Combining simulation modeling and stable isotope analyses to reconstruct the last known movements of one of Nature's giants

Clive N Trueman; Andrew L Jackson; Katharyn S Chadwick; Ellen J Coombs; Laura J Feyrer; Sarah Magozzi; Richard C Sabin; Natalie Cooper

doi:10.7717/peerj.7912

Combining simulation modeling and stable isotope analyses to reconstruct the last known movements of one of Nature's giants

PeerJ. 2019 Oct 18:7:e7912. doi: 10.7717/peerj.7912. eCollection 2019.

Authors

Clive N Trueman¹, Andrew L Jackson², Katharyn S Chadwick¹, Ellen J Coombs^{3

4}, Laura J Feyrer⁵, Sarah Magozzi^{1

6}, Richard C Sabin³, Natalie Cooper³

Affiliations

¹ School of Ocean and Earth Science, University of Southampton, Southampton, United Kingdom.
² School of Natural Sciences, University of Dublin, Trinity College, Dublin, Ireland.
³ Department of Life Sciences, Natural History Museum, London, United Kingdom.
⁴ Department of Earth Sciences, University College London, University of London, London, United Kingdom.
⁵ Department of Biology, Dalhousie University, Halifax, NS, Canada.
⁶ Department of Geology and Geophysics, University of Utah, Salt Lake City, UT, United States of America.

Abstract

The spatial ecology of rare, migratory oceanic animals is difficult to study directly. Where incremental tissues are available, their chemical composition can provide valuable indirect observations of movement and diet. Interpreting the chemical record in incremental tissues can be highly uncertain, however, as multiple mechanisms interact to produce the observed data. Simulation modeling is one approach for considering alternative hypotheses in ecology and can be used to consider the relative likelihood of obtaining an observed record under different combinations of ecological and environmental processes. Here we show how a simulation modeling approach can help to infer movement behaviour based on stable carbon isotope profiles measured in incremental baleen tissues of a blue whale (Balaenoptera musculus). The life history of this particular specimen, which stranded in 1891 in the UK, was selected as a case study due to its cultural significance as part of a permanent display at the Natural History Museum, London. We specifically tested whether measured variations in stable isotope compositions across the analysed baleen plate were more consistent with residency or latitudinal migrations. The measured isotopic record was most closely reproduced with a period of residency in sub-tropical waters for at least a full year followed by three repeated annual migrations between sub-tropical and high latitude regions. The latitudinal migration cycle was interrupted in the year prior to stranding, potentially implying pregnancy and weaning, but isotopic data alone cannot test this hypothesis. Simulation methods can help reveal movement information coded in the biochemical compositions of incremental tissues such as those archived in historic collections, and provides context and inferences that are useful for retrospective studies of animal movement, especially where other sources of individual movement data are sparse or challenging to validate.

Keywords: Blue whale; Carbon stable isotopes; Models; Movement; Movement models; Sclerochronology.

Grants and funding

This work was funded by the British Ecological Society (grant: 5771/6815) and the London NERC DTP (training grant: NE/L002485/1) to EJC. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.