Native and Invasive Freshwater Decapods in the UK: Conservation and Impacts Paula Joy Rosewarne Submitted in accordance with the requirements for the degree of Doctor of Philosophy The University of Leeds School of Biology September 2013 ii The candidate confirms that the work submitted is her own, except where work which has formed part of jointly authored publications has been included. The contribution of the candidate and the other authors to this work has been explicitly indicated below. The candidate confirms that appropriate credit has been given within the thesis where reference has been made to the work of others. This copy has been supplied on the understanding that it is copyright material and that no quotation from the thesis may be published without proper acknowledgement © 2013 The University of Leeds and Paula Rosewarne iii Chapter Four is based on a jointly authored publication: Rosewarne, P.J., Mortimer, R.J.G. & Dunn, A. M. (2013) Size-dependent impacts of the endangered white-clawed crayfish (Austropotamobius pallipes) (Lereboullet) on the littoral community, Knowledge and Management of Aquatic Ecosystems, 409, 06, p.1-10 P. Rosewarne formulated the idea, conducted the experiment, analysed the data and wrote the manuscript. A. Dunn and R. Mortimer supervised the research and contributed to writing the manuscript. Chapter Five is based on a jointly authored publication: Rosewarne, P., Mortimer, R. & Dunn, A. (2012) Branchiobdellidan infestation on endangered white-clawed crayfish (Austropotamobius pallipes) in the UK. Parasitology, 139, p.774-780. P. Rosewarne collected the data, analysed the data and co-wrote the manuscript. A. Dunn formulated the idea, provided research supervision, advised on data analysis and co-wrote the manuscript. R. Mortimer provided research supervision and contributed to writing the manuscript. Chapter Six is based on a jointly authored publication: Rosewarne, P., Svendsen, J. C., Mortimer, R. & Dunn, A. (in press) Muddied waters: suspended sediment impacts on gill structure and aerobic scope in an endangered native and an invasive freshwater crayfish. Hydrobiologia. P. Rosewarne formulated the idea, collected the data, analysed the data and wrote the manuscript. J. C Svendsen advised on study design, data collection, and data analysis, and commented on initial drafts of the manuscript. A. Dunn and R. Mortimer supervised the research and contributed to writing the manuscript. iv Professional Acknowledgments I sincerely thank my many collaborators who have always been generous with their time, knowledge and equipment. Research supervision for all the work presented in this thesis was provided by Dr Alison Dunn (AD) and Professor Robert Mortimer (RM). Additional supervision for Chapter Three was provided by Bobbie Millar. The specific contributions of others to each chapter are summarised below: Chapter Two: AD and RM provided feedback on initial drafts Chapter Three: Bobbie Millar, AD and RM assisted in idea formulation and provided feedback on initial drafts. Case partners Lafarge-Tarmac provided research support and background information. Graeme Smart (GSL Ecological Consultants) carried out the restoration work, crayfish translocation and post-translocation crayfish trapping. Emma Pickering, Neal Haddaway, Lucy Anderson, Nigel Taylor and Adam Piper assisted with fieldwork. Samuel Allshorn provided technical assistance. Chapter Four: AD and RM provided feedback on initial drafts. Emma Pickering, Chris Wright, Neal Haddaway, Fiona Reynolds, and Adam Piper assisted with fieldwork. Samuel Allshorn provided technical assistance. Chapter Five: AD formulated the idea, advised on data analysis and advised on writing. RM provided feedback on initial drafts. Chapter Six: Jon Svendsen provided loan of the respirometry equipment, advised on data collection methods and analyses, and provided feedback on initial drafts. AD and RM advised on experimental design and provided feedback on initial drafts. Chapter Seven: Chris Wing and Chris Grocock assisted with data collection. AD advised on experimental design, data analysis and writing. Rachel Paterson advised on analysis of functional response data. RM and Robert Newton provided advice and assistance with stable isotope work. Samuel Allshorn provided technical assistance. Chapter Eight: Adam Piper designed the telemetry antennas and assisted with fieldwork. Ros Wright provided research support. AD and RM advised on experimental design. AD provided feedback on initial drafts. I thank the Natural Environment Research Council and Case-partners Lafarge Tarmac for funding this work. I also thank Lafarge Tarmac, in particular Nick Beale and the staff at v Swinden Quarry, for their practical help and enthusiastic support. Thanks also to