1. Dept of Natural Resource Sciences; McGill Univ., Sainte-Anne-de-Bellevue; QC Canada
2. Dept of Biological Sciences; Bishop's Univ.; Sherbrooke QC Canada
3. Arctic Research Centre, Dept of Bioscience, Aarhus Univ.; Roskilde Denmark
4. Aarhus Inst. of Advanced Studies, Arctic Research Centre, Dept of Bioscience, Aarhus Univ.; Rønde Denmark