1. Mývatn Research Station; Mývatn IS-660 Iceland
2. Institute of Life- and Environmental Sciences; University of Iceland; Askja, Sturlugata 7 Reykjavík IS-101 Iceland
3. Faculty of Earth Sciences; University of Iceland; Askja, Sturlugata 7 Reykjavík IS-101 Iceland
4. Department of Biology; University of Regina; Regina Saskatchewan S4S 0A2 Canada
5. Department of Zoology; University of Wisconsin; Madison Wisconsin 53706 USA