1. Oceanlab, University of Aberdeen, Main Street, Newburgh, Aberdeenshire, Scotland AB41 6AA.
2. Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA 93106, USA.
3. Department of Zoology, Ohio Wesleyan University, Delaware, OH 43015, USA.
4. University of Maryland Center for Environmental Science, Appalachian Laboratory, 301 Braddock Road, Frostburg, MD 21532–2307, USA.
5. Department of Biology, University of Washington, Box 351800, Seattle, WA 98195, USA.