PRIORITISING THE MANAGEMENT OF INVASIVE NON-NATIVE SPECIES Olaf Booy Thesis submitted to the School of Natural and Environmental Sciences in fulfilment for the requirements of the degree of Doctor of Philosophy Newcastle University October 2019 Abstract Invasive non-native species (INNS) are a global threat to economies and biodiversity. With large numbers of species and limited resources, their management must be carefully prioritised; yet agreed methods to support prioritisation are lacking. Here, methods to support prioritisation based on species impacts, pathways of introduction and management feasibility were developed and tested. Results provide, for the first time, a comprehensive list of INNS in Great Britain (GB) based on the severity of their biodiversity impacts. This revealed that established vertebrates, aquatic species and non-European species caused greater impacts than other groups. These high impact groups increased as a proportion of all non-native species over time; yet overall the proportion of INNS in GB decreased. This was likely the result of lag in the detection of impact, suggesting that GB is suffering from invasion debt. Testing methods for ranking the importance of introduction pathways showed that methods incorporating impact, uncertainty and temporal trend performed better than methods based on counts of all species. Eradicating new and emerging species is one of the most effective management responses; however, practical methods to prioritise species based both on their risk and the feasibility of their eradication are lacking. A novel risk management method was developed and applied in GB and the EU to identify not only priority species for eradication and contingency planning, but also prevention and long term management. In this way, long lists of species were reduced to management focussed short lists that provided better cost- benefit than risk assessment alone. These pathway ranking and species prioritisation methods complement risk assessment and horizon scanning tools within a wider risk analysis framework for prioritisation. While applied here to identify management priorities in GB and the EU, they are flexible and could help prioritise INNS management at local, national and international scales. i Dedication To my grandparents, Phyllis Elizabeth Christina Harrison (née Haydon) and Ivan Redvars Harrison, who inspired my interest in ecology and started me on this PhD. ii Acknowledgements Thanks to Aileen Mill, Niall Moore, Peter Robertson and Helen Roy, who must be one of the best supervising teams it is possible to have. They provided exactly the right balance of inspiration, drive, support and critique that was needed to complete this research. From laughs while drinking Eurostar champagne to impromptu ‘educational’ trips to the Harry Potter studios, it has been a fantastic experience. I have also been fortunate to work with inspiring ecologists and invasive species experts from across GB and (the rest of) the EU as part of this work, all of whom provided great camaraderie as well as contributions. They are too numerous to mention, but are listed in the Appendices of this thesis. My thanks to the many policy officials and others that have guided me throughout my career (also too numerous to mention) and, in particular, to the biosecurity Minister Lord Gardner of Kimble, not only for being an unceasing champion of this area, but for his considerable support. It is because of an extensive range of recorders, researchers and citizen scientists that we have the GB Non-native Species Information Portal, which is funded by Defra and run by an excellent team at CEH with support from partners at the MBA, BSBI and BTO. I am grateful to them all, in particular to Steph Rorke and Colin Harrower who kindly helped with data management and extraction, as well as providing guidance on pathway classification. To the team at APHA, who not only funded this PhD, but have been incredibly understanding throughout, I am extremely grateful. In particular, thanks to Lucy Cornwell for being so supportive (‘I’m sure everything will be fine’), Linda Raine for generally sorting me out through my many scrapes and Jill Key for her tales from the Overseas Territories. While in Newcastle I have met some truly excellent people, including Matt Grainger and Gav Stewart, who helped me with my Bayesian statistics; Jess Ward, who handled much of the organisation for the EU workshop, despite Pete and my best efforts to thwart her; Mark Shirley, who taught me all I know about R … ; Kirsty Lees, who gave me at least two colds; and the irrepressible Steve Rushton, s’il vous plait. I am extremely thankful to have an incredible family (thanks mum, dad, Haydon, Dylan and all the rest of the Booy’s and Blake’s) who have put up with my PhD moaning, often while on holiday, and coming home at all hours after long shifts at the University. Most importantly, thanks to my fiancé Dominic Blake who has supported me through it all, though I am never sure he realises what a difference he makes. No more big projects, I promise*. iii * (I do not promise) iv Declaration The analysis in Chapters 2 and 3 utilised data held by the Non-native Species Information Portal (NNSIP) project, based at the Centre for Ecology and Hydrology and funded by Defra. This database has been collated by a wide range of experts and has benefited from extensive volunteer input across Great Britain (Roy et al., 2014c, Roy et al., 2015c). The expert elicitation methods used in Chapters 2, 4 and 5 utilised the knowledge and experience of a wide range of experts (n=93), all of whom are listed in the appendices to this thesis (Appendix A, E and F). Jess Ward helped to collect data and organise the experts involved in the EU risk management workshop (Chapter 5), which I co-facilitated with Piero Genovesi. Matt Grainger helped me to produce Figure 2.2. Chapter 4 has been published as Booy, O., A. C. Mill, H. E. Roy, A. Hiley, N. Moore, P. Robertson, S. Baker, M. Brazier, M. Bue, R. Bullock, S. Campbell, D. Eyre, J. Foster, M. Hatton-Ellis, J. Long, C. Macadam, C. Morrison-Bell, J. Mumford, J. Newman, D. Parrott, R. Payne, T. Renals, E. Rodgers, M. Spencer, P. Stebbing, M. Sutton-Croft, K. J. Walker, A. Ward, S. Whittaker and G. Wyn (2017). "Risk management to prioritise the eradication of new and emerging invasive non-native species." Biological Invasions 19(8): 2401-2417. I devised, led and completed this work. All co-authors provided individual risk management scores and comments on the draft manuscript. Chapter 5 is in preparation for being published. With support from my supervisorial team, all other work was done by Olaf Booy. v Table of Contents Abstract ....................................................................................................................................... i Dedication .................................................................................................................................. ii Acknowledgements ................................................................................................................... iii Declaration ................................................................................................................................. v Table of Contents ...................................................................................................................... vi List of Tables ............................................................................................................................ ix List of Figures ............................................................................................................................ x List of Boxes ............................................................................................................................. xi Chapter 1. Introduction ............................................................................................................ 13 1.1 Thesis aim.................................................................................................................. 18 1.2 Thesis outline ............................................................................................................ 19 Chapter 2. Comprehensive biodiversity impact scores reveal taxonomic, environmental, geographic and temporal patterns of invasiveness in Great Britain ......................................... 21 2.1 Introduction ............................................................................................................... 21 2.2 Methods ..................................................................................................................... 25 2.2.1 Species selection and screening ......................................................................... 25 2.2.2 Criteria for scoring impact ................................................................................ 26 2.2.3 Expert elicitation and consensus building ......................................................... 27 2.3 Analysis ..................................................................................................................... 29 2.3.1 Taxa, environment, functional group, native origin and impact ....................... 29 2.3.2 Changes in the number of invasive and ‘non-invasive’ species overtime.......... 30 2.3.3 Changes in taxa, environment and native origin over time ............................... 31 2.4 Results ......................................................................................................................