Invasive species and water resources: developing the evidence base for effective mitigation to prevent the spread of invasive non-native species through water transfer networks

Invasive Non Native  Species (INNS) cost the UK over £2bn pa and are an increasing  threat to aquatic biodiversity and ecosystems. For example, zebra mussels block pipes and reduce drinking water quality, floating pennywort clogs river intakes and increases flood risk, signal crayfish are driving the extinction of the native white clawed crayfish.

Changing climate and demography is placing increasing need on Water Service Companies (WSCs) to balance water supply and demand, hence the transfer of raw water across river and catchment basins is essential to ensuring water supplies.  Yorkshire Water (YW) is one of 26 regional and local WSCs in the UK with a statutory duty to provide a constant supply of safe drinking water. Water transfers are critical to the YW business: by balancing demand across their supply network, YW are provide 1.3 billion litres of water a day to their customers.

Accidental translocation of animals or plant fragments during water transfers can lead to the spread of INNS to new rivers or reservoirs. Critically, the likelihood of invasion of a new water body and subsequent ecological impact depends on the number of INNS individuals introduced. Hence, the aim of this studentship is to develop and test new mitigation practices to reduce the spread of INNS during bulk water transfers, focussing on key aquatic animal and plant INNS identified by the Environment Agency (EA) and the UK water industry. The student will receive interdisciplinary training in INNS biology, ecology and water engineering to develop solutions for the water industry.The outcomes of the project will protect the environment by helping water companies guard against the spread of harmful INNS and will feed into company business plans as well as future DEFRA policy and EA regulation.


A. Test potential new mitigation measures to reduce INNS density in water transfers.

    1. Changes to source water abstraction depth. INNS plants and animals live at different depths, and some INNS show daily or seasonal migration patterns in the water. The student will explore INNS distribution and compare the numbers of INNS in water sourced from different take-off depths.
    2. Timing and source of supply to bulk water transfer network. Using existing data on seasonal INNS growth and reproduction and YW INNS distribution maps, the student will test the effectiveness of avoiding affected water sources at high risk times of the yea

B. Investigate the viability of bringing existing water treatment unit processes upstream in the treatment chain from receptor to source

    1. Test the effectiveness of screening and sand filters in INNS removal and their impact on water quality and flow
    2. Test the effectiveness of chemical measures (ozone and chlorine) in killing INNS.
Zebra mussels encrust a water guage (wiki)
Zebra mussels lining a water transfer tunnel

Approach. A range of approaches will be used including GIS modelling to explore the distribution of INNS; laboratory testing of treatments to remove INNS; field based trials of methods to remove/kill INNS and monitoring.

Training. The student will be a pioneer working on one of the first projects to address this knowledge gap identified by the Environment Agency and YW. The project crosses ecological and engineering disciplines and will provide the student with the interdisicplinary training in academic and applied skills in both disciplines to inform the technological and risk based practices required to provide safe drinking water whilst reducing the ecological and economic impact of INNS. At the University of Leeds, they will be jointly supervised by Dr Alison Dunn and Professor Martin Tillotson. With AD’s research group, they will receive training in INNS ecology and in biosecurity treatments. With MT’s research group they will receive training in lab and field approaches to measure the impact of potential INNS mitigation on water quality, water flow and the security of water transfers. The CASE supervisor, YW will offer training in practical and project management skills, use of specialist equipment as well as involvement in their business planning process to understand the policy and investment implications of their work. In addition, regular meetings with the EA will provide regulatory advice and ensure results inform national policy.

Invasive Crassula blocking a trickle filter

Following induction with the CASE partner and the University, the student will undertake the Leeds NERC-DTP skills training programme in research and transferable skills.  The student will also join the Faculty of Biological Sciences post graduate induction which includes field work training, and become a member of the water@leeds Graduate School. They will undertake courses in statistics, R and GIS, which are essential training in experimental design and analysis for ecologists; first aid and water safety training; and INNS training developed by AD in collaboration with the GB Non-Native Species Secretariat.

