Search for a project

Invasive species: developing evidence-based conservation to control Invasive Non Native Species and to slow their spread to new areas.

Dr Alison M. Dunn (SOB), Dr Claire Quinn (SEE), Professor Bill Kunin (SoB)

Project partner(s): Yorkshire Wildlife Trust (CASE)

Contact email:

Invasive Non Native Species (INNS) are major drivers of environmental change and threaten ecosystem services, with increasing economic costs (~£1.7bn pa to GB).  Freshwaters provide key ecosystem services including fisheries and clean water for drinking, agriculture and recreation.  However, freshwaters are experiencing striking biodiversity declines that are much greater than those in terrestrial habitats, with INNS a key driver of this loss. Owing to their high connectivity and ecological sensitivity, aquatic ecosystems are disproportionately affected by INNS.  For example, zebra mussels block water pipes; New Zealand pygmy weed reduces native biodiversity and obstructs navigation and flood defenses (GB NNSS).

You will employ approaches from ecology and environmental social science to develop evidence based strategies to manage INNS, and to guard against future Invasions. You will work with  supervisors in Ecology and in Environmental Social Science, and with the Yorkshire Wildlife Trust (YWT). You will spend several months out in the field on YWT sites, investigating methods of INNS control, as well as working with staff and volunteers to explore how human attitudes and behaviour can slow the spread of INNS.

YWT is a charity working to protect and conserve Yorkshire’s wildlife. YWT cares for 104 nature reserves many of which have important freshwater habitats and include Special Areas for Conservation (SACs) and Special Protection Areas (SPAs). INNS are a huge threat to the functioning of these habitats. To meet their mission to protect and conserve wildlife, and to encourage people to rediscover and reconnect with nature, it is important that the YWT develops good strategies for controlling existing INNS and for protecting their reserves from new invasive species.  YWT have identified two key areas for research: evaluating control measures for aquatic invaders; and mapping pathways for invasion of new species to deliver improved biosecurity. 

Management of priority INNS. New Zealand pygmy weed (Crassula helmsii) is listed under Schedule 9 of the UK Wildlife and Countryside Act 1981 and on the Environment Agency’s “Top ten” INNS list. Its aggressive growth can cover the margins of ponds and lakes. At high densities, it spreads towards the centre of the lake, blocking light and oxygen needed by other plants. This in turn can reduce populations of invertebrates and fish as well as the mammals and birds which predate them. The YWT plans to trial different management options at Potterick Carr reserve, including: mechanical control, herbicides and hot foam. The PhD student will undertake a Before-After Impact-Control study to measure (i) the impact of Crassula helmsii on native diversity, (ii) the effectiveness of different treatment regimes in reducing/eliminating C. helmsii, and (iii) the recovery of native animal and plant populations following treatment.

Invasion pathways and biosecurity.  Once INNS become established it is often impractical and expensive to manage them. Our most effective response is robust biosecurity to prevent their introduction and spread.  INNS (animals, seeds or even fragments of plants that can form a new plant) may be spread through human activities including trade, transport and recreation.The YWT undertakes conservation and management programmes as well as recreational and public outreach activities. The student will work with YWT staff and volunteers to identify key invasion pathways and use these data to develop a suite of biosecurity protocols suitable to the different stakeholders (staff, volunteers, public etc) and activities (e.g. management, wildlife watches, recreation) undertaken by YWT.


1. Evaluate control measures for aquatic INNS by measuring

  • the impact of Crassula helmsii on native diversity
  • the effectiveness of different treatment regimes in reducing/eliminating C. helmsii
  • the recovery of native animal and plant populations following treatment.

2. Identify key invasion pathways and stakeholder requirements, awareness and attitudes to INNS

3. Use these data to develop a suite of biosecurity protocols suitable for different activities undertaken by YWT.

The studentship will contribute to both fundamental and applied science. The ecological studies will inform our understanding of the ecological impact of INNS, whilst the social studies will inform our understanding of human-wildlife interactions and the drivers of behavioural change. Identification and management of pathways for introduction, and management measures for established INNS are both core requirements of the recent EU legislation on Invasive Alien Species (EU 2015) and the GB Invasive Non Native Species strategy (GB NNSS 2015).  This evidence base will enable the YWT to undertake cost effective INNS control, and to deliver effective INNS biosecurity tailored to environmental risk the range of activities at their sites.


The student will develop an interdisciplinary approach. Field surveys will be used to evaluate the success and impact of INNS management. Data analysis will be in R. Mapping of invasion pathways will use existing INNS distribution data as well as quantitative (survey questionnaires) and qualitative (semi-structured interviews) social research methods to identify high risk activities and stakeholder groups. Qualitative analysis will be conducted using NVivo. By working with YWT partner from design through to output, the project will lead to improved INNS management and biosecurity across YWT reserves and will inform policy more widely throughout the wildlife trusts.

