Urban River Pollutants Impact Wild Bird Development and Health

It turns out that river pollutants found in urban areas may be doing more than impacting the water. Scientists have discovered that hormone disrupting pollutants are affecting the health and development of wild birds nesting along the urban rivers of South Wales.

Urban pollution has long been known to affect waterways and wildlife. PCBs (polychlorinated biphenyls) and PBDEs (polybrominated diphenyl ethers) in particular can act as hormone disruptors. Many species acquire these chemicals through the food that they eat.

In order to see how birds might be impacted, the researchers examined the health and development of wild birds nesting along urban rivers. They found that there was a strong correlation between contamination by PBDEs and PCBs with depressed thyroid hormone levels in chicks; in fact, one thyroid hormone was 43 percent lower in chicks from urban rivers than those from rural rivers.

"Our findings are important in showing that pollutants are still a source of concern for the wildlife along Britain's urban rivers despite very major recovery from the gross pollution problems of the past," said Steve Ormerod, one of the researchers, in a news release. "Wild birds, such as Dippers, are very important indicators of environmental well-being and food-web contamination, and we need ot know if populations, other species-or even people-are also at risk."

So how exactly do the chemicals impact Dippers? The researchers found that wild birds along urban rivers were underweight compared to their rural counterparts. In addition, birds nesting in urban rivers had altered hormone levels and hatched fewer female chicks.

The effects of thyroid hormone disruptors on birds can include impaired growth, cognitive dysfunction, compromised immune function, changes in motor activity, and behavioral abnormalities. Needless to say, this can greatly impact the overall health of a population of birds.

The findings reveal that while steps have been taken to clean up rivers, a lot more still needs to be done. Dippers are good indicators of the state of rivers, so learning about their health can help scientists determine what needs to be done in order to continue river improvement.

The findings are published in the journal Environmental Toxicology and Chemistry.