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Birds warn of hidden pollutants in rivers

22 July 2013

Much like the miners’ canaries of yesteryear, birds are once again warning of potentially damaging substances in the former South Wales coalfield.

Whereas deep miners once carried caged canaries to warn of suffocating gases, today’s equivalent comes from detailed chemical analysis of pollutant residues in the eggs of wild birds such as the dipper. These thrush-sized birds are the world’s only song-birds to feed directly on river insects and they have proven to be excellent indicators of river health.

Research* carried by scientists at Cardiff University shows that dipper eggs along urban South Wales rivers contain some pollutants at levels, on average, over four times greater than in adjacent rural rivers and are among the highest ever found in songbirds.

The pollutants – such as PCBs and PBDEs** – can persist in the environment for long periods and are among those believed to contribute to hormonal irregularities and abnormal development in fish along with abnormal development.

Some of these pollutants are a legacy of past industrial activity but others, such as PBDEs – widely used as flame retardants in building, industrial and domestic materials – might still be increasing.

This work is important in showing that such substances can find their way into water, particularly near towns and cities, and accumulate in river wildlife.

The research was led by Dr Christy Morrissey of Cardiff School of Biosciences, and currently Assistant Professor at the University of Saskatchewan, with contributions also from the University of Exeter, the Natural Environment Research Council and Centre for Ecology and Hyodrology***.

Speaking from Canada, Dr Morrissey said: "Work over 20 years has shown that dippers are excellent pollutant indicators in both North America and Europe, but this is the first time we’ve compared rural and urban rivers – where most people live. We’re now investigating whether the compounds found at these levels might in any way affect the birds".

Prof Steve Ormerod, an expert on dippers and river pollution, added:

"The rivers of South Wales have seen major clean-up since the 1970s as sewage treatment has improved and industry has retreated. This means, paradoxically, that clean-water organisms recolonizing these rivers, such as the dipper, are being exposed to new pollution problems that are still poorly understood."

The paper is published in the leading journal "Environmental Science and Technology" and the work is funded by the Leverhulme Trust and Natural Environment Research Council.


*Morrissey, C. A., Stanton, D. W., Pereira M. Glória, Newton, J., Durance, I., Tyler, C. R. and Ormerod, S. J. (2013) Eurasian dipper eggs indicate elevated organohalogenated contaminants in urban rivers. Environmental Science and Technology

** Polychlorinated biphenyl and Polybrominated diphenyl ethers

***NERC Centre for Ecology and Hydrology, Lancaster Environment Centre, and NERC Life Science Mass Spectrometry Facility, East Kilbride.

Useful links:

Cardiff School of Biosciences
University of Saskatchewan

For further information or to arrange an interview, please contact:

Tomas Llewelyn Barrett
Public Relations
Cardiff University
Tel: 029 20 875 596
Mobile: 07950792532

Cardiff University
Cardiff University is recognised in independent government assessments as one of Britain’s leading teaching and research universities and is a member of the Russell Group of the UK’s most research intensive universities. Among its academic staff are two Nobel Laureates, including the winner of the 2007 Nobel Prize for Medicine, University Chancellor Professor Sir Martin Evans. Founded by Royal Charter in 1883, today the University combines impressive modern facilities and a dynamic approach to teaching and research. The University’s breadth of expertise encompasses: the College of Humanities and Social Sciences; the College of Biomedical and Life Sciences; and the College of Physical Sciences, along with a longstanding commitment to lifelong learning. Cardiff's three flagship Research Institutes are offering radical new approaches to neurosciences and mental health, cancer stem cells and sustainable places.