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Abstract

Fatty acid signature analysis of blubber has been used to study the foraging ecology of some marine mammals. However,
species-specific information on fatty acid (FA) deposition, distribution and mobilization is required to develop further the
application of FA as trophic markers within the marine environment. Blubber samples were collected from adult female Weddell
seals post-parturition and end of lactation, and were divided into inner and outer half sections. We determined the degree to which
there was vertical stratification in FA composition, and how this changed over the lactation period. Inner and outer layers of postparturition
blubber cores separated into two distinct groups. Sixty-two per cent of the dissimilarity between the two layers was
accounted for by a higher abundance of monounsaturated fatty acids (18:1ω9c and 16:1ω7c) in the outer blubber layer, and more
saturated fatty acids (16:0 and 14:0) in the inner layer. By end of lactation, the FA composition of the inner layer was different to
post-parturition samples, and 20:5ω3 had the highest fractional mobilization of all FA. In contrast, the proportion of FA in the outer
layer did not change, and there was more variability in the fractional mobilization of FA indicating mobilization was not uniform
across the blubber layer. Dietary predictions changed considerably when highly mobilized FA were removed from analyses, and
predictions were more consistent with previous dietary studies. The lack of uniformity in FA mobilization adds problems to the
future use of FASA in dietary predictions, highlighting the need for more detailed information on FA mobilization.

Item Type:	Article
Authors/Creators:	Wheatley, KE and Nichols, PD and Hindell, MA and Harcourt, RG and Bradshaw, CJA
Keywords:	Blubber; Diet; Fatty acids; Lactation; Mobilization; Stratification
Journal or Publication Title:	Journal of Experimental Marine Biology and Ecology
Publisher:	Elsevier Science BV
ISSN:	0022-0981
DOI / ID Number:	https://doi.org/10.1016/j.jembe.2007.07.005
Additional Information:	The definitive version is available at http://www.sciencedirect.com
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