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In urban streams, pharmaceutical pollution is driving microbial resistance

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Resilient bacteria might help streams but could threaten human health

(Millbrook, NY) In urban streams, persistent pharmaceutical pollution can cause aquatic microbial communities to become resistant to drugs. So reports a new study published today in the journal Ecosphere

Emma Rosi, an aquatic ecologist at the Cary Institute of Ecosystem Studies and lead author on the study explains, "Wastewater treatment facilities are not equipped to remove many pharmaceutical compounds. We were interested in how stream microorganisms - which perform key ecosystem services like removing nutrients and breaking down leaf litter - respond to pharmaceutical pollution." 

Researchers evaluated the presence of pharmaceuticals - including painkillers, stimulants, antihistamines, and antibiotics - in four streams in Baltimore, Maryland. Then they measured the microbial response to drug exposure. Study sites were selected to represent a gradient of development, from suburban to urban.

Microorganisms like bacteria and algae grow in complex assemblages called biofilms - the slimy coatings found on rocks in streambeds. These taxonomically diverse communities are essential to maintaining freshwater health. They drive nutrient cycling, break down contaminants, and form the base of the stream food web.

Rosi notes, "Different types of microbes can withstand different types and concentrations of synthetic chemicals. When we expose streams to pharmaceutical pollution, we are unwittingly altering their microbial communities. Yet little is known about what this means for ecological function and water quality."

Continue reading at Cary Institute of Ecosystem Studies.

Image Credit: Heather Bechtold