Developing isotopic proxies to reconstruct the metabolic rates and thermal histories of octopus

Erica Durante; Gretchen Grammer; Jasmin Martino; Robert Klaebe; Ming-Tsung Chung; Justin Payne; Zoë Doubleday

doi:10.1016/j.marenvres.2024.106543

Developing isotopic proxies to reconstruct the metabolic rates and thermal histories of octopus

Mar Environ Res. 2024 May 7:198:106543. doi: 10.1016/j.marenvres.2024.106543. Online ahead of print.

Authors

Erica Durante¹, Gretchen Grammer², Jasmin Martino³, Robert Klaebe⁴, Ming-Tsung Chung⁵, Justin Payne⁶, Zoë Doubleday³

Affiliations

¹ Future Industries Institute, University of South Australia, South Australia, Australia. Electronic address: erica.durante@mymail.unisa.edu.au.
² South Australian Research and Development Institute Aquatic Sciences, South Australia, Australia.
³ Future Industries Institute, University of South Australia, South Australia, Australia.
⁴ Department of Earth Sciences, School of Physics, Chemistry and Earth Sciences, University of Adelaide, South Australia, Australia.
⁵ Institute of Oceanography, National Taiwan University, Taipei, Taiwan.
⁶ STEM, University of South Australia, Adelaide, South Australia, Australia.

PMID: 38728797
DOI: 10.1016/j.marenvres.2024.106543

Abstract

Understanding an animal's metabolic rate and thermal history is pivotal for ecological research. Recent studies have proposed the use of stable carbon and oxygen isotopes (δ¹³C and δ¹⁸O) in biogenic carbonates as proxies of metabolic rate and experienced temperature, respectively, to overcome the challenges of directly measuring these data in the field. Our study represents the first experimental investigation to develop δ¹³C and δ¹⁸O proxies in octopus. Octopus berrima hatchlings were raised in captivity, at varying water temperatures, for up to 110 days. O. berrima statoliths were then subsequently analysed for δ¹³C and δ¹⁸O values. The proportion of metabolically derived carbon, or respired carbon (C_resp), increased as the octopus grew (slope = 0.076, R² = 0.72), suggesting an influence of somatic growth rate and body mass on δ¹³C values. Additionally, we identified an inverse correlation between δ¹⁸O values and environmental temperature (slope = -0.163, R² = 0.91), which was subsequently used to develop a thermal reconstruction model. Our experiment aids in interpreting stable isotopic values in statoliths and their application as temperature and metabolic proxies in wild-caught octopus. Such proxies will increase our monitoring capabilities of these ecologically and commercially significant cephalopods and contribute to their conservation and effective management.

Keywords: Carbonates; Isotopes; Metabolic proxy; Temperature proxy; Temperature reconstruction.