The use of stable isotopes in marine animal trophic ecology

English. editorial reviewed

English. Stable isotope analysis has been recognised as a useful tool for studying animal diet, identifying trophic relationships, and delineating food web structures as well as their alteration by human activities. Over the past decade, the number of studies using stable isotopes of carbon and nitrogen in marine trophic ecology has increased rapidly as technological advancements greatly facilitate their use. This tool is now among the most popular in ecology and several fields of investigations have developed, including the extension of analyses to more ‘difficult’ stable isotope ratio measurements such as sulfur, the use of isotope mixing models, and the creation of compound-specific stable isotope analysis. Here, we present three case studies taken from our own investigations and previously published literature. The first investigates seagrass detritus ecosystem in which the coexistence of a rich number of species of crustacean raises the question of whether trophic diversity exist among these species. The second examines the feeding habits of coral reef fish and explores whether habitat choice on the reef and their behaviour emerges as good predictors of diet. The third presents the potential use of stable isotope analysis in studying the nutrition of scleractinian corals, which are complex symbiotic organisms that usually present both autotrophic and heterotrophic pathways. This tool has enhanced our understanding of coral species biology, yet it remains underused. Overall, we aim to provide initial insights into stable isotope analysis for illustrating their utility and potential applications to better understand food web structures and species diet in the waters around Taiwan.