Project specific training: ADs lab has facilities and expertise in experimental and field work on INNS biology and a track record of research into biosecurity to slow the spread of INNS.  AD will provide training in INNS biology, INNS biosecurity treatments and will provide training and supervision in lab and field based approaches to test the effectiveness of INNS mitigation techniques. The student also will join the Ecology and Evolution research group where they will interact (seminar series, workshops, social events) with ecologists working on natural and managed ecosystems.

MTs lab is based in the Public Health Laboratories in the School of Civil Engineering. The lab has access to world class analytical facilities including separate experimental areas for water, wastewater and solid waste related study, benchscale unit process replication, a Class II microbiology lab and clean room for molecular biology including PCR techniques. water@leeds (MT is Director) enjoys extensive collaboration with the UK water industry, EA and supply chain, and the student will become part of the water@leeds Graduate School (membership >185 students) which exists to promote interdisciplinary activity, scholarship and networking across Univ Leeds.

Training with Yorkshire Water This is a NERC CASE studentship with YW.  The student will spend up to 10 months embedded in the YW business, who

Invasive Crassula on reservoir shore

have extensive experience of supervising PhD students and offer a supportive environment to enabling the student to fulfil their project aims, undertake professional development and improve their career prospects. YW will enroll the student on internal training programmes on practical and project management skills, and will link the student with an industry mentor (either YW or an associated engineering company). The student will work alongside the YW Environment Assessment team as a team member. The team comprises of terrestrial and aquatic ecologists and scientists, who ensure that the companies impacts on rivers and catchments is understood and mitigated through measures such as regional scale fish and invertebrate monitoring, river restoration, NFM and habitat creation.  YW will provide access to diverse sites selected from its 116 reservoirs, major river abstraction points and water treatment works across Yorkshire. These sites include water bodies of high biodiversity and ecological importance  in the Yorkshire Dales and the Peak District, many of which are designated as SSSI or Local Wildlife Sites for their unique flora and fauna.  The company’s wide pool of reservoir and process engineers will provide practical support and specialist technical expertise and advice. It is planned the student will spend ~10 months (spread over the four years )working with YW:

Yr 1, Q1 – YW induction, H&S training, attendance at autumn water industry Catchment and Recreation conference to meet stakeholders for networking. Set up with career mentor.

Y1 Q2/3 – Specific relevant training

Yr 1 –Placement period embedded in Environment and Clean Water teams. Identification of suitable  elements  of treatment where INNS mitigation can be tested for effectiveness in laboratory conditions. Sampling of key INNS distributions (spatial and temporal sampling of zebra mussels, Crassula and other species) across relevant sources. Briefing YW support staff who will assist in sampling.

Yr 2 –INNS and water sample collection to test effectiveness of mitigation measures (Obj 1; pipe depth, timing and source of supply) on reducing INNS and on water supply. Presentation at water industry INNS forum event.

Yr 3 – Field trials with YW to test the effectiveness of water treatments on removing/killing INNS and on water supply.  Presentation at annual YW innovation dissemination event.

Impact of the project

This project is pioneering in testing mitigation and treatment of INNS for use in a large-scale, real world system.  It thus places environmental science and water engineering at the heart of responsible management of natural resources. Bringing together ecological and engineering expertise, the research will inform technology and risk based approaches required to safeguard drinking water supplies and our natural environment.  The research will lead to publications in high quality scientific journals as well as informing YW operational practice and future capital investment strategy. Through YW, the wider water industry is also expected to benefit from this research, hence impact on UK wide economy.  The results will inform EA guidance to meet regulations on INNS prevention and safe water. Societal impact includes ensuring safe water supply and benefits to biodiversity and ecosystems processes through the prevention of the spread of INNS.

Applicant Background

The student is expected to have a first degree in Biology, Ecology, Environmental Sciences, Civil Engineering (or related subjects). Preferred background includes a Masters/M Biol/M Eng in Biology, Ecology, Environmental Sciences, Civil Engineering, Engineering or related discipline.


  • L.G., DUNN, A.M., Rosewarne, P.J. & Stebbing, P.D. 2015. 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