[MARMAM] Paper on stable isotope screening of Australian sea lion breeding colonies

Andrew Damon Lowther andrew.lowther at adelaide.edu.au
Wed Nov 3 00:32:14 PDT 2010

Hi all,

Just to let you know of a new article reporting on the development of a
validated stable isotope screening technique to detect inter-individual
variation in adult female Australian sea lion foraging behavior across three
spatially close, asynchronously breeding colonies.  Abstract below, the full
article can be found in Marine Mammal Science Early View

Any queries should be directed to andrew.lowther at adelaide.edu.au - enjoy !

'Detecting alternate foraging ecotypes in Australian sea lion (Neophoca cinerea)
colonies using stable isotope analysis'


Article first published online: 26 OCT 2010
DOI: 10.1111/j.1748-7692.2010.00425.x

Stable carbon (δ13C) and nitrogen (δ15N) isotopes are used frequently
to describe the trophic ecology of top marine mammal predators. Australian sea
lions (Neophoca cinerea) are one of the world's rarest otariid seals and exhibit
the highest levels of natal site philopatry of any seal. We report the
development of a screening technique to identify different foraging ecotypes and
assess their relative frequencies in Australian sea lion breeding colonies using
stable isotope ratios in pups. Geospatial and dive data from 15 adult females at
three breeding colonies revealed alternate foraging strategies (inshore and
offshore foraging) that were reflected in significant changes in δ13C and
δ15N.  Isotope fractionation from mother to pup was validated using paired
whisker and blood serum samples with no significant difference between δ13C
and δ15N enrichment of +1.27‰ (whiskers) and +1.92‰ (blood serum) from
mothers to pups.Isotope ratios from whisker samples representing over 50% of
pups born at three colonies revealed significant intercolony differences in
maternal foraging ecotype frequencies. These results are unique in that
ecological partitioning over such a small spatial scale has not been described
in any other otariid species.

Andrew Lowther
PhD Candidate
Earth and Environmental Sciences, Faculty of Science
The University of Adelaide
North Terrace
Andrew.Lowther at Adelaide.edu.au

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