Carbon source estimation of Banggai cardinalfish, Pterapogon kauderni, otoliths using a novel tracer Δ14C: New implications for fish metabolism and otolith calcification

Abstract

Estimating the metabolic rates of fish is crucial for understanding their physiology and ecology. However, metabolic rate information derived from otolith geochemical data (Moto) has mainly been obtained from mid to high latitudes, leaving a critical information gap for low latitude fishes suffering from climate variability. In this study, we successfully estimated Moto of experimentally reared Banggai cardinalfish (Pterapogon kauderni), a species found exclusively in the Coral Triangle, using a novel method based on radiocarbon (Δ14C) analysis. Moto values for this species were generally consistent with previously reported Moto and temperature data, but were slightly higher, suggesting high metabolism. Furthermore, we found a new species‐specific carbon isotope fractionation in otoliths (εtotal), using a combination of radiocarbon and stable carbon isotopes. Our Δ14C results will improve the understanding of the temperature dependence of fish metabolic rates, which is crucial for assessing the species resilience to temperature variability.