[MARMAM] New paper on feeding South Australian Tursiops

sue.gibbs at internode.on.net sue.gibbs at internode.on.net
Wed Oct 26 14:20:14 PDT 2011



	Fellow Marmamers 

	I'm pleased to announce the publication of a new paper, “Niche
differentiation of bottlenose dolphin species in South Australia
revealed by stable isotopes and stomach contents”, by S E Gibbs, R G
Harcourt and C M Kemper. Wildlife Research 34(4): 261-270. 

	Available from: http://www.publish.csiro.au/paper/WR10108.htm [1] 

	  

	ABSTRACT 

	Animal species with overlapping ranges are common worldwide, but how
these species coexist is less obvious. Dolphins are protected in
Australia and yet little information is available on their resource
use which is essential for successful management and conservation. The
aim of this study was to determine the degree of overlap in diet and
feeding ecology of the two _Tursiops _spp. That have overlapping
ranges in South Australia. Stomach content (91 _Tursiops _sp. and 14
_T. truncatus_) and stable isotope (d13C, d15N) analyses (39 _Tursiops
_sp. and 14 _T. truncatus_) were conducted. Carcasses of dolphins were
opportunistically collected between 1974 and 2005. Diet was quantified
by  frequency of occurrence (FOO) and numerical abundance (NA) of
prey. Delta13C from teeth revealed distinct differences in primary
source of carbon, corresponding to coastal (_Tursiops _sp. _n _= 39,
_X _= –12.24, s.d. = 1.32) and offshore habitats (_T. truncatus n _=
14, _X _= –14.21, s.d. = 0.55). Differences in d15N revealed
_Tursiops _sp. (_X _= 11.66, s.d. = 0.58) feeds at a lower trophic
level than _T. truncatus _(_X _= 14.29, s.d. = 0.88). Stomach content
analyses for  _Tursiops _sp. corroborated stable isotope results.
There was a significant difference between the diets of _Tursiops _sp.
from north Spencer Gulf and south Spencer Gulf (ANOSIM R = 0.249, _P
_= 0.001). Prey were generally demersal in habit with the most
important from the cephalopod families Octopodidae, Sepiidae and
Loliginidae and fish families Carangidae, Clupeidae, Terapontidae and
Apogonidae. For _T. truncatus _there were insufficient stomach
contents for assessment. South Australian bottlenose dolphin species
exhibit distinct niche differentiation with clear evidence of regional
variation in the diet of _Tursiops _sp. The between and within species
diet differentiation demonstrated, highlights the importance of
regional management. Such results are internationally significant as
coastal and offshore forms of _Tursiops _spp. occur worldwide.

	Regards,  

	Sue Gibbs 

	sue.gibbs at internode.on.net [2] 

	  

	 

Links:
------
[1] http://www.publish.csiro.au/paper/WR10108.htm
[2] mailto:sue.gibbs at internode.on.net

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