The community context of trophic cascades

Abstract

Research Highlights: Baker, R., Whiteman, H., & Mott, C. L. (2025). Predation alters community structure through multiple trophic cascades. Journal of Animal Ecology. The trophic interactions of predators can strongly influence the biomass structure and species composition of ecosystems and can result in trophic cascades—namely, when predators reduce the biomass of their prey (e.g. grazers) and this indirectly increases the biomass of organisms lower in the food chain (e.g. primary producers). There has been long-standing interest in the causes of variation in the strength of trophic cascades and in the underlying mechanisms by which predators affect organisms lower in the food chain. In a recent study, Baker et al. (2025) experimentally test a specific hypothesis about how the size variation of a predator population (the predatory mole salamander: Ambystoma talpoideum) indirectly affects primary producers (i.e. periphyton) in pond ecosystems via cascading trophic interactions. In an outdoor mesocosm experiment, the authors show that predators triggered trophic cascades along two food chains, namely those supported by periphyton (a green chain) and detritus (a brown chain). Contrary to their expectations, predator populations with a wide range of body size caused stronger trophic cascades than those with a narrow range of body size. Their findings illustrate the importance of testing ecological theory in semi-natural environmental settings that are open to dispersing organisms and doing so over long enough time periods to observe the relevant community context of trophic interactions.