I have always been passionate about the sea which, from early on in my career, inspired me to conduct studies on the effects of anthropogenic changes on marine benthic ecosystems. Subsequently, I became very interested in studying biological invasions. I have primarily developed studies focussing on the interactions between native and introduced species. I have also studied biological factors such as life cycles and reproductive strategies that can determine the success of invasive species. I have been especially interested in the importance of ecological processes occurring during early life-history stages, and studied how these influence species distributions. An important part of my research is the use of genetic tools and I have been involved in several projects studying invasion histories of marine invertebrate species, as well as developing new molecular tools. In line with this, I have analysed several aspects of the invasion process by comparing populations from within both the native and introduced ranges. Finally, I have enhanced my understanding of marine ecosystems through studying the taxonomy of some marine invertebrate groups, most particularly ascidians from several regions around the world.