Colony-specific differences in decadal longitudinal body composition of a capital-breeding marine top predator
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1. Capital breeding animals such as true seals (Phocidae) rely on accumulated body reserves to rear offspring. A mother's body composition at the start of a breeding episode may depend on recent environmental conditions and sets the resources available for the reproductive episode. 2. At two grey seal (Halichoerus grypus) breeding colonies with contrasting demographic characteristics, factors influencing individual variation and temporal trends in the body composition (expressed as the lipid‐to‐protein mass ratio) of females were examined. 3. Maternal reproductive expenditure, and the consequences for mothers and their pups, were investigated. 4. Individual variation in postpartum maternal body composition was considerable. Mean values of 27% (±5%) lipid and 18% (±1%) protein were estimated by hydrogen isotope dilution. No evidence of age effects was detected. 5. Mothers with a high lipid‐to‐protein mass ratio expended a higher proportion of lipid resources, conserved protein and returned with more protein the following year. 6. Average maternal postpartum body composition was similar between the two colonies, but temporal patterns differed at one colony where pup production was decreasing from another where pup production was increasing. Mothers at the declining colony consistently weaned larger pups than mothers at the increasing colony across the range of mother sizes, but measures of maternal body composition did not predict pup weaning masses.
Hanson , N N , Smout , S C , Moss , S & Pomeroy , P 2019 , ' Colony-specific differences in decadal longitudinal body composition of a capital-breeding marine top predator ' , Aquatic Conservation: Marine and Freshwater Ecosystems , vol. 29 , no. 51 , pp. 131-143 . https://doi.org/10.1002/aqc.3093
Aquatic Conservation: Marine and Freshwater Ecosystems
Copyright © 2019 John Wiley & Sons, Ltd. This work has been made available online in accordance with publisher policies or with permission. Permission for further reuse of this content should be sought from the publisher or the rights holder. This is the author created accepted manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1002/aqc.3093
Descriptionhe long‐term studies included in this paper were funded by the Natural Environment Research Council through the grant ‘SMRU Long‐term measurement of marine mammal population structure, dynamics and trophic interactions’, grant reference SMRU1001. PP was in receipt of NERC grant no. NE/G008930/1 and Esmée Fairbairn Foundation funding during the work. SCS was supported as a postdoctoral fellow in an EPSRC award to RK and PP.
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