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Data from: Metabolic proxy for cephalopods: Stable carbon isotope values recorded in different biogenic carbonates

Citation

Chung, Ming-Tsung et al. (2021), Data from: Metabolic proxy for cephalopods: Stable carbon isotope values recorded in different biogenic carbonates, Dryad, Dataset, https://doi.org/10.5061/dryad.hqbzkh1g5

Abstract

1. Measuring the metabolic rate of marine animals in their natural environment is challenging, impeding our understanding of their physiological ecology. Recently, a novel metabolic proxy, namely the δ13C values of biogenic carbonates (otoliths), was experimentally validated in teleost fishes. Cephalopods possess several types of biogenic carbonates, such as statolith, cuttlebone, and other internal and external shells, which are all potential metabolic recorders, but few have been evaluated. 2. To test the feasibility of the δ13C metabolic proxy in cephalopods, we conducted a temperature-controlled experiment with the pharaoh cuttlefish Sepia pharaonis to assess whether the proportion of metabolically derived carbon (Cresp) incorporated into statoliths and cuttlebones increases with metabolism in a warm environment. Moreover, we conducted multiple-species analysis by using the published δ13C values of various biogenic carbonates to evaluate the consistency of the proxy among cephalopod species and between cephalopods and teleost fishes. 3. In the temperature-controlled laboratory experiment, Cresp values calculated from statoliths and cuttlebones increased with an increase of environmental temperature. Cresp values did not differ between statoliths and cuttlebones. Moreover, the Cresp values of cephalopod biogenic carbonates had a similar range to those of fish otoliths and were correlated with metabolism-related factors, such as ambient temperature, body mass, ontogeny, and functional behaviours, strengthening the feasibility of their use. 4. The δ13C metabolic proxy reflects the total energy used in the natural environment, and it can be transformed into the oxygen consumption rate for a broader comparison with other species and for further evaluation with current theories related to metabolic ecology. However, experimental validation is highly recommended because the relationship between the oxygen consumption rate and Cresp values derived from biogenic carbonates of cephalopods might be structure- and species-specific. Our study revealed that the newly developed metabolic proxy provides a valuable alternative approach to studying ecophysiology in cephalopods, and further development might broaden its applicability. --

Methods

Ten cephalopod species with δ13C and δ18O values from the literature were used in analyses of this study. δ13C and δ18O values were derived from external (Nautilus and Argonauta) and internal shells (ram’s horn squids and cuttlefishes) as well as statoliths (squids). The experienced temperature was extracted from the same study. If recorded temperatures were absent in previous studies, we estimated temperatures from the reported δ18O values by using the temperature-dependant equations.

The Cresp value was estimated based on the δ13C values of biogenic carbonates by using the two-component mixing model. In the model, the δ13CDIC values were based on published data in the same sampling area. The δ13Cdiet values were derived from the δ13C values in other tissues/structures (muscle, beaks, or organic matter in biogenic carbonate) minus assumed trophic enrichment factor 1, but for planktivores, the δ13Cdiet values were obtained from the δ13C values of zooplankton in the sample areas according to published spatial ocean modelling.

Usage Notes

The parameters in the dataset are described in the README file and the source of isotope values is shown in the dataset.

Funding

Ministry of Science and Technology, Taiwan, Award: MOST 106-2611-M-019-004