Invasion impacts on functions and services of aquatic ecosystems

Non-native species can simultaneously affect ecological structures, functions, and services of the invaded ecosystem. In this paper, we report that the study of non-native species impacts on ecosystem function is an emerging topic in aquatic ecology, though studies measuring functions remain relatively uncommon. We hypothesized that study of ecosystem function can reveal emergent effects of non-native species when community structure appears to be unimpacted and the study of multiple functions has the potential to identify impacts masked by food-web complexity. We compiled information from Web of Science to create a pool of papers (n = 199) addressing ecosystem functions and services that we surveyed to evaluate our hypotheses. The number of publications referencing ecosystem function has increased since 2002, but only 10% of papers measured ecosystem functions as defined in our work. Additionally, 80% of publications reporting functional metrics addressed primary production and nutrient fluxes, while a low number of manuscripts (6%) directly linked the impact of non-native species on ecosystem functions to ecosystem services. We recommend future work focus on less-studied functions (e.g., bioturbation, decay rate, biomagnification), assess multiple functional metrics, link functions to services, and use networks to understand impacts from multiple dimensions of an invaders ecology.