Effects of Diphenhydramine and Triclosan on Aquatic Biofilm Communities in Lake Wylie, South Carolina

Humans use a variety of compounds each day in products for personal health and hygiene, and these compounds can find their way into freshwater ecosystems through a variety of pathways. Although some research has been done to assess the effects of various compounds on individual species, ecologists still know very little about how they can affect aquatic assemblages and ecosystem function. We measured the effects of a commonly used pharmaceutical (diphenhydramine) as well as an antibacterial ingredient used in many personal care products (triclosan) on autotrophic and heterotrophic activity of aquatic biofilms in Lake Wylie, South Carolina. We measured gross primary production (GPP) and respiration (R) using pharmaceutical diffusing substrates that contained high and low concentrations of either diphenhydramine or triclosan. Due to high variability within treatments, there were no significant differences in gross primary production or respiration between treated and control samples for either compound. Several factors may have contributed to the lack of a treatment effect, including unexpectedly high prevalence of heterotrophic species living within the biofilms, low diffusion rates of the compounds, and decreased activity due to stress. Water samples were also taken for nutrient analysis, which suggested enrichment in Lake Wylie. Understanding how these commonly used compounds can affect ecosystem function and how they may interact with other stressors can help inform management of aquatic resources and design of wastewater treatment plants in the future