December 18, 2008

Climate change slows acid rain recovery

Welsh scientists say a 25-year study suggests climate change might be hampering the recovery of Earth's rivers from the effects of acid rainfall.

The research by Cardiff University Professor Steve Ormerod and biosciences researcher Isabelle Durance was undertaken in 14 middle-Wales rivers and involved assessing the number and variety of stream insects present each year. The scientists said they also measured concentrations of acid and other aspects of stream chemistry.

With average acidity in rivers falling due to improvements in the levels of acid rain, the researchers said they had expected up to 29 insect species to have re-colonized the less acidic waters. The findings however, showed a large shortfall in biological recovery, with just four new insect species added to the recovering rivers sampled.

Since the 1970s, there have been huge efforts to cleanup sources of acid rain, and our research shows that rivers are heading in the right direction, said Ormmerod. However, our results support the theory that acid conditions during rainstorms kill sensitive animals.

The study appeared in the Dec. 12 online edition of the Journal of Applied Ecology.