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Changes in marine iguana (Amblyrhynchus cristatus) heart rates suggest reduced metabolism during El Niño events

  • S. Dubiner*
  • , J. P.Muñoz Pérez
  • , D. Alarcón-Ruales
  • , E. Cohen
  • , D. Deresienski
  • , M. Hirschfeld
  • , E. Levin
  • , K. J. Lohmann
  • , S. Meiri
  • , G. Lewbart
  • *Corresponding author for this work
  • Universidad San Francisco de Quito
  • University of the Sunshine Coast
  • North Carolina State University
  • James Cook University Queensland
  • University of North Carolina at Chapel Hill

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Marine iguanas occasionally face severe food shortages because of algal dieback during El Niño events. Research on their adaptations to these periods has highlighted their unique ability to shrink in body length, which reduces their energetic needs. Additional mechanisms, like sustaining lower body temperatures and metabolic rates, could potentially also lower energy consumption, but have never been examined. We measured 665 iguanas over an 11-year period including three El Niño events, and examined how heart rates (a proxy for metabolic rates) and body temperatures change with sea-surface temperature oscillations (Oceanic Niño Index, ONI). Heart rate (adjusting for body size, temperature, season, and study site) was negatively correlated with ONI and lower during El Niño, whereas the adjusted body temperature did not correlate with ONI or differ between El Niño and other periods. We therefore hypothesize that marine iguanas can depress their metabolic rates in response to the harsh conditions, an adaptation that is complementary to shrinking and may further enhance their survival through periods of limited food. Direct metabolic measurements are needed to test this hypothesis.

Original languageEnglish
Pages (from-to)276-282
Number of pages7
JournalJournal of Zoology
Volume325
Issue number4
DOIs
StatePublished - Apr 2025

Funding

Funders
University of the Sunshine Coast
University of North Carolina at Chapel Hill
Galapagos Conservation Trust
COCIBA
Universidad San Francisco de Quito
Pontificia Universidad Católica del Ecuador
North Carolina State University
Maryuri Yépez
USFQ Colegio de Ciencias Biológicas y Ambientales
Tel Aviv University
Galapagos Science Center

    Keywords

    • ENSO
    • body temperature
    • food shortage
    • metabolic depression
    • metabolic rate
    • ocean warming
    • reptile
    • thermoregulation

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