David M Kristensen1
, Thomas R Jørgensen2
, Rasmus K Larsen3
, Mads C Forchhammer4
and Kirsten S Christoffersen3 
1Dept. of Medical Biochemistry and Genetics A, Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen, Denmark
2Dept. of Veterinary Pathobiology, Royal Veterinary and Agricultural University, Stigbøjlen 4, DK-1870 Frederiksberg C, Denmark
3Freshwater Biological Laboratory, Institute of Biology, University of Copenhagen, Helsingørsgade 51, DK-3400 Hillerød, Denmark
4Dept. of Arctic Environment, National Environmental Research Institute, Frederiksborgsvej 399, P.O. Box 358, DK-4000 Roskilde, Denmark