A multiaxial growth analysis of stable isotopes in the modern shell of <i>Saxidomus gigantea</i>: Implications for sclerochronology studies

Stable‐isotope ratios of two modern Saxidomus gigantea specimens from Namu, British Columbia, are presented to show intraspecimen and interspecimen isotopic variation. Isotopic profiles (δ13Cshell, δ18Oshell) were generated along the axis of maximum growth. The profiles show that analogous seasonal variation is recorded in δ18Oshell; however, significant variability is recorded in δ13Cshell. We suggest this is caused by differences in metabolic activity between individuals. Intrashell variability along a growth horizon shows good reproducibility in δ13Cshell but significant variability in δ18Oshell, especially at the sinistral margin. A multiaxial growth analysis generated several profiles from a single valve. Similar seasonal variations are recorded in δ18Oshell along all axes. δ13Cshell show significantly less covariation, possibly related to internal metabolic activity. This study highlights that δ18Oshell profiles generated from any portion of the shell can be used to evaluate seasonal fluctuations and may be excellent to evaluate types and rates of shell growth.

A multiaxial growth analysis of stable isotopes in the modern shell of Saxidomus gigantea: Implications for sclerochronology studies Journal Articles