Stable isotopic studies on chitin. III. The D/H and 18O/16O ratios in arthropod chitin

Stable hydrogen and oxygen isotope ratios are presented for carbon-bound hydrogen and for oxygen in chitin-derived substrates from 57 arthropod species collected in 50 different locations or grown under controlled conditions in the laboratory. No systematic isotopic differences were found among Insecta, Crustacea, and Merostomata. The determination of infra- and interindividual isotopic variabilities in a lobster and among individuals of crustacean populations yielded small variances of about ±3 per mil for δD values and ±0.3 per mil for δ¹⁸O values. Molting stage and sex of crustaceans showed no systematic effects on isotopic composition. The δD and δ¹⁸O values of ambient water showed only weak correlations with the respective δ values of chitin-derived substrates. Positive correlation was observed between δD values and trophic level. No temperature effects on δ¹⁸O and δD values from marine crustaceans were found that exceed the natural isotopic noise level. Taken together, these observations indicate that reconstruction of water isotopic composition from arthropod chitin δD and δ¹⁸O values will require specific information about the habits and habitats of the species involved in the analysis.