ABSTRACT Nutrient cycling across ecosystems is driven by complex ecological interactions, potentially impacting environmental stability. Savanna ecosystem processes are highly driven by large mammalian herbivores, so removing them likely causes significant changes in nutrient cycling in both terrestrial and aquatic habitats. Aquatic organisms in temporary savanna ponds, such as amphibian larvae (i.e., tadpoles), are good models to study this potential indirect impact. In the savanna of Comoé National Park, Ivory Coast, large mammalian herbivores declined through two civil war periods in 2002 and 2011. This led to a subsequent increase in terrestrial and aquatic vegetation density, and an altered tadpole community composition. In this study, we used stable isotope analysis to examine potential shifts in energy sources and food web positioning of savanna tadpoles. We compared tadpole samples collected before (1995 and 1996) and after the wars (2014, 2018, and 2019) from two ponds. We detected a general decrease in δ 15 N among tadpoles, which we interpret as a consequence of a baseline shift in δ 15 N values following mammalian declines. There was no overall shift in δ 13 C signals, suggesting that changes in primary energy resources were minimal. Observed interannual changes in isotope signals were taxon‐specific, reflecting differences in tadpoles' morphologies and respective diets, as well as site‐specific, reflecting different pond characteristics. Our findings indicate the potential importance of large mammalian herbivores in maintaining savanna ecosystem stability.
Ewald et al. (Wed,) studied this question.