Strengths of species interactions depend on temperature and predator community composition

Trophic and non-trophic species interactions determine energy flow in ecosystems and their strength underlies the stability of food webs. However, their dependence on environmental conditions is poorly understood, which limits our ability to understand the links between environmental drivers and species interactions. A new study from the Institute of Entomology of the Biology Centre CAS and University of South Bohemia elucidates the impact of temperature and predator diversity on trophic and non-trophic interaction strengths in a model community of predatory aquatic insects and their prey. The authors used a novel combination of laboratory experiments and numerical simulations. Their results show that both trophic and non-trophic interactions change predictably with prey density and temperature but at the same time, species interactions strengths cannot be predicted from feeding experiments alone. The study published in the July issue of Global Change Biology opens new avenues for the quantification of the relative importance of trophic and non-trophic components in species interactions and improves our understanding how environmental factors affect these interactions and the dynamics of ecological communities.

Trophic (red arrows) and non-trophic (blue dashed arrows) interactions in a community of invertebrate predators typified by two species of dragonflies and phantom midge larvae feeding on cladocerans. The study by A. Sentis et al. quantified these interactions and their dependence on temperature and cladoceran density.

A. Sentis, C. Gémard, B. Jaugeon, D. S. Boukal (2017) Predator diversity and environmental change modify the strengths of trophic and non-trophic interactions. Global Change Biology 23: 2629-2640.