PhD Investigating the influence of particle-toxicant interactions on toxicant bioavailability and toxicity in a tropical estuarine amphipod of mangrove wetlands

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 build on our foundation of knowledge of the ecotoxicology of P. hawaiensis from the development of the model (laboratory husbandry and testing, molecular biology, pathology, and behaviour) and responses to chemical toxicants (metals, natural and anthropogenic particles, and PAHs) to incorporate the critically important aspect of substance-particle interactions and consideration of application of science in policy or conservation advice. Our focus in the laboratory will be on investigating how particles (select natural colloids, plastic particles, and engineered nanoparticles) interact with toxicants (polycyclic aromatic hydrocarbons (PAHs), dissolved metals) and influence their bioavailability via sorption/desorption reactions and the effects of changes in salinity on these processes.

Our purpose-built particle dispersion chamber enables particles to remain suspended in the aqueous phase and manipulation of toxicant concentrations, application of UV light (for photo-induction), at the same time toxicological responses are measured in model aquatic organisms. The model organism for this research is the circumtropical estuarine amphipod Parhyale hawaiensis which has emerged as a particularly useful organism for laboratory research with direct relevance to critically important aquatic ecosystems (e.g., mangrove wetlands). Bioavailability of toxicants will be assessed by a combination of methods that include changes in target gene expression, immunotoxicology (blood cells), and behavioural ecotoxicology. Opportunities will be available for field investigations to be conducted in either Brazil or Malaysia in which the project supervisors have existing research collaborations.

The student to be selected for this project will need to have some experience in both laboratory and field research with some aptitude for both molecular biology and behavioural toxicology. An interest in physical and analytical chemistry will be useful as will be an appreciation for the importance of tropical aquatic environments. The student will become part of an established international team of researchers investigating ecotoxicology of tropical aquatic ecosystems.

What do you need to know

The aquatic toxicity of substances is controlled largely by factors that influence their bioavailability and among the most important of these are interactions with particles. Toxic substances sorb and desorb to particles in the aqueous phase and undergo transformation reactions mediated by photoactivation and microbial processes. As particles with sorbed toxicants are transported to river mouths and mangrove wetlands, rapid changes in salinity can alter toxicant-particle associations and affect toxicant bioavailability. Our established tropical amphipod model Parhyale hawaiensis and purpose-built particle-toxicant dispersion test chambers enable investigations into these critically important and understudied questions of environmental toxicology. The lead supervisor has existing research projects and long-term research collaborations with colleagues working with this model organism within mangrove ecosystems, which will provide access to these sites for field investigations.

What expertise and skills will the student develop?

The student will develop expertise in particle-substance interactions, assessment of toxicant bioavailability and toxicity, and ecotoxicology methods at multiple levels of biological organization including molecular biology (gene expression analyses), tissue (histopathology), and whole organism (behavioural toxicity). The student will also be able to develop competence in physical chemistry including aqueous-phase particles and analytical chemistry. The main project supervisor has long established research collaborations with supervisor in Brazil (Prof GA Umbuzeiro) and a joint academic appointment at the University of Campinas (Campinas, Brazil), and close partnerships with colleagues in Malaysia in which some research opportunities in tropical ecotoxicology will be available.

Why is the project novel?

The importance of particle-substance interactions on the bioavailability of toxicants to aquatic organisms are recognised as among the most critical and poorly understood areas of ecotoxicology. Our previous research has demonstrated the influence aqueous-phase particles on toxicant bioavailability, toxicant decomposition, and toxicant photo-induction and degradation/decomposition. This project will employ state-of-the-art techniques to enhance understanding of particle-toxicant interactions relevant to mangrove wetlands which are among the most threatened ecosystems in the world. The project will inform ecological protection and identify areas of interest for international conventions such as Ramsar and UN Environment Programme for tackling pollution in mangroves.

What real-life challenge does it address?

Mangrove ecosystems face mounting threats from the triple planetary crises of pollution, climate change and biodiversity loss. Particle-toxicant interactions result in complex scenarios in which toxicants are transformed and traditional ecotoxicity tests that do not include the influence of particles on toxicant bioavailability have limited ability to predict toxicity. This project will move forward understanding of particle-toxicant interactions and enhance knowledge of multiple factors that affect toxicity in a critically important relevant model organism of mangrove ecosystems. Findings will inform environmental policy, enhance risk assessment frameworks, and support conservation strategies for mangroves, critical buffers against climate impacts and biodiversity decline.

Timelines

The closing date for applications is 17:00 BST Friday 9 January 2026, and applicants must be available to start in October 2026.