PARENT SESSION
20 - Ecological Modelling in Exposure and Effect Assessment
8:00 AM to 6:30 PM, Monday, 13 May 2002
Strauss A & B

(20-02) Reproductive impairments in marine species exposed to produced water-based components: input to DREAM effect model.

BAUSSANT, Thierry^*,1, BECHMANN, Renee Katrin¹, TABAN, Ingrid Christin¹, BRACCO, Laura², SKADSHEIM, Arnfinn¹, BJRNSTAD, Anne¹, SANNI, Steinar³, SMITH, Mathijs⁴, KARMAN, Chris⁴, ¹ RF - Rogaland Research, postboks 8046, Stavanger, NORWAY² ENI Agip Division, San Donato, Milano, ITALY³ Akvamiljo as, Mekjarvik 12, Randaberg, NORWAY⁴ TNO, P.O. Box 157, Den Helder, THE NETHERLANDS

ABSTRACT- Produced water discharges require an evaluation of the environmental risk for marine biota. The conventional PEC/PNEC approach provides a likelihood of effects to individual chemicals but currently lacks for a full quantification of the environmental risk. DREAM has been developed based on the DEBtox theory of Kooijman and Bedaux (1996) to provide a more realistic risk assessment effect model. The model is based on mechanistic toxicological processes integrating important biological events and allows for time variable chronic exposures of complex mixtures. In this study, long-term exposures of produced water-based components to zooplankton and fish were carried out to provide the necessary data to the effect model in DREAM. Deviations from the expected sigmoid-shaped dose-response were observed in both organisms. They are exemplified with the egg production parameter. Stimulation or reduction were observed at low doses whilst reduction occurred at higher doses, close to the acute toxicity level. The ecological consequences of these disturbances in the low dose range are not well understood but deserve a further evaluation of the role they play in organisms life. These data were used to modify DREAM in order to integrate these complex relationships. The U-shaped type dose-response reported here is not a completely unprecedented phenomenon. Yet, these data illustrate the need to consider both dose and time in environmental risk assessment and raise important questions for the detection of threshold effect levels.

Key words: Reproductive impairments, Produced water, Effect model, DREAM