PARENT SESSION
1C Ecologically relevant and cost-effective toxicity test designs
9:00 AM to 7:00 PM, Monday, 07 May 2001

(M/EH030) Effects of storage method and duration on the toxicity of marine sediments.

Geffard, Olivier¹, His, Edouard¹, Budzinski, Hélène², Seaman, Matthias³, Garrigues, Philippe², ^{1 2 3}

ABSTRACT- Accurate evaluation of sediment toxicity in bioassays with test organisms requires a previous assessment of the effects of sediment storage.Therefore, we investigated storage effects on the toxicity of marine sediments to embryos and larvae of oysters, Crassostrea gigas. We compared three sediment treatments (fresh, frozen and freeze-dried sediment) and four storage periods (2, 15, 60 and 120 days) for three different sediment types (contaminated by heavy metals, by polyaromatic hydrocarbons-PAH, and by both pollutants). In each case, the toxicity was assessed using whole sediment and elutriate. Preservation by freezing and freeze-drying considerably increased the toxicity of whole sediments and elutriates, compared to fresh sediment. The duration of storage only affected the toxicity of elutriates obtained from fresh sediments that had been kept at 4°C. Their toxicity increased with increasing duration of storage, and it was correlated to the levels of ammonia (NH₄) present in the elutriates.

Key words: sediment storage, toxicity, embryos and larvae , Crassostrea gigas