Molecular Interactions as Drivers of Changes in Marine Ecosystems

Among the factors affecting community dynamics, bioactive natural products act as mediators of key biological processes, including competition, predation, defense, and reproduction. Their chemical diversity thus critically contributes to the stability of ecological systems. Accordingly, research in chemical ecology provides useful information for a better understanding of ecosystem functioning and biodiversity. On the other hand, the potential of bioactive molecules produced by invasive species to become disruptive to native communities has been recently emphasized in the literature, raising novel and urgent questions about the interactions of invasive metabolites with macromolecular counterparts of ecological and ecotoxicological interest. Relevant issues strongly emerged in the Mediterranean Sea where the green alga Caulerpa cylindracea and the seagrass Halophila stipulacea, both exotic macrophytes containing peculiar bioactive compounds, have become invasive. In particular, the study of these two species has led to the production of a recent literature focusing on "alien biomolecules" and their potential impact on the native community. This chapter summarizes the obtained results by giving special emphasis to the urgent need for individuating molecular interactions that are likely to exert cascade effects at all levels of biological organization, from molecules to ecosystems.