steve Garner attached accelerometers to five females as they laid their eggs, and then waited 8-12 days for the reptiles to return to the beach to lay more eggs having headed out to sea. Retrieving the accelerometers, the team found that only two of the five had collected usable data, but the data loggers that functioned showed 81 dives that the team could analyse ranging from 64m down to 462m.

Back in Swansea, Fossette, Adrian Gleiss, Graeme Hays and Rory Wilson analysed the temperature, pressure and acceleration data collected by the loggers. Describing the accelerometer data Fossette says, "You can almost see the animal swimming. It's the first time we could see the locomotor activity during those deep dives."

Extracting the acceleration data that showed the leatherbacks' movements, the team could see that the turtles dived deeply at an average angle of 41deg as they began their descent. Initially the turtles swam with each flipper stroke lasting 3s, but as they descended further they swam less hard until they stopped swimming all together, became negatively buoyant and began gliding down. At the bottom of the dive, the turtles began swimming as they heading to the surface and continued swimming until they regained buoyancy near the surface and began gliding again.

Fossette explains that many diving animals exhale before they leave the surface to minimise the risk of decompression sickness, however, leatherbacks do not. They dive carrying a lung full of air. Curious to find whether leatherbacks vary the amount of air that they inhale to regulate their buoyancy, Fossette and Gleiss compared the depths at which the turtles became negatively buoyant with the maximum depth that they reached. The team found that the deepest divers remained buoyant the longest and started gliding at deeper depths. So the turtles probably regulate their buoyancy before diving by varying the amount of air they inhale. Fossette also says, "The nesting turtles may glide for 80 percent of the dive's descent to optimise their energetic reserves, which is crucial for the production of eggs."

The team is now keen to look at the diving patterns of leatherbacks in their foraging grounds in the North Atlantic. Fossette explains that nesting turtles lose weight while foraging turtles are gaining weight and this could affect their buoyancy and diving behaviour. However, tagging a 400kg turtle in the ocean is a much bigger problem than tagging them on a beach.


'/>"/>

Contact: Kathryn Knight
kathryn@biologists.com
44-078-763-44333
The Company of Biologists
Source:Eurekalert

Related biology news :

1. Negligible impact on public safety from shark cage diving operations
2. Scientists identify worlds largest leatherback turtle population
3. Scientists call for protected swimways for the endangered leatherback sea turtle
4. Commercial fishing estimated to kill millions of sea turtles
5. How can accidental captures of loggerhead turtles be reduced?
6. Turtles Christmas journey tracked by scientists
7. National Science Foundation Fellow uses ultrasound to research bog turtles
8. Turtles no longer turned into souvenirs
9. Cost of hatchling turtles dash for freedom
10. No place like home: New theory for how salmon, sea turtles find their birthplace
11. Turtles alter nesting dates due to temperature change says ISU researcher
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:6/1/2016)... 1, 2016 Favorable Government Initiatives ... and Criminal Identification to Boost Global Biometrics System Market ... TechSci Research report, " Global Biometrics Market By ... and Opportunities, 2011 - 2021", the global biometrics market ... on account of growing security concerns across various end ...
(Date:5/9/2016)... -- Elevay is currently known as the ... high net worth professionals seeking travel for work   ... there is still no substitute for a face-to-face meeting. ... deal with a firm handshake. This is why wealthy ... citizenship via investment programs like those offered by the ...
(Date:4/26/2016)... April 27, 2016 Research ... Multi-modal Biometrics Market 2016-2020"  report to their offering.  ... The analysts forecast the global multimodal ... 15.49% during the period 2016-2020.  Multimodal ... sectors such as the healthcare, BFSI, transportation, automotive, ...
Breaking Biology News(10 mins):
(Date:6/27/2016)... Raleigh, NC (PRWEB) , ... June 27, 2016 ... ... have just published their findings on what they believe could be a new ... summary of the new research. Click here to read it now. ...
(Date:6/27/2016)... ... June 27, 2016 , ... Newly created ... and solutions to the healthcare market. The company's primary focus is on new ... and marketing strategies that are necessary to help companies efficiently bring their products ...
(Date:6/27/2016)... PHILADELPHIA , June 27, 2016  Liquid ... today announced the funding of a Sponsored Research ... study circulating tumor cells (CTCs) from cancer patients.  ... changes in CTC levels correlate with clinical outcomes ... therapies. These data will then be employed to ...
(Date:6/24/2016)... 24, 2016  Regular discussions on a range of subjects ... the two entities said Poloz. Speaking at a ... , he pointed to the country,s inflation target, which ... "In certain areas ... have common economic goals, why not sit down and address ...
Breaking Biology Technology: