PARENT SESSION

2K - Sediment Assays
Poster Hall
8:30 AM - Tuesday, 29 April 2003

(TUP/143) Sediment toxicity testing: Is the mudsnail Hydrobia ulvae a suitable candidate for LAS spiked sediment toxicity assessment ?

Hampel, Miriam¹, Moreno-Garrido, Ignacio¹, Gonzalez-Mazo, Eduardo², Blasco, Julian¹, ¹ Instituto de Ciencias Marinas de Andalucia (C.S.I.C.), Puerto Real, Cádiz, Spain² Dpto. Química-Física. Facultad de Ciencias del Mar. Universidad de Cádiz, Puerto Real, Cádiz, Spain

ABSTRACT- Two different sediment from clean sites of the Bay of Cadiz were saturated for 24 hours with commercial LAS mixture. Individuals of Hydrobia ulvae (15 males and 15 females) were exposed in triplicates during 10 days to different proportions of clean and spiked sediment, resulting in LAS exposure concentrations between 0.0 and 30.95 mgkg-1 and 0.28 and 150 mgkg-1 for sediment 1 and 2, respectively. Mortality was reported every 24 hours and obtained mortality percentages plotted versus exposure concentration for subsequent LC50 calculation. After three days of exposure, ambient temperature and photoperiod were increased slightly in order to induce pairment between the organisms. Appearing egg capsules were withdrawn daily and introduced in 3 mL of filtered seawater. After hatching, veliger larvae were counted three times and mean total offspring was calculated for each concentration. Additionally, number of larvae per egg capsule was estimated. In both sediments, 100% of mortality was reached in the two highest exposure concentrations at the end of the test. Individuals exposed to lethal concentrations avoided any contact with the sediment but emerged from the shell during the first three days when transferred into clean seawater for mortality control. Furthermore, no egg capsules were found due to the fact that the organisms had no contact between each other. At lower exposure concentrations, the individuals moved fastly, with a strong tendency to accumulate and consequently, egg capsules were found after increasing ambient temperature and photoperiod.

Key words: LAS, spiked sediment, toxicity , mudsnail