Honors College Theses

Publication Date



Biology (B.S.B.)

Document Type and Release Option

Thesis (restricted to Georgia Southern)

Faculty Mentor

Dr. Risa A. Cohen


Modern cleaning products containing low-toxicity surfactants such as alkylpolyglucosides (APGs) enter streams following rain events and wastewater discharge, and may ultimately affect aquatic organisms. Although APGs decreased overall phytoplankton abundance in static laboratory experiments and in pond mesocosms, APGs are more likely to enter stream systems in commercial mixtures and with other chemicals. Additionally, the effects of APG on aquatic systems vary between seasons due to the quicker degradation of the surfactant in warmer temperatures. We hypothesized that APG influences phytoplankton abundance and community composition differently alone than in a commercial product mixture, and that phytoplankton responses to APG differ across seasons. Artificial streams containing phytoplankton communities were established in a greenhouse. In winter and summer, communities were exposed to 1 or 5 mg l-1 APG, commercial product containing 1-5 mg l-1 APG, or a no-addition control. Cell density and species composition were measured after 7 days. In the winter, the commercial product decreased cell density relative to the control and 1 mg l-1 APG treatments, primarily due to loss of Navicula sp. In the summer, patterns were similar, but cells exposed to the commercial product increased before decreasing down to the initial level. These differential responses of phytoplankton communities in each season to APG alone vs. commercial product suggest the need to examine effects of other chemicals present in commercial products.