1. Hasselt University, Centre of Environmental Sciences, Environmental Biology Group, Agoralaan, Gebouw D, 3590 Diepenbeek, Belgium
2. Department of Biology, University of Oslo, P.O. Box 1066 Blindern, 0316 Oslo, Norway
3. Hasselt University, Biomedical Research Institute, Agoralaan, Gebouw A, 3590 Diepenbeek, Belgium