Date Approved


Degree Type

Open Access Thesis

Degree Name

Master of Science (MS)

Department or School


Committee Member

Kristin Judd, Ph.D.

Committee Member

Steven Francoeur, Ph.D.

Committee Member

Daniel Clemans, Ph.D.


Pharmaceuticals and personal care products (PPCPs) are a contaminant class of worldwide concern. Their environmental omnipresence indicates they may be a potential source of global change, and ecosystem-scale impacts at non-lethal levels have not been fully explored. We used stream biofilms to assess ecosystem responses to PPCPs. Biofilms were cultivated in streams draining areas of different land use and then exposed to triclosan, diphenhydramine, and sulfamethoxazole-trimethoprim treatments. We found evidence that low levels of these PPCPs affected some, but not all, aspects of biofilm processes and bacterial community composition. Bacterial carbon uptake was reduced (p = 0.06) and we found shifts in biofilm community composition following treatments. However, maximum photosynthetic efficiency, decomposition, and microbial physiological profiles showed no significant effect of PPCPs. Still, changes in bacterial activity and composition suggest that PPCPs may act as ecological disruptors at low levels, and further research is needed to assess ecosystem-scale effects.