ORIGINAL PAPER Semi-submersible rigs: a vector transporting entire marine communities around the world Ross M. Wanless • Sue Scott • Warwick H. H. Sauer • Timothy G. Andrew • James P. Glass • Brian Godfrey • Charles Griffiths • Eleanor Yeld Received: 6 June 2008 / Accepted: 16 November 2009 / Published online: 29 November 2009 Ó Springer Science+Business Media B.V. 2009 Abstract A virtually intact subtropical reef com- munity (14 phyla, 40 families and 62 non-native taxa) was associated with a rig under tow from Brazil that became stranded on the remote island of Tristan da Cunha. This exposes rigs as a significant vector spreading alien marine organisms, and includes the first records of free-swimming marine finfish popu- lations becoming established after unintentional movement. With relatively trivial effort, a pre-tow clean would have obviated the need to salvage and dispose of the rig (undertaken largely to address concerns about invasive species), at a cost of *US$20 million. Our findings show that towing biofouled structures across biogeographic boundaries present unexcelled opportunities for invasion to a wide diversity of marine species. Better control and management of this vector is required urgently. Simultaneous, unintentional introductions of viable populations of multiple marine organisms are rare events, and we develop a basic framework for rapid assessment of invasion risks. Keywords Invasive alien marine species Á Marine environmental management Á Oil rigs Á Risk assessment Introduction Invasive species have devastating biodiversity and economic impacts (Mack et al. 2000; Pimental 2002; Thresher and Kuris 2004). The increase in volume and speed of transoceanic travel from the 19th century to R. M. Wanless (&) Percy FitzPatrick Institute, DST/NRF Centre of Excellence, University of Cape Town, Rondebosch 7701, South Africa e-mail: rosswanless@gmail.com S. Scott Strome House, North Strome, Lochcarron, Ross-shire IV54-8YJ, Scotland, UK W. H. H. Sauer Department of Ichthyology and Fisheries Science, Rhodes University, Grahamstown 6140, South Africa T. G. Andrew Á B. Godfrey Enviro-Fish Africa, 22 Somerset Street, Grahamstown 6139, South Africa J. P. Glass Agriculture and Natural Resources Department, Tristan da Cunha TDCU 1ZZ, South Atlantic C. Griffiths Centre for Invasion Biology, Zoology Department, University of Cape Town, Rondebosch 7700, South Africa E. Yeld Marine Biology Research Centre, Zoology Department, University of Cape Town, Rondebosch 7700, South Africa 123 Biol Invasions (2010) 12:2573–2583 DOI 10.1007/s10530-009-9666-2