Variation of Iron Stable Isotopes in a Marine Ecosystem from the Northwest Pacific Ocean

Since iron (Fe) is an important trace nutrient for marine organisms, establishing a tracer of the Fe cycle through the food chain is crucial. Herein, we report the variation in delta Fe-56 in marine organisms (n = 32, nine species) collected around the Northwest Pacific Ocean. The delta Fe-56 value varied from -2.64 parts per thousand to -0.03 parts per thousand, which is consistently lower than the reported seawater value. This variation was predominantly controlled in terms of species rather than size and region, suggesting that this proxy is useful to assessing species-specific Fe metabolic processes.