Maternally transmitted isotopes and their effects on larval fish: a validation of dual isotopic marks within a meta-analysis context

Abstract

Transgenerational marking enables mass-marking of larval fishes via transmission of enriched stable isotopes from mother to offspring, but potential impacts on the resultant progeny are poorly understood. We injected enriched stable isotopes (137Ba and87Sr) into female purple-spotted gudgeon, Mogurnda adspersa, to produce multiple batch markers and examined larval morphology at hatch as well as survival and growth to 31 days posthatch in marked and unmarked offspring. Transgenerational marking had minimal effects on larval growth and survival, whereas body depth at hatch was significantly reduced in marked larvae. A meta-analysis of transgenerational marking effects on larval morphology at hatch and growth rates across multiple fish species found a nonsignificant positive effect of enriched stable barium isotopes on larval morphology at hatch, but a significant negative effect on growth. There were no significant effects of strontium on morphology or growth. Meta-regression analysis revealed that larval size at hatch increased with the dose of injected stable barium isotopes, but this result should be interpreted cautiously. Because of high levels of between-study heterogeneity, we caution against assuming there are no effects of transgenerational marking on fish offspring; any such effects should be validated and incorporated into transgenerational marking studies of fish dispersal.