Hidden costs of environmental pollutants: functional impacts on host-pathogen interactions

When predicting biological responses to global pollutants one of the greatest challenges is the potential of non-additive interactions between abiotic and biotic stressors. This is especially important in relation to chemical pollutants, one of the planetary boundaries that has yet to be reliably quantified. Freshwater habitats are recognised as the most affected global ecosystems by anthropogenic pollution. Indeed, freshwater fish face higher extinction rates than any other vertebrate group, and increasingly anthropogenic contaminants are implicated in this species loss. At the same time fish are highly vulnerable to infectious disease and the emerging threats of climate change. Parasites that cause infectious diseases comprise the dominant biomass within freshwaters and have the potential to influence any life-history trait (from metabolism to mortality) of individual hosts leading to population level effects. Parasites also represent the most significant threat to the sustainability and continued growth of aquaculture.
As wild and farmed fish stocks face a multiple of anthropogenic stressors, it is essential that fish managers and the aquaculture industry understand how current and developing fish maintenance and production will respond to interactions between existing and impending stressors. Whilst the cumulative effects of multiple stressors may result in predictable additive responses, interactive effects of multiple stressors may drive complex synergisms (amplified effects) or antagonisms (reduced effects) that create "ecological surprises". Understanding how multiple stressor interactions impact individual parasite fitness is essential for identifying underlying drivers of fish-parasite interactions, but also for understanding the wider ecosystem level impacts of such pollution.
Using the established stickleback-Gyrodactylus system, this studentship addresses knowledge gaps in the multi-stressor impacts of recalcitrant pollutants (microplastics, fibres, herbicides and antiparasitic treatments) on host-pathogen dynamics and food chain resilience. Specifically, they will: (i) investigate the interactions between pollutants (individually and combination) on host-pathogen-microbiome dynamics (behaviour, metabolism, transcriptomics, disease); (ii) assess the impact of environmentally polluted food chains on host-pathogen dynamics (for instance, how is fish resistance to infection impacted if they ingest Daphnia contaminated with microplastics); and (iii) working with our industrial stakeholder (BAM Bamboo Company) assess the impact of alternative plastic and fibre products to determine whether these also impact fish immunity and disease susceptibility.
The student will be based in Cable's research lab (currently two PDRAs, one technician and nine PhD students), attending weekly supervisory meetings (with Exeter and Cefas supervisors linked remotely) and fortnightly lab meetings. Kille's research group will provide ecotoxicology expertise. The co-designed project means that the student will spend at least three months in Cefas (Weymouth) analysing bioinformatic data but also getting to know their larger cohort of (currently 80) PhD students who are based around the UK - they will also present their work each year at the annual Cefas PhD conference (held in Weymouth or Lowestoft) and give presentations to BAM Bamboo. In addition, the student will make regular visits to Wilson's lab - where they will be trained in physiology. CO2 levels in aquaculture facilities have been largely ignored despite having well controlled O2 levels. This is due to basic physicochemical properties meaning it is much more difficult to remove CO2 than it is to replace O2. High levels of CO2 encountered in aquaculture, however, do affect animal health and behaviour so controlling this, and other standard, environmental variables is critical for all our pollutant trials.