1. Centre of Excellence in Biological Interactions, Department of Biosciences, University of Helsinki, Helsinki, Finland
2. Tvärminne Zoological Station, University of Helsinki, Hanko, Finland
3. Organismal and Evolutionary Biology, University of Helsinki, Helsinki, Finland
4. Umeå Marine Sciences Centre, Umeå University, Hörnefors, Sweden
5. Department of Ecology and Environmental Science, Umeå University, Umeå, Sweden
6. Department of Microbiology, University of Helsinki, Helsinki, Finland