The CASE partner the YWT offers an excellent environment for applied student research leading to impact. The YWT manages 104 nature reserves and conducts a range of activities including wildlife recording, conservation and recreation. Volunteers are crucial to the work of YWT, enabling the trust to manage great swathes of Yorkshire's wild places, run projects that safeguard habitats and species for future generations and educate young and old about the wildlife. Working alongside the mixture of staff and volunteers at YWT, will enable the student to understand their roles and requirements in addressing INNS, whilst the planned management trials provide a unique opportunity to evaluate management protocols.


PhD training will be managed through the Leeds/York NERC DTP and the student will undertake the Leeds NERC-DTP PGR skills training programme in research and transferable skills which includes the PGR induction field course, a 2 week course in statistics and R; first aid and field work safety; as well as the e-learning module in Invasive Species developed by Dunn in collaboration with the GB Non-Native Species Secretariat.

Project specific training will be undertaken with the supervisors and through CASE partner placements. The student will benefit from interdisciplinary training in biological and environmental social science. This NERC CASE partnership will provide the student with experience of academic and applied environmental science and with in-depth experience of a key conservation charity, fitting them for a future career in biological, environmental or social science, conservation or policy. They will also benefit from the breadth of expertise in water@leeds, one of the largest interdisciplinary centres for water research in any university in the world. water@leeds has a track record of collaborative research and development, knowledge transfer and joint innovation. The central tenet of water@leeds is an interdisciplinary approach to understanding and solving major water issues

Dr Dunn will provide training in Invasive Non Native Species, field work and experimental design and analysis. Dr Quinn will provide training in environmental social science, specifically in the relationships of business with governance and ecosystems. As a recent NERC Knowledge Exchange fellow, CQ is ideally placed to ensure impact from the project. Ailsa Henderson (CASE partner) will provide training in the role and requirements of the Yorkshire Wildlife Trust and the wider Wildlife Trust movement.

The student will be based at the University of Leeds and will undertake placements with the CASE partner as below

Training placements with the CASE partner.

Month 2.  Two week induction at the YWT to understand organisational structure. H&S training

Months 3-6. Use existing YWT datasets to develop understanding of range of nature reserves and habitats. Use existing datasets that map current knowledge of INNS on YWT sites.

Months 6-12. Series of mapping workshops with YWT staff and volunteers across range of reserves to identify key invasion pathways and associated stakeholder network

Months 3-30. Initial survey of key sites for management and of untreated control sites, with monthly surveys to measure treatment success and impact.


  • Anderson. L.G., Dunn, A.M., Rosewarne, P.J. & Stebbing, P.D. 2015a. Invaders in hot water: a simple decontamination method to prevent the accidental spread of aquatic invasive non-native species. Biological Invasions DOI 101.007/s10530-015-0875-6

  • Anderson, L.G., White, P.C.L., Stebbing, P.D., Stentiford, G.D. & Dunn, A.M. 2014.  Biosecurity and Vector Behaviour: Evaluating the Potential Threat Posed by Anglers and Canoeists as Pathways for the Spread of Invasive Non-Native Species and Pathogens. Plos One, 9.

  • Anderson. L.G., Rocliffe, S., Haddaway, N.R., Dunn, A.M. 2015b. The Role of Tourism and Recreation in the Spread of Non-Native Species: A Systematic Review and Meta-Analysis PLOS ONE 10.

  • EU 1143/2014 

  • GB NNSS Strategy  

  • Quinn CH; Ziervogel G; Taylor A; Takama T; Thomalla F (2011) Coping with multiple stresses in rural South Africa, Ecology and Society 16: 10-10.

  • Reed MS; Kenter J; Bonn A; Broad K; Burt TP; Fazey IR; Fraser EDG; Hubacek K; Nainggolan D; Quinn CH; Stringer LC; Ravera F (2013) Participatory scenario development for environmental management: A methodological framework illustrated with experience from the UK uplands, Journal of Environmental Management 128: 345-362. doi: 10.1016/j.jenvman.2013.05.016

  • Reed MS; Graves A; Dandy N; Posthumus H; Hubacek K; Morris J; Prell C; Quinn CH; Stringer LC (2009) Who's in and why? A typology of stakeholder analysis methods for natural resource management, Journal of Environmental Management 90: 1933-1949. doi: 10.1016/j.jenvman.2009.01.001

Related undergraduate subjects:

  • Biology
  • Ecology
  • Environmental science
  • Zoology