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Daniel Chadwick



Department of Geography 
University College London
Pearson Building
Gower Street





Dr. Carl Sayer (UCL)
Dr. Michael Chadwick (KCL)
Dr. Jan Axmacher (UCL)

Paul Bradley (Director, PBA Applied Ecology)

Current research

Conservation of the white-clawed crayfish Austropotamobius pallipes in the face of invasive non-native species pressures

Great Britain has one native crayfish species, the white-clawed crayfish Austropotamobius pallipes. A. pallipes has undergone extreme population declines since the 1970s, due in part to habitat degradation and pollution, but more recently to the invasive signal crayfish Pacifastacus leniusculus and the associated fungal pathogen Aphanomyces astaci, or ’Crayfish Plague’. The widespread biosecurity concerns posed by signal crayfish have influenced the strategies needed to conserve the remaining populations.

An important potential conservation strategy for white-clawed crayfish is the use of ark sites. Ark sites allow for the establishment of self-sustaining bio-secure white-clawed crayfish populations, isolated from signal crayfish. The initial establishment of ark sites has critically supported A. pallipes conservation science, however much remains undefined about the ecological requirements for a successful ark site.

Equally researching the impacts of the invasive P. leniusculus can be crucial in understanding both species-specific and ecosystem wide consequences. Invasive non-native species are a major and direct driver of global biodiversity loss (Millennium Ecosystem Assessment, 2005), with invasive species being estimated to cost the UK £1.7 billion year-1 (Williams et al., 2010).  The impacts are anecdotally pronounced at vulnerable headwater sites, which provide key habitat for spawning fish, and often provide final within-catchment refuges for populations of A. pallipes. The comparative impact of the indigenous crayfish species (ICS) A. pallipes and non-indigenous crayfish species (NICS) P. leniusculus on native ecological communities in headwaters requires research.



Considering the need for both action promoting the native species and further understanding the invasive species threats, the aims of this thesis are:

  1. Explore the impact of P. leniusculus populations on macroinvertebrate and fish communities in headwater streams
  2. Compare the relative impacts of an ICS and a NICS in headwater systems
  3. Compare the relative accuracy of methods of population density estimates for crayfish in headwater streams
  4. Produce a systematic review of the distribution and status of current ark sites in Britain
  5. Monitor populations of A. pallipes in established ark sites to report on population health and dynamics
  6. Compare key environmental characteristics between lotic and lentic ark sites


Academic Qualifications

2014 – Present, University College London

London NERC Doctoral Training Partnership PhD Candidate


2012-2013, Kings College London

MSc Aquatic Resource Management (Distinction)

MSc Dissertation: Bank substrate and gradient preferences in Pacifastacus leniusculus


2009 - 2012, Cardiff University/Prifysgol Caerdydd

BSc (Hons) Zoology, 2(i)
BSc Dissertation: Effects of localised grazing on adjacent mycelial networks


Work Experience

  • 2013-2014 – Event Support Team & Water Quality Monitor, Thames21
  • 2013 – Student Internship, Environment Agency
  • 2013 – Assistant Estuarine Ecologist, SC2



Peer-Reviewed Publications

A'Bear, A.D., Crowther, T.W., Ashfield, R., Chadwick, D.D.A., Dempsey, J., Meletiou, L., Rees, C.L., Jones, T. H., Boddy, L. (2013). Localised invertebrate grazing moderates the effect of warming on competitive fungal interactions Fungal Ecology6 (2), 137-140. doi: 10.1016/j.funeco.2013.01.001

Selected Conference Presentations

Impact of signal crayfish in headwater streams, D. Chadwick & L. Eagle, National Crayfish Conference, Giggleswick N. Yorkshire, 17th to 19th August, 2015

Impacts of ICS and NICS on fish and invertebrate communities in headwater streams, D. Chadwick & L. Eagle, Ninth Malham Tarn Research Seminar, 6th to 8th November, 2015