O' mother where wert thou? Maternal strategies in the southern elephant seal: a stable isotope investigation

Authier, Matthieu; Dragon, Anne-Cécile; Richard, Pierre; Cherel, Yves; Guinet, Christophe

doi:10.1098/rspb.2012.0199

Cited by 30 publications

(34 citation statements)

References 59 publications

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“…A mother's foraging success and her offspring's survival have broader demographic consequences, because survival during the non-breeding phase is the most important determinant of elephant seal abundance [43]. Female elephant seals are also faithful to their individual feeding areas [27], so any variability or persistent change in foraging area quality could be an important determinant of future survival and breeding success [44].…”

Section: Discussionmentioning

confidence: 99%

Bottom-up regulation of a pole-ward migratory predator population

et al. 2014

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As the effects of regional climate change are most pronounced at polar latitudes, we might expect polar-ward migratory populations to respond as habitat suitability changes. The southern elephant seal (Mirounga leonina L.) is a pole-ward migratory species whose populations have mostly stabilized or increased in the past decade, the one exception being the Macquarie Island population which has decreased continuously over the past 50 years. To explore probable causes of this anomalous trend, we counted breeding female seals annually between 1988 and 2011 in order to relate annual rates of population change (r) to foraging habitat changes that have known connections with atmospheric variability. We found r (i) varied annually from 20.016 to 0.021 over the study period, (ii) was most effected by anomalous atmospheric variability after a 3 year time lag was introduced (R ¼ 0.51) and (iii) was associated with sea-ice duration (SID) within the seals' foraging range at the same temporal lag. Negative r years may be extrapolated to explain, at least partially, the overall trend in seal abundance at Macquarie Island; specifically, increasing SID within the seals foraging range has a negative influence on their abundance at the island. Evidence is accruing that suggests southern elephant seal populations may respond positively to a reduced sea-ice field.

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Section: Discussionmentioning

confidence: 99%

Bottom-up regulation of a pole-ward migratory predator population

et al. 2014

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“…We found that some females repeatedly weaned heavier pups than others of similar age, perhaps suggesting difference in individual quality (here meaning important but unmeasured traits that contribute to among-individual fitness variation, Wilson and Nussey 2010). Such heterogeneity may arise from genetic makeup (Hunt et al 2004), other phenotypic traits (e.g., physiology), behavior (e.g., diet; Authier et al 2012), and variations in past or present environmental conditions experienced (Lindströ m and Kokko 2002, Chambert et al 2013, Stauffer et al 2013.…”

Section: Individual Heterogeneity and Age-related Variation In Weaninmentioning

confidence: 96%

“…v www.esajournals.org Notwithstanding large within-year variation, the increase in weaning mass that persisted through the 1990s and 2000s is thought to be biologically significant (McMahon et al 2000, Authier et al 2012. A potential pathway for population regulation may thus include improved adult female foraging success, a subsequent increase in weaning mass and associated improvement in juvenile survival.…”

Section: Individual Heterogeneity and Age-related Variation In Weaninmentioning

confidence: 99%

“…Extensive cloud cover causes a large percentage of missing pixels at southern latitudes, especially in winter. Following Authier et al (2012), we calculated chl-a anomalies about the monthly mean for each pixel for every month between October (t À 1) and May, the primary period for chl-a production in Subantarctic waters. An index of the total surface chl-a production was derived for every year from cumulated anomalies (Appendix: Fig.…”

Section: Time-varying Covariatesmentioning

confidence: 99%

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Decomposing the variance in southern elephant seal weaning mass: partitioning environmental signals and maternal effects

et al. 2015

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Abstract. Predator populations are likely to respond to bottom-up processes, but there remains limited understanding of how wide-ranging marine predators respond to environmentally driven temporal variation in food availability. Widespread declines of several Southern Ocean predators, including southern elephant seals Mirounga leonina, have been attributed to decreases in food availability following environmental changes. We used linear mixed models to examine temporal process variance in weaning mass (a key fitness component) of southern elephant seals at Marion Island over a 27-year period . We quantified the contribution of within-and between-year covariates to the total phenotypic variance in weaning mass and determined whether the observed reversal of population decline was associated with a continued increase in weaning mass, suggesting improvement in per capita food availability to adult females. Weaning mass initially increased rapidly with maternal age, but reached an asymptote when females were nine years old. Longitudinal data examining between-individual maternal differences suggested latent, age-independent maternal influences on weaning mass. Between-year differences accounted for only 6% of the total phenotypic variance in weaning mass. We found no evidence for a systematic trend in weaning mass, but model predicted weaning mass was 8.70 kg (95% CI ¼ 2.14-14.73) lower during the 1980s, suggesting that food limitation may have been most severe during these years when the population was declining. Model support for a population size effect was entirely driven by the low weaning mass and comparatively high (but declining) population size from 1986 to 1988; subsequent variation in population size had no detectable influence on weaning mass. Remotely sensed chlorophyll-a concentration within the seals' foraging distribution explained 45% of the between-year variation (1998-2013, n ¼ 9) in weaning mass, with higher weaning mass in years of positive chlorophyll-a anomalies. Environmental variation associated with variability in the Southern Annular Mode poorly predicted temporal variation in weaning mass. Our long-term data on elephant seal weaning mass provides a perspective on variation in food availability in a pelagic environment which is poorly known. Examining the long-term regionally specific effects of environmental variability aids our understanding of how these predators interact with their environment.

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“…Red blood cells (collected before the seal's foraging trip) and plasma samples (collected before and after the seal's foraging trip) were freeze-dried and powdered. Blood plasma can contain high and/or variable lipid content in animals (Cherel et al 2005), so we performed a lipid extraction using cyclohexane following the method used for elephant seals Mirounga leonina (Authier et al 2012). Blood subsamples were weighed (~0.4 mg) with a microbalance, packed in tin containers, and nitrogen and carbon isotope ratios were determined by a continuous flow mass spectrometer (Micromass Isoprime) coupled with an elemental analyser (Euro Vector EA 3024).…”

Section: Stable Isotopesmentioning

confidence: 99%