The value of regular monitoring and diverse sampling techniques to assess aquatic non-native species: a case study from Orkney Author Kakkonen, Jenni E. * & Marine Services, Harbour Authority Building, Scapa, Orkney, KW 15 1 SD, United Kingdom Author Worsfold, Tim M. APEM Ltd., Diamond Centre, Works Road, Letchworth Garden City, SG 6 1 LW, United Kingdom Author Ashelby, Christopher W. APEM Ltd., Diamond Centre, Works Road, Letchworth Garden City, SG 6 1 LW, United Kingdom Author Taylor, Andrea * & Marine Services, Harbour Authority Building, Scapa, Orkney, KW 15 1 SD, United Kingdom Author Beaton, Katy * & Marine Services, Harbour Authority Building, Scapa, Orkney, KW 15 1 SD, United Kingdom text Management of Biological Invasions 2019 2018-10-17 10 1 46 79 http://dx.doi.org/10.3391/mbi.2019.10.1.04 journal article 299406 10.3391/mbi.2019.10.1.04 a53d05d0-2083-4f05-a83c-8f418fdc5468 1989-8649 11969078 (17) Ctenodrilus serratus (Schmidt, 1857) Status in U.K. – cryptogenic. There are two records of this species from the monitoring programme, from Kirkwall Marina in 2015 and from a scrape sample from Stromness Marina in 2016. Ctenodrilus serratus has a worldwide distribution and is frequently found in aquaria ( Fauvel 1927 ). It was genetically demonstrated to be truly amphi-Atlantic in distribution by Westheide et al. (2003) , who concluded that the distribution must have been through dispersal and considered anthropogenic dispersal among the possibilities. It has been reported from the Plymouth area ( Marine Biological Association 1957 ) and listed from the English Channel by Dauvin et al. (2003) . It is found primarily in the vicinity of port facilities ( unpublished data ) and it is here considered to be cryptogenic in the U.K. The records presented here from 2015 and 2016 are the first from Orkney .