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In northern Europe otters are top predators of river food chains. Levels of pollutants in otter tissues can be a useful indicator of pollution in the environment in which it feeds.

Emerging contaminants

New chemical threats to wildlife and human health will be quantified and the main drivers will be identified, in collaboration with Centre for Ecology and Hydrology. These results will be used to:

  • produce risk maps for exposure across the UK
  • identify what actions might be taken to reduce risk. 

For example, with an increasing and ageing human population, the discharge into the environment of pharmaceuticals is now recognised as one of the top issues of global conservation concern.

Polychlorinated biphenyls and organochlorine pesticides

Aquatic contamination has been suggested as the primary cause of catastrophic otter population declines across their Eurasian range in the 1950s-1970s. Legislative controls have led to a gradual improvement in water quality, and populations are now recovering. 

In collaboration with the UK Environment Agency, our archive of liver samples was screened for a range of contaminants (e.g. Polychlorinated biphenyls (PCBs) and organochlorine (OCs) pesticides) between 1992 and 2010. 

A report completed in 2012 updates this analysis, and reveals declines in the majority of contaminants. Following this, CHEMTrust funded analysis to determine whether there were any associations between these contaminant data, and potential indicators of otter health (Kean et al 2013). The majority of health indicators examined (11/17) show some association with concentration of at least one of the measured persistent organic pollutants (POPs), but trends vary between pollutants and between subgroups of the otter population.

Inorganic elements

Ongoing screening for inorganic elements is conducted in collaboration with the Predatory Bird Monitoring Scheme (Richard Shore and Lee Walker, based at CEH Lancaster). Liver samples from otters found in 2007-2009 have been analysed for a suite of heavy metals (Walker et al. 2011) and analysis of samples from 2010 is underway. Recent research (with Vic Simpson, Wildlife Veterinary Investigation Centre, Cornwall) measured lead (Pb) levels in otter bone, and revealed a marked decline between 1992 and 2004, following legislative controls on Pb emissions. Spatial variation in bone Pb was positively correlated with modelled Pb emissions and stream sediment Pb, which interacted negatively with wind-speed and sediment Ca, respectively (Chadwick et al. 2011).