MEPS 258:283-289 (2003)  -  doi:10.3354/meps258283

ABSTRACT: While temperature records are available from otolith δ¹⁸O profiles in fish, interpreting changes in otolith δ¹³C remains ambiguous. We compiled a global database of published otolith δ¹³C values for 60 species representing 30 families of marine fishes. Species¹ mean otolith δ¹³C ranged from +0.5 to -8.6 ‰. Among-family variance in otoli δ¹³C was uniquely explained by a morphometric index for aerobic swimming activity (caudal aspect ratio, r² = 0.61). The models that consistently explained the maximum among-species variance in otolith &symbol;¹³C included caudal aspect ratio and maximum depth of occurrence. Our analysis supports the use of otolith carbon-isotope ratios to indicate metabolism (primarily active) in marine fish. This information may be applied to studies of fish feeding and related food-web structure, both past and present.

KEY WORDS: Otolith · Stable isotopes · δ¹³C · Marine fish · Metabolism · Swimming activity · Caudal aspect ratio · Morphometrics