PARENT SESSION
SA7 - Pharmaceuticals
Chair: Standley, Laurel¹, ¹ , Laurel, MD
8:00 AM to 12:00 PM - Sunday, 17 November 2002
Room Ballroom A

(062) Ecotoxicology of Pharmaceutical Mixtures in Aquatic Microcosms Part II: Responses of Freshwater Plankton Communities .

Wilson, Christian^*,1, Brain, Richard¹, Richards, Sean³, Johnson, David¹, Mabury, Scott², Lam, Monika², Sibley, Paul¹, Solomon, Keith¹, ¹ Centre for Toxicology, University of Guelph, Guelph, ON, Canada³ University of Tennssee at Chattanooga, Chattanooga, Tennssee, USA² University of Toronto, Toronto, ON, Canada

ABSTRACT- Complex mixtures are increasingly detected in North American surface waters. They are neither screened nor actively removed at sewage treatment plants. The effects on non-target aquatic organisms have not been characterized. In a preliminary 35-day microcosm study, effects of a mixture of 3 compounds at 4 concentrations were examined ([ciprofloxacin, fluoxetine, ibuprofen]: [0, 0, 0]; [10, 10, 6]; [100, 100, 60]; [1000, 1000, 600] g/L). Every 7 days, plankton samples were obtained from each 12000 L treatment pond. Zooplankton samples were analysed by light transmission microscopy, identifying all taxa in 3 mL aliquots. Data were normalized and further evaluated using CANOCO, a multivariate analysis tool providing Principal Response Curves (PRC). PRCs graphically describe and summarize information on communities and populations. Accompanying species weight data provides information on the contribution of various species to the PRC. The zooplankton and phytoplankton PRC showed treatment dependant response. Abundance of zooplankton increased at higher treatment concentrations while phytoplankton declined and recovered. Also, the taxonomic diversity was greatly reduced in all biota at high concentrations. Overall, community dynamics were heavily affected. Closer analysis reveals that the interaction between zooplankton and phytoplankton is important in the response of the two groups. Present studies include a complex mixture of 8 pharmaceuticals in microcosm experiments. Five treatment mixture concentrations were used ranging from 0.2 g/L to 2000 g/L. Laboratory studies using Daphnia sp. will be discussed to determine if additive synergistic responses are being observed. This is part II of a discussion on the effects of pharmaceutical mixtures.

Please note three other presentations by S.M. Richards, D.J. Johnson, and R.A. Brain; we respectfully request that all be considered for the same session.

Key words: Pharmaceuticals, microcosms, zooplankton, aquatic