Eurasian otters (Lutra lutra) as sentinels of persistent, bioaccumulative and toxic contaminants: investigating drivers of pollution, time trends and biomagnification in freshwater ecosystems

O'Rourke, Emily 2024. Eurasian otters (Lutra lutra) as sentinels of persistent, bioaccumulative and toxic contaminants: investigating drivers of pollution, time trends and biomagnification in freshwater ecosystems. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

The dramatic decline of Eurasian otter populations in Britain and western Europe in the mid-twentieth century underscores the broader environmental crisis posed by chemical pollution. Freshwater ecosystems are among the most threatened habitats on Earth due to numerous human pressures, which include the impacts of chemical contaminants. Protecting these ecosystems from chemicals requires comprehensive pollution management strategies, stringent regulatory frameworks and effective monitoring programmes. By using Eurasian otters as sentinels, researchers and policy makers can gain valuable insights into the overall health of freshwater environments and the success of policy action and mitigation measures aimed at reducing chemical pollution. This thesis used the extensive archive of otter samples collected by Cardiff University Otter Project to demonstrate the pervasive presence of chemical contaminants in otters, and therefore the wider freshwater environment. By integrating environmental datasets with contaminant and biotic data from otters, my research has enhanced our understanding of the spatial and temporal variation of persistent chemical contaminants. Specifically, I have provided evidence that the persistent presence of PCBs in sediment sinks is significantly contributing to ongoing and increasing contamination in freshwater environments, with individuals still exposed to toxicologically significant concentrations. Quantification of both legacy and replacement PFASs in the freshwater ecosystem has allowed me to infer the main anthropogenic drivers of their spatial variation, and has identified some emerging PFASs for the first time in Eurasian otters. Lastly, I highlighted the varying spatial resolutions shown by water, fish and otter samples when measuring mercury concentrations, and evaluated the advantages and disadvantages of monitoring using abiotic and biotic samples. Overall, this thesis highlights the important role of Eurasian otters as a sentinel species. It emphasises the interconnectedness of human, animal and environmental health, and underscores the need to protect the environment from the detrimental effects of chemical contaminants.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Schools > Biosciences
Subjects:	Q Science > Q Science (General)
Date of First Compliant Deposit:	8 May 2025
Last Modified:	09 May 2025 16:03
URI:	https://orca.cardiff.ac.uk/id/eprint/178161

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