[MARMAM] Thermoneutrality in dolphins

Dr Gareth Pearce gpp28 at cam.ac.uk
Sat Aug 8 15:23:47 PDT 2009


Dear Greig,

You could take a look at: 

Yeates and Houser (2008) Thermal tolerance in bottlenose dolphins (Tursiops 
truncatus). Journal of Experimental Biology 211, 3249-3257.

Summary: Water and air temperature are potentially limiting factors to the 
pole-ward distributions of coastal bottlenose dolphins. This study assessed 
the lower critical temperature of captive bottlenose dolphins to air 
temperature (LCTa) and water temperature (LCTw) through the use of open 
flow respirometry. Five dolphins, ranging from 14 to 33 years of age and 
acclimated to the waters of the southern California coast (14.2-22.5°C), 
were subjected to water temperatures ranging from 0.2 to 18.0°C. Two of the 
animals were additionally subjected to air temperatures ranging from -2.4 
to 17.8°C while maintaining water temperature approximately 3°C above their 
individual LCTw. The LCTw ranged from 5.5 to 10.6°C and generally decreased 
with increasing animal mass; for dolphins in excess of 187 kg, the LCTw 
ranged from 5.5 to 5.7°C. No LCTa could be determined across the range of 
air temperatures tested. Core body temperature remained within the limits 
of normal body temperatures reported for dolphins but demonstrated a direct 
relationship to water temperature in three subjects and varied across a 
range of 1.5°C. Air and water temperature had a minimal synergistic effect 
on dolphin thermoregulation, i.e. water temperature exerted the predominant 
impact on thermoregulation. For dolphins in excess of 187 kg, water 
temperature alone would appear to be insufficient to limit the use of 
habitat north of current bottlenose dolphin ranges along the coastal United 
States. However, thermal impacts to smaller dolphins, in particular 
adolescents, neonates and accompanying females, may work in concert with 
other factors (e.g. prey distribution, predator avoidance, social 
interactions) to influence coastal residency patterns and population 
structure.

Hope this helps.

I'd be really interested to hear the sort of additional research you decide 
needs to be carried out in the fiord system you describe.

Best regards

Gareth Pearce

***************************************************************************

Assoc. Prof. Gareth Pearce BSc(Hons) BVSc MA MVS PhD 
GradCertEd(HE)PGCertAqVetS PGCertWLBio&Cons DiplECPHM MRCVS

Head, Wildlife Health & Conservation Group,  Adjunct Assoc Professor in
                                             Marine Mammal Health 
                                             & Conservation, 

Department of Veterinary Medicine,           School of Veterinary & 
University of Cambridge,                     Biomedical Sciences,
Madingley Road, Cambridge, CB3 0ES,          Murdoch University, Perth,
United Kingdom.                              6150, WA, Australia.

Tel: 01223 337678. e-mail: gpp28 at cam.ac.uk                            


Fellow & Director of Studies, 
Magdalene College, Magdalene Street, Cambridge, CB3 0AG.

***************************************************************************


On Aug 7 2009, Greig Funnell wrote:

> 
>
>Dear MARMAMers,
>
> 
>
>We currently have what appears to be a relatively isolated population of
>bottlenose dolphins that has been declining in abundance over the last
>decade or so. I work for the Department of Conservation in New Zealand
>and we are trying to identify what the potential causes or contributors
>to this decline are. One of the unique features of their habitat is the
>discharge of freshwater into the fiord system that they occupy, and it
>has been proposed that this may alter the water temperature (at least at
>certain times of the year) and be causing thermal stress to the
>dolphins.
>
> 
>
>Therefore, I am interested in gathering information on temperature
>tolerances and thermoneutrality in dolphins, particularly in bottlenose.
>The only study that I have been able to find on dolphins is the work of
>Williams in the early 90's, so any further information would be greatly
>appreciated. Any information will be used to aid our management
>decisions and/or guide what additional research needs to be carried out
>rather than for a specific publication.
>
> 
>
>My contact details are gfunnell at doc.govt.nz
>
> 
>
>Kind Regards,
>
>Greig.
>
>
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>






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