Uptake of chemicals from legacy waste sites in coastal food webs and effects on higher predators

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Disused waste disposal sites (e.g. historic landfills, mining, coal gasification and fly ash spoil sites and 'night soil' disposal areas) may be important sources of legacy (e.g. metals, persistent organic compounds, biocides) and emerging (e.g. pharmaceuticals, personal care products, transformation products and micro and nano-polymers) pollutants into coastal environments. The occurrence of these pollutants in water and sediment compartments can result in the entry of a mixture of toxicants into aquatic food chains. Exposure to combinations of chemicals released from legacy waste sites could lead to demographic impacts on higher predators of high conservation concern, such as seabirds, that could affect population resilience. A spatial explicit exposure assessment framework that establishes the importance of disused waste sites as a source of exposure and risk for multiple pollutants through coastal food chains is therefore needed to support management decisions for legacy waste sites close to protected habitats and vulnerable wildlife populations. In this project, we will develop and test a food web exposure and risk assessment modelling framework for legacy waste site-derived pollutants. We will combine historic analyses of waste disposal practices with environmental monitoring, advanced analytical chemistry and food chain and hazard assessments to establish the transfer of waste site derived chemical contaminants through coastal marine food chains and the impacts of these exposures for seabird populations. The potential for our approach to estimate exposure and effects will be assessed by directly monitoring the demography and physiological status of a higher predator bird species, the European shag. European shags are an excellent choice for these studies because their coastal feeding habits may lead to high exposure to contaminated moving from legacy sites on land into the sea. Further, their ability to excrete some types of organic contaminants is potentially limited, as indicated by past work that has shown this species to have to some of the highest loading of any seabird species for persistent organic pollutants. We will develop, parameterise and test our exposure and risk models for colonies in the Firth of Forth, an area with a high density of legacy waste sites that is also a proposed Special Protection Area for seabirds. We will monitor individual shags at colonies with potentially high exposure (close proximity to multiple waste sites - Inchkeith to the West) and moderate exposure (fewer proximal sites - Isle of May to the East). Within colonies, we will study separate groups of birds displaying contrasting migratory habits. Some remain in the Firth of Forth all year round, while others head to the North Aberdeenshire coast outside of the breeding season (an area with few legacy waste sites, and hence potentially low exposure). By measuring the demography and physiology of individuals from different colonies and with different migratory patterns, we can compare how well our modelling framework predicts exposure and potential risk under different exposure scenarios. Throughout the project, we will work with key stakeholders from the policy, regulatory, industry and NGO sectors to explore how to use our models alongside existing regulatory regimes to mitigate any identified adverse impacts on coastal waste sites on wildlife populations. Our approach will be transferable to other coastal regions in the UK and beyond.