PARENT SESSION

2I - High-tiered Studies
Hall 7
8:30 AM - 12:30 PM, Monday, 28 April 2003
Chair: Streloke, M.¹, ¹
Co-chair: Schutz, R.², ²

(MO7/10) Importance of exposure duration: Responses of Daphnia magna to pulse vs. continuous exposures.

Reynaldi, Sebastián ¹, Wilson, Scott ¹, Pieters, Barry ¹, Duquesne, Sabine ², Liess, Matthias ¹, ¹ UFZ- Centre for Environmental Research, Leipzig-Halle, Germnay² Faculty of Applied Sciences, University of the West of England, Bristol, U.K.

ABSTRACT- The environmental risk assessment may be questionable if results are merely based on the effects of continuous exposures. In the field, organisms may potentially be exposed to elevated concentrations for relative short periods of time only. Therefore, it is necessary to study how and to what extent the contamination-response relationship is altered by the exposure duration. For this reason, reproduction tests with Daphnia magna were performed choosing continuous and pulse exposures of the pyrethroid insecticide fenvalerate. The results illustrated that according to the exposure duration the mortality, reproduction and individual recovery time were altered. Hence, it is suggested that such information should be included in higher-tier environmental risk assessment in order to decrease uncertainty.

Key words: concentration-response relationship, pulse exposure, high-tiered studies, environmental risk assessment