Actions of endocrine disrupting chemicals in seabirds

The exposure of humans and animals to endocrine disrupting chemicals (EDCs) is a global environmental problem. Increasing plastic waste in rivers and seas results in EDCs such as microplastics and plasticisers accumulating in marine habitats. Studies of the adaptations that species have evolved to cope with chronic EDC exposure, and of the population-level consequences of exposure to EDCs, are limited. Long-lived and top-level predator bird species share a similar pattern of EDC exposure to humans, making them an excellent sentinel species with which to carry out EDC exposure research.
The sentinel species that will be studied in this project is the Northern Fulmar, fulmar hereafter. The fulmar is a seabird defined by the Oslo-Paris Convention as an indicator species for plastic pollution. It is distributed mainly in subarctic regions of the Northern Hemisphere but is also found in the UK. The fulmar feeds on fish and other seafood in the open ocean. However, due to microplastic bioaccumulation in its prey, the fulmar also ingests microplastics. Concerningly, microplastics are often comprised of stiffeners such as bisphenol A, and softeners (e.g. phthalates), which are often EDCs which leach into their surroundings. Endocrine disruption by EDCs acts through epigenome modification which alters the fulmar's gene expression, causing declines in reproduction and overall health.
Long term sampling from a fulmar colony breeding on Eynhallow, Scotland has provided data over a sufficient time frame to investigate fulmar epigenetic adaptations. This population has sex-specific differences in foraging areas, likely resulting in differential microplastic exposures. This data permits individual and population-level study of fulmar epigenetic adaptations based on foraging behaviour, diet and distribution that, in turn, influence exposure to microplastics.
The project hypothesis is that microplastics produce adverse health outcomes for fulmars through epigenetic mechanisms, suggesting their potential risk to human health. The first objective is to develop a tool kit tailored to genomic analysis of the fulmar by constructing an evolutionary tree based on genome similarities and annotating the fulmar genome using bioinformatics tools. The second objective is to investigate methylation patterns and transcriptomic perturbations in the study population, linking it with phenotypic, contaminant burden, and migratory data. The final objective is to identify microplastic constituents present in study population tissues using Fourier-transform infrared spectroscopy, and linking this to methylation patterns and health outcomes.
Since the fulmar genome is sequenced, there is a foundation to develop biomarkers of exposure. Knowledge of fulmar moult patterns permits feathers to be exploited as a non-invasive sampling method. Further, due to avian red blood cells being nucleated, and the circulatory nature of blood, avian blood is an excellent surrogate tissue to assess epigenetic perturbations. Reduced representative bisulfite sequencing and transcriptomic analyses will be carried out on available tissues. Subsequent systems level modelling of the epigenome and the identification of variably expressed epiallelles will provide insights on adverse effects on bird health.
The Adverse Outcome Pathway (AOP) framework will be exploited to place these data in a context that can guide risk assessment. This tool can forecast end points of ecotoxicological processes on both individuals and populations. This will inform policy changes needed to mitigate the effects of microplastics in the marine environment and help protect the fulmar and other marine wildlife species from population declines and ecosystem disruption. Further, since the fulmar is a sentinel species, the findings can also be extrapolated to humans. Finally, as avian epigenetics is rarely studied, this project also provides a novel opportunity to investigate this branch of epigenetics.