PhD Toxicity of Pollutant Mixtures and Heat Waves on Threatened Freshwater Taxa

This project is part of the NERC-funded Centre for Doctoral Training, ECOWILD.

For more details, and for a full list of projects offered under this programme, please visit: https://ecowild.site.hw.ac.uk/

Project Description

This project will comprise site selection and optimisation of techniques. For the site selection objective, the work can be split into 3 distinct sampling seasons, which will take part in the Spring of 2027, 2028 and 2029. As ponds are highly heterogenous, initially (2027), a variety of ‘reference’ pond types will be selected, with regards to pollution pressure, in order to collect baseline data on amphibian and freshwater mollusc diversity (eDNA) under ‘non-polluted’ conditions.

These ‘reference’ ponds will comprise ephemeral and permanent water bodies with assumptions for low pollution pressure estimated by surrounding land classifications (e.g., unimproved grassland, native woodland). The geographic scope of the ponds will be limited to Southern Scotland and Northern England, aligning with the location of the partner Institutes.

Moving into the second field season (2028), the site selection will be broadend to include ponds with predicted pollution pressure – confirmed via chemical analysis – with ‘polluted’ ponds matched by geography & pond type with the previously identified ‘reference’ ponds. In this second field seaosn, in addition to diversity monitoring (eDNA), biomarker responses of representative amphibians and freshwater molluscs will be carried out. In the final field season (2029), depending on the initial two field seasons, either a mesocosm approach or further site selection will be carried out, with a greater focus on either ephemeral or permanent ponds to provide more in-depth profiling for one of these broad pond types.

Outwith field sampling timeframes, laboratory analyses of eDNA and oxidative stress/deotoxification responses will be carried out in the laboratory.

What do you need to know

This exciting project aims to investigate both community and individual level responses of amphibians and freshwater molluscs (comprising the most highly threatened vertebrate and invertebrate taxa, respectively) to environmental stressors. In this project, we will work with our partners – Natural England – to identify candidate ponds by analysing data already collected as part of the National Capital Ecosystem Assessment monitoring programme (water quality, amphibian/mollusc diversity). In selected ponds, we will investigate the combined effects of pollutant mixtures and heat waves using field-based and mesocosm approaches. Responses of both communities and ecotoxicological biomarkers (e.g., oxidative stress, detoxification) to these stressors will be assessed.

What expertise and skills will the student develop?

The student will learn how to design and carry out fieldwork in ponds/wetlands, as well as biochemical (oxidative stress) and molecular skills (eDNA, real-time quantitative PCR). The supervisor team will encourage the student to communicate scientific outcomes at seminars, meetings and showcase days.
With the supervisory team across two institutes (Heriot-Watt University, UKCEH) and a governmental department (Natural England), the student will have the opportunity to harness various course offers beyond ECOWILD and expand skills according to needs and interests, e.g., science to policy dissemination, course on scientific writing, project management, R training, fieldwork first aid or data visualisation.

Why is the project novel?

Although there are good data on river water quality and how this relates to invertebrate diversity in the UK and Europe, similar data are scarce for ponds/wetlands. Similarly, there are some good data on amphibian diversity in ponds, however, individual response data for wild amphibians are scarce (as is diversity data for UK ponds/wetlands). In this project, we will add to the diversity data for ponds in the UK – aligning with nationally significant monitoring project methodology to allow comparison and incorporation between data sets – and investigate the impacts on pollutant mixtures and heat waves on these communities. Further, we will produce novel data on biomarker responses in sensitive taxa across a range of pond types, with differing stressor intensities and combinations.

What real-life challenge does it address?

Biodiversity is declining at an alarming rate, with freshwater taxa particularly impacted. These taxa are experiencing various different environmental stressor simultaneously (and sequentially), with pollution only second to habitat loss in driving observed declines. Amphibians and freshwater molluscs are at the forefront of the biodiversity crisis, together comprising the most highly threatened phyla globally (> 40% of species threatened with extinction). This project will help to shed light on the potential causes of these declines, and how ubiquitous stressors interact to drive responses in wild organisms.