Dan Hayter and Ben Norrington at the Environment Agency for assistance with field sampling. Personal Acknowledgements I thank Alison Dunn for providing the bulk of my research supervision and for generously inputting your knowledge and time over the course of my PhD; your positivity, realism and sense of humour are hugely appreciated. I also thank my co-supervisor Rob Mortimer for his sound scientific and common sense advice; and for being immensely efficient at answering emails - it really helps. To all the Dunn lab group members, past and present, you have helped make my time in Leeds sociable, fun, productive and rewarding. I owe particular thanks to Katie Arundell, Freya (Asa) Johannesen, Lucy Anderson, and Neal Haddaway, with whom I have shared much of this journey. I thank all my family and friends for their part in helping me reach this goal. Particular thanks to Carol Rosewarne for sharing her home and lovely cooking, and to Vicki Stratton and Vicky Lacey for assistance with proof-reading. Finally, a huge ‘thank you’ to Adam Piper for his practical help and advice and, most importantly, his unwavering support and encouragement throughout our ‘PhD Years’. vi Abstract Crayfish species have been translocated by humans, with both positive and negative consequences. Conservation-led translocations of the endangered white-clawed crayfish (Austropotamobius pallipes) to safe ‘Ark sites’ where threats are minimised are underway. Restored quarries may represent ideal Ark sites and several questions pertaining to their suitability were addressed, along with a 3-year case study of Ark site creation in a limestone quarry. Quarries contain large quantities of unconsolidated sediment and crayfish experienced gill fouling and reduced aerobic scope after exposure to suspended solids concentrations of 62 mg L-1 and above. A novel parasite detected in the gills of A. pallipes caused gill pathology, highlighting the need for health assessment of donor stock prior to translocation. Most Ark sites do not historically hold crayfish and their introduction may cause strong effects on existing freshwater communities. In a mesocosm study, juvenile and adult A. pallipes reduced the abundances of grazers and shredders; however consumption of the gastropod Physa fontinalis and detritus varied between life-stages. The American signal crayfish (Pacifastacus leniusculus) is rapidly invading catchments and replacing A. pallipes. In a field-based telemetry study, a flow-gauging weir reduced upstream movements of P. leniusculus by 45%, highlighting the need to balance invasion risk with EU targets for improved riverine connectivity. P. leniusculus co-occurs with another invasive decapod, the Chinese mitten crab (Eriocheir sinensis), and their feeding behaviour was compared. Both consumed a range of prey items, including fish eggs. Juvenile E. sinensis had a higher per capita intake of the keystone shredder Gammarus pulex than native A. pallipes and showed greater preference for this prey item than did P. leniusculus. Overall, E. sinensis is likely to have an equal, if not higher, per capita impact on prey species than P. leniusculus. Recommendations for quarry Ark site creation and management of invasive decapods were formulated. vii Table of Contents Abstract ................................................................................................................................ vii List of Figures ..................................................................................................................... xiii List of Tables ...................................................................................................................... xvii Chapter 1 General Introduction ............................................................................................... 1 1.1. Freshwater Crayfish ..................................................................................................... 1 1.1.1 Morphology and Life History ................................................................................ 2 1.1.2. Crayfish as components of freshwater ecosystems ............................................... 5 1.1.3 Crayfish and humans .............................................................................................. 8 1.2. The white-clawed crayfish, a species in decline .......................................................... 8 1.3 Translocation for conservation .................................................................................... 10 1.4 Ark sites for white-clawed crayfish ............................................................................ 12 1.4.1. Ark site selection ................................................................................................. 12 1.4.2 Former