TRENDS IN AQUATIC ECOLOGY Recreational vessels as a vector for marine non-natives: developing biosecurity measures and managing risk through an in-water encapsulation system R. C. Roche • J. M. Monnington • R. G. Newstead • K. Sambrook • K. Griffith • R. H. F. Holt • S. R. Jenkins Received: 31 July 2014 / Revised: 4 November 2014 / Accepted: 22 November 2014 / Published online: 5 December 2014 Ó Springer International Publishing Switzerland 2014 Abstract Increasing recognition of non-natives as a threat to biodiversity and the functioning of marine ecosystems has brought with it the challenge of seeking novel management solutions. Hull fouling of recreational vessels is an important non-native vector, particularly in coastal areas where it is responsible for both introduction and secondary spread. This study introduces an in-water boat encapsulation system designed to limit transfer of marine non-natives, developed in response to the introduction of the ascidian Didemnum vexillum in Wales, UK. Here we describe the ‘‘decontamination berth’’, examine the chemical concentrations required to eliminate D. vexillum and review biosecurity approaches for recreational vessels. Laboratory tests of treatment chemicals showed that acetic acid and sodium hypo- chlorite were equally effective in reducing D. vexillum growth following exposures of \30 min. In situ trials confirmed the ability of both chemicals to decrease D. vexillum colonies growing on marina pontoons. Effi- ciency trials found the mean loss of chemical from the berth during each pumping cycle would be equivalent to 417 g of active chlorine. Our preliminary testing indicates that devices such as the decontamination berth may be usefully employed to contain the spread of existing marine non-native species and to prevent future introductions at marine transportation hubs. Keywords Biofouling  Marine invasive species  Biosecurity  In-water vessel encapsulation system  Vector management Introduction The introduction of invasive non-native species has been recognised as one of the most important threats to ecosystem functioning (Lubchenco et al., 1991; Carl- ton, 2001). Available evidence indicates that the frequency of new species introductions is increasing, whilst the ranges of established non-native species continue to expand (Dahlstrom et al., 2011). Once established, non-natives can have a variety of effects on native biota, ranging from insignificant to highly Guest editor: Koen Martens / Emerging Trends in Aquatic Ecology R. C. Roche (&)  J. M. Monnington  R. G. Newstead  K. Griffith  S. R. Jenkins School of Ocean Sciences, Bangor University, Menai Bridge, Anglesey LL59 5AB, UK e-mail: r.roche@bangor.ac.uk J. M. Monnington Xodus Group, 138 Cheapside, London EC2V 6BJ, UK K. Sambrook School of Marine and Tropical Biology, James Cook University, Townsville, QLD 4811, Australia R. H. F. Holt Natural Resources Wales, Maes y Fynnon, Ffordd Penrhos, Bangor LL57 4DN, UK 123 Hydrobiologia (2015) 750:187–199 DOI 10.1007/s10750-014-2131-y