Mercury (Hg) concentrations and stable isotope signatures in golden eagle eggs 2009-2013: a Predatory Bird Monitoring Scheme (PBMS) report

• Main Authors: Walker, L.A., Grant, H.K., Hughes, D., Lawlor, A.J., Pereira, M.G., Potter, E.D., Shore, R.F.
• Format: Report
• Language: English
• Published: NERC/Centre for Ecology & Hydrology 2015
• Subjects: Ecology and Environment; Zoology; Aquila chrysaetos; golden eagle
• Online Access: http://nora.nerc.ac.uk/id/eprint/510545/; https://nora.nerc.ac.uk/id/eprint/510545/7/N510545CR.pdf; https://wiki.ceh.ac.uk/download/attachments/134414860/PBMS_Golden_eagle_report_2013_FINAL.pdf?version=1&modificationDate=1424860901000&api=v2

The Predatory Bird Monitoring Scheme (PBMS; http://pbms.ceh.ac.uk/) is the umbrella project that encompasses the Centre for Ecology & Hydrology’s National Capability activities for contaminant monitoring and surveillance work on avian predators. The PBMS aims to detect and quantify current and emerging chemical threats to the environment and in particular to vertebrate wildlife. Mercury (Hg) is a neurotoxin and there has been global concern over its impact on humans and wildlife. It has been predicted that global Hg emissions may rise in the future because of increased coal-fired power generation, but, in 2013, the United Nations Environment Programme (UNEP) agreed The Minamata Convention on Mercury, a global treaty to protect human health and the environment from the adverse effects of mercury. An overarching aim of the convention is to control the anthropogenic releases of Hg to the environment. Therefore, long-term trends in environmental Hg concentrations are uncertain. One cost-effective means of assessing such trends is to monitor exposure in sentinel wildlife species. Golden eagles Aquila chrysaetos breed and forage in the Scottish uplands and could prove a sentinel for changing Hg deposition in upland terrestrial areas and associated wildlife exposure. We measured Hg residues in failed golden eagle eggs with the aim of providing baseline data on current levels of exposure. Specifically, we measured Hg concentrations in failed eggs laid between 2009 and 2013 in inland (> 3km from the coast) and coastal (<3 km from the coast) nests. We distinguished nests in this way because coastal nesting birds can feed on seabirds that can accumulate high levels of Hg themselves. Marine dietary Hg inputs could potentially obscure any changes in Hg accumulation associated with altered upland terrestrial Hg deposition, and so we hypothesized that only eggs from inland nests may be useful sentinels. In conjunction with Hg measurements, we examined stable isotope (SI) signatures (carbon (δ13C), nitrogen (δ15N) and ...