Along the formerly heavily polluted rivers of South Wales, the same team showed previously how urban Dippers are exposed to a complex mix of chemical contaminants and dominantly, PCBs and PBDEs. Given the sensitivity of the endocrine system responsible for controlling thyroid and other hormones researchers have recognised that alterations in thyroid hormone levels are an important predictor in pollution-induced developmental effects in animals.
The effects of thyroid hormone disruptors on birds are diverse but frequently include impaired growth; cognitive dysfunction; compromised immune function changes in motor activity; and behavioural abnormalities that can persist into adulthood.
As top predators, Dippers are valuable monitors of river pollution that can help assess whether urban contaminants are influencing wildlife reproduction and development. Given the latest findings, scientists are now planning to examine whether effects on dipper sex ratios and thyroid hormones have consequences on individual survival and fitness which could alter wider population dynamics. They also plan to locate the exact sources of the pollution.
Commenting on the research findings, the RSPB's Futurescape Officer John Clark said: "The return of Dippers to urban rivers is a fantastic outcome of pollution reduction in the UK. However, this study highlights the importance of birds as an indicator that some pollutants still persist in our rivers at harmful levels. We need to work in partnership with water companies, regulators, statutory agencies and communities at a catchment scale to address those practices that continue to introduce damaging chemicals to our ri
|Contact: Steve Ormerod|