Ciliated protists as indicators of ecosystem health: opportunities, challenges, and case studies in Italy

This communication aims to provide an overview of the outcomes and the challenges encountered in using ciliated protists as indicator of ecosystem health in the framework of several projects conducted in Italy since 2009. Ciliates (and, in general, protistan microorganisms) in spite of the key roles they play in the microbial loop, still constitute a neglected component of the biodiversity, which is rarely included in ecological risk assessment plans. Ciliates are important bacterial and fungal feeders and thus, they significantly contribute to channel nutrients up to the food web. Furthermore, numerous ciliate species can be easily cultured with a short generation time, such as those selected for the setting up of our ecotoxicological experimentation (i.e., Coleps hirtus, Euplotes aediculatus, and Rigidohymena tetracirrata). Thus, in this context, the present communication aims to highlight the usefulness of ciliates as test organisms for the development of simple and costeffective “prognostic” assays (i.e., able to detect sub-lethal toxicant effects of various environmental matrices) based on the exploitation of antioxidant responses as well as of “diagnostic” assays (i.e., able to detect overall ecosystem impairment) based on the analysis of the community structures of ciliates in arable soils to evaluate the potential impact of different agricultural managements.