With springtime come allergies. And as noses start to run, many of us use antihistamines to dry up nasal passages. Unfortunately, many of those antihistamines eventually pass into rivers and streams, where they are harming wildlife.
Research at the Cary Institute of Ecosystem Studies in Millbrook, N.Y., shows that the common antihistamine called diphenhydramine seriously hampers algal production and microbial respiration in waterways. When it passes into a stream, it was found to reduce photosynthesis by 99 percent and also restrict respiration. Diphenhydramine caused a change in the bacterial species present in the biofilms, including an increase in a bacterial group known to degrade toxic compounds and a reduction in a group that digests compounds produced by plants and algae.
“We know that diphenhydramine is commonly found in the environment. And its effect on biofilms could have repercussions for animals in stream food webs, like insects and fish,” warns researcher Emma Rosi-Marshall. “We need additional studies looking at the concentrations that cause ecosystem disruption, and how they react with other stressors, such as excess nutrients.”
The study at Cary shows that this antihistamine is distorting the ecology of colonies of microorganisms in rivers and streams.
“We focused on the response of biofilms — which most people know as the slippery coating on stream rocks — because they’re vital to stream health. They might not look like much to the naked eye, but biofilms are complex communities composed of algae, fungi, and bacteria all living and working together. In streams, biofilms contribute to water quality by recycling nutrients and organic matter,” says Rosi-Marshall. “They’re also a major food source for invertebrates that, in turn, feed larger animals like fish.”