My name is Anouk Goedknegt and currently I am in my third year of my PhD project at the Royal Netherlands Institute for Sea Research.
I am studying the in-direct effects of invasive species via native pathogen-host webs. When invasive species enter a new ecosystem they can affect native species in a variety of ways. For example, in their new habitat invasive species often lack natural enemies like predators and pathogens (enemy release hypothesis), giving them a competitive advantage over native species. At the same time, the risk for native species can become even higher as invaders can co-introduce pathogens. These new pathogens may infect native hosts and cause severe disease problems for native populations (spill-over effect). In turn, the invader can also serve as a new host for native pathogens, thereby increasing the number of potential hosts and consequently making it easier for the pathogen to spread and increase in native host (spill-back effect). Alternatively, the new invader can release native hosts from parasite pressure, for example by feeding on the parasites (dilution effects). This project investigates the interplay of these effects in a marine system, focusing on the most prominent invader in the Wadden Sea, the Pacific oyster (Crassostrea gigas), which is invading native mussel beds (Mytilus edulis).