2727_C06.fm Page 181 Thursday, February 9, 2006 2:08 PM THE ECOLOGY OF RAFTING IN THE MARINE ENVIRONMENT I THE FLOATING SUBSTRATA MARTIN THIEL1,2* & LARS GUTOW3 1Facultad Ciencias del Mar, Universidad Católica del Norte, Larrondo 1281, Coquimbo, Chile 2Centro de Estudios Avanzados en Zonas Áridas (CEAZA), Coquimbo, Chile *E-mail: thiel@ucn.cl Alfred Wegener Institute for Polar and Marine Research, Biologische Anstalt Helgoland, Box 180, 27483 Helgoland, Germany E-mail: lgutow@awi-bremerhaven.de Abstract Rafting has been inferred as an important dispersal mechanism in the marine environment by many authors The success of rafting depends critically on the availability of suitable floating substrata Herein currently available information on floating items that have been reported to carry rafting organisms is summarised Floating items of biotic origin comprise macroalgae, seeds, wood, other vascular plants, and animal remains Volcanic pumice (natural) and a diverse array of litter and tar lumps (anthropogenic) are the main floating items of abiotic origin Macroalgae, wood, and plastic macrolitter cover a wide range of sizes while pumice, microlitter, and tar lumps typically are