Density-dependent behavioural interactions influence coexistence between a native and a non-native mesopredator

Abstract The invasion of non-native species into an ecosystem can markedly alter the structure and functioning system. Yet, we have limited knowledge factors that determine success. Behavioural interactions been suggested as critical determinants success in animals, but exact mechanisms are less well known. We investigated if density-dependent behavioural could facilitated shrimp Palaemon elegans spawning habitat threespine stickleback Gasterosteus aculeatus Baltic Sea. This was done by manipulating densities two mesocosms. found to dominate behaviourally over through higher aggression, impact on density-dependent; a high density sticklebacks increased aggressive interactions, which caused shrimps decrease their activity restrict use dense vegetation, while low had no distribution shrimps. behaviour. These results suggest present has allowed habitat. However, current increase abundance human-induced ecological disturbances limit further expansion shrimp. Thus, our indicate mechanism–density-dependent aggression–can influence subsequent population expansion. At broader level, stress importance considering when investigating behind